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At least 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Geologic mapping of Northern Atla Regio on Venus: Preliminary data

The Northern part of Atla Regio within the frame of C1-formate Magellan photo map 15N197 was mapped geologically at scale 1:8,000,000. This is a part of Russia's contribution into C1 geologic mapping efforts. The map is reproduced here being reduced about twice. The map shows that the Northern Atla area is predominantly a volcanic plain with numerous volcanic features: shield volcanoes, domes and hills with various morphology, corona-like constructions, radar bright and dark spots often with flow-like outlines. Relatively small areas of tessera occurred in the area are mainly semi-flooded with the plain material. Tesserae are considered to be the oldest terrains within the map sheet. There are many lineated terrains in the region. They are interpreted as the old, almost-buried tesserae (those with crossed lineaments) or partly buried ridge belts (those with parallel lineaments). These lineated terrains have an intermediate age between the young volcanic plains and the old tessera areas. Two prominent high volcanic shields are located within the region - Ozza Mons and Sapas Mona. The most prominent structure in Northern Atla is Ganis Chasma rift. The rift cuts volcanic plain and is considered to be under formation during approximately the same time with Ozza Mons shield. Ganis Chasma rift valley is highly fractured and bounded with fault scarps. Rift shoulder uplifts are typical for Ganis Chasma. There are few relatively young volcanic features inside the rift valley. The analysis of fracturing and rift valley geometry shows the rift originated due to 5-10 percent crustal extention followed by the crustal subsidence. The age sequence summary for the main terrain types in the region is (from older to younger ones): tesserae; lineated terrains with crossed lineaments; lineated terrains with parallel lineaments; volcanic plains; and prominent volcanic shields and Ganis Chasma rift valley. The geologic structure of Atla Regio as it appeared now with the Magellan high resolution images is very close to that of Beta Regio. Such conclusion coincide with the earlier ones based on the coarser data.

Nikishin, A. M.↗
DOE OSTI2020

Heat Flow on the U.S. Beaufort Margin, Arctic Ocean: Implications for Ocean Warming, Methane Hydrate Stability, and Regional Tectonics

The Arctic Ocean represents one of the last geological frontiers on Earth. The formation of the Arctic Ocean remains unclear, and although it is well understood that the Arctic surface temperature is warming at a rate approximately twice as fast as the rest of the Earth, it is unclear how deep Arctic Ocean temperatures are changing. Understanding whether deep Arctic Ocean water is warming is important, since it can lead to the breakdown and release of huge quantities of frozen methane molecules trapped below the Arctic seafloor, which can increase ocean acidity and destabilize the seafloor. To understand both Arctic Ocean temperature change and geologic evolution, we collected temperature measurements at 103 sites. These measurements tell us how temperature increases with depth below the seafloor and can be used to understand both ocean temperature change and regional geology. Analysis of our data shows that at depths of 300–900 m below sea level, the Arctic Ocean has been warming steadily for perhaps several decades—nearly twice as deep as previous studies suggest. At ocean depths greater than 1,000 m, our analysis also reveals surprisingly high temperature increases with depth in the seafloor. The cause of these significant increases is unclear.

58 GEOSCIENCES↗
NASA NTRS1985

Geologic setting of the Apollo 15 landing site

Returned Apollo 15 samples were used to provide a remarkably comprehensive sampling of the Moon's profile and geologic history. The geological structure of the Apennine Bench Formation is described. The large collection of pigeonite and olivine basalts from the landing sites were viewed in the context of the site's geology.

Wilhelms, D. E.↗
NASA NTRS2020

Evidence for a Stratified Upper Mantle Preserved within the South Pole - Aitken Basin

The evolution and compositional structure of the lunar mantle has been extensively modeled but insufficiently constrained by observations. Here, we identify and characterize mantle materials exposed by the Moon's largest impact basin to better understand the composition, stratigraphy, and evolution of the upper mantle. The vast South Pole-Aitken Basin (SPA) exhibits a broad, crescent-shaped thorium and potassium distribution. These incompatible elements are predicted to be concentrated in the dregs of the lunar magma ocean during end-stage crystallization. Through consideration of basin formation models convolved with subsequent geologic evolution, we demonstrate that the distribution and implied stratigraphy of Th- and K-bearing materials across SPA are consistent with an upper mantle ejecta origin. The most pristine exposures of these materials are confined to northwest SPA and also exhibit elevated Ti and Fe (relative to the farside highlands) in association with a gabbronoritic mineralogy. This is consistent with latestage magma ocean assemblages predicted by petrologic models. In contrast, SPA impact melt derived from greater depths is associated with a low-Ca pyroxene-dominated assemblage. Together, these compositional patterns are evidence for a stratified ancient upper mantle. Importantly, the incompatible-element-enriched, ilmenite-bearing ferroan gabbronoritic cumulates evidently had not participated in gravitational overturn at the time of SPA formation. Contrary to recent hypotheses invoking nearside sequestration of incompatible elements to explain hemispherical differences in crustal building and volcanic resurfacing, it follows that incompatible elements were globally distributed in the magma ocean at the time of SPA formation.

