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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

The influence of Al2O3 on the structural properties of MgSiO3 akimotoite

Abstract Akimotoite, a MgSiO3 polymorph present in the lower transition zone within ultramafic portions of subducting slabs and potentially also in the ambient mantle, will partition some amount of Al, raising the question of how this will affect its crystal structure and properties. In this study, a series of samples along the MgSiO3-Al2O3 (akimotoite-corundum) solid solution have been investigated by means of single-crystal X-ray diffraction to examine their crystal chemistry. Results show a strong nonlinear behavior of the a- and c-axes as a function of Al content, which arises from fundamentally different accommodation mechanisms in the akimotoite and corundum structures. Furthermore, two Al2O3-bearing akimotoite samples were investigated at high pressure to determine the different compression mechanisms associated with Al substitution. Al2O3-bearing akimotoite becomes more compressible at least up to 20 mol% Al2O3, due likely to an increase in compressibility as the Al cation is incorporated into the SiO6 octahedron. This observation is in strong contrast to the stiffer corundum end-member having a KT = 250 GPa, which is larger than that of the akimotoite end-member [KT = 205(1) GPa]. These findings have implications for mineral physics models of elastic properties, which have in the past assumed linear mixing behavior between the MgSiO3 akimotoite and Al2O3 corundum end-members to calculate sound wave velocities for Al-bearing akimotoite at high pressure and temperature.

Geochemistry & Geophysics↗
DOE OSTI2021

Evolution of Pore Structure and Permeability of Rocks Under Hydrothermal Conditions (Final Report)

The physical and transport properties of porous rocks can be altered by a variety of diagenetic, metamorphic, and tectonic processes, and the changes that result are of critical importance to such industrial applications as resource recovery, carbon dioxide sequestration, and waste isolation in geologic formations. The associated interrelationships between rocks, pore fluids and deformation are also key to understanding many natural processes, including dynamic metamorphism, fault mechanics, fault stability and pressure solution creep. In this project, we investigated the changes of permeability and pore geometry owing to inelastic deformation by solution-transfer, brittle fracturing and dislocation creep. In particular, we studied the coupling between pore fluids and deformation in fluid-filled quartz, calcite, mudstones and ultramafic rocks and examine the effects of coupled mechanical and chemical processes on the evolution of porosity and permeability under hydrothermal conditions. The investigations used a combination of techniques, that included triaxial laboratory experiments; uniaxial compressive loading with in situ observations of microstructure; permeability under hydrostatic compression; observations of microstructure using optical and electron microscopes, and micro-CT imaging; and numerical calculations. Laboratory experiments were designed to provide mechanical and transport data under conditions that isolate the particular mechanisms responsible for the changes. The data obtained were used to quantify changes in surface roughness, porosity, pore dimensions and their spatial fluctuations. The results of the experiments and data from image analyses were compared to the results of network, finite-difference and other numerical models to verify the validity of experimentally established relations between permeability and other rock properties. A bibliography for the period from 2015-2019 is appended below. New results obtained in the final year and the unfunded extension period are detailed below.

58 GEOSCIENCES↗
DOE OSTI2025

Geochemical and Hydromechanical Stimulation for Reaction Acceleration (GeoHydRA) of Serpentinization for In Situ Hydrogen Production

The project team aims to develop an innovative approach to stimulate geological hydrogen generation by enhancing in-situ serpentinization of ultramafic rocks. This method can maximize hydrogen production by promoting reactive surface areas through controlled fracturing and optimizing fluid chemistry and flow rates. Key objectives include establishing optimal conditions for hydrogen generation, investigating subsurface limitations, and sustaining production via hierarchical crack systems.

08 HYDROGEN↗
DOE OSTI2021

Ferrotorryweiserite, Rh 5 Fe 10 S 16 , a New Mineral Species from the Sisim Placer Zone, Eastern Sayans, Russia, and the Torryweiserite–Ferrotorryweiserite Series

