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Sample records for martian meteorites studied

  1. Hydrogen in Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Peslier, A. H.; Hervig, R.; Irving, T.

    2017-01-01

    Most volatile studies of Mars have targeted its surface via spacecraft and rover data, and have evidenced surficial water in polar caps and the atmosphere, in the presence of river channels, and in the detection of water bearing minerals. The other focus of Martian volatile studies has been on Martian meteorites which are all from its crust. Most of these studies are on hydrous phases like apatite, a late-stage phase, i.e. crystallizing near the end of the differentiation sequence of Martian basalts and cumulates. Moreover, calculating the water content of the magma a phosphate crystallized from is not always possible, and yet is an essential step to estimate how much water was present in a parent magma and its source. Water, however, is primarily dissolved in the interiors of differentiated planets as hydrogen in lattice defects of nominally anhydrous minerals (olivine, pyroxene, feldspar) of the crust and mantle. This hydrogen has tremendous influence, even in trace quantities, on a planet's formation, geodynamics, cooling history and the origin of its volcanism and atmosphere as well as its potential for life. Studies of hydrogen in nominally anhydrous phases of Martian meteorites are rare. Measuring water contents and hydrogen isotopes in well-characterized nominally anhydrous minerals of Martian meteorites is the goal of our study. Our work aims at deciphering what influences the distribution and origin of hydrogen in Martian minerals, such as source, differentiation, degassing and shock.

  2. Martian Alteration in Unique Meteorite NWA 8159?

    NASA Astrophysics Data System (ADS)

    Hallis, L. J.; Simpson, S.; Mark, D.; Lee, M. R.

    2016-08-01

    This study aims to determine if the olivine alteration in martian meteorite NWA 8159 has a martian origin. If so, the unique nature of this meteorite presents evidence for aqueous processes at a new time and location on the martian surface.

  3. Reduced Martian Carbon: Evidence from Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Gibson, Everett K.; McKay, David S.; Thomas-Keprta, Kathie L.; Clemett, SImon J.; Pillinger, COlin T.; Wright, Ian P.; Verchovsky, A. P.

    2010-01-01

    Identification of indigenous reduced carbon species on Mars has been a challenge since the first hypotheses about life on Mars were proposed. Ranging from the early astronomical measurements to analyses of samples from the Martian surface in the form of Martian meteorites. The first direct attempt to analyze the carbon species on the surface was in 1976 with the Viking GC-MS in-situ experiment which gave inconclusive results at two sites on Mars [1]. With the recognition in 1983 that samples of the Martian surface were already present on Earth in the form of Martian meteorites by Bogard and Johnson [2] new opportunities became available for direct study of Mars's samples in te rlraesbtrioalratories. Carbon isotopic compositional information suggested a reduced carbon component was present in the Martian meteorites [3-5]. Polycyclic aromatic hydrocarbons associated with carbonate globules in ALH84001 were later identified [6,7]. Jull et al [8] noted that an insoluble component was present within Nakhla and more than 75% of its C lacked any 14C, which is modern-day carbon contaminant. This carbon fraction was believed to be either indigenous (i..e. Martian) or ancient meteoritic carbon phase. Within the fractures of Nakhla and ALH84001, Fisk et al [9,10] identified reduced carbon-enriched areas. Gibson et al. [11] using a combination of NanoSIMS, Focused Electron microscopy, Laser Raman Spectroscopy and Stepped-Combustion Static Mass Spectrometry analyses the presence of possible indigenous reduced carbon components within the 1.3 Ga old Nakhla.

  4. The provenance and formation of reduced carbon phases on Mars from the study of Martian meteorites.

    NASA Astrophysics Data System (ADS)

    Steele, A.; McCubbin, F. M.; Fries, M.

    2015-12-01

    Organic carbon compounds are essential building blocks of terrestrial life, so the occurrence and origin (biotic or abiotic) of organic compounds on Mars is of great significance. Indeed, the question of Martian organic matter is among the highest priority targets for robotic spacecraft missions in the next decade includ- ing the Mars Science Laboratory and Mars 2020. Sev- eral Martian meteorites contain organic carbon (i.e., macromolecular reduced carbon-rich material, not nec- essarily related to biota), but there is little agreement on its origins. Initial hypotheses for the origin of this organic carbon included: terrestrial contamination; chondritic meteoritic input; thermal decomposition of Martian carbonate minerals; direct precipitation from cooling aqueous fluids; and the remains of ancient Martian biota. We report on results from the analysis of 14 martian meteorites and show the distribution of organic phases throughout the samples analyzed. We will present formation scearios for each of the types of organic matter discovered. These studies when combined show 4 possible pools of reduced carbon on Mars. 1) impact generated graphite in the Tissint meteorite, 2) secondary hydrothermal generated graphite in ALH 84001, 3) primary igneous reduced carbon in 12 Martian meteorites associated with spinel inclusions in olivine and pyroxene 4) and potentially primary hydrothermally formed organic carbon / nitrogen containing organic species in the maskelynite phases of the Tissint meteorite. These studies show that Mars has produced reduced carbon / organic carbon via several mechanisms and reveal that the building blocks of life, if not life itself, are present on Mars.