Lunar dichotomy↗
NASA NTRS2010

The Formation and Evolution of Tessera and Insights into the Beginning of Recorded History on Venus: Geology of the Fortuna Tessera Quadrangle (V-2)

Today, and throughout its recorded history, Venus can be classified as a "one-plate planet." The observable geological record of the planet comprises only the last 1/4 or less of its overall geologic history. As shown by many authors, it started with intensive deformation in broad regions to form tessera [1-6] during the Fortunian period of history [7]. The period of tessera formation quickly changed to numerous zonal deformational belts of ridges and grooves that were followed by emplacement of vast volcanic plains (shield plains, regional plains) [7,8]. During the final epoch of the geologic history of Venus, large but isolated centers of volcanism formed extensive fields of lavas, with tectonics concentrated within fewer very prominent rift zones [8,9]. The observable changes in intensity and character of volcanism and tectonics suggest progressive changes from thin lithosphere early in the geologic history to thick lithosphere during later epochs [6,10]. We have little idea of the character of the first 3/4 of Venus' history. So, what does the earliest period of recorded history tell us about the transition from the Pre-Fortunian to the Fortunian period and what insight does this give us into this earlier period?

Head, J. W.↗
DOE OSTI2024

Hydrothermal solubility of Dy hydroxide as a function of pH and stability of Dy hydroxyl aqueous complexes from 25 to 250 °C

The rare earth elements (REE) have important applications in green energy technologies. The formation of mineral deposits in geologic systems commonly involves hydrothermal fluids which can mobilize the REE. However, the REE speciation is not well known as a function of pH. The thermodynamic properties of REE hydroxyl complexes used in geochemical models are based on the Helgeson-Kirkham-Flowers (HKF) equation of state parameters which were derived by extrapolation of low temperature experimental and estimated data. In this study, Dy hydroxide solubility experiments are combined with available literature data to improve these models from 25 to 250 °C and optimize the thermodynamic properties of Dy 3+ and Dy hydroxyl complexes using GEMSFITS. Batch-type solubility experiments were conducted from 150 to 250 °C and at saturated water vapor pressure in perchloric acid solutions with initial pH values of 2 to 5 in 0.5 pH unit increments. The measured solubility of Dy hydroxide is retrograde with temperature and decreases with pH. The logarithm of total dissolved Dy molality ranges from –2.3 to –5.3 at 150 °C (pH 4.7–5.5), from –2.4 to –5.6 at 200 °C (pH 3.9–5.1), and from –3.7 to –6.9 at 250 °C (pH of 3.4 and 5.0). The optimized standard partial molal Gibbs energies of formation (Δ f G° T ) derived for Dy 3+ and DyOH 2+ display a close to linear relationship with temperature, fitting with previous optimizations based on DyPO 4 solubility data in the literature. A comparison of the optimized ΔfG°T values for aqueous Dy species with predictions from available HKF parameters indicates significant differences ranging from +11 to –26 kJ/mol between 25 and 250 °C. The experimental fits are used to derive the Dy hydroxide solubility products (K s0 ) and formation constants for the hydrolysis of Dy (β n with n = 1 to 3; Dy 3+ + nOH – = DyOH n 3-n ) as a function of temperature. The optimization method presented yields accurate thermodynamic properties for the Dy 3+ aqua ions and the DyOH 2+ species at the acidic to mildly acidic pH studied whereas more experimental work is needed at near-neutral and alkaline conditions to better constrain the other hydroxyl complexes. Furthermore, the optimized thermodynamic data have a significant impact on geochemical modeling of the mobility and solubility of REE minerals in acidic hydrothermal fluids.

