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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS1998

Mineralization of Bacteria in Terrestrial Basaltic Rocks: Comparison With Possible Biogenic Features in Martian Meteorite Allan Hills 84001

The identification of biogenic features altered by diagenesis or mineralization is important in determining whether specific features in terrestrial rocks and in meteorites may have a biogenic origin. Unfortunately, few studies have addressed the formation of biogenic features in igneous rocks, which may be important to these phenomena, including the controversy over possible biogenic features in basaltic martian meteorite ALH84001. To explore the presence of biogenic features in igneous rocks, we examined microcosms growing in basaltic small-scale experimental growth chambers or microcosms. Microbial communities were harvested from aquifers of the Columbia River Basalt (CRB) group and grown in a microcosm containing unweathered basalt chips and groundwater (technique described in. These microcosms simulated natural growth conditions in the deep subsurface of the CRB, which should be a good terrestrial analog for any putative martian subsurface ecosystem that may have once included ALH84001. Here we present new size measurements and photomicrographs comparing the putative martian fossils to biogenic material in the CRB microcosms. The range of size and shapes of the biogenic features on the CRB microcosm chips overlaps with and is similar to those on ALH84001 chips. Although this present work does not provide evidence for the biogenicity of ALH84001 features, we believe that, based on criteria of size, shape, and general morphology, a biogenic interpretation for the ALH84001 features remains plausible.

Thomas-Keprta, K. L.↗
NASA NTRSDate not supplied

TEM and XRD Investigation of Impact Glass Alteration Products: Amorphous Materials, Phyllosilicates and Everything in Between

Impact cratering is one of the most ubiquitous geologic processes shaping the surface of all solid bodies in our solar system. Impacts are also a major source of clay minerals and poorly crystalline, clay-like materials on Earth and Mars[1,2].These phyllosilicates and related clay-like phases comprise an incredibly complex group of materials, and their characterization, even in controlled laboratory settings, remains a challenging endeavor. The nature and origin of clay minerals and amorphous materials on Mars, which form a major component (~20-70 wt %) of rock and soil samples in Gale Crater as determined by the CheMin instrument on Curiosity, have remained ambiguous[3]. These amorphous phases likely fall on a spectrum between pristine volcanic and/or impact-produced primary materials and clay minerals and related phases formed from aqueous alteration. Amorphous materials are common weathering products in terrestrial sediments, soils, and paleosols [e.g., 4,5].Primary impact materials (glass, melt rocks)are comparable in some ways to those generated volcanically [6], and so it may be possible that an amorphous component is preserved within altered impactites. There are hundreds of thousands of impact craters on Mars, and Curiosity and Perseverance are currently exploring ancient impact craters. We hypothesize that the sediments and lithologies in Gale and Jezero Craters and elsewhere contain altered impact products; it is therefore important to better understand the composition and structure of these materials. Here we present the first results from a study characterizing materials produced from impact glass alteration–clay minerals, poorly crystalline/amorphous materials–in terrestrial craters using Transmission Electron Microscopy (TEM), powder X-ray diffraction (pXRD)and chemical (EDS) analysis.

Impact crater↗
NASA NTRSDate not supplied

MastCam Multispectral Examination of Rocks in the Sulfate-Bearing Terrain of Marker Band Valley, Gale Crater, Mars

A primary objective of the 4th extended mission of the Mars Science Laboratory rover Curiosity is to characterize the sulfate-bearing beds exposed on the slopes of Mt. Sharp (Aeolis Mons) above the clay-bearing beds of the Glen Torridon region characterized in the 3rd extended mission. Orbital reflectance spectroscopy from CRISM has indicated the presence of polyhydrated Mg sulfates in the portion of Mt. Sharp dubbed “Marker Band Valley” (MBV). The Marker Band is a darker toned, high-Ca pyroxene bearing unit that extends around much of Mt. Sharp above the first exposures of sulfate-bearing beds. Standoff imaging of the Marker Band indicates that it is not monolithic, but contains at least two subunits. Curiosity measures multispectral reflectance in the 430 to 1012 nm range with its Mastcam. While diagnostic spectral features of Mg-sulfates are not present in the Mastcam spectral range, a water overtone feature of some polyhydrated sulfates can be observed as a drop in reflectance in the longest wavelength one to three bands of Mastcam multispectral data. Other minerals associated with sulfate-generating alteration processes, most notably Fe-bearing minerals, are more readily detectable in Mastcam multispectral data.