  5. High-Resolution Multiple Sulfur Isotope Studies of Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Mojzsis, S. J.

    2000-01-01

    Sensitive, high resolution measurements of S-32, S-31, and S-34 in individual pyrite grains in martian meteorite ALH84001 by an in situ ion microprobe multi-collection technique reveal mass-independent anomalies in Delta.S-33 (Delta.S-33 = delta.S-33 - 0.516delta.S-34) in addition to the lowest 634S found in an extraterrestrial material. Low delta.S-34 values in two pyrite grains intimately associated with carbonate in ALH84001 can be explained by the sensitivity of sulfur to fractionations in the geologic environment. Anomalies in Delta.S-33 recorded in ALH84001 pyrites probably formed by gas-phase reactions in the early martian atmosphere (>4 Ga). The discovery of clearly resolvable Delta-S33 anomalies in 2 of 12 ALH84001 pyrites analyzed in their petrographic context in thin section, is considered strong evidence for crust-atmosphere exchange and the global cycling of volatile sulfur species on early Mars. These results corroborate previous measurements by Farquhar and co-workers who used a different technique that measures that bulk Delta.S-33 values of martian meteorites. These independent techniques, and their results, suggest that sulfur affected by mass-independent fractionation is common on Mars.

  6. High-Resolution Multiple Sulfur Isotope Studies of Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Mojzsis, S. J.

    2000-01-01

    Sensitive, high resolution measurements of S-32, S-31, and S-34 in individual pyrite grains in martian meteorite ALH84001 by an in situ ion microprobe multi-collection technique reveal mass-independent anomalies in Delta.S-33 (Delta.S-33 = delta.S-33 - 0.516delta.S-34) in addition to the lowest 634S found in an extraterrestrial material. Low delta.S-34 values in two pyrite grains intimately associated with carbonate in ALH84001 can be explained by the sensitivity of sulfur to fractionations in the geologic environment. Anomalies in Delta.S-33 recorded in ALH84001 pyrites probably formed by gas-phase reactions in the early martian atmosphere (>4 Ga). The discovery of clearly resolvable Delta-S33 anomalies in 2 of 12 ALH84001 pyrites analyzed in their petrographic context in thin section, is considered strong evidence for crust-atmosphere exchange and the global cycling of volatile sulfur species on early Mars. These results corroborate previous measurements by Farquhar and co-workers who used a different technique that measures that bulk Delta.S-33 values of martian meteorites. These independent techniques, and their results, suggest that sulfur affected by mass-independent fractionation is common on Mars.

  7. Martian Meteorites Record Surface Temperatures on Mars

    NASA Astrophysics Data System (ADS)

    Taylor, G. J.

    2005-07-01

    Using published data for argon (Ar) released when Martian meteorites are heated, David Shuster (California Institute of Technology, now at Berkeley Geochronology Center, Berkeley, CA) and Benjamin Weiss (Massachusetts Institute of Technology) show that the nakhlite group of Martian meteorites and unique Martian meteorite ALH 84001 were probably not heated above about 0 degree C for most of their histories. This indicates that the surface of Mars has been cold for almost four billion years. If a warm, wet environment existed on Mars (inferred from previous studies of surface features and geochemical parameters), it occurred before four billion years ago.

  8. An Adulterated Martian Meteorite

    NASA Astrophysics Data System (ADS)

    Taylor, G. J.

    1999-07-01

    Martian meteorite, Elephant Moraine EETA79001, is composed of two distinct rock types. Scientists have thought that both formed from magmas, hence are igneous rocks and contain important information about the interior of Mars, the nature of lava flows on its surface, and the timing of igneous events on Mars. All that is now open to question, as a group of investigators at Lockheed Martin Space Operations and the Johnson Space Center led by David Mittlefehldt (Lockheed) has shown that one of the rock types making up EETA79001, designated lithology A, is almost certainly a melted mixture of other rocks. Mittlefehldt and coworkers suggest that formation by impact melting is the most likely explanation for the chemical and mineralogical features seen in the rock. If confirmed by other investigations, this may change the way we view the igneous evolution of Mars.

  9. Chlorine Abundances in Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Bogard, D.D.; Garrison, D.H.; Park, J.

    2009-01-01

    Chlorine measurements made in martian surface rocks by robotic spacecraft typically give Chlorine (Cl) abundances of approximately 0.1-0.8%. In contrast, Cl abundances in martian meteorites appear lower, although data is limited, and martian nakhlites were also subjected to Cl contamination by Mars surface brines. Chlorine abundances reported by one lab for whole rock (WR) samples of Shergotty, ALH77005, and EET79001 range 108-14 ppm, whereas Cl in nakhlites range 73-1900 ppm. Measurements of Cl in various martian weathering phases of nakhlites varied 0.04-4.7% and reveal significant concentration of Cl by martian brines Martian meteorites contain much lower Chlorine than those measured in martian surface rocks and give further confirmation that Cl in these surface rocks was introduced by brines and weathering. It has been argued that Cl is twice as effective as water in lowering the melting point and promoting melting at shallower martian depths, and that significant Cl in the shergottite source region would negate any need for significant water. However, this conclusion was based on experiments that utilized Cl concentrations more analogous to martian surface rocks than to shergottite meteorites, and may not be applicable to shergottites.