58 GEOSCIENCES↗
NASA NTRS1985

The materials and formation of the imbrium basin

The deposits around the Imbrium basin form a widespread stratigraphic datum, to which other lunar geological units may be relatively dated. More importantly, as a relatively well preserved multi-ring basin, Imbrium provides an important target of geologic investigation to study the processes involved in lunar basin formation and evolution. Two Apollo missions (Apollo 14 and 15) were send to landing sites chosen specifically to address problems of the Imbrium basin geology. Data about the deposits of the Imbrium basin are reviewed. Formational mechanics of lunar basins in general and the relations of materials collected at the highlands adjacent to the Apollo 15 landing site to Imbrium and other basins are examined.

Spudis, P. D.↗
NASA NTRS2004

Workshop on Oxygen in the Terrestrial Planets

This volume contains abstracts that have been accepted for presentation at the Workshop on Oxygen in the Terrestrial Planets, July 20-23,2004, Santa Fe, New Mexico. The contents include: 1) Experimental Constraints on Oxygen and Other Light Element Partitioning During Planetary Core Formation; 2) In Situ Determination of Fe(3+)/SigmaFe of Spinels by Electron Microprobe: An Evaluation of the Flank Method; 3) The Effect of Oxygen Fugacity on Large-Strain Deformation and Recrystallization of Olivine; 4) Plagioclase-Liquid Trace Element Oxygen Barometry and Oxygen Behaviour in Closed and Open System Magmatic Processes; 5) Core Formation in the Earth: Constraints from Ni and Co; 6) Oxygen Isotopic Compositions of the Terrestrial Planets; 7) The Effect of Oxygen Fugacity on Electrical Conduction of Olivine and Implications for Earth s Mantle; 8) Redox Chemical Diffusion in Silicate Melts: The Impact of the Semiconductor Condition; 9) Ultra-High Temperature Effects in Earth s Magma Ocean: Pt and W Partitioning; 10) Terrestrial Oxygen and Hydrogen Isotope Variations: Primordial Values, Systematics, Subsolidus Effects, Planetary Comparisons, and the Role of Water; 11) Redox State of the Moon s Interior; 12) How did the Terrestrial Planets Acquire Their Water?; 13) Molecular Oxygen Mixing Ratio and Its Seasonal Variability in the Martian Atmosphere; 14) Exchange Between the Atmosphere and the Regolith of Mars: Discussion of Oxygen and Sulfur Isotope Evidence; 15) Oxygen and Hydrogen Isotope Systematics of Atmospheric Water Vapor and Meteoric Waters: Evidence from North Texas; 16) Implications of Isotopic and Redox Heterogeneities in Silicate Reservoirs on Mars; 17) Oxygen Isotopic Variation of the Terrestrial Planets; 18) Redox Exchanges in Hydrous Magma; 19) Hydrothermal Systems on Terrestrial Planets: Lessons from Earth; 20) Oxygen in Martian Meteorites: A Review of Results from Mineral Equilibria Oxybarometers; 21) Non-Linear Fractionation of Oxygen Isotopes Implanted in Lunar Metal Grains: Solar, Lunar or Terrestrial Origin? 22) Isotopic Zoning in the Inner Solar System; 23) Redox Conditions on Small Bodies; 24) Determining the Oxygen Fugacity of Lunar Pyroclastic Glasses Using Vanadium Valence - An Update; 25) Mantle Redox Evolution and the Rise of Atmospheric O2; 26) Variation of Kd for Fe-Mg Exchange Between Olivine and Melt for Compositions Ranging from Alkaline Basalt to Rhyolite; 27) Determining the Partial Pressure of Oxygen (PO,) in Solutions on Mars; 28) The Influence of Oxygen Environment on Kinetic Properties of Silicate Rocks and Minerals; 29) Redox Evolution of Magmatic Systems; 30) The Constancy of Upper Mantlefo, Through Time Inferred from V/Sc Ratios in Basalts: Implications for the Rise in Atmospheric 0 2; 31) Nitrogen Solubility in Basaltic Melt. Effects of Oxygen Fugacity, Melt Composition and Gas Speciation; 32) Oxygen Isotope Anomalies in the Atmospheres of Earth and Mars; 33) The Effect of Oxygen Fugacity on Interdiffusion of Iron and Magnesium in Magnesiowiistite 34) The Calibration of the Pyroxene Eu-Oxybarometer for the Martian Meteorites; 35) The Europium Oxybarometer: Power and Pitfalls; 36) Oxygen Fugacity of the Martian Mantle from PigeoniteMelt Partitioning of Samarium, Europium and Gadolinium; 37) Oxidation-Reduction Processes on the Moon: Experimental Verification of Graphite Oxidation in the Apollo 17 Orange Glasses; 38) Oxygen and Core Formation in the Earth; 39) Geologic Record of the Atmospheric Sulfur Chemistry Before the Oxygenation of the Early Earth s Atmosphere; 40) Comparative Planetary Mineralogy: V/(CrCAl) Systematics in Chromite as an Indicator of Relative Oxygen Fugacity; 41) How Well do Sulfur Isotopes Constrain Oxygen Abundance in the Ancient Atmospheres? 42) Experimental Constraints on the Oxygen Isotope (O-18/ O-16) Fractionation in the Ice vapor and Adsorbant vapor Systems of CO2 at Conditions Relevant to the Surface of Mars; 43) Micro-XANES Measurements on Experimental Spinels andhe Oxidation State of Vanadium in Spinel-Melt Pairs; 44) Testing the Magma Ocean Hypothesis Using Metal-Silicate Partitioning of Te, Se and S; 45) Solubility of Oxygen in Liquid Iron at High Pressure and Consequences for the Early Differentiation of Earth and Mars Metallic Liquid Segregation in Planetesimals; 46) Oxygen Fugacity of Lunar Basalts and the Lunar Mantle. Range of fo2 and the Effectiveness of Oxybarometers; 47) Thermodynamic Study of Dissociation Processes of Molecular Oxygen in Vapor over Oxide Compounds; 48) Oxygen Profile of a Thermo-Haliophilic Community in the Badwater Salt Flat; 49) Oxygen Barometry Using Synchrotron MicroXANES of Vanadium; 50) Mass-Independent Isotopic Fractionation of Sulfur from Sulfides in the Huronian Supergroup, Canada; 51) Mass Independent Isotopes and Applications to Planetary Atmospheres; 52) Electrical Conductivity, Oxygen Fugacity, and Mantle Materials; 53) Crustal Evolution and Maturation on Earth: Oxygen Isotope Evidence; 54) The Oxygen Isotope Composition of the Moon: Implications for Planet Formation; 55) Oxygen Isotope Composition of Eucrites and Implications for the Formation of Crust on the HED Parent Body; and 56) The Role of Water in Determining the Oxygen Isotopic Composition of Planets.