W H Farrand↗
DOE OSTI2021

Infiltration metasomatism of the Allende coarse-grained calcium-aluminum-rich inclusions

We report on the mineralogy, petrography, and O and Al-Mg isotopic systematics of secondary mineralization in the metasomatically altered igneous Ca,Al-rich inclusions (CAIs) [compact type A (CTA), B1, B2, forsterite-bearing B (FoB), and C] from the CV3 carbonaceous chondrite Allende. This alteration affected mainly melilite, and to a lesser degree anorthite, and resulted in the formation of a variety of secondary minerals, including adrianite, Al-diopside, andradite, anorthite, calcite, celsian, clintonite, corundum, dmisteinbergite, ferroan olivine, ferroan monticellite, ferroan Al-diopside, forsterite, grossular, heazlewoodite, hedenbergite, hutcheonite, kushiroite, margarite, monticellite, Na-melilite, nepheline, pentlandite, pyrrhotite, sodalite, spinel, tilleyite, wadalite, and wollastonite. The secondary mineral assemblages are mainly defined by chemical compositions of the primary melilite replaced and elements introduced by an aqueous fluid. Gehlenitic melilite (Åk <35 ) in CTAs and mantles of B1s is mainly replaced by anorthite + grossular; clintonite, corundum, spinel, and Al-diopside are minor. Åkermanitic melilite (Åk 35-90 ) in type B2s, FoBs, and cores of B1s is replaced by the grossular + monticellite + wollastonite, grossular + monticellite, and grossular + Al-diopside assemblages; forsterite, spinel, clintonite, and Na-melilite are minor. In type Cs, lacy melilite (åkermanitic melilite with rounded inclusions of anorthite) is pseudomorphically replaced by the grossular + forsterite + monticellite and grossular + Al-diopside assemblages; Na-melilite is minor. Primary and secondary anorthites in the peripheral portions of CAIs are replaced by nepheline, sodalite, and ferromagnesian olivine. Some CAIs contain voids and cracks filled by andradite, hedenbergite, wollastonite, ±sodalite, ±grossular, ±monticellite, ±tilleyite, and ±calcite. All CAIs studied are surrounded by Wark-Lovering rims, fine-grained matrix-like rims composed of lath-shaped ferroan olivine and abundant nepheline grains, and a layer of salite-hedenbergite pyroxenes + andradite + wollastonite. Grossular associating with monticellite, Al-diopside, and forsterite and replacing åkermanitic melilite ( 27 Al/ 24 Mg ~ 2) has high 27 Al/ 24 Mg ratios (30–100) and shows no resolvable excess of radiogenic 26 Mg (26Mg*). The 27 Al/ 24 Mg ratios (7–10) and 26 Mg* (2–3‰) in the nearly monomineralic grossular veins crosscutting gehlenitic melilite are similar to those of the host melilite and plot along a regression line with 26 Al/ 27 Al ratio of ~5×10 –5 . Oxygen isotopic compositions of secondary minerals in the most Type Bs measured in situ with the UH Cameca ims-1280 and matrix-matched standards plot along mass-dependent fractionation line with Δ 17 O of ~ –3±2‰ with δ 18 O ranging from ~0 to ~10‰. Primary melilite and anorthite in the host CAIs are similarly 16 O-depleted, whereas spinel, forsterite, and most Al,Ti-diopside grains have 16 O-rich compositions (Δ 17 O ~ –25±2‰). Secondary grossular and forsterite in type Cs and type B1 CAI TS-34 show a range of Δ 17 O, from ~ –15 to ~ –1‰; the 16 O-enriched compositions of grossular and forsterite plot along the carbonaceous chondrite anhydrous mineral line. The similar ranges of Δ 17 O and positions on the three-isotope oxygen diagram are observed for primary anorthite; melilite is generally 16 O-depleted compared to anorthite (Δ 17 O ~ –5 to –1±2‰); spinel and fassaite are 16 O-rich (except very Ti-rich fassaite in TS-34 and CTA CAIs). We conclude that Allende CAIs experienced an open-system in situ metasomatic alteration at relatively high temperatures (200-250 °C) in the presence of CO 2 - and H 2 O-bearing fluid with Δ 17 O of ~ –3±2‰ followed by thermal metamorphism at ~ 500 °C on the CV chondrite parent asteroid. During the alteration, most elements were mobile: Si, Na, Cl, K, Fe, S, and Ni were introduced; Al, Ti, Mg, and Ba were locally mobilized; Ca and some Mg and Al were lost from the host inclusions. The alteration occurred after nearly complete decay of 26 Al, >3 Ma after crystallization of CAIs with the canonical ( 26 Al/ 27 Al) 0 of (5.25±0.02)×10 -5 ; 26 Mg* in grossular was inherited from the primary melilite and provide no chronological significance. Oxygen isotopic heterogeneity of primary minerals in the Allende CAIs at least partly is due to isotopic exchange with an aqueous fluid that largely affected melilite, anorthite, perovskite, Zr- and Sc-rich oxides and silicates, and possibly very Ti-rich fassaite.