  10. Life on Mars: Evidence from Martian Meteorites

    NASA Technical Reports Server (NTRS)

    McKay, David S.; Thomas-Keptra, Katie L.; Clemett, Simon J.; Gibson, Everett K., Jr.; Spencer, Lauren; Wentworth, Susan J.

    2009-01-01

    New data on martian meteorite 84001 as well as new experimental studies show that thermal or shock decomposition of carbonate, the leading alternative non-biologic explanation for the unusual nanophase magnetite found in this meteorite, cannot explain the chemistry of the actual martian magnetites. This leaves the biogenic explanation as the only remaining viable hypothesis for the origin of these unique magnetites. Additional data from two other martian meteorites show a suite of biomorphs which are nearly identical between meteorites recovered from two widely different terrestrial environments (Egyptian Nile bottomlands and Antarctic ice sheets). This similarity argues against terrestrial processes as the cause of these biomorphs and supports an origin on Mars for these features.

  11. Martian soil component in impact glasses in a Martian meteorite.

    PubMed

    Rao, M N; Borg, L E; McKay, D S; Wentworth, S J

    1999-11-01

    Chemical compositions of impact melt glass veins, called Lithology C (Lith C) in Martian meteorite EET79001 were determined by electron microprobe analysis. A large enrichment of S, and significant enrichments of Al, Ca, and Na were observed in Lith C glass compared to Lithology A (Lith A). The S enrichment is due to mixing of plagioclase- enriched Lith A material with Martian soil, either prior to or during impact on Mars. A mixture of 87% Lith A, 7% plagioclase, and 6% Martian soil reproduces the average elemental abundances observed in Lith C. Shock melting of such a mixture of plagioclase-enriched, fine-grained Lith A host rock and Martian soil could yield large excesses of S (observed in this study) and Martian atmospheric noble gases (found by Bogard et al., 1983) in Lith C. These mixing proportions can be used to constrain the elemental abundance of phosphorus in Martian soil.

  12. Martian Meteorite Ages and Implications for Martian Cratering History

    NASA Technical Reports Server (NTRS)

    Nyquist, Laurence E.

    2006-01-01

    New radiometrically determined ages of Martian meteorites add to the growing number with crystallization ages < 1.4 Ga. The observation of mainly geologically young ages for the Martian meteorites, the only exception being the 4.5 Ga ALH84001 [1], is paradoxical when viewed in context of a Martian surface thought to be mostly much older as inferred from the surface density of meteorite craters [2]. There appears to be at least a twofold difference between the observed ages of Martian meteorites and their expected ages as inferred from the ages of Martian surfaces obtained from crater densities.

  13. Studies of Magmatic Inclusions in the Basaltic Martian Meteorites Shergotty, Zagami, EETA 79001 and QUE 94201

    NASA Technical Reports Server (NTRS)

    Harvey, Ralph P.; McKay, Gordon A.

    1997-01-01

    inclusions; those found within early-forming pigeonite, intermediate and late-forming Ti, Fe-oxides and sulfides, and intermediate to late-forming phosphates. In this summer' s study we have made a detailed study of all of the various forms of inclusions found within the 4 basaltic martian meteorites listed above. Glasses and minerals within the inclusions were analyzed using the Camera SX-100 Electron Microprobe in Building 31. The mineralogy and textural context of the inclusions will then be used to explore the crystallization history of these specimens, and to investigate any differences in crystallization history or parental magma compositions between these rocks. In this manner, the magmatic inclusions provide a road map backwards toward the 'parental' compositions for the basaltic martian meteorites and provide significant insight into the igneous processes found within the crust of Mars.

  14. Martian "microfossils" in lunar meteorites?

    PubMed

    Sears, D W; Kral, T A

    1998-07-01

    One of the five lines of evidence used by McKay et al. (1996) for relic life in the Martian meteorite Allan Hills (ALH) 84001 was the presence of objects thought to be microfossils. These ovoid and elongated forms are similar to structures found in terrestrial rocks and described as "nanobacteria" (Folk, 1993; McBride et al., 1994). Using the same procedures and apparatus as McKay et al. (1996), we have found structures on internal fracture surfaces of lunar meteorites that cannot be distinguished from the objects described on similar surfaces in ALH 84001. The lunar surface is currently a sterile environment and probably always has been. However, the lunar and Martian meteorites share a common terrestrial history, which includes many thousands of years of exposure to Antarctic weathering. Although we do not know the origin of these ovoid and elongated forms, we suggest that their presence on lunar meteorites indicates that the objects described by McKay et al. (1996) are not of Martian biological origin.

