Hydrocarbon Formation and the Charge Field

Came across this article which followed up assorted research on this over various sources.  Wanted to get a post going similar to that on TB's forum just in case ideas develop around this:
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Proc Natl Acad Sci U S A. 2019 Sep 3;116(36):17666-17672. doi: 10.1073/pnas.1907871116. Epub
2019 Aug 19.

Abiotic methane synthesis and serpentinization in olivine-hosted fluid inclusions.

Klein F1, Grozeva NG2, Seewald JS3.

Author information

1 Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA 02543; fklein@whoi.edu.
2 Massachusetts Institute of Technology-Woods Hole Oceanographic Institution Joint Program in Oceanography, Cambridge, MA 02139.
3 Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA 02543.

Abstract

The conditions of methane (CH4) formation in olivine-hosted secondary fluid inclusions and their prevalence in peridotite and gabbroic rocks from a wide range of geological settings were assessed using confocal Raman spectroscopy, optical and scanning electron microscopy, electron microprobe analysis, and thermodynamic modeling. Detailed examination of 160 samples from ultraslow- to fast-spreading midocean ridges, subduction zones, and ophiolites revealed that hydrogen (H2) and CH4 formation linked to serpentinization within olivine-hosted secondary fluid inclusions is a widespread process. Fluid inclusion contents are dominated by serpentine, brucite, and magnetite, as well as CH4(g) and H2(g) in varying proportions, consistent with serpentinization under strongly reducing, closed-system conditions. Thermodynamic constraints indicate that aqueous fluids entering the upper mantle or lower oceanic crust are trapped in olivine as secondary fluid inclusions at temperatures higher than ∼400 °C. When temperatures decrease below ∼340 °C, serpentinization of olivine lining the walls of the fluid inclusions leads to a near-quantitative consumption of trapped liquid H2O. The generation of molecular H2 through precipitation of Fe(III)-rich daughter minerals results in conditions that are conducive to the reduction of inorganic carbon and the formation of CH4 Once formed, CH4(g) and H2(g) can be stored over geological timescales until extracted by dissolution or fracturing of the olivine host. Fluid inclusions represent a widespread and significant source of abiotic CH4 and H2 in submarine and subaerial vent systems on Earth, and possibly elsewhere in the solar system.

More at link with subscription: https://www.ncbi.nlm.nih.gov/pubmed/31427518

Wikipedia on the Lost City also covered in depth by NOAA:
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Geology and Chemistry

Lost City vents release methane and hydrogen into the surrounding water; they do not produce significant amounts of carbon dioxide, hydrogen sulfide or metals, which are the major outputs of volcanic black smoker vents. The temperature and pH of water surrounding the two types of vent is also significantly different.

Geology and Mineralogy

The Mid-Atlantic Ridge spreading center pulls the lithosphere apart, creating normal faults which expose sub-surface rocks to seawater.


Olivine, the mineral responsible for Lost City's serpentinization.

The Atlantis Massif is described as an ultramafic oceanic core complex of the Mid-Atlantic Ridge, with upper-mantle rock being exposed to seawater through faulting from tectonic extension associated with ocean spreading centers.[24] The spreading half-rate is approximated to about 12 mm/yr, classifying it as a slow-spreading ridge.[25] Seismic events have been detected at the massif of Richter magnitude 4 and 4.5.[13]

The dominant minerals found at Lost City are ultramafic, composed primarily of olivine and pyroxene with very little silica content. Peridotite (primarily spinel harzburgite) minerals undergo serpentinization and form magnetite and serpentine minerals.[6] Because little to no carbon dioxide or metals are released in the venting fluids, Lost City bears the appearance of a non-smoker, with few particulates to give a smokey appearance.

Once pore waters have permeated the surface and return to the surface, aragonite, brucite, and calcite chimneys as calcium carbonates precipitate out of solution.[26] Younger chimneys are primarily brucite and aragonite, being white and flaky in appearance. As vents mature, porosity decreases as precipitates clog fluid pathways. Mineral compositions change with aragonite succeeded by calcite and brucite being removed through dissolution, and the chimneys darken to a grey or brown color.[27]

On the side of the Atlantis Transform Fault, the Atlantis Massif wall terminates approximately 740 meters below sea level, where rock types deform to various mylonitic rocks with deformation fabric minerals of talc, tremolite, and ribbon serpentine.[6]

Serpentinization

Lost City is an exemplary location for the study of abiotic methanogenesis and hydrogenesis, as serpentinization reactions produce methane and hydrogen. Supplementing Fischer-Troph reactions;

   Olivine(Fe,Mg)2SiO4 + Watern·H2O + Carbon dioxideCO2 → SerpentineMg3Si2O5(OH)4 + MagnetiteFe3O4 + MethaneCH4
   

   (Methanogenesis)

   Fayalite (Olivine)3 Fe2SiO4 + water2 H2O → Magnetite2 Fe3O4 + Silica (aqueous)3 SiO2 + Hydrogen2 H2
 
   (Hydrogenesis)

The reactions are exothermic and warm surrounding waters via reaction heating, though fluid temperatures are still relatively low (40° - 90 °C) when compared to other hydrothermal systems.[28] Furthermore, pH is increased to values of over 9 which enables calcium carbonate precipitation. Since serpentinization is particularly extensive, carbon dioxide concentrations are also very low. Low temperature, carbon dioxide concentrations, combined with the low hydrogen sulfide and metal content of the plume make the vents more difficult to identify from CTD measurements or optical backscatter methods.

Biology
A visiting shark at the Lost City field.

Lost City and other vent systems support vastly different lifeforms due to Lost City's unique chemistry.

A variety of microorganisms live in, on, and around the vents. Methanosarcinales-like archaea form thick biofilms inside the vents where they subsist on hydrogen and methane; bacteria related to the Firmicutes also live inside the vents. External to the vents archaea, including the newly described ANME-1 and bacteria including proteobacteria oxidise methane and sulfur as their primary source of energy.[citation needed]

https://en.wikipedia.org/wiki/Lost_City_Hydrothermal_Field

I also came across this topic recently and have started reading "The Deep Hot Biosphere The Myth of Fossil Fuels" by: Thomas Gold. So far it seems like methane genesis is a gateway for the formation of heavier hydrocarbons and a gateway for our understanding of the processes involved since it reaches the surface more often(easily) and is easily detected/measured.

This could also align with Miles recent update (Dec 3) on the solar min. where he mentions "It means you have been like a battery on very low charge" Where these archaea and or bacteria evolved to use heat or decompose hydrocarbons for fuel. This book making the case that these organisms are a likely genesis for life on earth, We may have innate capabilities to harvest energy from the charge field. For example. the extreme energy density of the mitochondria. Comparable to the energy density of a lightning bolt and unexplained by mainstream science.

M11S wrote:I also came across this topic recently and have started reading "The Deep Hot Biosphere  The Myth of Fossil Fuels" by: Thomas Gold. So far it seems like methane genesis is a gateway for the formation of heavier hydrocarbons and a gateway for our understanding of the processes involved since it reaches the surface more often(easily) and is easily detected/measured.

This could also align with Miles recent update (Dec 3) on the solar min. where he mentions "It means you have been like a battery on very low charge" Where these archaea and or bacteria evolved to use heat or decompose hydrocarbons for fuel. This book making the case that these organisms are a likely genesis for life on earth, We may have innate capabilities to harvest energy from the charge field. For example. the extreme energy density of the mitochondria. Comparable to the energy density of a lightning bolt and unexplained by mainstream science.

Thanks MS11 this very interesting. There appears to be both natural biological processes and non-biological processes that create Hydrocarbons. The FTT (Fischer) process happening deep in the Earth as Gold has postulated is in effect. Super Critical Water (SCW) is another avenue with Olivine that needs further research.

The moon Titan with its massive Methane beds needs to be explained. This isn't "old biologically infused lakes-sea beds". Interesting that it is near poles reflecting Mathis' Charge Field channels for planets CF recycling:
https://www.astrobio.net/titan/titans-methane-cycle/
https://en.wikipedia.org/wiki/Lakes_of_Titan

"The Cassini mission affirmed the former hypothesis, although not immediately. When the probe arrived in the Saturnian system in 2004, it was hoped that hydrocarbon lakes or oceans might be detectable by reflected sunlight from the surface of any liquid bodies, but no specular reflections were initially observed.[6]

The possibility remained that liquid ethane and methane might be found on Titan's polar regions, where they were expected to be abundant and stable.[7] In Titan's south polar region, an enigmatic dark feature named Ontario Lacus was the first suspected lake identified, possibly created by clouds that are observed to cluster in the area.[8] A possible shoreline was also identified near the pole via radar imagery.[9] Following a flyby on July 22, 2006, in which the Cassini spacecraft's radar imaged the northern latitudes (which were at the time in winter), a number of large, smooth (and thus dark to radar) patches were seen dotting the surface near the pole.[10] Based on the observations, scientists announced "definitive evidence of lakes filled with methane on Saturn's moon Titan" in January 2007.[7][11] The Cassini–Huygens team concluded that the imaged features are almost certainly the long-sought hydrocarbon lakes, the first stable bodies of surface liquid found off Earth. Some appear to have channels associated with liquid and lie in topographical depressions.[7] Channels in some regions have created surprisingly little erosion, suggesting erosion on Titan is extremely slow, or some other recent phenomena may have wiped out older riverbeds and landforms.[12] Overall, the Cassini radar observations have shown that lakes cover only a few percent of the surface and are concentrated near the poles, making Titan much drier than Earth.[13] The high relative humidity of methane in Titan's lower atmosphere could be maintained by evaporation from lakes covering only 0.002–0.02% of the whole surface.[14] "

Hey guys, I'm back after a bit of a hiatus. I plan to blow this thread out with several articles. Hopefully, if Miles can help crack this nut of OG formation -- it could lead to a lot of great things. --Cr6
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Magnetite is interesting:

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Oil spill cleanup employing magnetite nanoparticles and yeast-based magnetic bionanocomposite

Author links open overlay panelKarina B.DebsaDébora S.CardonaaHeron D.T.da SilvaaNashaat N.NassarbElma N.V.M.CarrilhocPaula S.HaddadaGeórgiaLabutoa
Show more
https://doi.org/10.1016/j.jenvman.2018.09.094Get rights and content

Highlights
• A new magnetic bionanocomposite was synthetized and removed around  55  and 89% of different oils.
• The temperature is a relevant parameter on oil removal, affecting the 3 oils tested.
• The oils are different from each other, grouping themselves in distinct clusters.
• Oil removal is a physic phenomenon which can not be described as adsorption process.
• The neural networks and D-optimals models well describe the experimental data.

Abstract

Oil spill is a serious environmental concern, and alternatives to remove oils from water involving biosorbents associated to nanoparticles is an emerging subject. Magnetite nanoparticles (MNP) and yeast magnetic bionanocomposite (YB-MNP) composed by yeast biomass from the ethanol industry were produced, characterized, and tested to remove new motor oil (NMO), mixed used motor oil (MUMO) and Petroleum 28 °API (P28API) from water following the ASTM F726–12 method, which was adapted by insertion of a lyophilization step to ensure the accuracy of the gravimetric approach. Temperature, contact time, the type and the amount of the magnetic material were the parameters evaluated employing a fractional factorial design. It was observed the removal of 89.0 ± 2.6% or 3522 ± 118 g/kg (NMO) employing MNP; 69.1 ± 6.2% or 2841 ± 280 g/kg (MUMO) with YB-MNP; and 55.3 ± 8.2% or 2157 ± 281 g/kg (P28API) using MNP. The temperature was the most significant parameter in accordance with the Pareto's graphics (95% confidence) for all oil samples considered in this study as well as the two magnetic materials. Contact time and the interaction between the materials and temperature were also relevant. The D-Optimals designs showed that the NMO and P28API responded in a similar way for all evaluated parameters, while the uptake of MUMO was favored at higher temperatures. These behaviors demonstrate the influence of oil characteristics and the intermolecular forces between the oil molecules on the mechanism dragging process performed by the attraction between magnetite nanoparticles and a 0.7 T magnet. It was clear that this kind of experiment is predominantly a physic phenomenon which cannot be described as adsorption process.

https://www.sciencedirect.com/science/article/pii/S0301479718311046

After looking at various papers...I truly believe Miles' C.F. is involved directly in O&G formation and trapping.
His Salt Paper and Carbon Paper and various papers on Charge Flows through the Earth can point directly to formation characteristics? There are people starting to explore alternative ideas/physics around the formation of hydrocarbons.  

http://milesmathis.com/salt.pdf ---Salt in O/G formation with iron, carbon, olivine, heat, pressure and magnetite?
http://milesmathis.com/graphene.pdf -- Indicates Carbon Molecule properties
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Seepage-Induced Magnetic Anomalies Associated with Oil and Gas Fields: Onshore and Offshore Examples*

Dietmar (Deet) Schumacher and Robert S. Foote
Search and Discovery Article #80416 (2014)
Posted October 27, 2014

*Adapted from extended abstract prepared for oral presentation at AAPG International Conference and Exhibition, Istanbul, Turkey, September 14-17,
2014, AAPG 2014

E&P Field Services of Mora, NM (deetschumacher@gmail.com)

Geoscience International Inc., Dallas TX

Introduction

The presence of magnetic anomalies over oil and gas fields has been noted for several decades, but it is only in recent years that the phenomenon has been critically examined. Studies of geologically and geographically diverse regions document that:

1. Authigenic magnetic minerals occur in near-surface sediments over many petroleum accumulations,
2. This hydrocarbon-induced mineralization is detectable in high resolution, broad bandwidth magnetic data acquired at low altitude and with closely-spaced flight lines, and in ground magnetic surveys,
3. The magnetic susceptibility analysis of drill cuttings and near-surface sediments confirms the existence of the aeromagnetic anomalies,
4. Sediments with anomalous magnetic susceptibility frequently contain ferromagnetic minerals such as greigite, maghemite, magnetite, and pyrrhotite,
5. Approximately 80% of oil and gas discoveries are associated with hydrocarbon-induced magnetic anomalies.

The association between hydrocarbon seepage and the formation of authigenic magnetic minerals in the near-surface has important applications in hydrocarbon exploration. Application of this methodology can quickly identify the areas or prospects with the greatest petroleum potential. Although the discovery of shallow sedimentary magnetic anomalies does not guarantee the discovery of commercial hydrocarbon accumulations, it does identify areas requiring more detailed evaluation, thereby focusing attention and resources on a relatively small number of high potential sites. More significantly, these seep-induced magnetic anomalies have been documented over many deep-water discoveries in the Gulf of Mexico. Proper integration of near-surface magnetic data with geologic and seismic data can improve exploration success and reduce development costs. This presentation is illustrated with examples from North America (including the deep-water Gulf of Mexico) and Africa.

Methodology

Variation in the measurement of the earth's magnetic field can result from the following causes:

- Lithologic and magnetic changes associated with basement rocks
- Intrusive igneous bodies, volcanic deposits, shallow salt masses
- Cultural contamination from surface and near-surface iron material
- Solar modulation of the earth’s magnetic field
- Authigenic ferromagnetic minerals in near-surface sediments.

Low-terrain-clearance, high- sensitivity cesium vapor aeromagnetic measurements provide a composite of these effects on the magnetic field data. Data reduction techniques that remove the influence of magnetic basement rocks on the total magnetic field and, where possible, the effects of cultural iron contamination allow the identification of sedimentary residual magnetic (SRM) anomalies (Figure 1) as they exist along the flight line. When these SRM anomalies are positioned line-to-line adjacent to one another, they define SRM anomaly clusters. It is these clusters that define the micromagnetic anomaly – also referred to as “Magnetic Bright Spots” (Figure 2) – which provide valuable clues to an underlying oil or gas accumulation.

Applications for Deep-Water Exploration

The association between hydrocarbon seepage and the formation of authigenic magnetic minerals in near-surface sediments has important applications in deep-water hydrocarbon exploration. Sepage-induced sedimentary magnetic anomalies can reliably identify areas and prospects with the highest petroleum potential in water depths as great as 9000 feet (2800 m). The highresolution cesium vapor aeromagnetic data used in this study by Robert Foote and his colleagues were acquired between 1986 and 1992 and extend from East Breaks to Viosca Knoll in the Gulf of Mexico. A comparison of the specially processed and interpreted aeromagnetic data with post-survey drilling results documents that more than 80% of wells drilled on prospects within or adjacent to Magnetic Bright Spots have resulted in commercial discoveries. In contrast, only 40% of wells drilled on prospects located more than 800 m from the MBS have resulted in discoveries. Although the discovery of MBS anomalies does not guarantee the discovery of hydrocarbon accumulations, it does identify areas requiring more detailed evaluation, thereby focusing attention and resources on a relatively small number of high potential sites.

Selected References
Foote, R.S., 1996, Relationship of near-surface magnetic anomalies to oil and gas-producing areas: AAPG Memoir 66, p. 111-126.
Foote, R.S., 2007, Method helps find hydrocarbon areas; aids optimum seismic survey planning: Oil & Gas Journal, 5 Feb 2007,p. 3
(more at link: )
http://www.searchanddiscovery.com/documents/2014/80416schumacher/ndx_schumacher.pdf

Magnetics for Hydrocarbon Exploration

Christine Fichler, NTNU. Column Editors: Lasse Amundsen and Martin Landrø

How can a tiny mineral called magnetite help to unravel hydrocarbon seepage and subsurface petrology?

It’s not MAGIC – it’s MAGNETICS… in integrated workflows!This article appeared in Vol. 13, No. 6 - 2017

'Magnetism, as you recall from physics class, is a powerful force that causes certain items to be attracted to refrigerators.' Dave Barry

https://www.geoexpro.com/articles/2017/01/magnetics-for-hydrocarbon-exploration



Magnetite from Bolivia. These crystals measure over 1 cm across. (Source: Rob Lavinsky/Wikipedia)
Magnetite is the most important member in the family of magnetic minerals, which are found in varying amounts in crystalline rocks and to a lesser extent in sediments.

Magnetite has the ability to respond to a magnetic field by generating its own field, known as the induced magnetic field.

In oceanic crustal rocks, it is common for magnetic minerals to permanently hold substantial magnetic fields. These remanent fields date back to the moment when the rocks in the hot and just solidified magmas of mid-oceanic ridges cooled through the Curie point (the temperature at which magnetic materials undergo a sharp change in their magnetic properties) and captured and stored the acting magnetic field characteristics.

This can be used to unravel the paleomagnetic history of the rocks.

Magnetic Anomalies

We know the direction of the Earth’s magnetic field from the compass needle pointing north. The Earth’s field looks like that of a magnetic dipole - a huge blueprint of your refrigerator magnet, but which is located in the Earth’s core. All rocks on Earth, as well as you and me, are bathed in this magnetic field and respond with induced magnetic fields. But since we do not have much magnetic material in our bodies, the fields of the rocks will dominate.

Geophysics uses a parameter called magnetic susceptibility, which expresses the strength of the response of a rock to an imposed magnetic field - an easy alternative to estimating the amount of magnetic minerals in a rock sample. High magnetic susceptibility will give a strong induced magnetic field and vice versa. These induced magnetic fields, together with the remanent magnetic fields, cause very small deviations to the Earth’s magnetic field strength, known as magnetic anomalies. They are measured by intricate yet backpack-sized instruments, typically mounted on airplanes for hydrocarbon exploration applications. Onshore and offshore areas are mapped line by line and the results processed to create maps of magnetic anomalies, which present the sum of the induced and remanent magnetic anomalies of every single magnetic mineral in the subsurface; in other words, they reflect the distribution of magnetic susceptibility and remanence.

The Magnetic Choir

In order to understand the recorded anomalies at the surface, imagine that the magnetic minerals form a choir and you are the magnetometer ‘listening’ to the choir from the front. You will easily hear the nearest singers, but listening to those further away gets more and more difficult with increasing distance - only if somebody far away is singing very loudly with a megaphone, will you hear them. The shallowest magnetic rocks in the subsurface are nearest to the magnetometer and will as such generate the strongest anomalies and show a lot of details. With increasing depth, the anomalies become smaller in amplitude and lose details, as illustrated in the left part of Figure 1.


Figure 1: (Left) Magnetic anomalies caused by the same body at different depths; (Right) A synthetic section with calculated magnetic anomalies for magnetic rocks typically found in sedimentary basins. The induced Earth magnetic field (H) is typical for the North Sea. (Generated using GEOSOFT GMSYS2D)

The right-hand image of Figure 1 illustrates magnetic rocks in sediments and crust and their associated magnetic anomalies: in our choir analogy, the large anomalies (grey) from the crystalline rocks are the ‘singers with megaphones’, while the tiny, small scale anomalies (red) from just a very few structures in the sediments are the ‘singers in the front’. The most important thing to understand about sedimentary anomalies is that they are small in amplitude and as such are only detectable if located in the uppermost kilometer of the subsurface. Furthermore, mapping them needs high resolution data, which means acquisition with dense line spacing and high accuracy.

High pass filtering of the magnetic data brings out the shallow sedimentary anomalies of short wavelength. This is illustrated in Figure 2, which compares high pass filtered anomalies of both high resolution magnetic data and global magnetic data; note the difference!


Figure 2: Upper maps: seismically mapped Quaternary channels and high pass filtered, high-resolution magnetic data (modified from Fichler, Henriksen, Rueslåtten and Hovland, 2005; magnetic data: VGVG /TGS-Nopec , 1995). Lowermost map: global magnetic data (EMAG2; www.geomag.org, 2009) of the northern North Sea; the area marked by the larger white box is filtered in the same way as the high resolution data and shown in the second lowest map. The smaller box marks the area shown in Figure 4 and the white line shows the location of the profile in Figure 5.

Magnetic Anomalies as Hydrocarbon Indicators

Magnetic minerals deposited in sedimentary layers reflect the provenance of the sediments. For the continental shelf offshore Norway, Mørk, McEnroe and Olesen (2002) documented that the magnetic susceptibility and remanence are generally small, and few sands and shales were found to have high values. These workers also showed that diagenetic magnetic mineralization in the form of highly magnetic siderite cementation is observed in some dark shales, a phenomenon which can also be seen at outcrops of source rocks. In Venezuela an increased content of magnetic minerals was found in cap rocks of oil-filled reservoirs by Perez-Perez, Onofrio, Bosch and Zapata (2011). These and other effects may cause small magnetic anomalies and it has been suggested that they form indirect hydrocarbon indicators; many case histories can be found if you dig into the literature.

However, the big problem is the inherent ambiguity in the interpretation. Small magnetic anomalies are caused by many shallow sources, not just by chemical changes due to hydrocarbons. Common sources are depositional and erosional patterns, sills and dykes, hydrothermal systems and, looking at onshore environments, the tropical weathering product called laterite. How can you tell the difference? The only way forward is through integrating magnetic anomaly interpretation with other data.