58 GEOSCIENCES↗
NASA NTRS2023

An evolutionary system of mineralogy, Part VI: Earth’s earliest Hadean crust (> 4370 Ma)

Part VI of the evolutionary system of mineralogy catalogs 262 kinds of minerals, formed by 18 different processes, that we suggest represent the earliest solid phases in Earth’s crust. All of these minerals likely formed during the first tens of millions of years following the global-scale disruption of the Moon-forming impact prior to ~4.4 Ga, though no samples of terrestrial minerals older than ~4.37 Ga are known to have survived on Earth today. Our catalog of the earliest Hadean species includes 80 primary phases associated with ultramafic and mafic igneous rocks, as well as more than 80 minerals deposited from immiscible S-rich fluids and late-stage Si-rich residual melts. Earth’s earliest crustal minerals also included more than 200 secondary phases of these primary minerals that were generated by thermal metamorphism, aqueous alteration, impacts, and other processes. In particular, secondary mineralization related to pervasive near-surface aqueous fluids may have included serpentinization of mafic and ultramafic rocks, hot springs and submarine volcanic vent mineralization, hydrothermal sulfide deposits, zeolite and associated mineral formation in basaltic cavities, marine authigenesis, and hydration of subaerial lithologies. Additional Hadean minerals may have formed by thermal metamorphism of lava xenoliths, sublimation at volcanic fumaroles, impact processes, and volcanic lightning. These minerals would have occurred along with more than 180 additional phases found in the variety of meteorites that continuously fell to Earth’s surface during the early Hadean Eon.

Philosophy of mineralogy↗
DOE OSTI2024

M3SF-24LL010302052-Comprehensive Analysis of Radionuclide Interaction with Hydrothermally Altered Repository Materials

This progress report (Level 3 Milestone Number M3SF-24LL010302052) summarizes research conducted at Lawrence Livermore National Laboratory (LLNL) within the Crystalline Work Package Number SF-24LL01030205. The research is focused on actinide and radionuclide sequestration in hydrothermally altered repository materials. In FY24, we completed a rigorous analysis of Se sorption to iron oxide phases using our L-SCIE sorption database. This effort explicitly accounts for surface titration behavior of oxide surfaces that was the subject of a recently published manuscript (Han et al., 2023). With this in mind, our Se sorption analysis now yields a more robust workflow for developing self-consistent surface complexation modeling approaches that can be adapted to specific SCM conceptual and numerical approaches (i.e. non-electrostatic, diffuse layer, triple layer models). In late FY24, we plan to publish the results of our comprehensive surface complexation modeling of Se(IV) and Se(VI) sorption to iron oxide mineral phases and provide a path forward to developing robust radionuclide sorption models for use in performance assessment. In FY24, we also submitted a manuscript summarizing our approach to integrating radionuclide sorption and coprecipitation phenomena and evaluation of radionuclide partitioning values across a range of radionuclides relevant to performance assessment. We demonstrated our approach in detail using Se sorption and coprecipitation with iron oxide minerals as a test case. This manuscript was recently accepted for publication in Applied Geochemistry (Balboni et al., Accepted). We also continued experiments to identify radionuclide interaction with hydrothermally altered crystalline repository and backfill materials. Recent research performed at Los Alamos National Laboratory (LANL) and Sandia National Laboratory (SNL) has provided key insights regarding the hydrothermal alteration behavior of bentonite backfill in the presence of repository materials (steel, concrete, etc.). We are now examining how mineral alteration affects retardation behavior of a suite of radionuclides of interest to repository performance assessment. These experiments also allow us to test the predictive ability of our component additivity approach to surface complexation and ion exchange. Our guiding hypothesis is that a robust surface complexation/ion exchange model and associated database, developed using our L-SCIE approach, can effectively predict changes in radionuclide sorption behavior resulting from the hydrothermal alteration of mineralogy in a repository near field. A short update of results to date is presented below.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
NASA NTRS1986