Ferrotorryweiserite, Rh 5 Fe 10 S 16 , occurs as small grains (≤20 µm) among droplet-like inclusions (up to 50 μm in diameter) of platinum-group minerals (PGM), in association with oberthürite or Rh-bearing pentlandite, laurite, and a Pt-Pd-Fe alloy (likely isoferroplatinum and Fe-Pd-enriched platinum), hosted by placer grains of Os-Ir alloy (≤0.5 mm) in the River Ko deposit. The latter is a part of the Sisim placer zone, which is likely derived from ultramafic units of the Lysanskiy layered complex, southern Krasnoyarskiy kray, Russia. The mineral is opaque, gray to brownish gray in reflected light, very weakly bireflectant, not pleochroic to weakly pleochroic (grayish to light brown tints), and weakly anisotropic. The calculated density is 5.93 g·cm –3 . Mean results (and ranges) of four WDS analyses are: Ir 18.68 (15.55–21.96), Rh 18.34 (16.32–20.32), Pt 0.64 (0.19–1.14), Ru 0.03 (0.00–0.13), Os 0.07 (0.02–0.17), Fe 14.14 (13.63–14.64), Ni 13.63 (12.58–14.66), Cu 4.97 (3.42–6.41), Co 0.09 (0.07–0.11), S 29.06 (28.48–29.44), and total 99.66 wt.%. They correspond to the following formula calculated for a total of 31 atoms per formula unit: (Rh 3.16 Ir 1.72 Pt 0.06 Ru 0.01 Os 0.01 ) Σ 4.95 (Fe 4.48 Ni 4.11 Cu 1.38 Co 0.03 ) Σ10.00 S 16.05 . The results of synchrotron micro-Laue diffraction studies indicate that ferrotorryweiserite is trigonal; its probable space group is $R\bar{3}m$ (#166) based on its Ni-analog, torryweiserite. The unit-cell parameters refined from 177 reflections are a = 7.069 (2) Å, c = 34.286 (11) Å, V = 1484 (1) Å 3 , and Z = 3. The c:a ratio is 4.8502. The strongest eight peaks in the X-ray diffraction pattern derived from results of micro-Laue diffraction study [d in Å(hkil)(I)] are 2.7950 ($20\bar{2}5$) (100); 5.7143 (0006) (60); 1.7671 ($22\bar{4}0$) (44.4); 3.0486 ($20\bar{2}1$) (39.4); 5.7650 ($10\bar{1}2$) (38.6); 2.5956 ($20\bar{2}7$) (37.8); 3.0058 ($11\bar{2}6$) (36.5); and 1.5029 ($4\bar{2}\bar{2}12$) (35.3). Ferrotorryweiserite and the associated PGM crystallized from microvolumes of residual melt at late stages of crystallization of grains of Os- and Ir-dominant alloys occurred in lode zones of chromitites of the Lysanskiy layered complex. In a particular case, the residual melt is disposed peripherally around a core containing a disequilibrium association of magnesian olivine (Fo 72.9–75.6 ) and albite (Ab 81.6–86.4 ), with the development of skeletal crystals of titaniferous augite: Wo 40.8–43.2 En 26.5–29.3 Fs 20.3–22.6 Aeg 6.9–9.5 (2.82–3.12 wt.% TiO 2 ). Ferrotorryweiserite represents the Fe-dominant analog of torryweiserite. We also report occurrences of ferrotorryweiserite in the Marathon deposit, Coldwell Complex, Ontario, Canada, and infer the existence of the torryweiserite–ferrotorryweiserite solid solution in other deposits and complexes.

58 GEOSCIENCES↗
DOE OSTI2025

Geochemistry of Mars with Laser-Induced Breakdown Spectroscopy (LIBS): ChemCam, SuperCam, and MarSCoDe

Laser-induced breakdown spectroscopy (LIBS) has been used to explore the chemistry of three regions of Mars on respective missions by NASA and CNSA, with CNES contributions. All three LIBS instruments use ~100 mm diameter telescopes projecting pulsed infrared laser beams of 10–14 mJ to enable LIBS at 2–10 m distances, eliminating the need to position the rover and instrument directly onto targets. Over 1.3 million LIBS spectra have been used to provide routine compositions for eight major elements and several minor and trace elements on >3000 targets on Mars. Onboard calibration targets common to all three instruments allow careful intercomparison of results. Operating over thirteen years, ChemCam on Curiosity has explored lacustrine sediments and diagenetic features in Gale crater, which was a long-lasting (>1 My) lake during Mars’ Hesperian period. SuperCam on Perseverance is exploring the ultramafic igneous floor, fluvial–deltaic features, and the rim of Jezero crater. MarSCoDe on the Zhurong rover investigated for one year the local blocks, soils, and transverse aeolian ridges of Utopia Planitia. The pioneering work of these three stand-off LIBS instruments paves the way for future space exploration with LIBS, where advantages of light-element (H, C, N, O) quantification can be used on icy regions.