Let’s look at some examples from the North Sea where combining the interpretation of magnetic and 3D seismic data could explain some of the shallow anomalies. One distinct group of sedimentary magnetic anomalies is related to melt-water channels which are eroded and filled by glaciogenic sediments due to repeated glaciations and deglaciations in the Pleistocene. The resulting spaghetti pattern of cross-cutting channels is shown in Figure 2. Some channels generate positive anomalies, others negative ones as a consequence of the susceptibility contrast between infill and host rock, which can vary between negative, zero or positive. These channeled sands may form a reservoir rock, as proven by the small, shallow discovery, Peon, in the northern North Sea.

Figure 3: Gas blowout crater in the Russian Arctic. (Source: Vasily Bogoyavlensky)
Magnetic anomalies have yet further relevance in the search for hydrocarbons.

If hydrocarbon gas seeped into the permafrost during the Pleistocene glaciation periods, gas hydrates will have been precipitated and, in the next warm period, would melt and be released. The melting of gas hydrates below tight cap rocks is known to create blowout craters, as spectacularly observed in the Russian Arctic (see Figure 3 opposite, and Gas Blowouts on the Yamal and Gydan Peninsulas by Vasily Bogoyavlensky), and if such a crater is later filled with magnetic sediments, the result is a magnetic anomaly.

This rather special hydrocarbon seepage indicator is illustrated in Figure 4, showing a circular magnetic anomaly from the eastern shoulder of the Viking Graben.

Figure 4: Depression on seismic section correlating with a circular magnetic anomaly; interpreted as gas hydrate expulsion crater filled with magnetic glaciogenic sediments (modified from Fichler, Henriksen, Rueslåtten & Hovland, 2005); for location see Figure 2. Black line indicates line of section.

Basement Anomalies

Let’s now look at the ‘singers with the megaphone’ - the crystalline basement with wide and large magnetic anomalies as introduced in Figure 1.

Crustal magnetic anomalies rarely mimic the topography of the top basement, whereas gravity anomalies often do. There are several reasons for this. The magnetic susceptibility of crustal rocks varies between 10-4 and 10-1 SI units, i.e., by a factor of 1,000, whereas crustal densities just vary between 2.5 and 3.4 g/cm3, meaning that large magnetic anomalies can be generated by deep as well as by shallow rock units. An example is the deep mafic intrusion in Figure 1, which gives almost the same magnetic amplitude as the shallow basement high. However, the anomaly of the intrusion has a larger wavelength than the basement high. Such differences in shape can be used to find the depth to the top of the structure by various manual or automatic methods.

Another factor affecting induced magnetic anomalies is related to the change of the Earth’s magnetic field direction, from vertical at the poles to horizontal at the equator. This explains why a magnetic body at fixed depth generates different anomaly shapes depending on its location, with a maximum anomaly over its center at the poles, a minimum at the equator, and in between a combination of maximum and minimum. The North Sea shows near-polar characteristics.

Integrating Data

The final example (Figure 5) shows the workflow for crustal rock classification through the integration of different geophysical data. A deep seismic depth section along a 300 km-long transect crossing the northern North Sea was loaded into a gravity and magnetic modeling program. The subsurface was divided into polygons, each representing a different rock type. The divisions reflect the boundaries within sediments and crust as defined by the seismic data. Each polygon was assigned a magnetic susceptibility and density. Well data provided sedimentary densities and magnetic susceptibilities as well as the depth to the top crystalline basement, the latter found to consist of mainly granitic rocks. In the initial model, the parameters for granites were used for the entire crust. The mantle was assigned peridotite parameters and the high velocity body in the lower crust was given eclogite parameters.

Figure 5: Magnetic susceptibilities (Clark, 1999) cross-plotted against densities (Hinze, Frese and Saad, 2013); location of profile see Figure 1. (Modified from Fichler, Odinsen, Rueslåtten, Olesen, Vindstad and Wienecke, 2011)

The calculated gravity and magnetic anomalies of this simple model showed a large mismatch, especially in the long wave length-range, indicating a need for modification in the deep parts of the crust. The gravity and magnetic anomalies governed the crustal modification, which resulted in a model of more complex density and susceptibility distributions. The final model matches observed gravity and magnetic anomalies as well as rock types considered geologically reasonable with respect to the geological history. Modeling in general carries an inherent uncertainty and the interpreter should therefore include alternative models where feasible.

You can apply this workflow to detect granitic rocks, known for their high radiogenic heat production which influences hydrocarbon maturation (Hokstad, Tasarova, Kyrkjebø, Fichler, Wiik and Duffaut, 2016), or to map the boundary between oceanic and continental crust. Furthermore, detection of intrusives, which have brought hot magma into crust or sediments, may also be of importance for unraveling the thermal history of a sedimentary basin.

Summing up, magnetic data contributes to hydrocarbon exploration on a broad scale and in mainly integrated geophysical interpretation tasks. It can address problems from the deep crust to the shallowest sedimentary strata. Magnetic data on a large scale is globally available at low cost or even free. High resolution data is more expensive, but is still only a fraction of the cost of a seismic survey.

About the authors

Guest author, Christine Fichler holds a PhD in geophysics (1985) from the Karlsruhe Institute of Technology (KIT) in Germany.

A post-doc. position at the Dept. of Petroleum Engineering and Applied Geophysics at the Norwegian University of Science and Technology (NTNU) followed (1986-1990) and, in 1990, Christine became a Specialist Geophysicst at Statoil, Norway.

Since 2013 Christine has been Adjunct Professor at the Dept. for Geology and Mineral Resources Engineering, Norwegian University of Science and Technology (NTNU).

Editors Martin Landrø and Lasse Amundsen are regular contributors to Geo ExPro. You can find more articles by these authors by using the search function at the top of this page or by following this link.

NXT Energy
http://www.nxtenergy.com/sfd-technology/the-science-of-sfd

The Science of SFD

Hydrocarbon exploration utilizes many different geophysical methods to create models of the earth’s subsurface, with the goal of identifying areas which may be “anomalous” to permit the economic accumulations of oil and natural gas. This accumulation requires the combination of suitable structural or stratigraphic conditions with appropriate hydro-dynamic conditions. Mitigating geological exploration risks associated with factors such as trap configuration, reservoir quality and seal integrity is critical to overall exploration success.

Gravity based tools have long been used in the exploration process, and generally utilize mass-density or field-strength based measurements. The SFD airborne survey technology also utilizes gravity as a medium, but in a unique manner through exploiting wave attributes of the acquired signal to rapidly identify and rank prospect leads for oil and gas exploration.

The earth’s gravitational field is influenced by many sources, and has a complex three-dimensional shape, resulting in part from the inherent anisotropy within the crust. The basic operating premise of SFD is that it responds to subtle variations or perturbations in earth’s gravity field, and these can be indicative of anomalies which arise from subsurface changes relating to geologic features of interest, such as faults, fault blocks, anticlines, carbonate bank edges, channel systems, over-pressure of fluids, etc. This family of geologic features are commonly correlated with the potential for occurrence of hydrocarbon trapping conditions. In essence, changes in subsurface homogeneity are the fundamental factor of the physical contrast to which SFD responds.

In general, porous rocks and the presence of fluid cause a decrease in bulk density, which will produce a gravity low. If more fluid is accumulated in a trap with high porosity, then the reservoir system becomes more homogenous provided there is adequate permeability distribution. This results in greater spatial subsurface homogeneity.

In SFD exploration, a background condition is characterized by a random distribution of Δ ρ (change in density) with hydrostatic pressure gradients. An anomalous condition is characterized by an isolated homogeneous distribution of ρ due to enhanced porosity and fluid presence bounded by abnormal stress gradients. The anomalous condition is further characterized by a marked reduction in shear stress inside the reservoir and a reorientation of the horizontal principal stresses around it.

In addition to subsurface density changes, the principal stresses also play a significant role in the development of subsurface conditions associated with discontinuities. In general, fluid migration follows the direction of the maximum horizontal stress (SHmax) and fluid expulsion follows the direction of the minimum horizontal stress (Shmin). As fluid moves into reservoirs, SHmax will reduce and Shmin will increase as pore pressure increases. Also, shear stress will be further reduced as fluid accumulates in the reservoir. Reservoir rock permeability distribution is controlled by SHmax and a high value indicates an increase in homogeneity. Investigations of gravity gradients and stress changes have shown that there is a physical relationship between the two at small scale. The gravity field includes local-scale perturbations or distortions which arise from a combination of mass-density and field transmission effects.

To respond to small-scale changes in the gravitational acceleration (Δ g), the SFD device is designed:

to employ a reduced proof mass assembly for minimizing inertial effects and allow high frequency interaction with the field to allow a mechanical instability for enhancing detection sensitivity to utilize rectilinear motion for dynamic detection and continuously accumulating Δ g necessary to resolve reservoir scale features, and to obtain wave-based signal patterns for analysis as opposed to the standard magnitude measurement employed by standard gravity based tools.

Based on extensive empirical observation and past correlations with other geological and geophysical data, SFD data has proven highly effective in identifying potential hydrocarbon traps in a wide variety of geological settings, including thrust-fold belts, foreland basins, sub-salt plays, and extensional regimes. Interpretation of SFD signals involves a pattern recognition process. Based on extensive experience, recognizable SFD signal patterns (example below) have been empirically correlated to a variety of subsurface geologic fluid trapping conditions and are especially pronounced within regions of fluid-filled porosity bounded by abnormal stress gradients.

A sample SFD signal from Ladyfern gas field

(Devonian carbonate reef structure), British Columbia, Canada.

This example clearly illustrates amplitude and frequency effects embedded in the SFD signal.

The end result is that SFD is capable of detecting subsurface conditions which are favorable for fluid entrapment, using a unique detection system. SFD yields an independent dataset that is highly complementary to other geophysical methods such as 2D and 3D seismic surveys. In conjunction with other geological data, SFD can be a fundamental step in assessing whether lead areas are then elevated to prospects, aiding in the goal of focusing exploration efforts and reducing overall risk.

......


NXT Energy Solutions Inc.
Summary of Technical Reference Materials
(February 2015)

References

Anderson, B.M., Taylor, J.M. and Galitski, V.M. (2011). “Interferometry with synthetic gauge
fields.” Physical Review A 83, 031602.
Bell, J.S. (1996). “In situ stresses in sedimentary rocks (Part II): Applications of stress
measurements.” Geoscience Canada 23(3), 135–153.

Dake, L.P. (2001). The Practice of Reservoir Engineering, Elsevier.

Finkbeiner, T. (1999). In Situ Stress, Pore Pressure and Hydrocarbon Migration and
Accumulation in Sedimentary Basins, Ph.D. thesis, Stanford University.

Hayes, T.J. (2008). Using Gravity as a Proxy for Stress Accumulation in Complex Fault Systems,
Ph.D. thesis, University of Western Ontario.

Hayes, T.J., Tiampo, K.F., Fernandez, J. and Rundle, J.B. (2008). “A gravity gradient method
for characterizing the post-seismic deformation field for a finite fault.” Geophysical Journal
International 173, 802–805.

Hillis, R.R. (2001). “Coupled changes in pore pressure and stress in oil fields and sedimentary
basins.” Petroleum Geoscience 7, 419–425.

McCulloh, T.H. (1967). Mass Properties of Sedimentary Rocks and Gravimetric Effects of
Petroleum and Natural-Gas Reservoirs, Geological survey professional paper 528-A, U.S.
Department of the Interior.

Prieto, C. (1998). “Gravity/magnetic signatures of various geologic models - An exercise in
pattern recognition.” Geologic Applications of Gravity and Magnetics: Case Histories, AAPG &
SEG, 20–27.
Silva, P. R. (1997). “A new interpretation of the de Broglie frequency.” Physics Essays 10(4),
628-632.
Street, R.L., Watters, G.Z. and Vennard, J.K. (1996). Elementary Fluid Mechanics, 7th edition,
John Wiley & Sons.

NXT Publications

Cotton J. and Mustaqeem, A. (2010). The Geologic and Geophysical Integration of SFD Data
Offshore Colombia, Block RC 4 & 5, NXT Internal Report, Calgary, Canada.

Escalera, J.A., García, M.V., Olazarán, J.J.H., Ponce, A., García, O.V., Cardador, M.H. and
Liszicasz, G. (2013). “Application of stress field detection (SFD) technology for identifying
areas of hydrocarbon potential in the Gulf of Mexico region.” Next Generation Oil & Gas Summit
Latin America, Cartagena, Colombia.

Liszicasz, G., Mustaqeem, A., Khan, M.R., Bhatti, M.A. and Hussain, A. (2013). “SFD
(Stress Field Detection) and its integration with seismic in Kharan Forearc Basin and its implications for
hydrocarbon exploration in a frontier area.” SPE/PAPG Annual Technical Conference,
Islamabad, Pakistan.

Wikipedia on Magnetite. Has very interesting characteristics. We may need to use the C.F. to describe "color" as well as property. Why "Black"?  What does the C.F. radiate in ambient light to the eye?
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Magnetite

Magnetite is a rock mineral and one of the main iron ores, with the chemical formula Fe3O4. It is one of the oxides of iron, and is ferrimagnetic; it is attracted to a magnet and can be magnetized to become a permanent magnet itself.[5][6] It is the most magnetic of all the naturally-occurring minerals on Earth.[5][7] Naturally-magnetized pieces of magnetite, called lodestone, will attract small pieces of iron, which is how ancient peoples first discovered the property of magnetism. Today it is mined as iron ore.

Small grains of magnetite occur in almost all igneous and metamorphic rocks. Magnetite is black or brownish-black with a metallic luster, has a Mohs hardness of 5–6 and leaves a black streak.[5]

The chemical IUPAC name is iron(II,III) oxide and the common chemical name is ferrous-ferric oxide.

Properties

In addition to igneous rocks, magnetite also occurs in sedimentary rocks, including banded iron formations and in lake and marine sediments as both detrital grains and as magnetofossils. Magnetite nanoparticles are also thought to form in soils, where they probably oxidize rapidly to maghemite.[8]
Crystal structure

The chemical composition of magnetite is Fe2+Fe23+O42−. The main details of its structure were established in 1915. It was one of the first crystal structures to be obtained using X-ray diffraction. The structure is inverse spinel, with O2− ions forming a face centered cubic lattice and iron cations occupying interstitial sites. Half of the Fe3+ cations occupy tetrahedral sites while the other half, along with Fe2+ cations, occupy octahedral sites. The unit cell consists of 32 O2− ions and unit cell length is a = 0.839 nm.[9]

Magnetite contains both ferrous and ferric iron, requiring environments containing intermediate levels of oxygen availability to form.[10]

Magnetite differs from most other iron oxides in that it contains both divalent and trivalent iron.[9]

As a member of the spinel group, magnetite can form solid solutions with similarly structured minerals, including ulvospinel (Fe2TiO4), hercynite (FeAl2O4) and chromite (FeCr2O4). Titanomagnetite, also known as titaniferous magnetite, is a solid solution between magnetite and ulvospinel that crystallizes in many mafic igneous rocks. Titanomagnetite may undergo oxyexsolution during cooling, resulting in ingrowths of magnetite and ilmenite.

Crystal morphology and size

Natural and synthetic magnetite occurs most commonly as octahedral crystals bounded by {111} planes and as rhombic-dodecahedra.[9] Twinning occurs on the {111} plane.

Hydrothermal synthesis usually produce single octahedral crystals which can be as large as 10mm across.[9] In the presence of mineralizers such as 0.1M HI or 2M NH4Cl and at 0.207 MPa at 416-800 °C, magnetite grew as crystals whose shapes were a combination of rhombic-dodechahedra forms.[9] The crystals were more rounded than usual. The appearance of higher forms was considered as a result from a decrease in the surface energies caused by the lower surface to volume ratio in the rounded crystals.[9]

Reactions

Magnetite has been important in understanding the conditions under which rocks form. Magnetite reacts with oxygen to produce hematite, and the mineral pair forms a buffer that can control oxygen fugacity. Commonly, igneous rocks contain solid solutions of both titanomagnetite and hemoilmenite or titanohematite. Compositions of the mineral pairs are used to calculate how oxidizing was the magma (i.e., the oxygen fugacity of the magma): a range of oxidizing conditions are found in magmas and the oxidation state helps to determine how the magmas might evolve by fractional crystallization. Magnetite also is produced from peridotites and dunites by serpentinization.

Biological occurrences

Biomagnetism is usually related to the presence of biogenic crystals of magnetite, which occur widely in organisms.[23] These organisms range from bacteria (e.g., Magnetospirillum magnetotacticum) to animals, including humans, where magnetite crystals (and other magnetically-sensitive compounds) are found in different organs, depending on the species.[24][25] Biomagnetites account for the effects of weak magnetic fields on biological systems.[26] There is also a chemical basis for cellular sensitivity to electric and magnetic fields (galvanotaxis).[27]

Magnetite magnetosomes in Gammaproteobacteria

Pure magnetite particles are biomineralized in magnetosomes, which are produced by several species of magnetotactic bacteria. Magnetosomes consist of long chains of oriented magnetite particle that are used by bacteria for navigation. After the death of these bacteria, the magnetite particles in magnetosomes may be preserved in sediments as magnetofossils. Some types of anaerobic bacteria that are not magnetotactic can also create magnetite in oxygen free sediments by reducing amorphic ferric oxide to magnetite.[28]

Several species of birds are known to incorporate magnetite crystals in the upper beak for magnetoreception,[29] which (in conjunction with cryptochromes in the retina) gives them the ability to sense the direction, polarity, and magnitude of the ambient magnetic field.[24][30]

Chitons, a type of mollusk, have a tongue-like structure known as a radula, covered with magnetite-coated teeth, or denticles.[31] The hardness of the magnetite helps in breaking down food, and its magnetic properties may additionally aid in navigation.[dubious – discuss] Biological magnetite may store information about the magnetic fields the organism was exposed to, potentially allowing scientists to learn about the migration of the organism or about changes in the Earth's magnetic field over time.[32]

Human brain

Living organisms can produce magnetite.[25] In humans, magnetite can be found in various parts of the brain including the frontal, parietal, occipital, and temporal lobes, brainstem, cerebellum and basal ganglia.[25][33] Iron can be found in three forms in the brain – magnetite, hemoglobin (blood) and ferritin (protein), and areas of the brain related to motor function generally contain more iron.[33][34] Magnetite can be found in the hippocampus. The hippocampus is associated with information processing, specifically learning and memory.[33] However, magnetite can have toxic effects due to its charge or magnetic nature and its involvement in oxidative stress or the production of free radicals.[35] Research suggests that beta-amyloid plaques and tau proteins associated with neurodegenerative disease frequently occur after oxidative stress and the build-up of iron.[33]

Some researchers also suggest that humans possess a magnetic sense,[36] proposing that this could allow certain people to use magnetoreception for navigation.[37] The role of magnetite in the brain is still not well understood, and there has been a general lag in applying more modern, interdisciplinary techniques to the study of biomagnetism.[38]

Electron microscope scans of human brain-tissue samples are able to differentiate between magnetite produced by the body's own cells and magnetite absorbed from airborne pollution, the natural forms being jagged and crystalline, while magnetite pollution occurs as rounded nanoparticles. Potentially a human health hazard, airborne magnetite is a result of pollution (specifically combustion). These nanoparticles can travel to the brain via the olfactory nerve, increasing the concentration of magnetite in the brain.[33][35] In some brain samples, the nanoparticle pollution outnumbers the natural particles by as much as 100:1, and such pollution-borne magnetite particles may be linked to abnormal neural deterioration. In one study, the characteristic nanoparticles were found in the brains of 37 people: 29 of these, aged 3 to 85, had lived and died in Mexico City, a significant air pollution hotspot. A further eight, aged 62 to 92, came from Manchester, and some had died with varying severities of neurodegenerative diseases.[39] According to researchers led by Prof. Barbara Maher at Lancaster University and published in the Proceedings of the National Academy of Sciences, such particles could conceivably contribute to diseases like Alzheimer's disease. Though a causal link has not been established, laboratory studies suggest that iron oxides like magnetite are a component of protein plaques in the brain, linked to Alzheimer's disease.[40]

Increased iron levels, specifically magnetic iron, have been found in portions of the brain in Alzheimer's patients.[41] Monitoring changes in iron concentrations may make it possible to detect the loss of neurons and the development of neurodegenerative diseases prior to the onset of symptoms[34][41] due to the relationship between magnetite and ferritin.[33] In tissue, magnetite and ferritin can produce small magnetic fields which will interact with magnetic resonance imaging (MRI) creating contrast.[41] Huntington patients have not shown increased magnetite levels; however, high levels have been found in study mice.[33]

Magnetite nanoparticles

Magnetite micro- and nanoparticles are used in a variety of applications, from biomedical to environmental. One use is in water purification: in high gradient magnetic separation, magnetite nanoparticles introduced into contaminated water will bind to the suspended particles (solids, bacteria, or plankton, for example) and settle to the bottom of the fluid, allowing the contaminants to be removed and the magnetite particles to be recycled and reused.[46] This method works with radioactive and carcinogenic particles as well, making it an important cleanup tool in the case of heavy metals introduced into water systems.[47] These heavy metals can enter watersheds due to a variety of industrial processes that produce them, which are in use across the country. Being able to remove contaminants from potential drinking water for citizens is an important application, as it greatly reduces the health risks associated with drinking contaminated water.

Another application of magnetic nanoparticles is in the creation of ferrofluids. These are used in several ways, in addition to being fun to play with. Ferrofluids can be used for targeted drug delivery in the human body.[46] The magnetization of the particles bound with drug molecules allows “magnetic dragging” of the solution to the desired area of the body. This would allow the treatment of only a small area of the body, rather than the body as a whole, and could be highly useful in cancer treatment, among other things. Ferrofluids are also used in magnetic resonance imaging (MRI) technology.[48]

Coal mining industry

For the separation of coal from waste, dense medium baths were used. This technique employed the difference in densities between coal (1.3-1.4 tonnes per m³) and shales (2.2-2.4 tonnes per m³). In a medium with intermediate density (water with magnetite), stones sank and coal floated.[49]

https://en.wikipedia.org/wiki/Magnetite

Nevyn's MBL engine representation of Magnetite:

Magnetic Bright Spots Can Identify the Most Prospective Deep-Water Areas and Prospects*

(updated from October 27, 2014 paper above --Cr6)

Robert S. Foote1
and Dietmar Schumacher
http://www.searchanddiscovery.com/documents/2016/41871foote/ndx_foote.pdf

Search and Discovery Article #41871 (2016)**
Posted September 12, 2016

*Adapted from poster presentation given at AAPG 2016 Annual Convention and Exhibition, Calgary, Alberta, Canada, June 19-22, 2016
**Datapages 2016 Serial rights given by author. For all other rights contact author directly.