  15. Radiometric Ages of Martian Meteorites compared to Martian Surfaces Ages

    NASA Technical Reports Server (NTRS)

    Nyquist, L. E.; Shih, C.-Y.

    1999-01-01

    The surprisingly young Rb-Sr age of the Shergotty meteorite contributed to early suggestions that it might be of martian origin. their redox state and oxygen isotopic compositions linked the shergottites to the clino-pyroxenite nakhlites and the dunite Chassigny, causing them to be grouped as SNC meteorites. These characteristics, but especially the similarity of the elemental and isotopic compositions of gases trapped in shergottites to those of the martian atmosphere, have caused the martian origin of the SNC and related meteorites to be widely accepted. Although the young ages were one of the early hints of a martian origin for the SNC meteorites, their interpretation has remained somewhat ambiguous. We will review the radiometric ages of the martian meteorites and attempt to place them into the context of martian surface ages.

  16. The Germanium Dichotomy in Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Humayun, M.; Yang, S.; Righter, K.; Zanda, B.; Hewins, R. H.

    2016-01-01

    Germanium is a moderately volatile and siderophile element that follows silicon in its compatibility during partial melting of planetary mantles. Despite its obvious usefulness in planetary geochemistry germanium is not analyzed routinely, with there being only three prior studies reporting germanium abundances in Martian meteorites. The broad range (1-3 ppm) observed in Martian igneous rocks is in stark contrast to the narrow range of germanium observed in terrestrial basalts (1.5 plus or minus 0.1 ppm). The germanium data from these studies indicates that nakhlites contain 2-3 ppm germanium, while shergottites contain approximately 1 ppm germanium, a dichotomy with important implications for core formation models. There have been no reliable germanium abundances on chassignites. The ancient meteoritic breccia, NWA 7533 (and paired meteorites) contains numerous clasts, some pristine and some impact melt rocks, that are being studied individually. Because germanium is depleted in the Martian crust relative to chondritic impactors, it has proven useful as an indicator of meteoritic contamination of impact melt clasts in NWA 7533. The germanium/silicon ratio can be applied to minerals that might not partition nickel and iridium, like feldspars. We report germanium in minerals from the 3 known chassignites, 2 nakhlites and 5 shergottites by LAICP- MS using a method optimized for precise germanium analysis.

  17. Nature of Reduced Carbon in Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Gibson, Everett K., Jr.; McKay, D. S.; Thomas-Keprta, K. L.; Clemett, S. J.; White, L. M.

    2012-01-01

    Martian meteorites provide important information on the nature of reduced carbon components present on Mars throughout its history. The first in situ analyses for carbon on the surface of Mars by the Viking landers yielded disappointing results. With the recognition of Martian meteorites on Earth, investigations have shown carbon-bearing phases exist on Mars. Studies have yielded presence of reduced carbon, carbonates and inferred graphitic carbon phases. Samples ranging in age from the first approximately 4 Ga of Mars history [e.g. ALH84001] to nakhlites with a crystallization age of 1.3 Ga [e.g. Nakhla] with aqueous alteration processes occurring 0.5-0.7 Ga after crystallizaton. Shergottites demonstrate formation ages around 165-500 Ma with younger aqueous alterations events. Only a limited number of the Martian meteorites do not show evidence of significance terrestrial alterations. Selected areas within ALH84001, Nakhla, Yamato 000593 and possibly Tissint are suitable for study of their indigenous reduced carbon bearing phases. Nakhla possesses discrete, well-defined carbonaceous phases present within iddingsite alteration zones. Based upon both isotopic measurements and analysis of Nakhla's organic phases the presence of pre-terrestrial organics is now recognized. The reduced carbon-bearing phases appear to have been deposited during preterrestrial aqueous alteration events that produced clays. In addition, the microcrystalline layers of Nakhla's iddingsite have discrete units of salt crystals suggestive of evaporation processes. While we can only speculate on the origin of these unique carbonaceous structures, we note that the significance of such observations is that it may allow us to understand the role of Martian carbon as seen in the Martian meteorites with obvious implications for astrobiology and the pre-biotic evolution of Mars. In any case, our observations strongly suggest that reduced organic carbon exists as micrometer- size, discrete structures

  18. Lunar and martian meteorite delivery services

    NASA Technical Reports Server (NTRS)

    Warren, Paul H.