47 OTHER INSTRUMENTATION↗
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↗
DOE OSTI2026

Modeling supercritical CO 2 flow and mineralization in reactive host rocks with PFLOTRAN v7.0

Understanding the flow and reactivity of CO 2 injected into geological reservoirs is important for many subsurface applications including secure geologic carbon storage (GCS), critical mineral extraction, enhanced geothermal systems (EGS), and enhanced oil recovery (EOR). Traditionally, subsurface CO 2 injection for GCS applications has focused on geologic formations with favorable subsurface configurations for CO 2 migration and trapping through non-reactive mechanisms such as structural, solubility, and petrophysical trapping. Recently, CO 2 -reactive rocks such as mafic and ultramafic basalts have been investigated for their potential to react with injected CO 2 in situ to simultaneously dissolve host rock minerals and mineralize CO 2 as carbonates. Engineering rapid CO 2 mineralization in the subsurface is attractive because of the increased density of stored CO 2 , the additional safety factors associated with solidification, and the potential to extract valuable critical minerals. Here we present recent developments in the parallel flow and reactive transport simulator PFLOTRAN to model coupled CO 2 -brine flow and reactive transport for a wide range of injection and production applications involving reactive CO 2 -brine systems. These developments are based on the well established and trusted CO 2 flow capabilities in the STOMP-CO 2 simulator. New capabilities added to PFLOTRAN include new CO 2 -brine equations of state with optional thermal coupling, several new constitutive relationships like capillary pressure smoothing and scanning path hysteresis, a fully implicit well model, and native linkage with PFLOTRAN's well-established reactive transport libraries. A series of benchmarks between PFLOTRAN and STOMP-CO 2 verify the newly developed CO 2 -brine flow capabilities. Demonstrations of coupled CO 2 -brine flow modeling and reactive transport show how CO 2 mineralization can be engineered in reactive host rocks. Finally, an example use case involving copper leaching by CO 2 and critical mineral extraction is presented to showcase the strengths of this new implementation. Several limitations still remain, including limited availability of field data to parameterize models. Future work should constrain the evolution of mineral surface area during mineralization and the temperature and/or pH dependence of geochemical reactions for specific systems of interest.

Critical Minerals↗
NASA NTRS1971

Mineralogy of Apollo 15415 ?genesis rock' - Source of anorthosite on moon.

Results of electron microprobe analyses of plagioclase points and pyroxene grains of Apollo 15415 ?genesis rock.' It is pointed out that no evidence of cumulate textures has yet appeared to support suggestions of extensive crystal-liquid differentiation producing an anorthositic crust or a lunar crust composed of a mixture of plagioclase-rich rock, basalts and minor ultramafic material, which require that plagioclase crystals float in a basaltic liquid. The plagioclase in 15415 does not show cumulate texture either. It is noted that it remains to be seen whether rock 15415 is correctly named the ?genesis rock.'

Steele, I. M.↗
NASA NTRS1972

Highly differentiated subalkaline rhyolite from Glass Mountain, Mono County, California.

Available data on the partition of Sr between coexisting feldspar and melt phases re interpreted as an indication that a rhyolite from Glass Mountain represents about 25% of a hypothetical 'parent' magma of silicic composition having a norm ntent of 150 ppm. Available Sr and Pb isotope data on nearby Pleistocene rhyolite lavas suggest that the 'parent' magmas of volcanic rocks of the area came from mafic or ultramafic source marl.

Noble, D. C.↗
NASA NTRS1972

Lunar 'dunite', 'pyroxenite' and 'anorthosite.'

Photomicrographic study of 200 thin sections of Apollo 14 rock samples suggests that these monomineralic aggregates are recrystallized single-mineral grains. It is contended, therefore, that the source rocks are not properly characterized by igneous rock names, being more moderately coarse-grained gabbroic rather than ultramafic rocks.