1Geoscience International Inc., Euless, TX, USA

E&P Field Services, Mora, NM, USA (deetschumacher@gmail.com)

Abstract

The presence of magnetic anomalies over oil and gas fields has been noted for decades, but only in recent years has the phenomenon has been critically examined. Studies of geologically and geographically diverse regions document that:
(1) authigenic magnetic minerals occur in nearsurface sediments over many petroleum accumulations,
(2) this hydrocarbon-induced mineralization is detectable in high resolution, broad bandwidth magnetic data acquired at low altitude and with closely-spaced flight lines,
(3) the magnetic susceptibility analysis of drill cuttings confirms the existence of the aeromagnetic anomalies,
(4) sediments with anomalous magnetic susceptibility frequently contain ferromagnetic minerals such as greigite, maghemite, magnetite, and pyrrhotite, and
(5) 80% or more of offshore deep-water oil and gas discoveries in Gulf of Mexico are associated with these shallow, sedimentary hydrocarbon-induced magnetic anomalies.
The association between hydrocarbon seepage and authigenic magnetic minerals has important applications in deep-water hydrocarbon exploration. Seep-induced sedimentary magnetic anomalies, known as Magnetic Bright Spots (MBS), can reliably identify areas and prospects with the highest petroleum potential in water depths as great as 9000 feet (2800 m). The high-resolution cesium vapor aeromagnetic data used in this study were acquired between 1986 and 1992, and extend from East Breaks to Viosca Knoll in the Gulf of Mexico. A comparison of the processed and interpreted aeromagnetic data with post-survey drilling results documents that 89% of wells drilled on prospects within or adjacent to Magnetic Bright Spots have resulted in commercial discoveries. In contrast, fewer than 30% of wells drilled on prospects located more than 800 m from the MBS have resulted in discoveries. Furthermore, MBS areas account for 65% of production – almost 5 times that from within salt-covered areas where no MBS could be determined, although the areas are roughly similar in size. Although the discovery of MBS anomalies does not guarantee the discovery of commercial oil or gas, it does identify areas requiring more detailed evaluation, thereby focusing attention and resources on a relatively small number of high potential sites.

References Cited

Foote, R.S., 1996, Relationship of near-surface magnetic anomalies to oil and gas producing areas: in D. Schumacher and M.A. Abrams,
Hydrocarbon Migration and its Near-Surface Expression: AAPG Memoir 66, p. 111-126.
Foote, R.S., R. Novak, and J. Sobehrad, 1997, Aeromagnetic near-surface profiling as an exploration tool: in Applications of Emerging
Technologies: Unconventional Methods in Exploration for Petroleum and Natural Gas, V: SMU Press, ISEM, p. 183-193.
Machel, H.G. and E.A. Burton, 1991, Chemical and microbial processes causing anomalous magnetization in environments affected by
hydrocarbon seepage: Geophysics, v. 56, p. 598-605.
Schumacher, D., 1996, Hydrocarbon-induced alteration of soils and sediments: in D. Schumacher and M.A. Abrams, Hydrocarbon Migration
and its Near-Surface Expression, AAPG Memoir 66, p. 111-126.

Interesting links on Magenetic Bacteria from biological and geophysical perspectives.  
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https://www.intechopen.com/online-first/biology-and-physics-of-magnetotactic-bacteria
https://phys.org/news/2007-01-hatching-biomineralization.html
http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132017000100429

Martian Olivine and Magnetite (but not found from living bacteria):
https://www.hou.usra.edu/meetings/habitability2019/presentations/1032_Treiman.pdf


Research Methods in Biomineralization Science
Jinhui Tao, in Methods in Enzymology, 2013

1 Introduction

Biomineralization is the process by which living organism manufactures minerals for different functional purposes, such as mechanical stiffening of tissue, magnetic or gravitational sensing, and element storage (Mann, 1988; Sigel, Sigel, & Sigel, 2008; Weiner & Lowenstam, 1989). From the perspective of taxonomic distribution, the most widespread biominerals are calcium carbonate and calcium phosphate, which are firmly associated with organic matrices such as chitin and collagen to form hybrid structure for shells and bones (Arias & Fernández, 2008; Boskey, 1998; Palmer, Newcomb, Kaltz, Spoerke, & Stupp, 2008; Sarikaya, 1999). The structures of these composites have hierarchical levels from the nano- to microscale. Because of the potential application in guiding new composite material design and controllable synthesis, there has been an increasing interest in deciphering the mechanisms of biomineralization over the past decades.

https://www.sciencedirect.com/topics/immunology-and-microbiology/biomineralization
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Magnetotactic bacteria, magnetosomes and their application

https://doi.org/10.1016/j.micres.2012.04.002
Get rights and content
Under an Elsevier user licenseopen archive

Abstract

Magnetotactic bacteria (MTB) are a diverse group of microorganisms with the ability to orient and migrate along geomagnetic field lines. This unique feat is based on specific intracellular organelles, the magnetosomes, which, in most MTB, comprise nanometer-sized, membrane bound crystals of magnetic iron minerals and organized into chains via a dedicated cytoskeleton. Because of the special properties of the magnetosomes, MTB are of great interest for paleomagnetism, environmental magnetism, biomarkers in rocks, magnetic materials and biomineralization in organisms, and bacterial magnetites have been exploited for a variety of applications in modern biological and medical sciences. In this paper, we describe general characteristics of MTB and their magnetic mineral inclusions, but focus mainly on the magnetosome formation and the magnetisms of MTB and bacterial magnetosomes, as well as on the significances and applications of MTB and their intracellular magnetic mineral crystals.

1. Introduction

MTB are a group of Gram-negative prokaryotes that passively align and actively swim along the geomagnetic field and other fields (Bazylinski and Williams 2007). This ability is based on specific intracellular structures, the magnetosomes, which, in most MTB, are nanometer-sized, membrane-bound crystals of the magnetic iron minerals magnetite (Fe3O4) or greigite (Fe3S4) (Lefèvre et al. 2011). These intriguing microorganisms were first documented by Salvatore Bellini as early as 1963 (Jogler and Schüler 2009). He microscopically observed a certain group of bacteria swam toward the Earth's North Pole and hence named them “magnetosensitive bacteria”. Eleven years later, Blakemore (1975) independently described these microorganisms and coined the terms magnetotaxis for the phenomena and MTB for the bacteria. The discovery of MTB proved to have a serious impact in a number of diverse research fields including microbiology, geology, mineralogy and biomineralization, crystallography, chemistry, biochemistry, physics, limnology and oceanography, and even astrobiology (Bazylinski and Schübbe 2007).

Despite the ubiquitous occurrence of MTB and their high abundance in the sediments of many freshwater and marine habitats, the isolation and cultivation of MTB are difficult due to their fastidious lifestyle (Postec et al. 2012). Because of this, the research in this area has been slow at times. However, with the development in biotechnology and magneto-technology, some progress has been made in laboratory MTB culture, biomineralization, ecology of MTB, magnetisms of MTB and magnetosomes, and identification of fossil magnetosomes in sediments.

The goal of this review is to give a broad overview over the current knowledge of the physiology, ecology, phylogeny, and molecular biology of MTB. Further, we will summarize new insights into the general feature and formation mechanism of magnetosomes. And what is more, the magnetism, significance, and application of MTB and magnetosomes will be presented. Finally, we will briefly discuss some related perspectives and possible directions for future studies.

2. Magnetotactic bacteria

2.1. Physiology, ecology, and phylogeny of MTB

MTB are commonly distributed in water columns or sediments with vertical chemical stratification (Bazylinski and Williams 2007). They can propel themselves through the water by rotating their helical flagella. One interesting microbiological aspect of MTB is that they can swim at speeds nearly twice that of Escherichia coli cells in spite of being larger in size and in spite of having less flagellar proteins (Sharma et al. 2008). Further, in presence of magnetic fields, different strains of MTB show different morphological properties and adjustments as swimmers, presumably due to intracellular magnetosome arrangements (Sharma et al. 2007). These observations highlight the interesting diversity of microbiological species. Generally, they swim to the magnetic north in the northern hemisphere, to the magnetic south in the southern hemisphere, and both ways on the geomagnetic equator (Lefèvre et al. 2011). Almost all the MTB are microaerophiles or anaerobes or facultatively anaerobic microaerophiles. Therefore, they are generally found in relatively high cell numbers at the oxic–anoxic interface (OAI) and the anoxic regions of the habitat or both (Bazylinski and Williams 2007). MTB have been shown to be the dominant species of the bacterial population in some environments, implying a remarkable ecological significance (Spring et al. 1993). The sulfate concentration in freshwater systems is very low and the OAI is located on the water-sediment interface or several millimeters below it (Bazylinski and Schübbe 2007).

The MTB of various morphological types have been found from the freshwater sediments (Thornhill et al., 1994, Amann et al., 2006), including bacillus, vibrios, spirilla, cocci, and multicellular forms (Fig. 1). MTB are known to produce two types of minerals, i.e., iron oxides and iron sulfides (Bazylinski and Frankel 2004). Those that produce iron oxides only biomineralize magnetite (Fe3O4) (Frankel et al. 1979), those that only produce iron sulfides biomineralize greigite (Fe3S4) (Heywood et al. 1990), and those that both produce iron oxide magnetite (Fe3O4) and iron sulfide greigite (Fe3S4) (Bazylinski et al. 1995). In freshwater systems, only iron oxide-producing MTB have been found (Faivre and Schüler 2008). Recently, MTB were found in freshwater in Lake Miyun, northern China (Lin et al. 2009). Moreover, MTB were also detected in extreme environments. Mono Lake, located in California in the United States, is an alkaline and saline lake which is iron limited due to the low solubility of the metal at high pH. Nevertheless, MTB were still found in this environment (Faivre and Schüler 2008). In addition, various magnetic cocci were discovered in mud sediments which have a high content of organic matter (Flies et al. 2005). The distribution of OAI in marine and freshwater is similar, but in many mostly undisturbed marine coastal habitats, the situation is markedly different (Bazylinski and Williams 2007). MTB which can produce both iron oxide and iron sulfide are present in marine and lake environments (Faivre and Schüler 2008). A wide variety of MTB were found in salt marshes, particularly in the surface layers of sulfidic sediments where they co-occur with sulfide oxidizing bacteria (Simmons and Edwards 2007). Large quantities of marine magnetotactic cocci were found in a seawater pond within an intertidal zone at Huiquan Bay in the China Sea (Pan et al. 2008). A marine magnetotactic spirillum was isolated and characterized from an intertidal zone of the China Sea (Zhu et al. 2010). It is reported that in some harbor with chemical stratification, various chemicals can create vertical concentration gradient with depth in the water, MTB were also found in the aqueous layer in microaerobic zone of this environment (Bazylinski et al. 1995).


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Fig. 1. Various morphology of MTB, vibrios: a; rods: b (Bar = 1.0 μm) and d; coccoid: c (Bar = 200 nm); spirilla: e; multicellular organism: f (Bar = 1.0 μm). Figure a and d reproduced from Scheffel and Schüler (2006), figure b reproduced from Baumgartner and Faivre (2011), figure c reproduced from Lefèvre et al. (2011), with permission from Springer. Figure e and f reproduced from Schüler (2008) and Keim et al. (2004), respectively, with permission from John Wiley and Sons.

Only a limited number of MTB have been isolated in pure culture so far (Arakaki et al. 2008). Among them, Magnetospirillum gryphiswaldense MSR-1, Magnetospirillum magneticum AMB-1, Magnetospirillum magneticum MGT-1, Magnetovibrio MV-1, Magnetococcus sp. MC-1, Marine magnetic spirillum QH-2, Magnetospirillum sp. WM-1 and Magnetospirillum magnetotacticum MS-1 are all affiliated to the α-Proteobacteria; Desulfovibrio magneticus RS-1 is affiliated to the δ-Proteobacteria (Fig. 2). Additionally, the 16S rDNA analysis of uncultured MTB was also reported. Previous studies (Keim et al., 2004, Simmons et al., 2004) suggested that different sources of multicellular magnetotactic prokaryotes are affiliated to the δ-Proteobacteria. It has been reported that the Corynebacterium tentatively named Magnetobacterium bavaricum is affiliated to Nitrospira (Fig. 2). 16S rDNA analysis of MTB MHB-1 was carried out by Flies et al. (2005) and the results showed that the sequence homology of MHB-1 with M. bavaricum was 91.0%.


Download : Download full-size image
Fig. 2. Phylogenetic relationships of MTB. Pure culture MTB are indicated in bold characters.

2.2. Molecular biology of MTB
M. magnetotacticum MS-1 was first used for molecular genetic study (Schüler and Frankel 1999). It was suggested that some genes of this bacterium can be expressed in E. coli, the transcription and translation elements of the two microorganisms are compatible, which is necessary for molecular genetic manipulation (Waleh 1988). The recA gene of this organism was cloned and expressed in E. coli by Berson et al. (2006). They cloned a 2 kb DNA fragment from M. magnetotacticum MS-1 that complemented iron-uptake deficiencies in E. coli and Salmonella typhimurium mutants lacking a functional aroD gene. These indicate that this 2 kb DNA may regulate the uptake of iron (Berson et al. 2006).

Development of MTB culture technology on agar plate provides the possibility of screening nonmagnetic mutants which have no magnetosomes. Non-magnetic mutant of M. magneticum AMB-1 in which Tn5 was shown to be integrated into the chromosome were obtained on agar plate (Matsunaga et al. 1992). Using transposon mutagenesis, Nakamura et al. (1995) identified a gene, designated magA, that encodes for a protein with significant sequence homology to the cation efflux proteins, KefC, a potassium-ion-translocating protein in E. coli. The gene of magA was expressed in E. coli and inverted membrane vesicles prepared from E. coli cells indicated that energy was required for iron transport (Nakamura et al. 1995). The expression of magA was higher when wild-type M. magneticum AMB-1 cells were grown under iron-limited conditions rather than iron-sufficient conditions in which they would produce more magnetosomes (Nakamura et al. 1995). Therefore, the role of the magA gene in magnetosome formation is uncertain. However, recent reports suggested that magA could serve as a candidate for a genetically encoded contrast agent for magnetic resonance imaging (MRI) (Goldhawk et al. 2009). Wahyudi et al. (2003) identified a gene, designated as aor, that encodes for a protein with homology to the tungsten-containing aldehyde ferredoxin oxidoreductase (AOR) from Pyrococcus furiosus, which functions for aldehyde oxidation. The gene of aor was found to be expressed under microaerobic conditions and localized in the cytoplasm of M. magneticum AMB-1 (Wahyudi et al. 2003). Additionally, iron uptake and growth of non-magnetic mutant of M. magneticum AMB-1 were lower than wild type. These indicated that aor gene may contribute to ferric iron reduction during magnetosome formation in M. magneticum AMB-1 under microaerobic respiration. Calugay et al. (2004) inserted Tn5 transposon into an open reading frame (ORF) coding for a periplasmic transport binding protein kinase gene homolog. The growth inhibition imposed by the exogenous non-assimilable iron chelator nitrilotriacetate was relieved in wild type but not in non-magnetic mutant of M. magneticum AMB-1, by the addition of the isolated wild type siderophore (Calugay et al. 2004). These implied that the interruption of periplasmic transport binding protein kinase gene homologue is required for siderophore transport into M. magneticum AMB-1.

Using reverse genetics, the mam22 gene was cloned in M. magnetotacticum MS-1 (Okuda et al. 1996) and a gene encoding for a homologous protein, mamA, was found in M. gryphiswaldense MSR-1, M. magneticum AMB-1, and Magnetococcus sp. MC-1 (Grunberg et al., 2001, Komeili et al., 2004, Amemiya et al., 2005). Okuda et al. (1996) used the N-terminal amino acid sequence from a 22 kDa protein specifically associated with the magnetosome membrane to clone and sequence its gene. On the basis of the amino acid sequence, the protein shows high homology to protein of the tetratricopeptide repeat (TPR) protein family (Okuda et al. 1996). However, the function of the protein in magnetosome formation is still unclear. A deletion of mamA in M. magneticum AMB-1 resulted in shorter magnetosome chains and it was concluded that mamA is required for functional magnetosome vesicle formation (Komeili et al. 2004). Recent study showed that the loss of mamA resulted in the change of the number of crystals produced per cell, while the formation of the magnetosome membrane was not affected (Murat et al. 2010). The majority of the genes essentially participating in magnetosome formation are grouped in four conserved gene clusters present within a large unstable genomic region called the magnetosome island (MAI) (Murat et al. 2010). Although the size and gene content of the MAI vary significantly between species, this region shares common characteristics in all MTB analyzed thus far: it is well conserved; it has a low GC content; it is located between two repetitive sequences; and an integrase is present in the flanking region of the first repetitive sequence (Matsunaga et al., 2007, Lefèvre et al., 2011). Dynamic analysis of MAI in M. magneticum AMB-1 revealed that this region as undergone a lateral gene transfer (Fukuda et al. 2006). Similar genomic regions have been found in the genomes of other MTB (Schübbe et al., 2003, Ullrich et al., 2005, Richter et al., 2007).

(more at link:  https://www.sciencedirect.com/science/article/pii/S094450131200047X )

JANUARY 3, 2020
(more at link: https://phys.org/news/2020-01-scientists-evidence-venus-volcanoes.html )\


Scientists find evidence that Venus has active volcanoes
by Suraiya Farukhi, Universities Space Research Association

This figure shows the volcanic peak Idunn Mons (at 46 degrees south latitude, 214.5 degrees east longitude) in the Imdr Regio area of Venus.
...
...

Dr. Filiberto and his colleagues recreated Venus' hot caustic atmosphere in the laboratory to investigate how the observed Venusian minerals react and change over time. Their experimental results showed that an abundant mineral in basalt—olivine—reacts rapidly with the atmosphere and within weeks becomes coated with the iron oxide minerals—magnetite and hematite. They further found that the Venus Express observations of this change in minerology would only take a few years to occur. Thus, the new results by Filiberto and coauthors suggest that these lava flows on Venus are very young, which in turn would imply that Venus does indeed have active volcanoes.

The Nano-Magnetic Dancing of Bacteria Hand-in-Hand with Oxygen

Ayesha Talib1
Abid Ali Khan1  *
Haroon Ahmed1
Ghulam Jilani2

Braz. arch. biol. technol. vol.60  Curitiba  2017  Epub Aug 17, 2017
http://dx.doi.org/10.1590/1678-4324-2017160769

1Department of Biosciences, COMSATS Institute of Information Technology, Park Road, Tarlai Kalan, 45550 Islamabad, Pakistan. ;
2University of Arid Agriculture - Department of Soil Sciences Rawalpindi, Punjab.

ABSTRACT

Magnetotactic bacteria are mostly microaerophilic found at the interface between oxic-anoxic zones. We report a magnetotactic bacterial strain isolated from an oil refinery sludge sample that grows aerobically in simple chemical growth medium, 9K. They open a new window of isolation of magnetic nanoparticles through an easy natural living system.

Key words: Magnetotactic Bacteria; Bacillus; Aerobic; Magnetosomes

Magnetotactic bacteria (MTB) are considered as self-propelled oxygen sensors with overall sizes of only 1 to 2 μm across. The cells contain chains of magnetic nanoparticles that act as magnetic nanocompasses and portray the best example of a nanoscale navigation system in nature (1,2 ). Magnetotaxis directional control can be applied from a weak magnetic field to force the cells towards specific areas where oxygen gradient is present (3).

MTB are widespread, motile, morphologically, phylogenetically, and physiologically diverse group of ubiquitous, gram-negative bacteria with the ability to orientate and migrate along geomagnetic field lines (4,5 ). This ability is based on intracellular magnetic structures, the magnetosomes, which comprise membrane bound nano-sized crystals of magnetic iron minerals, organized into chains via a dedicated cytoskeleton and are responsible for the cell magnetotactic behavior (6).

MTB are a heterogeneous group of aquatic prokaryotes and due to their high abundance in marine and freshwater they play an important role in biogeochemical cycling of iron and other elements (7). They are ubiquitous in sediments of freshwater, brackish, marine, and hypersaline habitats as well as in chemically stratified water columns of these environments. The presence of these bacteria depends on opposing gradient of reducing and oxidizing sulfur species and oxygen. Availability of soluble iron (Fe2+/Fe3+) is also the reason for their abundance in the particular environment (.

MTB provide an interesting example for the biosynthesis of magnetic nanoparticles (MNP) in nature. Intracellular (enveloped) crystals of (magnetite-Fe3O4) magnetic nanoparticles are synthesized through a process known as Biologically Controlled Mineralization (BCM) which results in monodispersed, complex nanostructure with unique magnetic properties useful for a variety of medical and industrial applications (9-11). MTB use biomineralization proteins to produce these magnetic crystals. Fe2+ and Fe3+ are first taken up in an energy-dependent process by a periplasmic binding-protein-dependent iron-transport system, accumulated and then rapidly precipitate in specialized sub cellular compartments, the magnetosome vesicles under chemically defined conditions (12,13 ). These vesicles serve as nanobioreactors by providing controlled redox, pH conditions and supersaturating iron concentrations for biomineralization. The membrane of the magnetosome is formed by the invagination of the cytoplasmic membrane and provides a natural coating to the matured magnetic crystal (14). MTB are microaerophiles or anaerobes which prefer environment with little or no oxygen and are considered as typical example of gradient organisms that are present at oxic/anoxic interface (OAI) (15,16 ). MTB play an important role in bioremediation by digesting heavy metals from toxic compounds in industrial areas.

On the basis of the aforementioned interesting properties of MTB, we have isolated aerobic bacteria from a nearby oil refinery sludge sample. To the best of our knowledge this is the first report of an MTB isolation from Pakistan.

A sludge sample was collected from a nearby oil refinery in a pre-sterilized 15 mL plastic tube and returned to the lab. 2 g of the sample was dissolved in 50 mL sterile distilled water and passed through a filter paper to remove the larger particles. 20 µL of the filtrate was added to 15 mL Luria broth and incubated on a shaker at 30 °C overnight. The medium was also added Clotrimazole (0.025 mg/mL) to avoid fungal growth. 10 µL of bacterial suspension from Luria broth was cultured in the 9K medium (pH 2.0) (17) at 30 °C on continuous shaking (120 rpm). The growth of the bacterial was regularly catered by measuring the Optical Density (OD) of the culture at a wavelength of 600 nm and subsequently plotted against time. Cells were harvested during the exponential phase, washed thrice in 0.9 M saline solution and tested for response (alignment) towards a permanent magnet. The live cells were imaged under a light microscope at 100X magnification. The bacterial cells were also Gram stained as per the standard procedure to classify them. Magnetometry analysis was performed in a MPMS-VSM (Magnetic Property Measurement System-Vibrating Sample Magnetometer) (Quantum Design, US). Specially designed diamagnetic containers were filled with (dried) purified bacterial cell mass and the M-vs-H was performed at room temperature (300 K). The samples were centered using a magnetic field of 1000-2000 Oe.

Most of the reported MTB are microaerophilic (or anaerobic) as per their oxygen requirements (17, 18). This very property of these bacteria makes them difficult candidates for culture under lab conditions (13). However, the reported bacterial strain in this study is totally aerobic and thrives well in simple medium, i.e. 9k. This make them suitable candidates to exploit them for magnetic nanoparticles biosynthesis and isolation in lab conditions.