    1994-01-01

    Launch mechanisms for lunar and martian meteorites have been investigated, by integrating physical modeling constraints, geochemical cosmic-ray exposure (CRE) constraints, and petrologic constraints. The potential source region for lunar meteorites is remarkably small compared to the final crater volume. CRE constraints indicate that most launches start at depths of less than or equal to 3.2 m, and cratering theory implies derivation of suitably accelerated objects from a subvolume with diameter only about 0.3 x the final crater diameter. The shallow depth provenance is probably related to shock-wave interference, enhanced by the lunar regolith's extremely low compressional wave velocity. CRE constraints alone imply that four to five separate launch events are represented among the eight well-studied lunar meteorites. Most of the lunar meteorites are regolith breccias, which tend to show only limited compositional diversity within any kilometer-scale region of the Moon. Several others are polymict breccias, which also show relatively subdued compositional diversity, compared to igneous rocks. The observed diversity among these samples in terms of abundances of mare basalt and KREEP, and in Mg/(Mg + Fe) ratio, implies that among eight well-studied lunar meteorites only two potential source craters pairings are plausible: between Asuka-881757 + Y-793169 (most probable) and between Y-793274 + EET875721. Altogether, these eight lunar meteorites apparently represent at least six separate source craters, including three in the past 10(exp 5) years and five in the past 10(exp 6) years. CRE constraints imply that SNC meteorites are launched from systematically greater than lunar meteorites. SNCs are also systematically bigger, and all nine well-studied SNCs are uncommonly young (by martian standards) mafic igneous rocks. Comparison between Viking and Apollo results reveals that rocks the size of common meteorites are remarkably scarce in the martian regolith, probably due

  19. New Martian Meteorite is Similar to Typical Martian Crust

    NASA Astrophysics Data System (ADS)

    Taylor, G. J.

    2013-01-01

    A newly-identified Martian meteorite from Northwest Africa is not like other Martian meteorites, but has a chemical composition similar to the average Martian crust. Carl Agee, Institute of Meteoritics at the University of New Mexico (UNM), led a team with wide scientific expertise from UNM, the University of California at San Diego, and the Carnegie Institution of Washington in examining what turned out to be a unique Martian meteorite, Northwest Africa (NWA) 7034. The ratio of iron to manganese clearly links it to Mars. Yet, its overall chemical composition makes it unique among Martian meteorites: high concentrations of rare earth elements (five times more than the typical Martian meteorite) and H2O (ten times higher than any other Martian meteorite) and old age of 2.09 billion years (compared to less than 500 million years for the largest group of Martian meteorites, and 1.3 billion years for another group; one sample has an older age of 4.1 billion years). The chemical composition of NWA 7034 is more like that of the Martian crust observed from orbit by the Mars Odyssey Gamma-Ray Spectrometer and on the ground by the Pathfinder and Mars Exploration Rovers. The sample appears to be a volcanic rock with a basaltic composition like most of the crust and formed in the early part of the Amazonian era of Martian geologic history. Small differences in the oxygen isotoptic composition of NWA 7034 compared to other Martian meteorites indicate that rocks on Mars vary somewhat in the proportions of oxygen isotopes. This unique rock shows the importance of continued searches for meteorites in the hot and cold deserts of Earth to recover additional samples of Mars. The fact that NWA 7034 is the 112th Martian meteorite identified on Earth, also proves the value of persistent searching. More importantly, it also shows us the importance of being able to analyze rocks in terrestrial laboratories with the battery of continuously-improving instruments available to us.

  20. [Meteoritics and mineralogy on possible ancient Martian life].

    PubMed

    Tsuchiyama, A

    1996-12-01

    Possible relic biogenic activity in martian meteorite ALH84001 was proposed by McKay et al. (Science, 273, 924-930, 1996). This ancient meteorite of 4.5 billion years old contains abundant carbonates as secondary minerals precipitated from a fluid on the martian surface. They showed the following lines of evidence for the ancient life; (1) unique mineral compositions and biominerals, (2) polycyclic aromatic hydrocarbons (PAHs) in association with the carbonates, and (3) unique structures and morphologies typical of nanobacteria or microfossils. This review is divided into two parts; one is on the martian meteorites in general and ALH84001, which has many features unlike other martian meteorites, and the other is on mineralogical (biomineralogical) and geochemical features of the carbonates and microfossil-like structures. There is little doubt that ALH84001 is from Mars as well as eleven other SNC meteorites. However, the mineralogical and biomineralogical evidence for martian bacteria given by McKay et al. (1996) is controversial, and could be formed by non-biogenic processes. Thus, further study of ALH84001 and other martian meteorites is required. We also need to consider the future Mars mission especially sample return mission.

  1. 40 Years of Collecting Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Funk, R. C.; Sattershite, C. E.; Righter, K.; Harrington, R.

    2017-01-01

    This year marks the 40th anniversary of the first Martian meteorite found in Antarctica by ANSMET, ALH 77005. Since then, an additional 14 Martian meteorites have been found by the ANSMET team making for a total of 15 Martian meteorites in the Antarctic collection at Johnson Space Center. Of the 15 meteorites, some have been paired so the 15 meteorites actually represent a total of approximately 9 separate meteorites. The first Martian meteorite found by ANSMET was ALH 77005 (482.500 g), a lherzolitic shergottite. When collected, this meteorite was split as a part of the joint expedition with the National Institute of Polar Research (NIPR) Japan. Originally classified as an "achondrite-unique", it was re-classified as a Martian lherzolitic shergottites in 1982 [1]. This meteorite has been allocated to 125 scientists for research and there are 181.964 g remaining at Johnson Space Center (JSC). Two years later, one of the most significant Martian meteorites of the collection at JSC was found at Elephant Moraine, EET 79001 (7942.000 g), a shergottite. This meteorite is the largest in the Martian collection at JSC and was the largest stony meteorite sample collected during the 1979 season. In addition to its size, this meteorite is of particular interest because it contains a linear contact separating two different igneous lithologies, basaltic and olivine-phyric. EET 79001 has glass inclusions that contain chemical compositions that are proportionally identical to the Martian atmosphere, as measured by the Viking spacecraft [2]. This discovery helped scientists to identify where the "SNC" meteorite suite had originated, and that we actually possessed Martian samples. This meteorite has been allocated to 195 scientists for research and there are 5304.770 g of sample is available. Five years later, ANSMET found ALH 84001 (1930.900 g), the only Martian orthopyroxenite. This meteorite was initially classified as a diogenite but was reclassified as being a Martian