Martian dust particles as condensation nuclei - A preliminary assessment of mineralogical factors

Experiments were performed to determine the factors influencing ice nucleation detected in Viking Lander data from the Mars surface. The study focused on the relationship between mineral properties and condensate formation under Mars conditions. Pulverized particles of the primary phases of basaltic rocks and their alteration products, expandable clay minerals and a nonexpandable clay mineral, and petrologically well-characterized regolith materials ranging from 10-60 microns in size, were studied. The powders were individually or in combinations mixed with water in a flowing CO2 atmosphere while calorimetry data was taken on the ice nucleation threshold. The ice-forming characteristics of the mixes were found to be a function of the crystallographic disregistry, chemical bonding, and active-site properties of the individual minerals. The crystalline materials were better nucleators of condensates than were the cryptocrystalline mineral specimens, while nonexpandable clay materials, particularly zeolite, were the more effective nucleators among the weathering product materials.

Gooding, J. L.↗
NASA NTRS1986

Terrestrial analogues of the surface rocks of Mars?

Evidence is presented which suggests that hisingerite, iddingsite, and several ferric sulfate minerals derived from deuteric alteration of iron-rich basalts on earth may provide clues to the evolutionary history of the surface of Mars. The characteristics of these minerals are pointed out, and their strong compositional and paragenetic similarities to Martian regolith materials are pointed out. These similarities are consistent with a mineral assemblage on Mars consisting of ferric-bearing phyllosilicate, sulfate, and oxyhydroxide phases. These phases could have been derived from postmagmatic deuteric alteration of volatile-rich iron-rich basaltic rocks containing fayalitic olivine, Fe pyroxenes, and accessory pyrrhotite.

Burns, R. G.↗
NASA NTRS1991

Use of high spectral resolution airborne visible/infrared imaging spectrometer data for geologic mapping: An overview

Specific examples of the use of AVIRIS (Airborne Visible/Infrared Imaging Spectrometer) high spectral resolution data for mapping, alteration related to ore deposition and to hydrocarbon seepage, and alluvial fans are presented. Correction for atmospheric effects was performed using flat field correction, log residuals, and radiative transfer modeling. Minerals of interest (alunite, kaolinite, gypsum, carbonate iron oxides, etc.) were mapped based upon the wavelength position, depth and width of characteristic absorption features. Results were checked by comparing to existing maps, results from other sensors (Thematic Mapper (TM) and TIMS (Thermal Infrared Multispectral Scanner)), and laboratory spectra of samples collected in the field. Alteration minerals were identified and mapped. The signal to noise ratio of acquired AVIRIS data, long to 2.0 microns, was insufficient to map minerals of interest.