The isolated strain from an oil refinery sludge was cultured in 9K (medium) a number of times to reproduce and confirm our results. It was found out that the bacterial strain was able to grow in 9K aerobically at 30-32 ºC. Reproduced growth plots of these bacterial cells are given in Fig. 1 which shows that these cells required around 3 hours as their lag phase followed by active cell division and rapid increase in the cell number until 15th hour. This was followed by a 2.5 hours stationary phase embarked by a balance between viable and dead cells. The toxic waste material accumulation and depletion of nutrients (to thrive) led to the decline phase of these cells 22-24 hours. The cell viability was found to be drastically reducing in the following measurements. Gram staining showed that they are gram negative rods (Inset of Fig. 1).


Figure 1.  Reproduced growth plots of bacterial cells cultured in 9K. Inset shows a light microscopy image of the gram (negative) stained bacilli.

The bacterial cells harvested (in exponential phase), washed 2-3 times in 0.9 M saline and a permanent magnet of strength (gradient) approximately 0.2 T was applied to one end of the tube to check if the bacterial cells would respond to it or not? The cultured bacterial cells upon exposure to a permanent magnet externally aligned parallel towards the field gradient (Fig. 2A). It was observed in this experimental test even by naked eye that these cells harboured magnetic content inside them which pushed them to swim towards the magnetic field gradient and aligned towards it. This experiment proved the fact that the bacterial cells isolated in this work are magnetic or to be precise magnetotactic. However, when 9K was treated

the same way, it showed no alignment of any particles towards the magnet. This proves the fact that these bacteria have the capacity to grow in 9K aerobically capable of utilizing iron ions and biosynthesize magnetosomes (magnetic nanoparticles).

As already discussed, these bacterial cells were magnetically responsive towards a permanent magnet, however, it was also noticed that these cells were not strongly magnetic but rather had a weak magnetic response, i.e. it always took them some time to swim towards the applied magnetic gradient. To investigate further the magnetism of these nanomachineries, we performed physical characterization in a VSM, i.e. magnetization was plotted as a function of the applied magnetic field at room temperature. The purified cell mass (as shown in Fig. 2A) was dried and evaluated for their magnetic properties. The aim was to check if the magnetic moment of these particles is good enough to be detected by the magnetometer. The results proved that these dried cells were superparamagnetic at room temperature (300 K). The hysteresis loop resulted (Fig. 2B) clearly indicated the presence of magnetic nanoparticles inside these bacterial cells. This strengthen our previous results that we had obtained with permanent magnet exposure to these cells.

http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132017000100429

USGS Identifies Largest Continuous Oil and Gas

Resource Potential Ever Assessed

Estimates Include 46.3 Billion Barrels of Oil, 281 Trillion Cubic feet of Natural Gas, and 20 Billion Barrels of Natural Gas Liquids in Texas and New Mexico’s Wolfcamp Shale and Bone Spring
Formation

12/6/2018
Last edited 12/6/2018
Date: December 6, 2018
Contact: Interior_Press@ios.doi.gov

WASHINGTON - Today, the U.S. Department of the Interior announced the Wolfcamp Shale and overlying Bone Spring Formation in the Delaware Basin portion of Texas and New Mexico’s Permian Basin province contain an estimated mean of 46.3 billion barrels of oil, 281 trillion cubic feet of natural gas, and 20 billion barrels of natural gas liquids, according to an assessment by the U.S. Geological Survey (USGS). This estimate is for continuous (unconventional) oil, and consists of undiscovered, technically recoverable resources.

"Christmas came a few weeks early this year," said U.S. Secretary of the Interior Ryan Zinke. "American strength flows from American energy, and as it turns out, we have a lot of American energy. Before this assessment came down, I was bullish on oil and gas production in the United States. Now, I know for a fact that American energy dominance is within our grasp as a nation."

“In the 1980s, during my time in the petroleum industry, the Permian and similar mature basins were not considered viable for producing large new recoverable resources. Today, thanks to advances in technology, the Permian Basin continues to impress in terms of resource potential. The results of this most recent assessment and that of the Wolfcamp Formation in the Midland Basin in 2016 are our largest continuous oil and gas assessments ever released,” said Dr. Jim Reilly, USGS Director. “Knowing where these resources are located and how much exists is crucial to ensuring both our energy independence and energy dominance.”

Although the USGS has previously assessed conventional oil and gas resources in the Permian Basin province, this is the first assessment of continuous resources in the Wolfcamp shale and Bone Spring Formation in the Delaware Basin portion of the Permian. Oil and gas companies are currently producing oil here using both traditional vertical well technology and horizontal drilling and hydraulic fracturing.

The Wolfcamp shale in the Midland Basin portion of the Permian Basin province was assessed separately in 2016, and at that time it was the largest assessment of continuous oil conducted by the USGS. The Delaware Basin assessment of the Wolfcamp Shale and Bone Spring Formation is more than two times larger than that of the Midland Basin. The Permian Basin province includes a series of basins and other geologic formations in West Texas and southern New Mexico. It is one of the most productive areas for oil and gas in the entire United States.

“The results we’ve released today demonstrate the impact that improved technologies such as hydraulic fracturing and directional drilling have had on increasing the estimates of undiscovered, technically recoverable continuous (i.e., unconventional) resources,” said Walter Guidroz, Program Coordinator of the USGS Energy Resources Program.

Undiscovered resources are those that are estimated to exist based on geologic knowledge and already established production, while technically recoverable resources are those that can be produced using currently available technology and industry practices. Whether or not it is profitable to produce these resources has not been evaluated.

USGS is the only provider of publicly available estimates of undiscovered technically recoverable oil and gas resources of onshore lands and offshore state waters. The USGS Delaware Basin Wolfcamp shale and Bone Spring Formation assessment was undertaken as part of a nationwide project assessing domestic petroleum basins using standardized methodology and protocols.

The new assessment of the Delaware Basin Wolfcamp shale may be found online. To find out more about USGS energy assessments and other energy research, please visit the USGS Energy Resources Program website.

PRESS RELEASE
https://newatlas.com/largest-continuous-oil-gas-us/57579/

https://newatlas.com/bacteria-convert-co2-calcium-carbonate/11069/


Naturally occurring bacteria converts CO2 into calcium carbonate

By Darren Quick
February 23, 2009

Microbiologically induced calcite precipitation



Microbiologically induced calcium carbonate precipitation (MICP) is a bio-geochemical process that induces calcium carbonate precipitation within the soil matrix.[1] Biomineralization in the form of calcium carbonate precipitation can be traced back to the Precambrian period.[2] Calcium carbonate can be precipitated in three polymorphic forms, which in the order of their usual stabilities are calcite, aragonite and vaterite.[3] The main groups of microorganisms that can induce the carbonate precipitation are photosynthetic microorganisms such as cyanobacteria and microalgae; sulfate-reducing bacteria; and some species of microorganisms involved in nitrogen cycle.[4] Several mechanisms have been identified by which bacteria can induce the calcium carbonate precipitation, including urea hydrolysis, denitrification, sulphate production, and iron reduction. Two different pathways, or autotrophic and heterotrophic pathways, through which calcium carbonate is produced have been identified. There are three autotrophic pathways, which all result in depletion of carbon dioxide and favouring calcium carbonate precipitation.[5] In heterotrophic pathway, two metabolic cycles can be involved: the nitrogen cycle and the sulfur cycle [6]. Several applications of this process have been proposed, such as remediation of cracks and corrosion prevention in concrete,[7][8][9][10][11][12][13][14][15] biogrout,[16][17][18][19][20][21][22][23] sequestration of radionuclides and heavy metals.[24][25][26][27][28][29]

https://en.m.wikipedia.org/wiki/Microbiologically_induced_calcite_precipitation

Article
Open Access
Published: 18 February 2019

Carbonate formation in salt dome cap rocks by microbial anaerobic oxidation of methane

K. H. Caesar, J. R. Kyle, […]S. J. Loyd
Nature Communications volume 10, Article number: 808 (2019) Cite this article

1997 Accesses

3 Citations

9 Altmetric

Metrics details

Abstract

Major hydrocarbon accumulations occur in traps associated with salt domes. Whereas some of these hydrocarbons remain to be extracted for economic use, significant amounts have degraded in the subsurface, yielding mineral precipitates as byproducts. Salt domes of the Gulf of Mexico Basin typically exhibit extensive deposits of carbonate that form as cap rock atop salt structures. Despite previous efforts to model cap rock formation, the details of subsurface reactions (including the role of microorganisms) remain largely unknown. Here we show that cap rock mineral precipitation occurred via closed-system sulfate reduction, as indicated by new sulfur isotope data. 13C-depleted carbonate carbon isotope compositions and low clumped isotope-derived carbonate formation temperatures indicate that microbial, sulfate-dependent, anaerobic oxidation of methane (AOM) contributed to carbonate formation. These findings suggest that AOM serves as an unrecognized methane sink that reduces methane emissions in salt dome settings perhaps associated with an extensive, deep subsurface biosphere.

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Introduction

Earth’s climate is modulated by the concentration of atmospheric greenhouse gases. These gases (e.g., CO2 and CH4) are largely generated at depth and subsequently transported to surface environments. These gases may fail to reach the surface due to chemical reaction along the way, resulting in their degradation and the subsequent precipitation of mineral phases. The geochemical compositions of these diagenetic minerals can provide insight into the nature of degradation mechanisms, thus leading to a better understanding of the fate of subsurface gaseous and aqueous chemical species.

Evaporites, elemental sulfur, metal sulfides, and carbonate minerals can co-occur in unique diagenetic settings. Examples of this association include those observed in cap rocks formed atop Jurassic salt in the Gulf of Mexico Basin (GMB)1, Permian salt of Germany and the North Sea Basin2, and Triassic salt in northern Tunisia3. Similar deposits occur in Permian, hydrocarbon-bearing evaporite successions of the Delaware Basin in western Texas and Miocene strata in Carpathian basins of Poland, Ukraine, and Iraq4. These systems have been studied extensively due to their association with economic hydrocarbon and mineral resources5. Such environments provide appropriate conditions for microbial communities to take advantage of mineral-, aqueous-, and hydrocarbon-sourced reactants for metabolic gain. Despite the likelihood of active microbial cycling, little is known about the specific natures and impacts of these interactions.

The GMB subsurface represents one of the world’s best-developed salt dome provinces (Fig. 1), containing hundreds of salt structures associated with post-depositional diapiric movement of the Jurassic Louann Salt6,7,8. The Louann Salt consists primarily of halite with minor (1–5%) anhydrite and gypsum9. Dome structures form when salt mobilizes and intrudes into overlying strata, partially as a result of the preferential subsidence of surrounding sediments. The GMB is also known for its large deposits of oil and natural gas that typically accumulate along the flanks of salt domes as a result of confinement by structural traps10.


https://www.nature.com/articles/s41467-019-08687-z

Methane formation by metal-catalyzed hydrogenation of solid calcium carbonate

Noritetsu Yoshida, Takeshi Hattori, […]Takayuki Wada
Catalysis Letters volume 58, pages119–122(1999)Cite this article

238 Accesses

14 Citations

Abstract

A study of the hydrogenation of solid CaCO3 has shown that the addition of Pd and Ir catalysts causes a change in the gaseous product and, consequently, in the kinetics of the reaction. In the absence of catalyst, CO is formed at higher than 700 K with the activation energy of 236 kJ/mol and a nearly half order with respect to H2 pressure, which is explained by the mechanism consisting of predecomposition and reduction. In the presence of the catalysts, CH4 is exclusively formed even at 573 K at which the equilibrium decomposition pressure of CaCO3 is extremely low, 1.1 × 10−5 Torr. Activation energies found in the range 105–118 kJ/mol and the H2-pressure dependence of the initial rate suggest the direct interaction of CaCO3 with spilt-over hydrogen atoms.

https://link.springer.com/article/10.1023%2FA%3A1019017615013

Thermodynamics and kinetics of methane hydrate formation and dissociation in presence of calcium carbonate

Author links open overlay panelEktaChaturvediAjayMandal
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https://doi.org/10.1016/j.apt.2018.01.021
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Highlights
•
Dissolution of CaCO3 in water increases with pH of the solution.

•
Hydrate formation thermodynamics is affected by presence of CaCO3 powder in water.

•
Nucleation point for the hydrate formation is increased with % carbonate in water.

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Hydrate formation rate decreases with increase in concentration of CaCO3.

•
Phase stability curve shifts with the variation in CaCO3 concentration.


Abstract

Huge amount of gas hydrate deposits are identified in deep marine sediments, which may be considered as a future source of energy. Since carbonate is one of the major components of marine sediments, in the present study attention has been given to characterize methane hydrate formation and dissociation in presence of calcium carbonate. Experiments were performed with 0%, 2%, 4%, 6% and 10% by weight of calcium carbonate in distilled water. Extensive investigations have been done on pressure-temperature equilibrium behavior of hydrate formation and dissociation at varying concentrations of calcium carbonate. Hydrate formation rate was found to vary with concentration of calcium carbonate as the solubility of calcium carbonate in water is controlled by the presence of simultaneous chemical equilibria involving a high number of species like Ca2+, CO32−, HCO3−, CO2, etc. Induction time for hydrate formation has also been measured at different concentrations of carbonate. Nucleation point for the hydrate formation was observed to be slightly higher at higher concentration of calcium carbonate due to increased heat absorption. Dissociation enthalpy of hydrates was calculated by using Clausius-Clapeyron at different measured conditions. Moles consumption of methane gas during hydrate formation at different concentrations of carbonate was measured using real gas equation and found to be minimum at 10 wt%.

https://www.sciencedirect.com/science/article/pii/S0921883118300347

Deep Diving Scientists Discover Bubbling CO2 Hotspot


Gordz At Soda Springs

A researcher collects gas samples at Soda Springs in the Philippines. Photo: University of Texas Jackson School of Geosciences.

AUSTIN, Texas — Diving 200 feet under the ocean surface to conduct scientific research can lead to some interesting places. For University of Texas at Austin Professor Bayani Cardenas, it placed him in the middle of a champagne-like environment of bubbling carbon dioxide with off-the-chart readings of the greenhouse gas.

Cardenas discovered the region – which he calls “Soda Springs” – while studying how groundwater from a nearby island could affect the ocean environment of the Verde Island Passage in the Philippines. The passage is one of the most diverse marine ecosystems in the world and is home to thriving coral reefs.

The amazing bubbling location, which Cardenas captured on video, is not a climate change nightmare. It is linked to a nearby volcano that vents out the gases through cracks in the ocean floor and has probably been doing so for decades or even millennia. However, Cardenas said that the high CO2 levels could make Soda Springs an ideal spot for studying how coral reefs may cope with climate change. The site also offers a fascinating setting to study corals and marine life that are making a home among high levels of CO2.


“These high CO2 environments that are actually close to thriving reefs, how does it work?” said Cardenas, who is a professor in the Jackson School of Geosciences at UT Austin. “Life is still thriving there, but perhaps not the kind that we are used to. They need to be studied.”

Cardenas and his coauthors from institutions in the Philippines, the Netherlands and UT described Soda Springs along with multiple scientific findings about groundwater in a paper published this month in the journal Geophysical Research Letters.

The scientists measured CO2 concentrations as high as 95,000 parts per million (ppm), more than 200 times the concentration of CO2 found in the atmosphere. The readings range from 60,000 to 95,000 and are potentially the highest ever recorded in nature. The CO2 levels fall quickly away from the seeps as the gas is diluted in the ocean, but the gas still creates an elevated CO2 environment along the rest of the coastline of the Calumpan Peninsula, with levels in the 400 to 600 ppm range.

Cardenas is a hydrologist and not an expert on reef systems. He discovered Soda Springs while researching whether groundwater from the nearby land could be discharging into the submarine ocean environment, which is a phenomenon that is generally ignored by scientists looking at the water cycle, Cardenas said.

“It’s an unseen flux of water from land to the ocean,” he said. “And it’s hard to quantify. It’s not like a river where you have a delta and you can measure it.”

More at link... https://news.utexas.edu/2020/01/22/deep-diving-scientists-discover-bubbling-co2-hotspot/

Generation of methane in the Earth's mantle: In situ high pressure–temperature measurements of carbonate reduction

Henry P. Scott, Russell J. Hemley, [...], and Sorin Bastea

Additional article information

ABSTRACT

We present in situ observations of hydrocarbon formation via carbonate reduction at upper mantle pressures and temperatures. Methane was formed from FeO, CaCO3-calcite, and water at pressures between 5 and 11 GPa and temperatures ranging from 500°C to 1,500°C. The results are shown to be consistent with multiphase thermodynamic calculations based on the statistical mechanics of soft particle mixtures. The study demonstrates the existence of abiogenic pathways for the formation of hydrocarbons in the Earth's interior and suggests that the hydrocarbon budget of the bulk Earth may be larger than conventionally assumed.

Understanding the speciation of carbon at the high pressures and temperatures that prevail within the Earth has a long and controversial history. It is well known that terrestrial carbon exists in several forms: native, oxidized, and reduced in a wide variety of hydrocarbons. This complexity is demonstrated by many examples: diamonds in kimberlite formations; graphite in metamorphic rocks; CO2 emission from volcanoes; ubiquitous carbonate minerals in the crust; methane hydrates on and beneath the ocean floor; and petroleum reservoirs in sedimentary basins. Of particular interest are the stability and formation of reduced species such as methane and heavier hydrocarbons. The stability, formation, and occurrence of methane under low-pressure conditions of the Earth's crust are well established. Recently, methane and C2-C4 alkanes have been documented to occur in many locations for which isotopic evidence points to an abiogenic origin (
1, 2). Furthermore, it has been shown that nickel-iron alloys can catalyze the formation of CH4 from bicarbonate
(3), and that a variety of transition metal-bearing minerals can catalyze Fischer–Tropsch-type formation of hydrocarbons at conditions relevant to the upper crust
(4, 5). Yet the evidence is considered to rule out a globally significant abiogenic source of hydrocarbons
(2), and hydrothermal experiments suggest that with the exception of methane a vapor phase is required for the formation of heavier hydrocarbons (5). In contrast, theoretical calculations and experimental data have been presented in support of a persistent assertion that petroleum originates chiefly through abiogenic processes at the high pressures and temperatures found <100 km (6). The experiments, extending to 5 GPa and 1,500°C, involved mass spectroscopic analysis of quenched samples and found methane and smaller amounts of C2-C6 hydrocarbons. We report here in situ high pressure and temperature experiments to show that methane readily forms by reduction of carbonate under conditions typical for the Earth's upper mantle. The results may have significant implications for the hydrocarbon budget at depth in the planet.

Many factors are known to control the stability of carbon-bearing phases in the C-O-H system, including pressure, temperature, C/H ratio, and oxidation state, and it has long been appreciated that the relevant species in this system are C, O2,H2, CO, CO2,CH4, and H2O (7). At low pressures this system is well understood, and available thermodynamic databases can accurately predict phase stability. For example, studies of the C-O-H system in relation to crustal fluids and fluid inclusions have been carried out by using well established techniques (7, . Notably, theoretical modeling is both thermodynamically and observationally consistent at pressures <≈1 GPa (e.g., ref. 9) and can satisfactorily treat organic species (10). Previous experimental and theoretical work has shown that methane may be an important fluid phase at pressures of up to 1 GPa and low oxygen fugacities, and that methane may be the dominant C-bearing fluid phase at substantially reducing conditions (e.g., ref. . Furthermore, it has been shown that meteorite hydrocarbons can be formed by the thermal decomposition of FeCO3-siderite at low pressure (11). Thermodynamic calculations can be performed at higher pressures (12), but the system is poorly constrained by experimental work under the high-pressure conditions of the upper mantle (13). The importance of pressure is straightforward as it increases by ≈1 GPa (10 kbar) for every 30 km of depth in the Earth. Kimberlite eruptions, for example, typically come from depths near 150 km (5 GPa). Higher-pressure work has been completed on the effects of various species in the C-O-H system on the melt characteristics of mantle minerals (14, 15), but these results do not directly assess the stability of carbon-bearing phases.

METHODS
We have conducted in situ high-pressure and temperature experiments specifically designed to detect methane formation under geologically relevant conditions for the Earth's upper mantle. Starting materials were natural CaCO3-calcite, FeO-wüstite, and distilled H2O. Experiments were conducted by using diamond anvil cell (DAC) techniques: simultaneous high-pressure and high-temperature conditions were produced by both resistive (16) (T < 600°C) and laser heating (T > 1,000°C) methods. We used three different laser heating systems, including both single- and double-sided and both CO2 and Nd-YLF lasers (17, 18). DACs with anvil culets ranging between 350 and 700 μm in diameter were used. Sample chambers were constructed by drilling a hole ≈70% of the culet diameter into an initially 260-μm-thick spring steel foil, which was used as a gasket material; the gaskets were preindented before drilling to a thickness of ≈60 μm. Pressure was measured by use of the ruby fluorescence technique (19). CO2 and double-sided Nd-YLF laser heating experiments and Raman scattering and optical microscopy analyses were performed at the Geophysical Laboratory (17, 18). Pyrometry was used to determine sample temperature in selected runs. The x-ray measurements and double-sided Nd-YLF laser heating were performed at the High Pressure Collaborative Access Team facilities of the Advanced Photon Source, Argonne National Laboratory, Argonne, CA.

More at link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC521091/

Formation processes of methane-derived authigenic carbonates from the Gulf of Cadiz

Author links open overlay panel
Vitor H.Magalhãesa  LuisSomozaf

Show more at link
https://doi.org/10.1016/j.sedgeo.2011.10.013


Abstract

The Gulf of Cadiz, NE Atlantic, represents an area of extensive formation of methane-derived authigenic carbonates (MDAC), indicative of fluid seepage. These MDAC, that reach extraordinary length and thickness, were geophysically mapped and sampled and the recovered carbonate-cemented material has δ13C values as low as − 56.2‰ VPDB, indicating methane as the major carbon source. The MDAC form two main lithologic groups, one mainly comprising dolomite and the second dominated by aragonite. The dolomite-dominated samples were found along fault-controlled diapiric ridges, on some mud volcanoes and mud diapirs, all on the pathway of the Mediterranean Outflow Water, and along fault scarps. Aragonite pavements were found associated with mud volcanoes and along fault scarps, but are otherwise not restricted to the pathways of the Mediterranean Outflow Water. Based on the results from this study, we propose that the two lithologic groups reflect different geochemical formation environments associated with a formation model based on their morphology, mineralogy and geochemistry. The aragonite-dominated samples represent precipitation of authigenic carbonates at the sediment–seawater interface or close to it, in a high alkalinity environment resulting from anaerobic oxidation of methane-rich fluids venting into sulphate-bearing porewaters. In contrast, the dolomite-dominated samples result from cementation along fluid conduits inside the sedimentary column with a somewhat restricted seawater ventilation. The dolomite chimneys form in places presently swept by the strong flow of the Mediterranean undercurrent so that the unconsolidated sediments are eroded and the chimneys are exposed at the seafloor. The widespread and large abundance of MDAC is a direct evidence of extensive methane seepage episodes in the Gulf of Cadiz. The coincidence of the different lithologic types in close spatial and temporal association indicates a persistence of seepage episodes in some structures over large periods of time.