Wilshire, H. G.↗
NASA NTRS1974

On the age of the Onverwacht Group, Swaziland sequence, South Africa

Some rocks of the Onverwacht Group, South Africa, have been analyzed for Rb and Sr concentrations and Sr isotopic composition. These rocks include volcanic rocks, layered ultramafic differentiates and cherty sediments. Whole rock data indicate that the Rb-Sr isotopic systems in many samples were open and yield no reasonable isochron relationships. However, the data of mineral separates from a basaltic komatiite define a good isochron of 3.50 (plus or minus .2) b.y. with an initial Sr-87/Sr-86 ratio of 0.70048 plus or minus 5. The orthodox interpretation of this age is the time of the low grade metamorphism. It is reasonable to assume that the age of 3.50 b.y. might also represent the time of initial Onverwacht volcanism and deposition. The initial Sr-87/Sr-86 ratio obtained above is important to an understanding of the Sr isotopic composition of the Archean upper mantle.

Jahn, B.-M.↗
NASA NTRS1974

Results from the Apollo passive seismic experiment

Recent results from the Apollo seismic network suggest that primitive differentiation occurred in the outer shell of the moon to a depth of approximately 300 km; and the central region of the moon is presently molten to a radius of between 200 and 300 km. If early melting to a depth of 300 to 400 km was a consequence of accretional energy, very short accretion times are required. The best model for the zone of original differentiation appears to be a crust 40 to 80 km thick, ranging in composition from anorthositic gabbro to gabbro; overlying an ultramafic cumulate (olivine-pyroxene) about 250 km thick. The best candidate for the molten core appears to be iron or iron sulphide. A new class of seismic signals has recently been identified that may correspond to shallow moonquakes. These are rare, but much more energetic than the more numerous, deep moonquakes.

Lathum, G.↗
NASA NTRS1977

Sm-Nd-Pu timepieces in the Angra dos Reis meteorite

Isotope ratios and age estimations are presented for the ultramafic pyroxenite Angra dos Reis meteorite. A pyroxene-phosphate internal isochron age of 4.55 plus or minus 0.04 eons was obtained, in agreement with reported Pb-Pb ages. It is suggested that Sm-146 decay led to an increase in the ratio of Nd-142 to Nd-144 in pyroxene, which is greater than the ratio of the Nd isotopes in phosphates. The effect of Pu-244 on the fission xenon components in pyroxene and phosphate is examined. The ratios of Pu-244 to Nd, U-238, and Th-232 are compared for pyroxene and phosphate separates. The exposure age of the meteorite, as obtained by the Kr-81 to Kr-83 method, was found to be 55.5 plus or minus 1.2 million years.

Lugmair, G. W.↗
NASA NTRS1977

A survey of lunar rock types and comparison of the crusts of earth and moon

The principal known types of lunar rocks are briefly reviewed, and their chemical relationships discussed. In the suite of low-KREEP highland rocks, Fe/(Fe + Mg) in the normative mafic minerals increases and the albite content of normative plagio-clase decreases as the total amount of normative plagioclase increases, the opposite of the trend predicted by the Bowen reaction principle. The distribution of compositions of rocks from terrestrial layered mafic intrusives is substantially different: here the analyses fall in several discrete clusters (anorthositic rocks, norites, granophyres and ferrogabbros, ultramafics), and the chemical trends noted above are not reproduced. It is suggested that the observed trends in lunar highland rocks could be produced by crystal fractionation in a deep global surface magma system if (1) plagiociase tended to float, upon crystallization, and (2) the magma was kept agitated and well mixed (probably by thermal convection) until crystallization was far advanced and relatively little residual liquid was left. After the crustal system solidified, but before extensive cooling had developed a thick, strong lithosphere, mantle convection was able to draw portions of the lunar anorthositic crust down into the mantle.

Wood, J. A.↗
NASA NTRS1977

Results from the Apollo passive seismic experiment

Recent results from the Apollo Seismic Network suggest that primitive differentiation occurred in the outer shell of the moon to a depth of approximately 300 km and the central region of the moon is presently molten to a radius of between 200 and 300 km. If early melting to a depth of 300 to 400 km was a consequence of accretional energy, very short accretion times are required. It was shown that the best model for the zone of original differentiation is a crust 40 to 80 km thick, ranging in composition from anorthositic gabbro to gabbro, and overlying an ultramafic cumulate about 250 km thick. The best candidate for the molten core appears to be iron or iron sulphide. A new class of seismic signals recently were identified that may correspond to shallow moonquakes. These are rare, but much more energetic than the more numerous, deep moonquakes.

Latham, G.↗