Carrere, Veronique↗
NASA NTRS1999

Origin and Reactivity of the Martian Soil: A 2003 Micromission

The role of water in the development of the martian surface remains a fundamental scientific question. Did Mars have one or more "warm and wet" climatic episodes where liquid water was stable at the surface? If so, the mineral phases present in the soils should be consistent with a history of aqueous weathering. More generally, the formation of hydrated mineral phases on Mars is a strong indicator of past habitable surface environments. The primary purpose of this investigation is to help resolve the question of whether such aqueous indicators are present on Mars by probing the upper meter for diagnostic mineral species. According to Burns [1993], the formation of the ferric oxides responsible for the visible color of Mars are the result of dissolution of Fe (+2) phases from basalts followed by aqueous oxidation and precipitation of Fe" mineral assemblages. These precipitates likely included iron oxyhydroxides such as goethite (a-FeOOH) and lepidocrocite (g-FeOOH), but convincing evidence for these phases at the surface is still absent. The stability of these minerals is enhanced beneath the surface, and thus we propose a subsurface search for hydroxylated iron species as a test for a large-scale chemical weathering process based on interactions with liquid water. It is also possible that the ferric minerals on Mars are not aqueous alteration products of the rocks. A chemical study of the Pathfinder landing site concluded that the soils are not directly derived from the surrounding rocks and are enhanced in Mg and Fe. The additional source of these elements might be from other regions of Mars and transported by winds, or alternatively, from exogenic sources. Gibson [1970] proposed that the spectral reflectivity of Mars is consistent with oxidized meteoritic material. Yen and Murray [1998] further extend Gibson's idea and show, in the laboratory, that metallic iron can be readily oxidized to maghemite and hematite under present-day martian surface conditions (in the absence of liquid water). A test for a meteoritic component of the soil can be conducted, as described below, by searching for the presence of Ni at the martian surface. The average abundance of nickel in an Fe-Ni meteorite is about 7% and, if present at measurable levels in the soil, would be indicative of an exogenic contribution. In addition, it may be possible to directly search for mineral phases common in meteorites. An understanding of the formation and evolution of the martian soil would not be complete without addressing the unusual reactivity discovered by the Viking Landers The presence of an inorganic oxidant, possibly one produced as a results of photochemical processes, is the most widely accepted explanation of the Viking results. Are these chemical species simply adsorbed on soil grains, or have they reacted with the metal oxide substrates and altered the mineral structures? Could a completely different (non-photochemical) process be responsible for the soil reactivity? The various ideas for the nature of this putative oxidant could be constrained by a measurement of the change in reactivity with depth. Different compositions will have different lifetimes and mobilities and thus will have different vertical profiles. Because the oxidizing compounds are believed to actively destroy organic molecules, determination of the reactivity gradient also has significant implications for the search for life on Mars. A DS2-based microprobe system can be instrumented for a 2003 micromission to investigate the origin and reactivity of the martian soil. These measurements would provide invaluable information regarding the climate history and exobiological potential of the planet. The NMR, X ray and chemiresistor measurement approach described embodies a highly synergistic and general set of soil interrogation methods for elements, compounds, and crystal structures and can also be applied to other geologic questions of interest. For example, if the capability for precise targeting of the probes is available, then in-situ investigations of suspected evaporite and hydrothermal deposits would be possible with the same set of instruments. Additional information is contained in the original.

Yen, Albert S.↗
NASA NTRS2019

Saponite Dissolution Experiments and Implications for Mars

Recent work suggests that the mineralogical sequence of the Murray formation at Gale crater may have resulted from diagenetic alteration after sedimentation, or deposition in a stratified lake with oxic surface and anoxic bottom waters. Fe-containing clay minerals are common both at Gale crater, and throughout the Noachian-aged terrains on Mars. These clay minerals are primarily ferric (Fe3+), and previous work suggests that these ferric clay minerals may result from alteration of ferrous (Fe2+) smectites that were oxidized after deposition. The detection of trioctahedral smectites at Gale crater by CheMin suggests Fe2+ smectite was also deposited during the early Hesperian. However, due to their sensitivity to oxygen, Fe2+ smectites are difficult to analyze on Earth and very few saponite dissolution rates exist in the literature. To the best of our knowledge, no experiments have measured the dissolution rates of ferrous saponites under oxidizing and reducing conditions. In order to better understand the characteristics of water-rock interaction at Gale crater, particularly the oxidation state, we report our results to date on ongoing syntheses of ferrous and magnesium saponites and dissolution experiments of natural saponite under ambient conditions. Future experiments will include the dissolution of synthetic ferric, ferrous, and magnesium saponites under oxidizing and anoxic conditions at a range of pH values.

Luu, N. C.↗
DOE OSTI2021

Solid phase characterization and transformation of illite mineral with gas-phase ammonia treatment

In situ remediation applications of ammonia (NH 3 ) gas have potential for sequestration of subsurface contamination. Ammonia gas injections initially increase the pore water pH leading to mineral dissolution followed by formation of secondary precipitates as the pH is neutralized. However, there is a lack of understanding of fundamental alteration processes due to NH 3 treatment. In these batch studies, phyllosilicate minerals (illite and montmorillonite) were exposed to NH 3 gas with subsequent aeration to simulate in situ remediation. Following treatments, solids were characterized using a variety of techniques, including X-ray diffraction, N 2 adsorption-desorption analysis for surface area, Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR), and microscopy methods to investigate physicochemical transformations. The results of this study indicate that, at high pH, the clays are altered as observed by differences in morphology and particle size via microscopy. However, the two clays interact differently with NH 3 . While montmorillonite interlayers collapsed due to intercalation, illite layers were unaffected as confirmed by FTIR analysis. Further, structural changes in silicate ([SiO 4 ] n- ) and aluminol (Al-OH) groups were identified by NMR and FTIR. This research showed that mineral alteration processes occur during and after NH 3 gas treatment which may be used to remove radionuclides from the aqueous phase through sorption, co-precipitation, and coating with secondary phyllosilicate alteration products.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Chromium-for-Aluminum Substitution in Synthetic Serpentine