Graphical abstract

https://ars.els-cdn.com/content/image/1-s2.0-S0037073811002648-fx1_lrg.jpg

An Inexhaustible Source of Energy from Methane in Deep Earth

September 15, 2004

Untapped reserves of methane, the main component in natural gas, may be found deep in Earth’s crust, according to a recently released report in the Proceedings of the National Academy of Sciences of the United States of America (PNAS). These reserves could be a virtually inexhaustible source of energy for future generations. The team of researchers from Lawrence Livermore National Laboratory, Carnegie Institution’s Geophysical Laboratory, Harvard University, Argonne National Laboratory and Indiana University, South Bend, through a series of experiments and theoretical calculations, showed that methane forms under conditions that occur in Earth’s upper mantle.

Methane is the most plentiful hydrocarbon in Earth’s crust and is a main component of natural gas. However, oil and gas wells are typically only drilled 5 to 10 kilometers beneath the surface. These depths correspond to pressures of a few thousand atmospheres.

Using a diamond anvil cell, the scientists squeezed materials common at Earth’s surface — iron oxide (FeO), calcite (CaCO3) (the primary component of marble) and water to pressures ranging from 50,000 to 110,000 atmospheres and temperatures more than 2,500 degrees Fahrenheit — to create conditions similar to those found deep within Earth.

Methane (CH4) formed by combining the carbon in calcite with the hydrogen in water. The reaction occurred over a range of temperatures and pressures. Methane production was most favorable at 900 degrees Fahrenheit and 70,000 atmospheres of pressure.

The experiments show that a non-biological source of hydrocarbons may lie in Earth’s mantle and was created from reactions between water and rock — not just from the decomposition of living organisms.

“The results demonstrate that methane readily forms by the reaction of marble with iron-rich minerals and water under conditions typical in Earth’s upper mantle,” said Laurence Fried, of Livermore’s Chemistry and Materials Science Directorate. “This suggests that there may be untapped methane reserves well below Earth’s surface. Our calculations show that methane is thermodynamically stable under conditions typical of Earth’s mantle, indicating that such reserves could potentially exist for millions of years.”

The study is published in the Sept. 13-17 early, online edition of the PNAS.

The mantle is a dense, hot layer of semi-solid rock approximately 2,900 kilometers thick. The mantle, which contains more iron, magnesium and calcium than the crust, is hotter and denser because temperature and pressure inside Earth increase with depth. Because of the firestorm-like temperatures and crushing pressure in Earth’s mantle, molecules behave very differently than they do on the surface.

“When we looked at the samples under these pressures and temperatures, they revealed optical changes indicative of methane formation,” Fried said. “At temperatures above 2,200 degrees Fahrenheit, we found that the carbon in calcite formed carbon dioxide rather than methane. This implies that methane in the interior of Earth might exist at depths between 100 and 200 kilometers. This has broad implications for the hydrocarbon reserves of the planet and could indicate that methane is more prevalent in the mantle than previously thought. Due to the vast size of Earth’s mantle, hydrocarbon reserves in the mantle could be much larger than reserves currently found in Earth’s crust.”

https://m.phys.org/news/2004-09-inexhaustible-source-energy-methane-deep.html

FEATURE ARTICLE

22-AUG-2005

The search for methane in Earth's mantle

DOE/LAWRENCE LIVERMORE NATIONAL LABORATORY

In one experiment, a sample of iron oxide, calcite, and water is heated to 600°C at a pressure of about 2 gigapascals. Raman spectra of the sample show a carbon-hydrogen (C-H) stretching vibration at 2,932 centimeters-1, which is the industry-standard signature for methane.
Click here for a high resolution photograph.
Petroleum geologists have long searched beneath Earth's surface for oil and gas, knowing that hydrocarbons form from the decomposition of plants and animals buried over time. However, methane, the most plentiful hydrocarbon in Earth's crust, is also found where biological deposits seem inadequate or improbable--for example, in great ocean rifts, in igneous and metamorphic rocks, and around active volcanoes. Some scientists thus wonder whether untapped reserves of natural gas may exist in Earth's mantle.

A collaboration of researchers from Lawrence Livermore and Argonne national laboratories, Carnegie Institution's Geophysical Laboratory, Harvard University, and Indiana University at South Bend is finding that methane may also be formed from nonbiological processes. Experiments and calculations conducted by the team indicate that Earth's mantle may provide the temperature and pressure conditions necessary to produce methane.

The idea that methane could be formed nonbiogenically came from observing the solar system. In the 1970s, astronomer Thomas Gold proposed that methane must form from nonbiogenic materials as well as from biological decomposition because large amounts of methane and other hydrocarbons could be detected in the atmospheres of Jupiter, Saturn, Uranus, and Neptune. In fact, in studying Titan, Saturn's largest moon, researchers found seven different hydrocarbons. At the time Gold proposed this theory, conventional geochemists argued that hydrocarbons could not possibly reside in Earth's mantle.

They reasoned that at the mantle's depth--which begins between 7 and 70 kilometers below Earth's surface and extends down to 2,850 kilometers deep--hydrocarbons would react with other elements and oxidize into carbon dioxide. (Oil and gas wells are drilled between 5 and 10 kilometers deep.)

However, more recent research using advanced high-pressure thermodynamics has shown that the pressure and temperature conditions of the mantle would allow hydrocarbon molecules to form and survive at depths of 100 to 300 kilometers. Because of the mantle's vast size, its hydrocarbon reserves could be much larger than those in Earth's crust.

Simulating Thermochemical Conditions

Livermore's work on the methane research, led by chemist Larry Fried, uses a thermodynamics code called CHEETAH to simulate chemical reactions using data from the collaboration's experiments. Fried developed CHEETAH in 1993 for the Department of Defense (DoD) to predict the performance of different explosives formulations. Since then, Fried and his colleagues have continued to improve the code. (See S&TR, May 1999, Leveraging Science and Technology in the National Interest; June 1999, Unraveling the Mystery of Detonation; July/August 2003, A New Generation of Munitions; July/August 2004, Going to Extremes.)
Thermochemical calculations for a mixture of iron oxide, calcite, and water heated to 500°C show that methane is produced at pressures up to almost 7 gigapascals.

Click here for a high resolution photograph.
One improvement was to include intermolecular interaction potentials. As a result, CHEETAH can model accurate equations of state, describing the relationship of a material's pressure, volume, and temperature at the molecular level, for a broad range of thermodynamic conditions. Because materials behave differently under extreme pressures than they do at normal atmospheric pressure, the equation-of-state data produced with CHEETAH help improve the precision of other computer codes used to model materials for stockpile stewardship.

With funding from the Laboratory Directed Research and Development Program, Fried's team is using CHEETAH to analyze the data from experiments conducted at the Geophysical Laboratory and at Argonne. "CHEETAH was designed for defense-related efforts," says Fried. "Our current studies for the methane collaboration are validating the code for work in high-pressure chemistry. These results will in turn help us better understand the processes occurring in a high-explosive detonation."

For the methane experiments, researchers at the Geophysical Laboratory used Argonne's diamond anvil cell (DAC)--a small mechanical press that forces together the tips of two diamond anvils and creates extremely high pressures on a sample of a material held within a metal gasket. DACs allow researchers to measure material properties under static pressure and at varying pressures and temperatures over many hours. (See S&TR, December 2004, Putting the Squeeze on Materials.) Diamonds are used because they can withstand these ultrahigh pressures.

More at link: https://www.eurekalert.org/features/doe/2005-08/drnl-tsf082205.php

Abiotic methane formation during experimental serpentinization of olivine

Profile Thomas M. McCollom
PNAS December 6, 2016 113 (49) 13965-13970; first published November 7, 2016

https://doi.org/10.1073/pnas.1611843113

Edited by John M. Hayes, Woods Hole Oceanographic Institution, Berkeley, CA, and approved September 13, 2016 (received for review July 18, 2016)

Significance

Abiotic methane discharged from serpentinizing rocks supplies metabolic energy to chemosynthetic microbial communities and may have done so since the earliest lifeforms evolved on Earth. Several recent reports have claimed observation of abiotic formation of methane during low-temperature serpentinization of olivine-rich rocks during laboratory experiments. However, using 13C-labeled carbon sources, this study shows that the methane observed in such experiments is predominantly derived from background sources rather than abiotic synthesis. Conversely, more rapid production of methane is observed when an H2-rich vapor phase is present within the reaction vessel. Overall, the results indicate that in situ abiotic synthesis may contribute less methane to near-surface serpentinites than some recent studies have suggested.

Abstract

Fluids circulating through actively serpentinizing systems are often highly enriched in methane (CH4). In many cases, the CH4 in these fluids is thought to derive from abiotic reduction of inorganic carbon, but the conditions under which this process can occur in natural systems remain unclear. In recent years, several studies have reported abiotic formation of CH4 during experimental serpentinization of olivine at temperatures at or below 200 °C. However, these results seem to contradict studies conducted at higher temperatures (300 °C to 400 °C), where substantial kinetic barriers to CH4 synthesis have been observed. Here, the potential for abiotic formation of CH4 from dissolved inorganic carbon during olivine serpentinization is reevaluated in a series of laboratory experiments conducted at 200 °C to 320 °C. A 13C-labeled inorganic carbon source was used to unambiguously determine the origin of CH4 generated in the experiments. Consistent with previous high-temperature studies, the results indicate that abiotic formation of CH4 from reduction of dissolved inorganic carbon during the experiments is extremely limited, with nearly all of the observed CH4 derived from background sources. The results indicate that the potential for abiotic synthesis of CH4 in low-temperature serpentinizing environments may be much more limited than some recent studies have suggested. However, more extensive production of CH4 was observed in one experiment performed under conditions that allowed an H2-rich vapor phase to form, suggesting that shallow serpentinization environments where a separate gas phase is present may be more favorable for abiotic synthesis of CH4.

serpentinizationabiotic methanehydrothermal systems

Fluids discharged from actively serpentinizing ultramafic rocks in both subaerial and submarine settings are often enriched in methane (CH4) as well as molecular hydrogen (H2) (1⇓⇓⇓–5). The CH4 in these fluids can provide chemical energy to support chemosynthetic microbial communities (6, 7), and metabolic pathways linked to CH4 in serpentinizing environments may have been among the first to evolve on Earth (8⇓–10). Serpentinization has also been proposed as a possible source for the transient CH4 that has been reported in the atmosphere of Mars (11, 12).

The origin of the elevated CH4 found in many serpentinizing fluids has been the subject of considerable scientific study over the last several decades, with possible contributors including microbial methanogenesis, thermal decomposition of larger organic compounds, and abiotic synthesis from reduction of inorganic carbon in the subsurface (reviewed in ref. 13). Although laboratory experiments can help to constrain the contribution of abiotic synthesis to fluxes of CH4 in serpentinites, published studies have reported some seemingly conflicting results with regard to the potential for reduction of inorganic carbon to CH4 during serpentinization (14, 15). Experimental studies performed at high temperatures (300 °C and above) have shown that there exist strong kinetic barriers to abiotic CH4 synthesis unless certain catalytic minerals, such as NiFe alloys, are present (16⇓⇓⇓⇓–21). Conversely, several recent studies have reported abiotic synthesis of CH4 during reaction of olivine with aqueous solutions at much lower temperatures (25 °C to 200 °C) (22⇓⇓–25), although the kinetic barriers might be expected to preclude abiotic CH4 synthesis at these conditions.

Massive production of abiotic methane during subduction evidenced in metamorphosed ophicarbonates from the Italian Alps

Article

Open Access

Published: 22 February 2017
Massive production of abiotic methane during subduction evidenced in metamorphosed ophicarbonates from the Italian Alps

Alberto Vitale Brovarone, Isabelle Martinez, […]Imène Esteve


Nature Communications volume 8, Article number: 14134 (2017) Cite this article
More at link...
https://www.nature.com/articles/ncomms14134

Abstract

Alteration of ultramafic rocks plays a major role in the production of hydrocarbons and organic compounds via abiotic processes on Earth and beyond and contributes to the redistribution of C between solid and fluid reservoirs over geological cycles. Abiotic methanogenesis in ultramafic rocks is well documented at shallow conditions, whereas natural evidence at greater depths is scarce. Here we provide evidence for intense high-pressure abiotic methanogenesis by reduction of subducted ophicarbonates. Protracted (≥0.5–1 Ma), probably episodic infiltration of reduced fluids in the ophicarbonates and methanogenesis occurred from at least ∼40 km depth to ∼15–20 km depth. Textural, petrological and isotopic data indicate that methane reached saturation triggering the precipitation of graphitic C accompanied by dissolution of the precursor antigorite. Continuous infiltration of external reducing fluids caused additional methane production by interaction with the newly formed graphite. Alteration of high-pressure carbonate-bearing ultramafic rocks may represent an important source of abiotic methane, with strong implications for the mobility of deep C reservoirs.


Introduction

Alteration of ultramafic rocks generates highly reducing fluids that, in the presence of C may yield hydrocarbons of purely abiotic origin1,2. Abiotic methanogenesis in ultramafic rocks has been shown at natural conditions spanning seafloor hydrothermalism, magmatism and on-land subaerial serpentinization3. This is an important process in geo-astrobiology, as it is considered as a source of prebiotic organic compounds on Earth and Mars and their possible role on the origin of life4. At shallow depth on Earth, serpentinite-hosted seeps can produce high methane (CH4) fluxes, and play an important role at the geo-bio-hydrosphere/atmosphere interface3,5,6. At greater depth, abiotic methanogenesis may occur as well and has the potential to be an important process controlling the redistribution of C reservoirs and the redox state of the mantle, including via the precipitation of condensed organic C molecules. Although the possibility for abiotic CH4 and other hydrocarbons to form at high-pressure conditions is demonstrated by experimental studies7,8,9, the geological conditions and processes at their origin, as well as their manifestations in the rock record, are still poorly constrained.

Subducted sections of altered oceanic mantle lithosphere represent suitable environments for the production of H2 and abiotic CH4 at high-pressure conditions, as they may contain both ultramafic minerals with a high reducing potential (for example, unaltered olivine), and carbonated lithologies10, also known as ophicarbonates11,12. So far, the role of ophicarbonates in the deep C cycle has been considered as negligible above depths exceeding 200 km in subduction zones10,11,13. However, this conclusion refers to the behaviour of these rocks under closed-system conditions, while their role in open systems affected by fluid percolation is still barely known.

Metamorphosed ophicarbonates affected by fluid-rock interactions at high-pressure conditions provide the opportunity to assess whether H2 and abiotic CH4 are released at subduction zones, and to which extent. Here we present natural evidence for intense high-pressure abiotic methanogenesis, and related graphitization of ultramafic mantle rocks, induced by percolation of ultra-reduced fluids in metamorphosed ophicarbonates in the Lanzo peridotite massif, Italian Alps (Fig. 1). Alteration of carbonate-bearing ultramafic rocks in subduction zones, and plausibly other high-pressure settings, generates important fluxes of abiotic CH4 and can precipitate high amount of reduced C. Our finding may have significant impacts on our global understanding of the deep C cycle and deep hydrocarbon generations. These processes may have substantial consequences for the redox state of mantle rocks and magma generation, as well as for the mobility of reduced C species from deep reservoirs to shallow environments on Earth and possibly on other bodies of the Solar System, including the supply of pre-biotic molecules and nutrients to the biosphere, to gas reservoirs and to the atmosphere.

Methane seeps in the ocean are much more important to life in the ocean than we previously have suspected

More at link... http://martinhovland.weebly.com/icture

Sketch showing the effects of methane (and light oil) seeps in the ocean.
In this sketch, the following legend applies:
1) ebullition of bubbles,
2) hydroacoustic flares,
3) methane concentration anomalies,
4) aureoles (visual, chemical, mineralogical, biological),
5) topographical effects,
6  ) MDAC development,
7) bacterial mats,
8 ) upwelling seawater,
9) downwelling water / entrainment,
10) slicks and nutrients on surface /birds feeding,
11) attraction of fish and other macro-fauna,
12) methane anomalies in atmosphere.
Note, that not all of these effects occur at all methane macro-seeps that have been described so far.

Discussion and conclusions

With numerous macro seeps and abundant gas-charged sediments and an apparently reliable and steady flux of methane and other nutrients to the water column, there are the following beneficial (significant) effects:
1)     A rugged terrain, which undoubtedly leads to induced turbulence in the bottom
currents,
2)     Hard-rock surfaces with many nooks and crannies, for benthic organisms to utilize for attachment and fish and other organisms to utilize for shelter
3)     Cryptic micro-environments for many types of microorganisms to utilize for primary production
4)     Flow of allochtonous chemicals, some of which will act as ‘fertilizers’ for primary producers
5)     Plenty of authigenically precipitated (inorganic) carbonate (calcite and aragonite) for boring organisms to utilize and extract.

There are still several questions remaining to be answered in relation to seeps like the Heincke seep.

One is an old question:

to which extent does visible, not to say diffusive and invisible (micro) seeps of hydrocarbons contribute to the total carbon cycle in the regional area? Another important question is to what extent such seeps contribute to the total atmospheric methane and carbon dioxide content (Hovland et al., 1993; Judd e al., 2002). A third question is if the seeps can be used for general hydrocarbon exploration (Thrasher et al., 1996). Although all of these questions have been addressed before, it is only ongoing and future quantitative and holistic research and more fieldwork that can positively contribute to answer them.

The increased use of high-resolution multibeam systems for seafloor mapping has led, not only to pockmarks being recognized and mapped worldwide, but also to the distinction between various types of pockmarks (Pinet et al., 2010; Judd and Hovland, 2007; Hovland et al., 2010; Weibull et al., 2010). Even though it is very rare to find pockmarks directly associated with macro-seepage,
as in the Scanner and REGAB examples, the pockmarks, and especially, the smallest ones, the unit-pockmarks, represent foci of ongoing active micro-seepage. Pockmarks are generally associated with any kind of fluid flow, where the fluids (gas, and/or liquids) originate from any depth in the subsurface (Judd and Hovland, 2007). Even though the first to discover and name pockmarks, Lew King and Brian MacLean (1970) suggested them to be solely related to hydrocarbon-prone areas, the occurrence of pockmarks in areas underlain by
metamorphic basement rocks (Pinet et al., 2010; Brothers et al., 2011) and hydrothermal activity, clearly demonstrates that thermogenic fluids and derivatives (biogenic methane) are not the only fluids responsible for these morphological features (Kelley et al., 1994). Thus, the fluids responsible for
pockmarks may be any fluid, ranging from groundwater to deeply sourced CO2, CH4, or locally sourced fluids of biogenic origin associated with the degradation of recently buried, organic-rich material.

Most of the significant effects of methane macro-seeps we have described and discussed herein, are, on a large scale, regarded as being positive, or beneficial to the marine and lacustrine environment. This is because the allochtonous input from the substratum may be regarded as causing a
general fertilization effect. Furthermore, this fact has also been recognised by the paleontologists, some of which have seeked to find seep-related carbonates in ancient sedimentary rock, as guides for the finding of spectacular animal remains, from large animals that utilized the seep-related organisms (Hammer et al., 2011).

Hydrothermal Salt Theory
Abstract AGU, 2010 Fall meeting

Session: EP01 Earth and Planetary Surface Processes General Contributions
A universal salt model based on under-ground precipitation of solid salts due to supercritical water ‘out-salting’

Martin Hovland, Centre for Geobiology, University of Bergen, Bergen, Norway, and Statoil ASA, Stavanger, Norway
Håkon Rueslåtten, NumericalRocks ASA, Trondheim, Norway
Hans Konrad Johnsen, Det Norske ASA, Trondheim, Norway
Tore Indreiten, Statoil ASA, Stavanger, Norway
More at link... http://martinhovland.weebly.com/the-hydrothermal-salt-theory.html

Abstract

One of the common characteristics of planets Earth and Mars is that both host water (H2O) and large accumulations of salt. Whereas Earth’s surface-environment can be regarded as ‘water-friendly’ and ‘salt hostile’, the reverse can be said for the surface of Mars. This is because liquid water is stable on Earth, and the atmosphere transports humidity around the globe, whereas on planet Mars, liquid water is unstable, rendering the atmosphere dry and, therefore, ‘salt-friendly’.

The riddle as to how the salt accumulated in various locations on those two planets, is one of long-lasting and great debate. The salt accumulations on Earth are traditionally termed ‘evaporites’, meaning that they formed as a consequence of the evaporation of large masses of seawater. How the accumulations on Mars formed is much harder to explain, as an ocean only existed briefly. Although water molecules and OH-groups may exist in abundance in bound form (crystal water, adsorbed water, etc.), the only place where free water is expected to be stable on Mars is within underground faults, fractures, and crevices. Here it likely occurs as brine or in the form of ice.

LokbSalt4

Based on these conditions, a key to understanding the accumulation of large deposits of salt on both planets is linked to how brines behave in the subsurface when pressurized and heated beyond their supercritical point. At depths greater than about 3 km (P>300 bars) water will no longer boil in a steam phase. Rather, it becomes supercritical and will attain the phase of supercritical water vapor (SCRIW) with a specific gravity of typically 0.3 g/cm3. An important characteristic of SCRIW is its inability to dissolve the common sea salts. The salt dissolved in the brines will therefore precipitate as solid particles when brines (seawater on the Earth) move into the supercritical P&T-domain (above 400ºC and 300 bars).

Numerical modeling of a hydrothermal system in the Atlantis II Deep of the Red Sea indicates that a shallow magma-chamber causes a sufficiently high heat-flow to drive a convection cell of seawater. The model shows that salt precipitates along the flow lines within the supercritical region (Hovland et al., 2006). During the various stages of planet Mars’ development, it must be inferred that zones with very high heat-flow also existed there. This meant that water (brine) confined in the crust of Mars was mobilized in a convective manner and would pass into the supercritical water zone during the down-going leg (the recharge leg) of the convective cell. The zones with supercritical out-salting would require accommodation space for large masses of solid salt, as modeled in the Red Sea analogy. However, as the accommodation space for the solid salt fills up, it will pile up and force its way upwards to form large, perhaps layered anticlines, as seen in the Hebes Mensa area of Mars and at numerous locations on Earth, including the Red Sea. Thus, we offer a universal ‘hydrothermal salt model’, which would be viable on all planets with free water in their interiors or on their surfaces, including Mars and Earth.