  2. Ar-40/Ar-39 Studies of Martian Meteorite RBT 04262 and Terrestrial Standards

    NASA Technical Reports Server (NTRS)

    Park, J.; Herzog, G. F.; Turrin, B.; Lindsay, F. N.; Delaney, J. S.; Swisher, C. C., III; Nagao, K.; Nyquist, L. E.

    2014-01-01

    Park et al. recently presented an Ar-40/Ar-39 dating study of maskelynite separated from the Martian meteorite RBT 04262. Here we report an additional study of Ar-40/Ar-39 patterns for smaller samples, each consisting of only a few maskelynite grains. Considered as a material for Ar-40/Ar-39 dating, the shock-produced glass maskelynite has both an important strength (relatively high K concentration compared to other mineral phases) and some potentially problematic weaknesses. At Rutgers, we have been analyzing small grains consisting of a single phase to explore local effects that might be averaged and remain hidden in larger samples. Thus, to assess the homogeneity of the RBT maskelynite and for comparison with the results of, we analyzed six approx. 30 microgram samples of the same maskelynite separate they studied. Furthermore, because most Ar-40/Ar-39 are calculated relative to the age of a standard, we present new Ar-40/Ar-39 age data for six standards. Among the most widely used standards are sanidine from Fish Canyon (FCs) and various hornblendes (hb3gr, MMhb-1, NL- 25), which are taken as primary standards because their ages have been determined by independent, direct measurements of K and A-40.

  3. Carbonates in Martian Meteorites - A Reappraisal

    NASA Astrophysics Data System (ADS)

    Grady, M. M.; Wright, I. P.; Douglas, C.; Pillinger, C. T.

    1995-09-01

    the mineralogy of the carbonates to be constrained. since the peak decomposition temperature of carbonates varies with mineralogical composition. Preliminary results indicate that the carbonates in martian meteorites might indeed be more 13C-enriched than previously inferred [6]. Stepped combustion of Nakhla reveals a maximum in yield at 475 degrees C, corresponding to the release of an iron-rich carbonate, with delta^(13)C +21 per mil. Since there is an overlap of the carbonate with low temperature carbonaceous material, this value is a lower limit. Indeed, delta^(13)C from acid leaching experiments reaches a value around +50 per mil, similar to the ALH 84001 studies [1, 5]. Models of surface processes on Mars [e.g. 4, 6] have assumed that C07 from the martian atmosphere is in equilibrium with CO2 dissolved in circulating crustal fluids, resulting in the precipitation of isotopically heavy carbonates. However, if the delta^(13)C of martian carbonates is ~ +50 per mil, then the models must be re-adjusted. It is unlikely that delta^(13)C of the carbonate has increased with time, e.g. by decarbonation reactions, since there is no parallel effect in delta^(18)O, and no petrographic evidence for the reaction. The delta^(13)C of the martian atmosphere is poorly-constrained; it is possible that its isotopic composition is heavier than believed, and that delta^(13)C has decreased with time, perhaps by the addition of isotopically light magmatic carbon degassed from the planet [8]. Additional measurements of carbonates in martian meteorites will allow better comprehension of fluid-atmosphere interactions on Mars. References: [1] Carr R. H. et al. (1985) Nature, 314, 248-250. [2] Gooding J. L. et al. (1991) Meteoritics, 26, 135-143. [3] Grady M. M. et al. (1994) Meteoritics, 29, 469. [4] Romanek C. S. et al. (1994) Nature, 372, 655-657. [5] Jull A. J. T. et al. (1995) Meteoritics, 30, 311-318. [6] Wright I. P. et al. (1992) GCA, 56, 817-826. [7] Rosenbaum J. and Sheppard S. F

  4. Transmission Electron Microscope Studies of Martian 'Iddingsite' in the Nakhlite Meteorite MIL 090032

    NASA Astrophysics Data System (ADS)

    Hallis, L.; Ishii, H.; Bradley, J. P.; Taylor, J.