Source record↗
NASA NTRS1974

Surface geology of the moon

Questions regarding the formation of major lunar surface features are discussed, giving attention to the multiringed circular basins, the craters, and the mare material. Aspects of lunar stratigraphy are explored. At the present time, a lunar-wide time-stratigraphic sequence exists, in which surface units belong to one of a number of systems, including the Copernican, the Eratosthenian, Imbrian, Nectarian, and pre-Nectarian system. Details of Apollo surface exploration as conducted in each individual mission are considered along with the chemistry and the age of lunar materials, the lunar interior, and the evolution of the lunar surface.

El-Baz, F.↗
NASA NTRS1989

Impact cratering: A geologic process

The mechanisms involved in the formation of impact craters are examined theoretically, reviewing the results of recent investigations. Topics addressed include crater morphology, stress waves in solids, the contact and compression stage, the excavation stage, and ejecta deposits. Consideration is given to the scaling of crater dimensions, the crater modification stage, multiring basins, cratered landscapes, atmospheric interactions, and the implications of impact cratering for planetary evolution. Extensive diagrams, graphs, tables, and images of typical craters are provided.

Melosh, H. J.↗
DOE OSTI2020

Investigation of Mass Transfer and Sorption in CO 2 /Brine/Rock Systems via In Situ FT-IR