Hovland, M., Rueslåtten, H.G., Johnsen, H.K., Kvamme, B., Kutznetsova, T., 2006. Salt formation by supercritical seawater and submerged boiling. Marine and Petrol. Geol. 23, 855-69

Picture
Salt Cauldrons in the Red Sea

The Red Sea is the modern analogy of what happened to the Atlantic Ocean about 112 million years ago. It is a modern rifting ocean, where seawater comes very close to the magmachamber ("MC" in the above sketch). Here the water becomes supercritical and most of the salt is precipitated subsurface. Because there is no room for salt in the sub-surface, the solid salt particles flow upwards towards the surface, where it either flows out onto the seafloor or builds great salt domes and ridges (yellow hills on the sketch). These are salt domes (previously called salt diapirs). Such structures also occur on Mars, for example Hebes Mensa. Such salt domes can also pipe internal flows of water and petroleum.

See our article here: http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2117.2006.00290.x/abstract;jsessionid=12C5F2B88630441A2E8B3EFBFC6BFB1E.d01t02?deniedAccessCustomisedMessage=&userIsAuthenticated=false

Oil Seeps in the Gulf of Mexico

More.... https://earthobservatory.nasa.gov/images/36873/oil-seeps-in-the-gulf-of-mexico


×This page contains archived content and is no longer being updated. At the time of publication, it represented the best available science.
Oil Seeps in the Gulf of Mexico
May 13, 2006

Oil Seeps in the Gulf of Mexico
May 13, 2006JPEG

May 13, 2006TIFF

Google Earth - May 13, 2006KML

Although accidents and hurricane damage to infrastructure are often to blame for oil spills and the resulting pollution in coastal Gulf of Mexico waters, natural seepage from the ocean floor introduces a significant amount of oil to ocean environments as well. Oil spills are notoriously difficult to identify in natural-color (photo-like) satellite images, especially in the open ocean. Because the ocean surface is already so dark blue in these images, the additional darkening or slight color change that results from a spill is usually imperceptible.

Remote-sensing scientists recently demonstrated that these “invisible” oil slicks do show up in photo-like images if you look in the right place: the sunglint region. This pair of images includes a wide-area view of the Gulf of Mexico from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite on May 13, 2006 (top), and a close up (bottom) of dozens of natural crude oil seeps over deep water in the central Gulf.

The washed-out swath running through the scene is where the Sun is glinting off the ocean’s surface. If the ocean were as smooth as a mirror, a sequence of nearly perfect reflections of the Sun, each with a width between 6-9 kilometers, would appear in that line, along the track of the satellite’s orbit. Because the ocean is never perfectly smooth or calm, however, the Sun’s reflection gets blurred as the light is scattered in all directions by waves. The slicks become visible not because they change the color of the ocean, but because they dampen the surface waves. The smoothing of the waves can make the oil-covered parts of the sunglint area more or less reflective than surrounding waters, depending on the direction from which you view them.

Formation of Si-Al-Mg-Ca-rich zoned magnetite in an end-Permian phreatomagmatic pipe in the Tunguska Basin, East Siberia

Neumann, Else-Ragnhild; Svensen, Henrik H.; Polozov, Alexander G.; Hammer, Øyvind

Abstract

Magma-sediment interactions in the evaporite-rich Tunguska Basin resulted in the formation of numerous phreatomagmatic pipes during emplacement of the Siberian Traps. The pipes contain magnetite-apatite deposits with copper and celestine mineralization. We have performed a detailed petrographic and geochemical study of magnetite from long cores drilled through three pipe breccia structures near Bratsk, East Siberia. The magnetite samples are zoned and rich in Si (≤5.3 wt% SiO2), Ca, Al, and Mg. They exhibit four textural types: (1) massive ore in veins, (2) coating on breccia clasts, (3) replacement ore, and (4) reworked ore at the crater base. The textural types have different chemical characteristics. "Breccia coating" magnetite has relatively low Mg content relative to Si, as compared to the other groups, and appears to have formed at lower oxygen fugacity. Time series analyses of MgO variations in microprobe transects across Si-bearing magnetite in massive ore indicate that oscillatory zoning in the massive ore was controlled by an internal self-organized process. We suggest that hydrothermal Fe-rich brines were supplied from basalt-sediment interaction zones in the evaporite-rich sedimentary basin, leading to magnetite ore deposition in the pipes. Hydrothermal fluid composition appears to be controlled by proximity to dolerite fragments, temperature, and oxygen fugacity. Magnetite from the pipes has attributes of iron oxide-apatite deposits (e.g., textures, oscillatory zoning, association with apatite, and high Si content) but has higher Mg and Ca content and different mineral assemblages. These features are similar to magnetite found in skarn deposits. We conclude that the Siberian Traps-related pipe magnetite deposit gives insight into the metamorphic and hydrothermal effects following magma emplacement in a sedimentary basin.


Publication:
Mineralium Deposita, Volume 52, Issue 8, pp.1205-1222
Pub Date:
December 2017
DOI:
10.1007/s00126-017-0717-9
Bibcode:
2017MinDe..52.1205N
https://ui.adsabs.harvard.edu/abs/2017MinDe..52.1205N/abstract

.......

Intense basic magmatism in the Tunguska petroleum basin, eastern Siberia, Russia

April 1997
Petroleum Geoscience 3(4):359-369
DOI: 10.1144/petgeo.3.4.359
AE Kontorovich
AV Khomenko
Lev BurshteinShow all 7 authors

Abstract

The Tunguska basin, eastern Siberia, contains 3.5-8 km of Late Precambrian to Triassic sedimentary and igneous rocks. Source-reservoir-seal systems are present throughout the Upper Precambrian to Permo-Carboniferous interval. Hydrocarbon generation and accumulation largely preceded the formation of the Siberian traps, a Late Permian to Middle Triassic association of effusive and explosive extrusives and intrusive dolerites. The intrusives occur mainly in Palaeozoic strata and have profoundly affected hydrocarbon accumulation. The major process is of destruction of hydrocarbon accumulations, owing to the fact that substantial volumes of the Palaeozoic basin fill has been heated to 150°C plus. At lower temperatures experienced further from the contacts between the intrusions and the country rocks, organic matter thermal maturation levels may significantly exceed those related to burial alone. Water-mineral-hydrocarbon interactions in association with magmatic heating have produced a range of effects, including the generation of hydrocarbons rich in sulphur compounds such as mercaptans.

https://www.researchgate.net/publication/258049512_Intense_basic_magmatism_in_the_Tunguska_petroleum_basin_eastern_Siberia_Russia

Magnetotellurics (MT)

MT is an electromagnetic geophysical method for inferring the earth's subsurface electrical conductivity from measurements of natural geomagnetic and geoelectric field variation at the Earth's surface. Investigation depth ranges from 300 m below ground by recording higher frequencies down to 10,000 m or deeper with long-period soundings. Proposed in Japan in the 1940s, and France and the USSR during the early 1950s, MT is now an international academic discipline and is used in exploration surveys around the world. Commercial uses include hydrocarbon (oil and gas) exploration, geothermal exploration, carbon sequestration, mining exploration, as well as hydrocarbon and groundwater monitoring. Research applications include experimentation to further develop the MT technique, long-period deep crustal exploration, deep mantle probing, and earthquake precursor prediction research.


Hydrocarbon exploration

For hydrocarbon exploration, MT is mainly used as a complement to the primary technique of reflection seismology exploration.[3][4][5][6] While seismic imaging is able to image subsurface structure, it cannot detect the changes in resistivity associated with hydrocarbons and hydrocarbon-bearing formations. MT does detect resistivity variations in subsurface structures, which can differentiate between structures bearing hydrocarbons and those that do not.[7]

At a basic level of interpretation, resistivity is correlated with different rock types. High-velocity layers are typically highly resistive, whereas sediments – porous and permeable – are typically much less resistive. While high-velocity layers are an acoustic barrier and make seismic ineffective, their electrical resistivity means the magnetic signal passes through almost unimpeded. This allows MT to see deep beneath these acoustic barrier layers, complementing the seismic data and assisting interpretation.[8] 3-D MT survey results in Uzbekistan (32 x 32 grid of soundings) have guided further seismic mapping of a large known gas-bearing formation with complex subsurface geology.[9][10]

China National Petroleum Corporation (CNPC) and Nord-West Ltd use onshore MT more than any other oil company in the world, conducting thousands of MT soundings for hydrocarbon exploration and mapping throughout the globe.[11]

Link: https://en.m.wikipedia.org/wiki/Magnetotellurics

http://www.nlvocables.com/images/telluric_current/magnetotellurics.jpg

Water purification with magnetic particles
B. A. Bolto & T. H. Spurling

Environmental Monitoring and Assessment volume 19, pages139–143(1991)Cite this article

215 Accesses
13 Citations
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Abstract

CSIRO (Commonwealth Scientific and Industrial Research Organization) has for some years carried out research into more efficient ways of purifying water and wastewater. More intensive processing has been achieved by the use of finely divided solid reagents which can be regenerated and reused. The age-old problem of quickly separating the very small particles of loaded reagent from the accompanying liquid has been solved by utilizing a magnetic reagent in the form of magnetite, Fe3O4. A water clarification process is fully developed for the production of potable supplies from low quality ground and surface waters, with five plants in operation or under construction in Australia, the United Kingdom and Taiwan. The method has been extended to the removal of heavy metals from tailings dams, which has also reached full-scale with a plant near Canberra, to other industrial effluents, and more recently to sewage treatment. Successful pilot plant studies of the latter in Melbourne and Sydney have led to the decision to carry out a large-scale trial at Malabar, near Sydney.

https://link.springer.com/article/10.1007/BF00401305

Magnetic water treatment–A review of the latest approaches

Author links open overlay panel

Emil Chibowski, Aleksandra Szcześ

Show more
https://doi.org/10.1016/j.chemosphere.2018.03.160

Highlights
•Mechanisms of magnetic field (MF) effects are discussed.

•The effects are considered to be due to ion mechanism or surface mechanism.

•MF gradient is more important for the effects than the strength of field itself.

•Changes in the in the inter- and intra-cluster hydrogen bonds of water occur.

•Dynamically ordered liquid like oxyanion polymers allow explain the MF effects.

Abstract

Understanding of magnetic field (MF) effects observed during and after its action on water and aqueous solutions is still a controversial issue although the effects have been reported for at least half of century. The purpose of this paper was a brief review of the literature which deals with the magnetic force treatment effects. However, it is especially focused on the latest approaches, published mostly in the last decade which have developed our understanding of the mechanisms accompanying the field action. Generally, the changes in water structure via hydrogen bonding changes, as well as in intraclusters and between interclusters were taken into account, but the most remarkable progress was achieved in 2012 by Coey who applied the non-classical theory of nucleation mechanism of the formation of dynamically ordered liquid like oxyanion polymers (DOLLOP) to explain the magnetic field action. His criterion for the magnetic field effect to occur was experimentally verified. It was also proved that the gradient of the magnetic field is more important than the magnetic field strength itself. Some interesting approaches explaining an enhanced evaporation rate of water by MF are also discussed. More experimental results are needed for further verification of the DOLLOP theory to achieve a more profound understanding of the MF effects.

https://link.springer.com/article/10.1007/BF00401305

Related to magnetite and oil and gas formation. My bet is that pole flips cause and trap hydrocarbons as volcanic heat increases:
-----
https://milesmathis.forumotion.com/t577-the-last-magnetic-pole-flip-saw-22000-years-of-weirdness#5889

Presentation:  https://www.osti.gov/servlets/purl/1244477

Salt Tectonics: Fluid Era
-Fluid era (1934-1989)
-Both salt and surrounding sediments behave as viscous liquids
-Dense fluid overburden (sediments 1.7 – 2.0 gm/cc surface; 2.4-2.8 gm/cc at depth) sinks into the less dense salt (2.2 gm/cc) displacing it upward
-Once salt was buried deep enough to create a density inversion the salt would bulge and punch through the surface
-Internal structures mapped
-Diapirs comprised of a series of spines moving at different speeds
-Rock strength and faulting ignored
-By the end of the era - downbuilding (passive diapirism) considered the most important driving force for salt flow.
---------
Salt Tectonics: Brittle Era
 Brittle era (current)
 Sediments are strong, brittle, fractured overburden, NOT weak fluid
one.
 Fluid diapirs accelerated by thicker overburden, but diapirs inhibited
by brittle overburden that exceeded a certain critical thickness.
 i.e. diapirs stop rising when roof becomes too thick
 Density is a secondary factor and diapirs are triggered by a variety of
mechanisms.
 Three modes of diapirism recognized with reactive diapirism being the
most important way to initiate salt flow
 Reactive, Active, & Passive

Sanidia National Laboratories

Stable prenucleation mineral clusters are liquid-like ionic polymers

Raffaella Demichelis, Paolo Raiteri, Julian D. Gale, David Quigley & Denis Gebauer
Nature Communications volume 2, Article number: 590 (2011) Cite this article

Abstract

Calcium carbonate is an abundant substance that can be created in several mineral forms by the reaction of dissolved carbon dioxide in water with calcium ions. Through biomineralization, organisms can harness and control this process to form various functional materials that can act as anything from shells through to lenses. The early stages of calcium carbonate formation have recently attracted attention as stable prenucleation clusters have been observed, contrary to classical models. Here we show, using computer simulations combined with the analysis of experimental data, that these mineral clusters are made of an ionic polymer, composed of alternating calcium and carbonate ions, with a dynamic topology consisting of chains, branches and rings. The existence of a disordered, flexible and strongly hydrated precursor provides a basis for explaining the formation of other liquid-like amorphous states of calcium carbonate, in addition to the non-classical behaviour during growth of amorphous calcium carbonate.

Introduction

Calcium carbonate is a ubiquitous mineral, often created as a result of biomineralization, that is used by nature to perform many diverse functions in marine organisms, from skeletons and shells1 to even optical devices2. It also represents a common scale forming from hard water leading to technological problems3, though deposition of carbonates can be put to beneficial use as a means of sequestering carbon dioxide4. Despite its economic, ecological and scientific relevance, our knowledge is far from complete in regard to the early stages of the complex process that can ultimately produce this mineral.

Recently, there have been several key advances in our understanding of the nucleation and growth of calcium carbonate. It has been established that formation of amorphous calcium carbonate (ACC) and its subsequent transformation into crystalline phases provides a competing pathway to direct creation of the minerals calcite, aragonite and vaterite5,6,7. There is growing evidence that organisms exploit this alternative route for biomineralization as the amorphous phase can be stored until needed, at which point crystallization can be directed to yield the required crystalline polymorph. Furthermore, this process may not follow a conventional mechanism of the type envisaged within classical nucleation theory, in which an activation barrier must be overcome before significant association of ions can occur beyond simple ion pairing. The existence of stable prenucleation clusters of calcium carbonate before nucleation was initially shown by ion potential measurements in combination with analytical ultracentrifugation8, and later confirmed by cryogenic transmission electron microscopy9. The size of these clusters has been estimated to be either ~2 nm or 0.6–1.1 nm from the two experimental techniques, respectively; the discrepancy may be explained depending on the differing sensitivity of the methods to the surrounding hydration layer. While evidence grows for the presence of such stable clusters, the nature of these species in terms of composition and structure remains 'open to speculation'10.

Following the above experimental work, there have been attempts to use computer simulation to understand the formation of ACC11. Based on a force field model that was accurately calibrated against experimental free energies of solvation12, we have previously shown that both the free energy of ACC should monotonically decrease as more ion pairs of calcium carbonate add from solution and that the initial association of ion pairs also lowers the free energy, suggesting that nucleation of this material may be barrierless and therefore completely non-classical13. This finding unfortunately appears to contradict experiment. These earlier simulations were for solutions of pure calcium (Ca2+) and carbonate (CO32−) ions, that is, at high pH, whereas at experimental conditions, the pH is lower and bicarbonate ions (HCO3−) dominate the equilibrium. Experimental measurements of the drop in free calcium at the point of nucleation (Δn) show that the magnitude of this event decreases with increasing pH8, as shown in Supplementary Figure S1, apparently consistent with the simulations in the limit of high pH.

Despite the above investigations, the details of the prenucleation form of calcium carbonate remain unclear. The challenge is to conceive of a structural form that can exist with a stability intermediate between ion pairs in solution and the amorphous phase. Any such structure must retain a high degree of hydration otherwise its enthalpy would be less exothermic than that of the ion pairs, which are strongly solvated in water. Conversely, such clusters must also exhibit a high level of disorder to compete entropically with ACC.

To resolve this issue, we have performed molecular dynamics simulations of ions in solution to probe the details of their association. While it would normally be highly improbable to observe significant levels of aggregation using unbiased simulations, in this case a direct approach is feasible due to the spontaneous nature of cluster formation. In general, both the concentration of ions and pH can influence the balance of equilibria in solution, and we have therefore explored their impact for the specific case of calcium carbonate. Concentrations between 0.5 and 0.06 M are explored using extensive simulations of up to 70 ns. Here, the lower bound is approximately an order of magnitude greater than the experimental values at which it is possible to maintain solutions containing prenucleation clusters without them undergoing nucleation. In order to make direct contact with the actual experimental conditions, we have also performed more limited simulations for systems containing up to 6.4 million atoms that allow the bicarbonate and calcium concentrations to be reduced to 10 and 0.4 mM, respectively. By varying the relative concentrations of carbonate and bicarbonate ions, we have also simulated pH values in the range of 8.5–11.5, thereby spanning the experimental conditions.

In the present work, we show that the stable prenucleation clusters of calcium carbonate are in fact ionic polymers consisting of chains of cations and anions held together by only ionic interactions. These chains can be linear or branched, with a dynamic structure that is constantly evolving, yet stable with respect to the separated solvated ions.

Results
Atomistic simulation of speciation
Starting from free ions in solution, the initial stages of speciation involve the expected formation of the ion pair, CaCO30, and to a lesser extent, CaHCO3+ (ref 14). At the lower end of the pH range studied, where there is an excess of bicarbonate anions, further association is observed to form species of calcium coordinated to two or even three bicarbonate anions at 0.5 M, though bicarbonate ion pairing becomes unimportant as the concentration decreases. In contrast, calcium and carbonate begin to assemble themselves into a new structural motif consisting of chains of ions resembling a polymer (Fig. 1). These clusters can also include bicarbonate ions at low pH, but normally only at the end of the chain. As time progresses these chains lengthen by further collisions with ion pairs and/or ions.

Figure 1: Species observed in simulations of calcium (bi)carbonate solutions.
figure1

(a,b) Illustration of the species observed at low and high pH, respectively, with snapshots of the simulation box for 0.5 M at the centre (animations of the time–evolution of the simulation are available as Supplementary Movies 1 & 2 for pH 10 and 9.5, respectively). Here atoms are represented as spheres where calcium, carbon of carbonate, carbon of bicarbonate, oxygen and hydrogen are coloured green, blue, yellow, red and white, respectively. Ca–C and C–C distances below the cutoffs of 3.9 and 5.0 Å, respectively, are highlighted by purple bonds. For the largest cluster (top of b), the oxygen atoms are omitted for clarity so that the connectivity is apparent.

Full size image
Where the above chains differ from a conventional organic polymer is in the dynamic nature of their structure. Being held together only by ionic interactions, the chains can frequently break and reform allowing them to explore a range of configurations involving linear chains, rings and branched structures (Fig. 2). Full details of the coordination numbers of ions within clusters can be found in the Supplementary Figures S2–S7, including as a function of concentration and pH. Here, we focus on the high concentration case of 0.5 M where the majority of carbonate ions are part of clusters instead of ion pairs. In this case, the most common coordination number of carbonate by calcium is 2, which is consistent with the chain-like model. The next most common coordination numbers are 1 and 3, corresponding to an ion at the end of the chain and a branching point, respectively. Higher coordination numbers, which are characteristic of crystalline or ACC, are rarely observed. By forming a chain, only two waters are removed from the solvation sphere per ion, thereby retaining much of the enthalpy of solvation. Furthermore, these clusters have a dynamic structure, which includes the ability to fold and coil like a polymer. This conformational freedom and the associated entropic contribution to the free energy is the key to the stability of these dynamic clusters.

Figure 2: Cluster coordination environment.
figure2

Probability of finding a given coordination number of carbonate by calcium as a function of pH, conditional on the ion being part of a cluster. Points are labelled in the figure to indicate the underlying cluster structure corresponding to the coordination number. Here 'terminal' indicates a carbonate either at the end of a chain or in an ion pair; 'chain' represents a carbonate that bridges two calciums in a chain or ring; 'branch' denotes anions where the chain bifurcates. Error bars represent the s.d. of the average for successive 1-ns data windows.

Full size image
Formation of chain-like structures is observed in all simulations, regardless of pH and composition. What varies with these conditions is the size distribution, the lifetime of a given length and the degree of branching along the chain. At low pH, the chain length is limited by competition between carbonate and bicarbonate, with the latter species generally acting as a chain terminator as it forms a weaker link between two calcium ions. At low concentration, growth is limited by the total number of ions available within the simulation cell. Furthermore, the growth of clusters becomes diffusion limited and so as the concentration decreases, the time taken to grow larger aggregates increases.

The differing stability of clusters involving carbonate and bicarbonate can be determined from the cluster size distribution and its time evolution (Fig. 3 and also Supplementary Fig. S8 for intermediate pH values). In the presence of excess HCO3−, an exponential decay in cluster size is observed. Here, the simulations are limited by the amount of carbonate and the timescale for species to encounter each other in the solution. For carbonate-rich systems, we find a size distribution with multiple peaks that shift to increasing values with time until a limiting size is reached at higher concentration. This indicates that the clusters we observe are stable, rather than metastable, with respect to solvated ions or ion pairs in solution. The limiting size reached in the simulations is a consequence of the number of ions present, whereas at lower concentrations the size would be limited by the balance between the frequency of collisions between ions and the cluster, versus the rate of ion loss.

more at link: https://www.nature.com/articles/ncomms1604

Strong Gradients in Weak Magnetic Fields Induce DOLLOP Formation in Tap Water
Martina Sammer 1
, Cees Kamp 2
, Astrid H. Paulitsch-Fuchs 1
, Adam D. Wexler 1
,
Cees J. N. Buisman 1 and Elmar C. Fuchs 1,*

1 Wetsus, European Centre of Excellence for Sustainable Water Technology, Oostergoweg 9, 8911 MA
Leeuwarden, The Netherlands; martina.sammer@wetsus.nl (M.S.);
astrid.paulitsch-fuchs@wetsus.nl (A.H.P.-F.); adam.wexler@wetsus.nl (A.D.W.);
cees.buisman@wetsus.nl (C.J.N.B.)
2 Kamp Consult, Deventerweg 81, 7203 AD Zutphen, The Netherlands; ceeskamp@xs4all.nl
* Correspondence: elmar.fuchs@wetsus.nl; Tel.: +31-58-284-3162
Academic Editor: Wilhelm Püttmann

Received: 21 January 2016; Accepted: 23 February 2016; Published: 3 March 2016

Abstract:

In 2012 Coey proposed a theory on the mechanism of magnetic water treatment based
on the gradient of the applied field rather than its absolute strength. We tested this theory by
measuring the effect of very weak field magnets (ď 10 G) containing strong magnetic inhomogeneities
(∆B = 2 kG¨m´1) on tap water samples by the use of electric impedance spectroscopy (EIS) and laser
scattering. Our results show an increased formation of nm-sized prenucleation clusters (dynamically
ordered liquid like oxyanion polymers or “DOLLOPs”) due to the exposure to the magnetic field
and thus are consistent with Coey’s theory which is therefore also applicable to very weak magnetic
fields as long as they contain strong gradients.