    2012-12-01

    As with the other nakhlites, MIL 090032 contains iddingsite-like alteration veins in the olivine phenocrysts that reportedly originated on Mars[1]. These 'iddingsite' veins have been analysed in a number of the nakhlite meteorites[2], and the presence of hydrous silicate gel, smectite clays, siderite, Fe-oxides, gypsum and carbonate have been reported. The presence and proportion of these phases in the different nakhlites appears to relate to the composition and concentration of the martian brine that flowed through each, thus supporting the theory that the nakhlite secondary alteration phases were produced by an evaporation sequence on the surface of Mars[3]. We analyzed these martian 'iddingsite' veins in MIL 090032 with the aim of placing it and its three paired meteorites within the nakhlite alteration sequence. By expanding our knowledge of this alteration sequence, we will gain extra insight into the conditions on the martian surface at the time these 'iddingsite' veins formed (<1.3 Ga). We utilized the 80-300 kV aberration-corrected FEI Titan (Scanning) Transmission Electron Microscope (S-TEM) system at Lawrence Livermore National Laboratory to analyse a ~15×8μm Focused Ion Beam (FIB) section of an 'iddingsite' vein in MIL 090032. To allow the electrons to be transmitted through the FIB section, it was milled down to ~150 nm thickness. Our initial TEM data indicate this FIB section contains hydrous amorphous silicate gel towards the center, with areas of phyllosilicate (possibly nontronite) interspersed within this central zone. Towards the outer edge of the vein jarosite and then gypsum sulfates were present. At the very edge only partially broken down olivine was observed. The presence of phyllosilicate and silicate gel in this vein suggests the 'iddingsite' in MIL 090032 was produced by water-rich brine, and the abundance of sulfates suggests the brine was enriched in sulfur. This assemblage of minerals is most in line with that of the 'iddingsite

  5. Phosphates and Carbon in Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Mojzsis, Stephen J.

    2000-01-01

    This paper proposes tests for exobiological examination of samples prior to obtaining martian rocks of known provenance via future sample-return missions. If we assume that all of the secondary minerals in martian meteorite ET79001 were indeed cogenetic and originate from Mars, we list conclusions that can be drawn that are of exobiological interest. This work serves as a preamble for the subsequent work listed below.

  6. Phosphates and Carbon in Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Mojzsis, Stephen J.

    2000-01-01

    This paper proposes tests for exobiological examination of samples prior to obtaining martian rocks of known provenance via future sample-return missions. If we assume that all of the secondary minerals in martian meteorite ET79001 were indeed cogenetic and originate from Mars, we list conclusions that can be drawn that are of exobiological interest. This work serves as a preamble for the subsequent work listed below.

  7. The Chlorine Isotope Composition of Martian Meteorites

    NASA Astrophysics Data System (ADS)

    Sharp, Z. D.; Shearer, C. K.; Agee, C.; Burger, P. V.; McKeegan, K. D.

    2014-11-01

    The Cl isotope composition of martian meteorites range from -3.8 to +8.6 per mil. Ol-phyric shergottites are lightest; crustally contaminated samples are heaviest, basaltic shergottites are in-between. The system is explained as two component mixing.

  8. Alteration of Sedimentary Clasts in Martian Meteorite Northwest Africa 7034

    NASA Technical Reports Server (NTRS)

    McCubbin, F. M.; Tartese, R.; Santos, A. R.; Domokos, G.; Muttik, N.; Szabo, T.; Vazquez, J.; Boyce, J. W.; Keller, L. P.; Jerolmack, D. J.; Anand, M.; Moser, D. E.; Delhaye, T.; Shearer, C. K.; Agee, C. B.

    2014-01-01

    The martian meteorite Northwest Africa (NWA) 7034 and pairings represent the first brecciated hand sample available for study from the martian surface [1]. Detailed investigations of NWA 7034 have revealed substantial lithologic diversity among the clasts [2-3], making NWA 7034 a polymict breccia. NWA 7034 consists of igneous clasts, impact-melt clasts, and "sedimentary" clasts represented by prior generations of brecciated material. In the present study we conduct a detailed textural and geochemical analysis of the sedimentary clasts.

  9. Formation of a Martian Pyroxenite: A Comparative Study of the Nakhlite Meteorites and Theo's Flow

    NASA Technical Reports Server (NTRS)

    Friedman, R. C.; Taylor, G. J.; Treiman, A. H.

    1999-01-01

    The unusual composition of the nakhlites, a group of pyroxenitic martian meteorites with young ages, presents an opportunity to learn about nonbasaltic magmatic activity on another planet. However, the limited number of these meteorites makes unraveling their history difficult. A promising terrestrial analog for the formation of the nakhlites is Theo's Flow in Ontario, Canada. This atypical, 120 m-thick flow differentiated in place, forming distinct layered lithologies of peridotite, pyroxenite, and gabbro. Theo's pyroxenite and the nakhlites share strikingly similar petrographies, with concentrated euhedral to subhedral augite grains set in a plagioclase-rich matrix. These two suites of rocks also share specific petrologic features, mineral and whole-rock compositional features, and size and spatial distributions of cumulus grains. The numerous similarities suggest that the nakhlites formed by a similar mechanism in a surface lava flow or shallow intrusion. Their formation could have involved settling of crystals in a phenocryst-laden flow or in situ nucleation and growth of pyroxenes in an ultramafic lava flow. The latter case is more likely and requires steady-state nucleation and growth of clusters of pyroxene grains (and olivine in the nakhlites), circulating in a strongly convecting melt pool, followed by settling and continued growth in a thickening cumulate pile. Trapped pockets of intercumulus liquid in the pile gradually evolved, finally growing Fe-enriched rims on cumulus grains. With sufficient evolution, the melt reached plagioclase supersaturation, causing rapid growth of plagioclase sprays and late-stage mesostasis growth.