CO 2 geological storage in deep saline formations is considered a promising method to mitigate anthropogenic CO 2 emissions and, thereby, minimize changes to the Earth’s atmosphere. A fundamental understanding of CO 2 mass transfer and sorption phenomena in brine-saturated reservoir formations is necessary to understand the long-term fate of injected CO 2 as it is subjected to different (physical, dissolution, and mineral) trapping mechanisms. In this work, we investigate CO 2 sorption in brine-saturated and dry Mt. Simon sandstone samples via in-situ Fourier Transform infrared spectroscopy (FT-IR) at elevated pressures, ranging from 0.3 MPa to 8.3 MPa, at a temperature of 50 ⁰C. The FT-IR spectra of bulk-phase CO 2 were simultaneously recorded under the same conditions. For bulk-phase CO 2 , we observed, in agreement with past studies, a doublet peak at 2361 cm -1 and 2336 cm -1 and another peak (ν 2 bending mode) at 667 cm -1 . With increasing pressure, the position of the peak at 667 cm -1 remains invariant, however, when crossing into the supercritical region the doublet peak degenerates onto a single peak at 2336 cm -1 with a barely visible shoulder at 2361 cm -1 . The bulk CO 2 data provide a perfect fit for Beer’s law for the whole range of pressure conditions. For the dry sample, the IR spectrum is experimentally indistinguishable from the bulk CO 2 spectrum, signifying that if physical adsorption occurs to any significant extent, the adsorbed CO 2 molecules are not substantially more rotationally constrained than the dense bulk CO 2 molecules. For the brine-saturated sample, we observe a strong band centered at 2342 cm -1 and a small companion peak at 2360-2361 cm -1 that degenerates into a barely visible shoulder peak at the higher pressures. The 2342 cm -1 band has been previously observed by other investigators for CO 2 dissolved in bulk water/brine as well during its adsorption on a variety of other wet natural porous media. We observe no peaks corresponding to bicarbonate or carbonate bulk species, which correlates well with the prior literature on similar low-pH aqueous solutions. The integrated peak area for the CO 2 sorbed in the brine-saturated sample correlates linearly with its solubility in the same bulk brine, as measured separately via a PVT-cell approach. Here, this validates the accuracy of both techniques, and the potential of the FT-IR method to be used in the study of mass transfer and adsorption in such systems. To that effect, a simple mathematical model is presented to analyze the FT-IR data to determine the CO 2 effective diffusivity in the brine-saturated sandstone sample.

58 GEOSCIENCES↗
DOE OSTI2023

Insight into multi-step geological evolution of C-type asteroids from Ryugu particles

C-type asteroids are the source of the carbonaceous chondrite meteorites and represent remnants of primitive planetesimals that formed at the outer margins of the early Solar System and may have delivered volatiles to the inner Solar System, in particular the early Earth. However, the nature of carbonaceous chondrites is not well understood owing to terrestrial alteration. Here, in this work, we present the petrology and mineral chemistry of surface materials collected by the Japan Aerospace Exploration Agency (JAXA) Hayabusa2 spacecraft from the C-type asteroid Ryugu. The Ryugu particles we studied are similar to CI (Ivuna-type) chondrites but with some important differences, such as the presence of Na–Mg phosphates and Na-rich phases and the lack of ferrihydrite and gypsum. Ryugu particles experienced several steps of aqueous alteration, metasomatism and brecciation under variable conditions. These materials represent mixed lithologies and formed at different locations within their parent asteroid. The evidence presented here demonstrates that the C-type asteroid Ryugu experienced a complex geologic evolution shortly after its formation.

58 GEOSCIENCES↗
DOE OSTI2024

Characterization of the Structural–Stratigraphic and Reservoir Controls on the Occurrence of Gas Hydrates in the Eileen Gas Hydrate Trend, Alaska North Slope

One of the most studied permafrost-associated gas hydrate accumulations in Arctic Alaska is the Eileen Gas Hydrate Trend. This study provides a detailed re-examination of the Eileen Gas Hydrate Trend with a focus on the gas hydrate accumulation in the western part of the Prudhoe Bay Unit. This integrated analysis of downhole well log data and published geophysical data has provided new insight on structural, stratigraphic, and reservoir controls on the occurrence of gas hydrates in the Eileen Gas Hydrate Trend. This study revealed the relatively complex nature of the gas hydrate occurrences in the Eileen Gas Hydrate Trend, with gas hydrates present in a series of coarsening upward, laterally pervasive, mostly fine-grained sand beds exhibiting high gas hydrate saturations. Most of the gas hydrate-bearing reservoirs in the Eileen Gas Hydrate Trend are laterally segmented into distinct northwest- to southeast-trending fault blocks, occur in a combination of structural–stratigraphic traps, and are only partially hydrate filled with distinct down-dip water contacts. These findings suggest that the traditional parts of a petroleum system (i.e., reservoir, gas source, gas migration, and geologic timing of the system formation) also control the occurrence of gas hydrates in the Eileen Gas Hydrate Trend.