1. Introduction
1.1. Magnetic Water Treatment

For a long time claims that the influence of a magnetic field on hard water influences the structure
and morphology of the calcium carbonate crystallisation have been met with scepticism by the
scientific community. This was mostly due to the absence of any plausible mechanism that could
explain the lasting effect of magnetic fields even after the exposure itself had ceased. Over the past
40 years a lot of research has been done on the effects of magnetic or electromagnetic treatment on
water, and over a hundred articles and reports are available in the literature [1–20]. Most of these
papers deal with calcium carbonate precipitation, a few report on biological effects. Researches
have convincingly shown [4,13,15,16] that magnetic treatment can influence the size and morphology
of calcium carbonate crystals, shifting the preferred habitus from calcite to aragonite. A probable
explanation was offered by Coey [21] based upon the works of Gebauer et al. [22] and Pouget et al. [23].
They describe a non-classical nucleation mechanism through the existence of stable prenucleation
clusters in subsaturated calcium carbonate solutions. Such clusters are discussed by Raiteri and
Gale [24], Gebauer and Cölfen [25], and were experimentally verified by ultracentrifuge experiments,
cryo-TEM and mass spectrometry [23–26]. It has been found that they remain hydrated [24]. They
can account for up to 50% of the calcium present in solution [23]. Whereas their structure has not
been determined yet, molecular dynamics simulations [27] describe them as disordered, hydrated
flexible ionic polymers or DOLLOPs (dynamically ordered liquid like oxyanion polymers). They
can aggregate into larger particles (up to about 100 nm) and form a liquid emulsion [26]. Coey [21]
Water 2016, 8, 79; doi:10.3390/w8030079 www.mdpi.com/journal/water Water 2016, 8, 79 2 of 19
describes how a magnetic field gradient can act on the DOLLOPs, which could account for the so-called
“magnetic memory” of water. He shows that contrary to pure mechanical stress, which is unable
to induce changes to the structure of DOLLOPs directly, a magnetic field gradient can act on the
DOLLOP surface and affect its growth dynamics. Bicarbonate ions, the predominant carbonate species
in solution at neutral pH, are considered to sit next to each other on one side of a polar nucleation
cluster and form the negatively charged surface. The other, positive, side is occupied by Ca2+ ions.
For the cluster to grow on the negatively charged side, protons in the HCO´3 ions must be replaced by
Ca2+ ions. It is upon these protons that the magnetic field acts: An inhomogeneous magnetic field,
i.e., gradients in the magnetic field, can force the exchange of singlet and triplet states of the proton spin
dimers present in the HCO´3l ayer, thereby facilitating their replacement by Ca2+ ions. This facilitation
is achieved by spin-dephasing of a proton dimer induced by the magnetic field gradient, because
proton spins precess at different rates at different field strengths. More exactly, the proton spins precess
in a given field B at the Larmor frequency fpB (fp = 42.6 MHzT´1
). In order to dephase the spins in
a proton dimer; they must precess at different frequencies so that the accumulated phase difference
∆φ fulfils the condition
∆φ ě π (1)
Based on this inequality Coey [21] derived a condition for an appreciable magnetic field effect, by
the use of which the effectiveness of the magnetic fields in this work will be analysed,
C “ 2
L
v
fpa∇B ě 1 (2)
where C is the Coey criterion, L the length of the magnetic device, v the velocity of the DOLLOPs, fP the
Larmor frequency of a proton, a the spin separation (0.25 nm) and ∇B the magnetic field gradient.
If C ě 1, then the magnetic device can effectively influence the crystallisation of calcium carbonate.
1.2. Water Core Magnets (WCMs)

Even before a reasonable theory on their mechanism was derived many companies had
commercialized various types of magnetic water treatment devices [28,29]. WCMs, a type of
commercially available devices, are employed to treat different kinds of water, like, e.g., potable
tap water or water in cooling loops [30]. A WCM consists of two parallel stainless steel cylinders,
welded together. Each cylinder is weakly magnetized and filled with water. The WCM is placed
into the water to be treated. There is experimental evidence [2] that treatment devices can leak small
amounts of iron from their casing changing the chemical and physical properties of the fluid to be
treated and can thus influence scaling in a merely chemical way [31]. In order to avoid such leakage,
we chose to expose our water samples to the WCM without contact to the device itself. Thus any
effects measured would stem only from exposure to the magnetic field. The average absolute field
strength of the WCMs used in this study is very weak, < 10 G at a distance of 5 mm from the surface,
only one order of magnitude above the earth’s field and 2–3 orders of magnitude lower than that of a
hard ferrite magnet [32]. However, its field contains a remarkable fine structure of strong gradients
(~2 kG¨m´1, see results section). Such strong gradients are, as described above, a prerequisite for
Coey’s theory. Therefore, WCMs provide an excellent basis for testing this theory.

1.3. Electrical Impedance Spectroscopy (EIS)

EIS allows the depiction and simulation of a liquid as simple electric circuit. An aqueous solution
behaves like a resistor and a capacitor in parallel: At frequencies below 105–106 Hz ions can move
along with the field (resistive behaviour), and at frequencies above that, the dielectric properties
of the solution begin to show (capacitive behaviour). At low frequencies (<104 Hz), ions are fast
enough to form layers at the electrodes, causing the so-called electrode polarisation (also referred
to as Maxwell-Wagner polarisation). Mesoscale objects like DOLLOPs are much heavier than ions.
Water 2016, 8, 79 3 of 19

They cannot follow the field as quickly and do not show the same polarisation behaviour. Electrode
polarisation has no direct electric circuit equivalent, but can be simulated as a combination of certain
elements [33]: A constant phase element (CPE) [34] with a Warburg impedance (W) in parallel to
account for ion migration; R and W impedance represent bulk properties of the electrolyte solution
and diffusion features of the probe in the solution [35]. The formation of DOLLOPs should thus be
detectable by EIS in a threefold manner: the increase of Raq due to the lower number of ions available,
the decrease of the electrode polarisation for the same reason, and the inability of the (much heavier)
DOLLOPs to follow the electric field and build layers, which should appear as a change of the CPE
and W parameters, respectively. Figure 1 depicts the measured spectrum of a tap water sample (dots)
and the calculated spectrum (line). The contribution of electrode polarisation is shown by simulating
curves using the equivalent circuit (Figure 1a) without both Warburg impedance and CPE. These
simulations are shown as dotted curves in Figure 1a,b. The contributions of the electrode polarisation
are highlighted as blue areas.

Water 2016, 8, 79 3 of 19 account for ion migration; R and W impedance represent bulk properties of the electrolyte solution and diffusion features of the probe in the solution [35]. The formation of DOLLOPs should thus be detectable by EIS in a threefold manner: the increase of Raq due to the lower number of ions available,the decrease of the electrode polarisation for the same reason, and the inability of the (much heavier)

DOLLOPs to follow the electric field and build layers, which should appear as a change of the CPE
and W parameters, respectively. Figure 1 depicts the measured spectrum of a tap water sample (dots)
and the calculated spectrum (line). The contribution of electrode polarisation is shown by simulating
curves using the equivalent circuit (Figure 1a) without both Warburg impedance and CPE. These
simulations are shown as dotted curves in Figure 1a,b. The contributions of the electrode polarisation
are highlighted as blue area

more at link:  https://res.mdpi.com/d_attachment/water/water-08-00079/article_deploy/water-08-00079-v2.pdf

Theoretical Foundations of Molecular Magnetism
Roman Boča, in Current Methods in Inorganic Chemistry, 1999

SUMMARY
1.
The magnetic susceptibility is introduced as a thermodynamic quantity which requires a partial differentiation of the magnetisation according to the applied field. This differential (isothermal) magnetic susceptibility differs from the frequent definition of mean magnetic susceptibility if the behaviour of the magnetic material is nonlinear.

2.
Different experimental techniques, depending on whether they register the magnetic response in static or alternating fields, yield different types of magnetic susceptibility. In certain situations a correction to the demagnetisation effects is necessary.

3.
A linkage between quantum theory (Hamiltonian, energy levels) and the macroscopic thermodynamical quantities (magnetisation, magnetic heat capacity, magnetic susceptibility) is given by statistical thermodynamics, in which the partition function adopts a key role.

More at link:s  https://www.sciencedirect.com/topics/materials-science/magnetic-susceptibility
https://www.sciencedirect.com/topics/physics-and-astronomy/ferromagnetic-materials
......

CALPHAD: Calculation of Phase Diagrams
In Pergamon Materials Series, 1998

4.3.1.3 Magnetic susceptibility measurements

Magnetic susceptibility measurement is an interesting technique for determining phase boundaries in magnetic systems as there is a distinct change in magnetic properties during a phase transition. In this technique the alloy is suspended on a pendulum and a magnetic field is applied. The sample is then heated or cooled through the phase transition and the sample is deflected from its position due to the change in its inherent magnetism. The magnetic field is then altered by changing the applied current and the pendulum brought back to its original position. The magnetic susceptibility (χ) is then defined as

(4.7)
where K is a constant, m is the mass of the sample and I is the compensating current. The magnetic susceptibility is then plotted as a function of temperature and sharp changes can be seen. Figure 4.7 shows a plot of χ vs temperature for a Fe-0.68at%Nb alloy (Ferrier et al. (1964)) where the phase boundaries are delineated very clearly. These results were then combined with DTA measurements for the liquidus to define the Fe-Nb phase diagram between 1200 and 1550°C (Ferrier et al. (1964)). Other examples of the use of the magnetic susceptibility technique can be found in Fe-P (Wachtel et al. 1963) and Fe-Si (Übelacker 1965).

...

Magnetic Hysteresis

A. Hernando, ... A. González, in Encyclopedia of Materials: Science and Technology, 2001

1 Technical and Fundamental Importance of the Magnetization Curve

Ferromagnetic materials are used for two main technological applications: (i) as flux multipliers forming the nucleus of electromagnetic machines, and (ii) as stores of either energy (magnets) or information (magnetic recording). The technical requirements to improve the material performance for both functions are related to the characteristics of the hysteresis loop and magnetization process. Flux multiplication requires high permeability and narrow hysteresis loop or low coercivity, μ0Hc. These properties are characteristic of the so-called “soft” magnetic materials. Storage requires high remanence and wide hysteresis loop in order to prevent demagnetization. Both properties are characteristic of “hard” magnetic materials.Even though for all types of applications the higher the spontaneous magnetization, Ms, the better the performance, the difficulty of increasing Ms artificially yields coercivity as the key parameter to be controlled by the material scientist. In fact, the history of the magnetic material research is the history of the progressive increase of the available coercivity spectrum. The maximum spontaneous magnetization is that corresponding to 0 K and it is known as saturation magnetization; its value is roughly given by the atomic magnetic moment, of the order of Bohr magneton, 10−23 JT−1, times the number of atoms per unit volume, typically 1029, that leads to μ0Ms of the order of 1 T. At the beginning of the twentieth century, just as at Plato’s time, the harder material, “hard steels,” had a coercivity μ0Hc=10−2 T, only two orders of magnitude larger than that of the known softer material, “purified iron.” At the beginning of the twenty-first century, the softer material is nanocrystalline Fe84Zr7B9 with coercivity μ0Hc=10−7 T whereas the harder material is nanocrystalline Fe84Nd7B9 with coercivity μ0Hc=1 T.Seven orders of magnitude separate the coercivity from the harder to the softer ferromagnetic material which compositionally differs only in 7 at.% of atoms, zirconium for the softer and neodymium for the harder. This result summarizes the best achievement of the science of magnetic materials. It has been the control of the magnetization curve, made possible from the deep understanding of its governing parameter, anisotropy, which has allowed the outstanding enhancement of the required properties. Anisotropy can be tailored through both composition and microstructure. Since μ0M and μ0H have the same units it is possible to compare the hysteresis loops of soft and hard materials, taking into account that the height of the loop of soft materials is seven orders of magnitude larger than its width, whereas the hysteresis loop of the best hard materials are square, exhibiting the same height as width, typically 1 T.

The central characteristics of ferromagnetic materials, the magnetization curve and the hysteresis loop, depend on the macroscopic magnetization measured along the direction of the applied field as a function of the field strength. We have seen that magnetization curve features are of maximum relevance for material application. From the fundamental point of view, the problems involved in the physical processes underlying hysteresis, such as relaxation, nonlinearity, metastability, energy dissipation, irreversibility, domain wall nucleation and propagation, coherent rotation, or incoherent modes, are the more attractive issues for basic scientists.

More at link: https://www.sciencedirect.com/topics/physics-and-astronomy/ferromagnetic-materials

RETURN TO ISSUE

Oxyanions catalyze group-transfer polymerization to give living polymers

Ira B. Dicker Gordon M. Cohen William B. Farnham Walter R. Hertler Evan D. LaganisDotsevi Y. Sogah
Cite this: Macromolecules 1990, 23, 18, 4034-4041
Publication Date:September 1, 1990
https://doi.org/10.1021/ma00220a002

More at link: https://pubs.acs.org/doi/abs/10.1021/ma00220a002

Magmatism, serpentinization and life: Insights through drilling the Atlantis Massif (IODP Expedition 357)

Author links open overlay panel
Gretchen L.Früh-Greena…Laura Bilenkeraa

Show more
https://doi.org/10.1016/j.lithos.2018.09.012
Get rights and content
Highlights

•
Seabed rock drills and real-time fluid monitoring for first time in ocean drilling

•
First time recovery of continuous sequences along oceanic detachment fault zone

•
Highly heterogeneous rock type and alteration in shallow detachment fault zone

•
High methane and hydrogen concentrations in Atlantis Massif shallow basement

•
Oceanic serpentinites potentially provide important niches for microbial life


Abstract

IODP Expedition 357 used two seabed drills to core 17 shallow holes at 9 sites across Atlantis Massif ocean core complex (Mid-Atlantic Ridge 30°N). The goals of this expedition were to investigate serpentinization processes and microbial activity in the shallow subsurface of highly altered ultramafic and mafic sequences that have been uplifted to the seafloor along a major detachment fault zone. More than 57 m of core were recovered, with borehole penetration ranging from 1.3 to 16.4 meters below seafloor, and core recovery as high as 75% of total penetration in one borehole. The cores show highly heterogeneous rock types and alteration associated with changes in bulk rock chemistry that reflect multiple phases of magmatism, fluid-rock interaction and mass transfer within the detachment fault zone. Recovered ultramafic rocks are dominated by pervasively serpentinized harzburgite with intervals of serpentinized dunite and minor pyroxenite veins; gabbroic rocks occur as melt impregnations and veins. Dolerite intrusions and basaltic rocks represent the latest magmatic activity. The proportion of mafic rocks is volumetrically less than the amount of mafic rocks recovered previously by drilling the central dome of Atlantis Massif at IODP Site U1309. This suggests a different mode of melt accumulation in the mantle peridotites at the ridge-transform intersection and/or a tectonic transposition of rock types within a complex detachment fault zone. The cores revealed a high degree of serpentinization and metasomatic alteration dominated by talc-amphibole-chlorite overprinting. Metasomatism is most prevalent at contacts between ultramafic and mafic domains (gabbroic and/or doleritic intrusions) and points to channeled fluid flow and silica mobility during exhumation along the detachment fault. The presence of the mafic lenses within the serpentinites and their alteration to mechanically weak talc, serpentine and chlorite may also be critical in the development of the detachment fault zone and may aid in continued unroofing of the upper mantle peridotite/gabbro sequences.

New technologies were also developed for the seabed drills to enable biogeochemical and microbiological characterization of the environment. An in situ sensor package and water sampling system recorded real-time variations in dissolved methane, oxygen, pH, oxidation reduction potential (Eh), and temperature and during drilling and sampled bottom water after drilling. Systematic excursions in these parameters together with elevated hydrogen and methane concentrations in post-drilling fluids provide evidence for active serpentinization at all sites. In addition, chemical tracers were delivered into the drilling fluids for contamination testing, and a borehole plug system was successfully deployed at some sites for future fluid sampling. A major achievement of IODP Expedition 357 was to obtain microbiological samples along a west–east profile, which will provide a better understanding of how microbial communities evolve as ultramafic and mafic rocks are altered and emplaced on the seafloor. Strict sampling handling protocols allowed for very low limits of microbial cell detection, and our results show that the Atlantis Massif subsurface contains a relatively low density of microbial life.

Magnetic signatures of serpentinization at ophiolite complexes

Article (PDF Available) in Geochemistry Geophysics Geosystems 17(:2969-2986 · September 2016 with 443 Reads 
DOI: 10.1002/2016GC006321

Abstract

We compare magnetic properties of 58 variably serpentinized peridotites from three ophiolite complexes (Pindos, Greece; Oman; Chenaillet, France) and the mid-Atlantic Ridge near the Kane fracture zone (MARK). The Pindos and Oman sites show low susceptibility and remanence (K < 0.02 SI; M s < 0.4 Am 2 / kg), while the Chenaillet and MARK sites show instead high susceptibility and remanence (K up to 0.15 SI; M s up to 6 Am 2 /kg), regardless of serpentinization degree. Petrographic observations confirm that Pindos and Oman samples contain serpentine with very little magnetite, while Chenaillet and MARK samples display abundant magnetite in serpentine mesh cells. Bulk rock analyses show similar amounts of ferric iron at a given serpentinization degree, suggesting that iron is oxidized during the serpentinization reaction in both cases, but that its distribution among phases differs. Microprobe analyses show iron-rich serpentine minerals (5–7 wt % FeO) in low-susceptibility samples, while iron-poor serpentine minerals (2–4 wt % FeO) occur in high susceptibility samples. The contrasted magnetic properties between the two groups of sites thus reflect different iron partitioning during serpentinization, that must be related to distinct conditions at which the serpentinization reaction takes place. We propose that magnetic properties of ophiolitic serpen-tinites can be used as a proxy to differentiate between high temperature serpentinization (>250–3008C) occurring at the axis (i.e., Chenaillet, similar to serpentinites from magmatically poor mid-ocean ridges), from lower temperature serpentinization (<200–2508C), likely occurring off axis and possibly during obduction (i.e., Pindos and Oman). At both settings, serpentinization can result in significant hydrogen release.

https://www.researchgate.net/publication/308695513_Magnetic_signatures_of_serpentinization_at_ophiolite_complexes

On Silica Activity and Serpentinization

B. Ronald Frost, James S. Beard
Journal of Petrology, Volume 48, Issue 7, July 2007, Pages 1351–1368, https://doi.org/10.1093/petrology/egm021
Published: 28 May 2007

Abstract

Serpentinites have the lowest silica activity of common crustal rocks. At the serpentinization front, where olivine, serpentine, and brucite are present, silica activities (relative to quartz) are of the order of 10−2·5 to 10−5, depending on the temperature. Here we argue that this low silica activity is the critical property that produces the unusual geochemical environments characteristic of serpentinization. The formation of magnetite is driven by the extraction of silica from the Fe3Si2O5(OH)4 component of serpentine, producing extremely reducing conditions as evinced by the rare iron alloys that partially serpentinized peridotites contain. The incongruent dissolution of diopside to form Ca2+, serpentine, and silica becomes increasingly favored at lower T, producing the alkalic fluids characteristic of serpentinites. The interaction of these fluids with adjacent rocks produces rodingites, and we argue that desilication is also part of the rodingite-forming process. The low silica activity also explains the occurrence of low-silica minerals such as hydrogrossular, andradite, jadeite, diaspore, and corundum in serpentinites or rocks adjacent to serpentinites. The tendency for silica activity to decrease with decreasing temperature means that the presence of certain minerals in serpentinites can be used as indicators of the temperature of serpentinization. These include, with decreasing temperature, diopside, andradite and diaspore. Because the assemblage serpentine + brucite marks the lowest silica activity reached in most serpentinites, the presence and distribution of brucite, which commonly is a cryptic phase in serpentinites, is critical to interpreting the processes that lead to the hydration of any given serpentinite.

Onset and Progression of Serpentinization and Magnetite Formation in Olivine-rich Troctolite from

IODP Hole U1309D
James S. Beard, B. Ronald Frost, Patricia Fryer, Andrew McCaig, Roger Searle, Benoit Ildefonse, Pavel Zinin, Shiv K. Sharma
Journal of Petrology, Volume 50, Issue 3, March 2009, Pages 387–403, https://doi.org/10.1093/petrology/egp004
Published: 19 February 2009

Abstract

Serpentinization of olivine-rich troctolite from core 227, Integrated Ocean Drilling Program (IODP) Hole U1309D ranges from <10% to >90%. Two episodes of serpentinization are recognized. The first, dominant in weakly serpentinized samples, is an approximately isochemical (except for water) replacement of olivine (Fo84–85) by a mixture of serpentine (antigorite, Mg-number 92) and brucite (amakinite-rich; Mg-number 65). The compositions of the minerals in type 1 veins are a reflection of Fe–Mg exchange between olivine and the brucite + serpentine formed during early serpentinization. The early serpentinite veins (type 1) are thin (< 0·05 mm), irregular, and exploit pre-existing cracks in olivine. The presence of antigorite suggests that early serpentinization occurred at T > 300°C. Type 1 veins reflect rock-dominated serpentinization, became isolated early in their history, and persist as relicts in all but the most altered samples. The main episode of serpentinization is manifested by through-going lizardite (average Mg-number 96)–magnetite veins (type 2). Type 2 veins define an anastomosing foliation, may be several millimeters in width and appear to exploit pre-existing, favorably oriented type 1 veins. Type 2 veins reflect open-system serpentinization. Magnetite in these veins formed by oxidation of the Fe in brucite and serpentine, whereas addition of silica to the system converted the Mg-component of the brucite to serpentine. Magnetite forms one or more distinct bands in the interior of the vein and is never in direct contact with relict olivine. A brucite–serpentine mixture, similar to that found in type 1 veins, but with lizardite instead of antigorite, is commonly present at the margins of type 2 veins (i.e. where they are in reaction contact with relict olivine). We interpret type 2 veins as a steady-state system where brucite continually forms at the olivine–vein contact and then reacts out in the interior of the vein. This continual formation and destruction of brucite imposes an exceptionally low aSiO2 on the system. Magnetite and olivine are never in contact in type 2 veins (or anywhere else) because the olivine-out reaction yields ferroan brucite and not magnetite. The desilication of serpentine in the type 2 veins is a reflection of the inherent instability of Fe-rich serpentine with respect to magnetite at low silica activity. Thus, the composition of serpentine in equilibrium with magnetite in serpentinites is a function of serpentine–magnetite and not serpentine–olivine equilbria.