Cr-bearing clay minerals are products of hydrothermal alteration and fluid–rock interactions of ultramafic rocks that form serpentine minerals. Cr is typically observed to substitute for Al in serpentine minerals, but the crystal chemistry and environmental constraints on this substitution are unknown. Here, we synthesized endmember and Cr-substituted amesite, a typical Al-serpentine mineral, via the hydrothermal method. We found that the phase purity highly depends on the pH of the hydrothermal solution, which should be controlled at ~12.7 to avoid the formation of impurity phases. Additionally, amesite can incorporate Cr at a concentration equivalent to ~39.5% substitution of Al. The Cr-free and Cr-substituted amesite are highly defective and contain multiple polytypes, including 6R 2 , 2M 1 , and possibly 2H 2 . However, the relative proportions of these polytypes do not change with increasing chromium substitution.

Al-lizardite↗
NASA NTRS2021

An evolutionary system of mineralogy, Part V: Aqueous and thermal alteration of planetesimals (~4565 to 4550 Ma)

Part V of the evolutionary system of mineralogy explores phases produced by aqueous alteration, metasomatism, and/or thermal metamorphism—relicts of ancient processes that affected virtually all asteroids and that are preserved in the secondary mineralogy of meteorites. We catalog 166 historical natural kinds of minerals that formed by alteration in the parent bodies of chondritic and non-chondritic meteorites within the first 20 Ma of the solar system. Secondary processes saw a dramatic increase in the chemical and structural diversity of minerals. These phases incorporate 41 different mineral-forming elements, including the earliest known appearances of species with essential Co, Ge, As, Nb, Ag, Sn, Te, Au, Hg, Pb, and Bi. Among the varied secondary meteorite minerals are the earliest known examples of halides, arsenides, tellurides, sulfates, carbonates, hydroxides, and a wide range of phyllosilicates.

Robert M. Hazen↗
NASA NTRS1978

Alteration of glass as a possible source of clay minerals on Mars

Thermodynamic calculations show that, under present Martian surface conditions, favorable gas-solid weathering products of feldspar glasses should include beidellites (clays of the montmorillonite series) + carbonates + quartz. The gas-solid weathering of mafic silicate glass ( of volcanic or impact origin) may similarly favor the production of metastable Fe-rich montmorillonite clays. Simple mass-balance calculations suggest that gas-solid weathering of Martian proto-regolith containing 10% glass could conceivably produce a global blanket of clays at a rate of at least 0.4 cm/b.y. The production rate should be expected to increase significantly with the glass content and rate of reworking of the proto-regolith and with the availability of water. Complete extraction of altered glass from a lunar-like proto-regolith might yield a global Martian clay blanket about 10-100 cm in thickness.

Gooding, J. L.↗
DOE OSTI2024

Reaction path model of the formation of abiotic immiscible hydrocarbon fluids in subducted carbonated serpentinites, Lanzo Massif (Western Italian Alps)