20 FOSSIL-FUELED POWER PLANTS↗
NASA NTRS1972

Mineral exploration potential of ERTS-1 data

The author has identified the following significant results. Preliminary analysis of a mosaic composing eight individual ERTS frames (1:1,000,000) extending well beyond the test site has revealed a number of tectonic structural trends that are controlled by regional lineations. So far most of the regional lineations fall into three general directions: east by northeast, northwest, and north-south. From preliminary examination, it appears that the older Precambrian basement predominates in the NE-bearing structural trends, whereas the predominate NW trend is most likely associated with the Texas Structural Zone, and the north-south trend being the Utah-Arizona belt and/or part of the southern Basin and Range Province. One major lineation, made up of many parallel lineations, is noticeable just north of Lake Pleasant which extends for approximately 100 miles in a northern direction out of the target area. This feature corresponds to a Precambrian schist formation shown on the USGS geologic map of Arizona.

Brewer, W. A.↗
NASA NTRS1982

The intercrater plains of Mercury and the Moon: Their nature, origin and role in terrestrial planet evolution. Thermal histories of Mercury and the Moon

To determine a planet's thermal history, a wide range of data is necessary. These data include remote sensing results, photogeologic evidence, magnetic field and remanent magnetization data, composition and ages of samples, and physical parameters of the planet and its orbit. Few of these data form unambiguous constraints for thermal models of Mercury. Igneous Chronology as the time history of the differentiation and igneous activity, is defined. Igneous Chronology is used here in the sense of the apparent igneous or relative chronology of geologic events, such as plains formation (through whatever mechanism) relative to the crater production and tectonic history (lineament and scarp formation).

Leake, M. A.↗
NASA NTRS1987

Elemental composition of the Martian surface

The Viking landers carried X-ray fluorescence spectrometers (XRFS) to the surface of Mars for direct in-situ measurements of the elemental composition of samples that could be acquired by the surface sampler scoops. A total of 21 samples at two landing sites were acquired and analyzed. In this review, the constraints imposed on the design and operation of the XRFS; the accuracy and precision limitations of XRF; and the interpretation of the results are discussed. The latter includes relevance of the investigation to Martian geological processes, SNC meteorites, the formation and history of Mars, and future mission objectives/capabilities.

Clark, Benton C.↗
NASA NTRS1988

Application of imaging spectrometer data to the Kings-Kaweah ophiolite melange

The Kings-Kaweah ophiolite melange in east-central California is thought to be an obducted oceanic fracture zone and provides the rare opportunity to examine in detail the complex nature of this type of terrain. It is anticipated that the distribution and abundance of components in the melange can be used to determine the relative importance of geologic processes responsible for the formation of fracture zone crust. Laboratory reflectance spectra of field samples indicate that the melange components have distinct, diagnostic absorptions at visible to near-infrared wavelengths. The spatial and spectral resolution of AVIRIS is ideally suited for addressing important scientific questions concerning the Kings-Kaweah ophiolite melange and fracture zones in general.

Mustard, John F.↗
NASA NTRS2015

Mineralogy of the Pahrump Hills Region, Gale Crater, Mars

The Pahrump Hills region of Gale crater is a approximately 12 millimeter thick section of sedimentary rocks in the Murray formation, interpreted as the basal geological unit of Mount Sharp. The Mars Science Laboratory, Curiosity, arrived at the Pahrump Hills in September, 2014, and performed a detailed six-month investigation of the sedimentary structures, geochemistry, and mineralogy of the area. During the campaign, Curiosity drilled and delivered three rock samples to its internal instruments, including the CheMin XRD/XRF. The three targets, Confidence Hills, Mojave 2, and Telegraph Peak, contain variable amounts of plagioclase, pyroxene, iron oxides, jarosite, phyllosilicates, and X-ray amorphous material. Hematite was predicted at the base of Mount Sharp from orbital visible/near-IR spectroscopy, and CheMin confirmed this detection. The presence of jarosite throughout Pahrump Hills suggests the sediments experienced acid-sulfate alteration, either in-situ or within the source region of the sediments. This acidic leaching environment is in stark contrast to the environment preserved within the Sheepbed mudstone on the plains of Gale crater. The minerals within Sheepbed, including Fe-saponite, indicate these sediments were deposited in a shallow lake with circumneutral pH that may have been habitable.

Rampe, E. B.↗