Issue Section: Original Papers

Introduction

Peridotite serpentinization and carbonation play important roles in facilitating large-scale cycling of volatiles between the atmosphere, hydrosphere, and lithosphere1, 2. The uptake of atmospheric and hydrospheric carbon during ultramafic rock carbonation particularly represents a natural analog to geologic carbon sequestration and is considered as one potential pathway to offset anthropogenic CO2 emissions into the Earth’s atmosphere3,4,5,6,7. Natural carbonation of ophiolite—alpine-type ultramafic rocks forms alteration assemblages known as ophicarbonate, soapstone, and listvenite. These different carbonation products differ in the composition of secondary sheet silicate phases and the abundance of carbonate and thus their bulk rock CO2 content. Listvenite is predominantly composed of carbonate and quartz and represents a desirable product during in situ CO2 sequestration in ultramafic formations. While natural ultramafic rock carbonation may take place over long time scales, its efficiency has yet to be proven on human time scales. Carbonation reaction parameters are extensively investigated by laboratory-scale hydrothermal experiments8,9,10,11, thermodynamic modeling3, 12. and natural analog studies13,14,15,16,17,18,19. However, a scheme that can delineate the carbonation reaction progress in situ has not yet been fully explored and upscaling of reaction parameters from small scale, controlled laboratory experiments to large scale, complex natural processes remains challenging20,21,22. Along the reaction path of hydrothermal alteration of ultramafic rock, silicate mineral replacement reactions concomitantly release Fe for incorporation into secondary oxide, sulfide, and carbonate phases23, 24. Of particular interest is the production and consumption of magnetite during reaction of ultramafic rock with hydrothermal fluids due to its strong influence on bulk rock magnetic properties25. If coherently observable at multiple scales, we propose that changes in rock magnetic properties related to peridotite serpentinization and subsequent carbonation can be linked to distinct steps along the reaction path, and hence that the reaction progress can be monitored by field magnetometry.

In this study, we investigate magnetic anomaly changes related to natural serpentinite carbonation using regional, outcrop-, and thin section-scale magnetometry coupled with microtextural analysis of mineral replacement reactions. The results show that the magnetic character of distinct alteration product assemblages changes in response to the stability of magnetic carrier phases. Progressive serpentinite carbonation is characterized by a transient increase in the magnetic field strength during intermittent carbonation. The final alteration product is almost devoid of magnetic carrier phases and thus characterized by a very weak magnetic field strength. These findings indicate that magnetic field measurements can be used to detect carbonation fronts in the field and to monitor reaction progress in space and time.

Multi-scale magnetic mapping of serpentinite carbonation

Masako Tominaga, Andreas Beinlich, […]Yumiko Harigane

Nature Communications volume 8, Article number: 1870 (2017) Cite this article

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Abstract

Peridotite carbonation represents a critical step within the long-term carbon cycle by sequestering volatile CO2 in solid carbonate. This has been proposed as one potential pathway to mitigate the effects of greenhouse gas release. Most of our current understanding of reaction mechanisms is based on hand specimen and laboratory-scale analyses. Linking laboratory-scale observations to field scale processes remains challenging. Here we present the first geophysical characterization of serpentinite carbonation across scales ranging from km to sub-mm by combining aeromagnetic observations, outcrop- and thin section-scale magnetic mapping. At all scales, magnetic anomalies coherently change across reaction fronts separating assemblages indicative of incipient, intermittent, and final reaction progress. The abundance of magnetic minerals correlates with reaction progress, causing amplitude and wavelength variations in associated magnetic anomalies. This correlation represents a foundation for characterizing the extent and degree of in situ ultramafic rock carbonation in space and time.

Introduction

Peridotite serpentinization and carbonation play important roles in facilitating large-scale cycling of volatiles between the atmosphere, hydrosphere, and lithosphere1, 2. The uptake of atmospheric and hydrospheric carbon during ultramafic rock carbonation particularly represents a natural analog to geologic carbon sequestration and is considered as one potential pathway to offset anthropogenic CO2 emissions into the Earth’s atmosphere3,4,5,6,7. Natural carbonation of ophiolite—alpine-type ultramafic rocks forms alteration assemblages known as ophicarbonate, soapstone, and listvenite. These different carbonation products differ in the composition of secondary sheet silicate phases and the abundance of carbonate and thus their bulk rock CO2 content. Listvenite is predominantly composed of carbonate and quartz and represents a desirable product during in situ CO2 sequestration in ultramafic formations. While natural ultramafic rock carbonation may take place over long time scales, its efficiency has yet to be proven on human time scales. Carbonation reaction parameters are extensively investigated by laboratory-scale hydrothermal experiments8,9,10,11, thermodynamic modeling3, 12. and natural analog studies13,14,15,16,17,18,19. However, a scheme that can delineate the carbonation reaction progress in situ has not yet been fully explored and upscaling of reaction parameters from small scale, controlled laboratory experiments to large scale, complex natural processes remains challenging20,21,22. Along the reaction path of hydrothermal alteration of ultramafic rock, silicate mineral replacement reactions concomitantly release Fe for incorporation into secondary oxide, sulfide, and carbonate phases23, 24. Of particular interest is the production and consumption of magnetite during reaction of ultramafic rock with hydrothermal fluids due to its strong influence on bulk rock magnetic properties25. If coherently observable at multiple scales, we propose that changes in rock magnetic properties related to peridotite serpentinization and subsequent carbonation can be linked to distinct steps along the reaction path, and hence that the reaction progress can be monitored by field magnetometry.

In this study, we investigate magnetic anomaly changes related to natural serpentinite carbonation using regional, outcrop-, and thin section-scale magnetometry coupled with microtextural analysis of mineral replacement reactions. The results show that the magnetic character of distinct alteration product assemblages changes in response to the stability of magnetic carrier phases. Progressive serpentinite carbonation is characterized by a transient increase in the magnetic field strength during intermittent carbonation. The final alteration product is almost devoid of magnetic carrier phases and thus characterized by a very weak magnetic field strength. These findings indicate that magnetic field measurements can be used to detect carbonation fronts in the field and to monitor reaction progress in space and time.

https://www.nature.com/articles/s41467-017-01610-4

The effects of serpentinization on density and magnetic susceptibility: a petrophysical model

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Paul B.Tofta Stephen E.Haggerty
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https://doi.org/10.1016/0031-9201(90)90082-9
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Abstract

New measurements are presented of initial magnetic susceptibility and density for serpentinized harzburgites from the Josephine Peridotite (Oregon). An inverse correlation between density and susceptibility, which is typical of these rocks and similar rocks from other localities, is not explained by simple serpentinization reactions. Calculations of density and susceptibility as a function of reaction progress for reactions that produce magnetite show susceptibilities that are larger than those observed at low degrees of serpentinization. Susceptibilities of Fe-bearing serpentine and brucite are calculated from a molecular field model initially developed for the olivine and orthopyroxene solid solutions. At high degrees of serpentinization, susceptibilities that are lower than those observed are predicted by reactions where iron is sequestered by serpentine and brucite. Observed density-susceptibility trends of serpentinized harzburgites fall between the values predicted by these limiting reactions. The observed properties may be modelled by multiple reactions involved in multi-stage serpentinization processes such that the production of magnetite increases with the degree of serpentinization. The empirical and calculated properties provide a complementary characterization of density and susceptibility values of serpentinites.

https://www.sciencedirect.com/science/article/abs/pii/0031920190900829

The magnetism of mantle xenoliths and potential implications for sub-Moho magnetic sources

Eric C. Ferré, Sarah A. Friedman, Fatíma Martín-Hernández, Joshua M. Feinberg, James A. Conder, Dmitri A. Ionov

Earth Sciences

Abstract

Mantle xenoliths provide our clearest look at the magnetic mineral assemblages below the Earth's crust. Previous investigations of mantle xenoliths suggested the absence of magnetite and metals, and proposed that even if such minerals were present, they would be above their Curie temperatures at mantle conditions. Here we use magnetic measurements to examine four exceptionally fresh suites of xenoliths, and show that magnetite occurs systematically, albeit in variable amounts depending on the tectonic setting. Specimens from low geotherm regions hold the largest magnetic remanence. Petrographic evidence shows that this magnetite did not form through serpentinization or other alteration processes. Magnetite, which is generally stable at the P-T-fO 2 conditions in the uppermost mantle, had to have formed either in the mantle or, less likely, in the volcanic conduit. In some cases, the source of the xenoliths was at temperatures <600°C, which may have allowed this portion of the lithospheric mantle to carry a magnetic remanence. Whether such magnetite carries a remanent magnetization or is simply the source of a strong induced magnetization, these new results suggest that the concept of the Moho as a major magnetic boundary needs to be revisited.

https://experts.umn.edu/en/publications/the-magnetism-of-mantle-xenoliths-and-potential-implications-for-

RESEARCH ARTICLE| OCTOBER 23, 2018
Near-seafloor magnetic signatures unveil serpentinization dynamics at ultramafic-hosted hydrothermal sites

Florent Szitkar ; Bramley J. Murton
Geology (2018) 46 (12): 1055–1058.
https://doi.org/10.1130/G45326.1
Article history

Abstract

A near-seafloor magnetic and bathymetric survey conducted by the autonomous underwater vehicle AutoSub 6000 over intermediate-temperature, ultramafic-hosted Von Damm Vent Field (Mid-Cayman spreading center, Caribbean Sea) revealed a moderate positive magnetic anomaly, in accordance with the magnetic response of other known ultramafic-hosted hydrothermal vent fields. However, compared with low-temperature ultramafic-hosted hydrothermal activity, the magnetic signature of this intermediate-temperature site indicates a slightly stronger magnetization contrast between the hydrothermal system and its host, but it remains considerably weaker than at high-temperature ultramafic-hosted hydrothermal vent fields. This observation highlights the nonlinear increase of magnetization production with temperature, as iron partitions into weakly magnetic brucite under 200 °C, but magnetite dominates above this temperature, leading to a sudden increase in the magnetic signature of a site. Our study is consistent with recent laboratory experiments and unveils the dynamics of the serpentinization reaction, enabling fine tuning of the magnetic technique for remotely locating hydrothermal systems. In addition to refining our understanding of the magnetic behavior of hydrothermal vent fields, these new results also reveal the orientation of the fluid pathway feeding the hydrothermal site and indicate the nonvertical structure of the complex network of fissures within the host rock and its associated tectonic feature—an oceanic core complex.

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Atlantic Ocean magnetite metasomatism igneous rocks Mid-Cayman Rise oxides plutonic rocks paleomagnetism North Atlantic Caribbean Sea geophysical methods ultramafics


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acoustical methods Atlantic Ocean bathymetry Caribbean Sea geophysical methods geophysical surveys hydrothermal vents igneous rocks magnetic anomalies magnetic methods magnetite magnetization metasomatism Mid-Cayman Rise North Atlantic oxides paleomagnetism plutonic rocks serpentinization sonar methods surveys temperature ultramafics Von Damm hydrothermal field

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https://pubs.geoscienceworld.org/gsa/geology/article-abstract/46/12/1055/565813/Near-seafloor-magnetic-signatures-unveil

Magnetic Monitoring of Serpentinization Reactions, Experimentation vs Oceanic Rocks

Carlut, J. H.; Malvoisin, B.; Brunet, F.; Cannat, M.; Horen, H.

Abstract

Ultramafic rocks are commonly exhumed in the seafloor. Serpentinization reactions take place during exhumation and are responsible for the growth of magnetite and the occurrence of an important magnetic signal. Characterization of the relationship between the degree of serpentinization and intensity of the magnetic signal is of interest for seafloor magnetic modeling, another interest is the prospect to quantify hydrogen and methane fluxes linked to magnetite creation. We have conducted an experimental study of serpentinization using olivine and pure water confined at 500bar and 250 to 350°C. The magnetic signal was used to monitor the reaction on a batch of samples. The sensitivity of magnetic signal allows to detect even low degree of reaction. The kinetics of the reaction could thus be continuously followed during the course of the experiments which lasted several months allowing to explore the importance of parameters such as temperature. At the end of experiments reaction products were characterized using SEM, X ray diffraction and rock magnetic methods. Results of the experiments show a linear relationship between the degree of serpentinization and magnetite production and the production of homogeneous grains of magnetite. Results are compared to new and already published data collected on serpentinized ultramafic rocks from the deep sea and ophiolites. Differences in the rock magnetic parameters are apparent and likely reflect contrasts in iron distribution within the alteration phases.

Publication:
American Geophysical Union, Fall Meeting 2010, abstract id. GP11A-0735

https://ui.adsabs.harvard.edu/abs/2010AGUFMGP11A0735C/abstract

Volume 178, 15 September 2013, Pages 55-69

Compositional controls on hydrogen generation during serpentinization of ultramafic rocks

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FriederKleina Thomas M.McCollomc
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https://doi.org/10.1016/j.lithos.2013.03.008
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Highlights
•
H2 generation during serpentinization varies as a function of protolith composition.

•
H2 generation during serpentinization varies as a function of temperature.

•
Serpentinization of olivine can cause the formation of a free H2 gas phase.

•
Peridotite + water → Fe-poor serpentine + Fe-bearing brucite ± magnetite.

•
Pyroxenite + water → Fe-rich serpentine + Fe-poor talc, but no magnetite.


Abstract

Where ultramafic rocks are exposed to water at temperatures < 400 °C, they inevitably undergo serpentinization reactions to form serpentine ± brucite ± talc ± magnetite (in addition to minor or trace phase like chlorite, tremolite, secondary diopside, garnet, Ni-Fe sulfides, alloys). In many circumstances, this process releases substantial amounts of hydrogen. Since the compositional controls of the primary lithology on the secondary mineralogy, fluid composition, Fe-distribution, and H2 formation are not well established, we used thermodynamic computations to examine the equilibrium mineral assemblages, mineral compositions and the chemistry of fluids during serpentinization of 21 different ultramafic rock compositions and 10 distinct compositions of olivine between 25 °C and 400 °C at 50 MPa. Our models predict some systematic differences between serpentinization of olivine-dominated lithologies (i.e. peridotite) and of orthopyroxene-dominated lithologies (i.e. pyroxenite). Most notably, it is predicted that serpentinization of peridotite causes the formation of serpentine having elevated Fe+ 3/(Fe+ 3 + Fe+ 2) values, Fe-bearing brucite (at temperatures ≤ ca. 320 °C), and magnetite (at temperatures > ca. 200 °C), while serpentinization of pyroxenite does not produce magnetite, but instead forms Fe-rich serpentine with relative low Fe+ 3/(Fe+ 3 + Fe+ 2) values and Fe-poor talc. The predicted activities of dissolved hydrogen (aH2(aq)), dissolved silica (aSiO2(aq)), as well as the pH vary accordingly. At temperatures ≤ ca. 350 °C, fluids interacting with peridotite are more reducing, have lower aSiO2(aq) and higher pH than fluids interacting with pyroxenite. A direct correlation between the iron content of olivine, its stability relative to water, temperature and aH2(aq) is apparent from our calculations. In contrast to forsterite-rich olivine, fayalite-rich olivine can be stable to temperatures as low as 180 °C in the presence of water. As a consequence, the predicted aH2(aq) for serpentinization of fayalite is maximal at temperatures ≤ 180 °C.

https://www.sciencedirect.com/science/article/pii/S0024493713000960

Effect of water activity on rates of serpentinization of olivine

Hector M. Lamadrid, J. Donald Rimstidt, […]Robert J. Bodnar
Nature Communications volume 8, Article number: 16107 (2017) Cite this article


Abstract

The hydrothermal alteration of mantle rocks (referred to as serpentinization) occurs in submarine environments extending from mid-ocean ridges to subduction zones. Serpentinization affects the physical and chemical properties of oceanic lithosphere, represents one of the major mechanisms driving mass exchange between the mantle and the Earth’s surface, and is central to current origin of life hypotheses as well as the search for microbial life on the icy moons of Jupiter and Saturn. In spite of increasing interest in the serpentinization process by researchers in diverse fields, the rates of serpentinization and the controlling factors are poorly understood. Here we use a novel in situ experimental method involving olivine micro-reactors and show that the rate of serpentinization is strongly controlled by the salinity (water activity) of the reacting fluid and demonstrate that the rate of serpentinization of olivine slows down as salinity increases and H2O activity decreases.


Introduction

Serpentinization encompasses a series of hydration reactions that occur when ultramafic rocks are exposed to circulating aqueous fluids at temperatures lower than ∼400 °C, leading to the formation of serpentine phases (lizardite and chrysotile)±brucite±talc±magnetite, among other minerals1. Serpentinization affects the chemical composition, rheology, magnetic properties, seismic structure and habitability of the shallow lithosphere at slow- and ultraslow-spreading mid-ocean ridges, continental margins and forearc settings of subduction zones2,3,4,5,6,7,8. Serpentinization also influences subduction related processes9 and the geochemical cycling of volatile species (that is, H2O, CO2 and H2S) and fluid-mobile elements10,11,12,13. Recent findings suggest that serpentinization of olivine-rich lithologies also takes place on other planetary bodies, such as the icy moons of Jupiter and Saturn, which in turn, has important implications concerning their habitability14,15.

Despite the pivotal role that serpentinization plays in a number of geological and biological processes and its central role in current origin of life hypotheses16,17,18,19, few experimental studies have attempted to determine the rates of serpentinization reactions and the rates that have been reported diverge widely20,21,22,23,24,25. Furthermore, the environmental factors that affect the reaction rates are incompletely constrained. In the present work, we used synthetic fluid inclusions (SFIs)26,27 as micro-reactors in olivine crystals to monitor the serpentinization reaction with time. We trapped fluid with different initial salinities and followed reaction progress at serpentinization conditions (280 °C). The results show that the rates of olivine serpentinization are strongly influenced by the aqueous fluid salinity. The micro-reactor technique presents several advantages and permits monitoring mineral precipitation and water activity in situ and in real time.

https://www.nature.com/articles/ncomms16107

Thermodynamic evidence of giant salt deposit formation by serpentinization: an alternative mechanism to solar evaporation

Mathieu Debure, Arnault Lassin, […]Eric C. Gaucher
Scientific Reports volume 9, Article number: 11720 (2019) Cite this article

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Abstract

The evaporation of seawater in arid climates is currently the main accepted driving mechanism for the formation of ancient and recent salt deposits in shallow basins. However, the deposition of huge amounts of marine salts, including the formation of tens of metres of highly soluble types (tachyhydrite and bischofite) during the Aptian in the South Atlantic and during the Messinian Salinity Crisis, are inconsistent with the wet and warm palaeoclimate conditions reconstructed for these periods. Recently, a debate has been developed that opposes the classic model of evaporite deposition and argues for the generation of salt by serpentinization. The products of the latter process can be called “dehydratites”. The associated geochemical processes involve the consumption of massive amounts of pure water, leading to the production of concentrated brines. Here, we investigate thermodynamic calculations that account for high salinities and the production of soluble salts and MgCl2-rich brines through sub-seafloor serpentinization processes. Our results indicate that salt and brine formation occurs during serpentinization and that the brine composition and salt assemblages are dependent on the temperature and CO2 partial pressure. Our findings help explain the presence and sustainability of highly soluble salts that appear inconsistent with reconstructed climatic conditions and demonstrate that the presence of highly soluble salts probably has implications for global tectonics and palaeoclimate reconstructions.
....

Alternative Mechanisms of Salt Production

Emerging theories propose deep salt formation by supercritical fluids27 or exothermic serpentinization in mantle exhumation zones28,29,30. Several thermodynamic processes occur at depth and involve thermal reactions influenced by rifts and/or water consumption by precipitation of hydrated minerals31. Seawater infiltrates the crust due to fractures and faults induced by rifting (Fig. 1). When the seawater reaches supercritical conditions (407 °C and 300 bars), water splits off from the NaCl-rich brine. Thus, salts are segregated due to the dependence of solubility on temperature and pressure, with halite on one side and Mg- and Ca-rich salts on the other side, eventually forming the ponds observed today at the bottom of the Red Sea29. Serpentinization of mantle rocks produces brines as well. Serpentine contains approximately 13 wt% water; hence, the alteration of 1 m3 of peridotite into serpentine by seawater yields 10.5 kg of salt and additional by-products (e.g., magnetite, quartz, and hydrogen32). Thus far, theoretical calculations of the amount of salt formed by serpentinization have considered full serpentinization of the minerals constituting the mantle (e.g., olivine and pyroxenes). However, serpentines have a higher molar volume than mantle minerals and cause not only porosity clogging but also fracking, which can propagate serpentinization and thus contribute to enhancing the amount of concentrated brine production. In addition, the fractures caused by the mechanical stress induced by the volume increase31 allow the salt-bearing fluids to migrate upward within a hydrothermal plume or by buoyancy30,33. The temperature decrease that accompanies the ascent of the brine in the crust and/or the sediments lowers the salt solubility and allows salt deposition.

Figure 1
figure1
How and where evaporites and dehydratites (salts formed without solar evaporation) form depending on climate and geological contexts. Once formed, Mg-rich brines are able to migrate upward, react with sediments and then precipitate as dolomite or Mg-salts at the bottom of a sea.

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The mineralogical sequence of salts formed by serpentinization (hereafter referred to as dehydratites) is similar to that observed by seawater evaporation34. However, the origin of Mg-rich salt is under debate due to the uptake of Mg in serpentine and the formation of other by-products (e.g., brucite and talc). Nevertheless, it is worth noting that different retrograde processes after serpentinization (as a consequence of oceanic crust ageing) release abundant Mg in the fluid phase, hence favouring the formation of Mg-rich brines or salts, such as bischofite, kainite and carnallite. For example, post-serpentinization processes may produce brucite dissolution and hence the formation of Mg-rich fluids35. In addition, post-serpentinization processes produce Mg-rich, high-salinity fluids that can be effective agents in the metasomatism of country rocks. Low-temperature calcite replacing magnesite (and dolomite) previously formed after serpentine also releases aqueous Mg36. Some authors disregard the large-scale formation of salt by serpentinization arguing, without thermodynamic calculations, that the fluid resulting from the interaction between seawater and mantle rocks would be depleted in Mg, enriched in K and Ca and finally converted to CaCl2-rich brine37. To investigate this process, we calculate the processes by using the Pitzer formalism38, which is suited to describing salt solubility in complex mixtures of aqueous electrolytes.

Salt Formation by Serpentinization
We examine the interaction of Mg-rich orthopyroxene (enstatite) in peridotites with seawater as a function of temperature (25, 150, and 250 °C) and CO2 partial pressure (pCO2) (free, atmospheric pressure, 1.01325 MPa and 10.1325 MPa) but without considering volumetric expansion consequences on the permeability. We start the calculations with a solid/liquid ratio established according to an initial porosity of 10% (see Methods and Table 1), but serpentinization systematically stops because it completely consumes the water according to the reaction summarized by equation 1. As a result, 70 wt% of pristine orthopyroxene remains unaltered (Fig. 2 and Supplementary Information 1):

3MgSiO3+2H2O→Mg3Si2O5(OH)4+SiO2
(1)

https://www.nature.com/articles/s41598-019-48138-9