Fluids generated from subducted slabs participate in the cycling of deep carbon in the crust and upper mantle. In these fluids, aqueous carbon species vary in oxidation state between +IV and -IV depending on whether the fluids are oxidizing or reducing, respectively. Most studies of subduction-zone fluids have focused on oxidized carbon species. However, recent studies of natural samples have demonstrated the occurrence of deep, reducing fluids, generated in both subducted oceanic upper mantle and crustal rocks. CH 4 -H 2 -rich fluid inclusions in subducted carbonated serpentinites have demonstrated the existence of abiotic, immiscible, hydrocarbon fluids at upper mantle conditions. To investigate the formation of such immiscible hydrocarbon fluids during the evolution of subducted carbonated serpentinites, we used equilibrium constants from the Deep Earth Water model to carry out predictive chemical mass transfer modeling to simulate the alteration reactions. A novel feature of the models was the inclusion of an immiscible hydrocarbon fluid containing six components (CH 4,f , C 2 H 6,f , C 3 H 8,f , isoC 4 H 10,f , CO 2,f , H 2,f ). This feature enabled prediction of the formation of a separate immiscible fluid in equilibrium with aqueous species and minerals. We developed a predictive reaction path model of invasive H 2,f reacting with carbonated serpentinites and interstitial aqueous fluids for comparison with the natural samples from the Lanzo Massif, western Italian Alps. Over a range of temperatures and pressures, immiscible hydrocarbon fluids formed in association with altered mineral assemblages. Reaction progress caused the transformation of carbonated serpentinites and the formation of clinopyroxene, brucite, graphite, and hydrocarbon fluids, along with changes of pH, logfO 2 , and aqueous species. CH 4,f was the most abundant hydrocarbon species in all the models. The overall results at 2.0 GPa and 400 to 450 °C were consistent with the natural samples from the Lanzo Massif. Interestingly, large amounts of H 2 O formed due to oxidation of H 2 . More hydrocarbons and H 2 O formed in models with lower fluid/rock mass ratios or with more reactant H 2 . Models at different pressure and temperature conditions showed similar results with some variation in the relative stabilities of aragonite, graphite and olivine solid solution, and associated differences in mineral sequences, hydrocarbon fluids, values of aqueous species, and the final log fO 2 and pH. As a result, our models strongly support the laboratory and field evidence that reduction of carbonated serpentinites by infiltrating H 2 fluids can cause the formation of immiscible, abiotic hydrocarbon fluids in subduction zones.

58 GEOSCIENCES↗
NASA NTRSDate not supplied

Magma-Sediment Interaction Induced Alteration Mineralogy on Mars: Detectability and Analytical Method Comparison Using the Curtis Sandstone as A Terrestrial Analog

Basaltic magmatism is a ubiquitous feature of the Martian crust, and would have interacted with sediments and fluids through the geologic history of Mars to potentially produce higher temperature hydrothermal systems , and contact metamorphic rocks. On Earth, comparable hydrothermal systems represent habitable environments, which can be used as an analog for Mars. Nevertheless, evidence of aforementioned hydrothermal systems on Mars has remained elusive, despite the efforts of both orbital and in-situ analyses. Limited low grade metamorphic minerals typically indicative of hydrothermal systems (prehnite, zeolites, serpentine) have been detected in the Martian crust, though the detections are typically isolated occurrences, and do not necessarily indicate an in-place metamorphic sequence. It is possible that orbital spectroscopy alone is not capable of detecting such an alteration front, with higher resolution in-situ analyses being required to detect the changes in mineralogy and species of alteration minerals associated with magma-sediment interaction. To constrain this, we have investigated a terrestrial analog on the Colorado Plateau, USA, where a mafic dike intrudes a quartz areinite of the Jurassic Curtis Sandstone. The investigation was carried out using Mars relevant instruments: Visible to Near-Infrared (VNIR) spectroscopy analogous to orbital spectroscopy, and X-ray Diffraction (XRD) analogous to CheMin on Mars Sample Laboratory Curiosity. While quartz sandstones have not been, and are unlikely to be, detected on Mars, the relatively mineralogically uniform Curtis Sandstone serves as analog here as it avoids complications of multiple mineral systems or significant element exchange with the surrounding area.

J R Crandall↗
NASA NTRSDate not supplied

Comparing the Volatile Contents of Basaltic Rocks Through the Inner Solar System

Volatiles in planetary interiors play important roles in magma genesis, crust formation, eruption style, and even habitability of planetary surfaces. Allan Treiman’s career has touched on volatiles in the Moon, Mars, HED-parent body, the Earth, Venus, and other planetary bodies through studies of igneous rocks, volatile-bearing igneous minerals within these rocks, and the secondary alteration products produced from these rocks and minerals. His seminal work in many of these fields has inspired our careers and many others in our field. Here, we will build on and summarize what we know of the volatile content of basaltic rocks in the inner solar system. Specifically, this talk will focus on using volatile-bearing minerals (amphibole and apatite) along with bulk compositions to constrain the pre-eruptive, and potentially predegassed, volatile content of the magma and their source regions. We will then use these estimates to compare the volatile content of the Earth, Moon, Mars, Venus, and Mercury and what open questions there are for each planetary body.

Justin Filiberto↗