  10. Lunar and Planetary Science XXXV: Martian Meteorites: Chemical Weathering

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The session "Martian Meteorites: Chemical Weathering" included the following reports:Chemical Weathering Records of Martian Soils Preserved in the Martian Meteorite EET79001; Synchrotron X-Ray Diffraction Analysis of Meteorites in Thin Section: Preliminary Results; A Survey of Olivine Alteration Products Using Raman Spectroscopy; and Rb-Sr and Sm-Nd Isotope Systematics of Shergottite NWA 856: Crystallization Age and Implications for Alteration of Hot Desert SNC Meteorites.

  11. A Pb isotopic resolution to the Martian meteorite age paradox

    NASA Astrophysics Data System (ADS)

    Bellucci, J. J.; Nemchin, A. A.; Whitehouse, M. J.; Snape, J. F.; Kielman, R. B.; Bland, P. A.; Benedix, G. K.

    2016-01-01

    Determining the chronology and quantifying various geochemical reservoirs on planetary bodies is fundamental to understanding planetary accretion, differentiation, and global mass transfer. The Pb isotope compositions of individual minerals in the Martian meteorite Chassigny have been measured by Secondary Ion Mass Spectrometry (SIMS). These measurements indicate that Chassigny has mixed with a Martian reservoir that evolved with a long-term 238U/204Pb (μ) value ∼ two times higher than those inferred from studies of all other Martian meteorites except 4.428 Ga clasts in NWA7533. Any significant mixing between this and an unradiogenic reservoir produces ambiguous trends in Pb isotope variation diagrams. The trend defined by our new Chassigny data can be used to calculate a crystallization age for Chassigny of 4.526 ± 0.027 Ga (2σ) that is clearly in error as it conflicts with all other isotope systems, which yield a widely accepted age of 1.39 Ga. Similar, trends have also been observed in the Shergottites and have been used to calculate a >4 Ga age or, alternatively, attributed to terrestrial contamination. Our new Chassigny data, however, argue that the radiogenic component is Martian, mixing occurred on the surface of Mars, and is therefore likely present in virtually every Martian meteorite. The presence of this radiogenic reservoir on Mars resolves the paradox between Pb isotope data and all other radiogenic isotope systems in Martian meteorites. Importantly, Chassigny and the Shergottites are likely derived from the northern hemisphere of Mars, while NWA 7533 originated from the Southern hemisphere, implying that the U-rich reservoir, which most likely represents some form of crust, must be widespread. The significant age difference between SNC meteorites and NWA 7533 is also consistent with an absence of tectonic recycling throughout Martian history.

  12. Magmatic water in the martian meteorite Nakhla

    NASA Astrophysics Data System (ADS)

    Hallis, L. J.; Taylor, G. J.; Nagashima, K.; Huss, G. R.

    2012-12-01

    Mars does not recycle crustal materials via plate tectonics. For this reason the magmatic water reservoir of the martian mantle has not been affected by surface processes, and the deuterium/hydrogen (D/H) ratio of this water should represent the original primordial martian value. Following this logic, hydrous primary igneous minerals on the martian surface should also carry this primordial D/H ratio, assuming no assimilation of martian atmospheric water during crystallization and no major hydrogen fractionation during melt degassing. Hydrous primary igneous minerals, such as apatite and amphibole, are present in martian meteorites here on Earth. Providing these minerals have not been affected by terrestrial weathering, martian atmospheric water, or shock processes after crystallization, they should contain a good approximation of the primordial martian D/H ratio. As Nakhla was seen to fall in the Egyptian desert in 1911, terrestrial contamination is minimized in this meteorite. The nakhlites are also among the least shocked of the martian meteorites. Therefore, apatite within Nakhla could contain primordial martian hydrogen isotope ratios. We produced in-situ measurements of the D/H ratios in Nakhla apatite grains, using a Cameca ims 1280 ion-microprobe. Our measurements produced D/H values in Nakhla apatite similar to terrestrial values, despite strong evidence that our samples were not significantly contaminated by terrestrial hydrogen. These results suggest that water trapped in the martian mantle has a similar D/H to that of the Earth. Therefore, the water of these two planets may have originated from the same source material. The D/H ratios of the carbonaceous chondrite meteorites, and the Jupiter-family comet 103P/Hartley 2, are similar to the D/H of the two planets, making both these primitive inner solar system materials strong candidates for the source of the terrestrial planets water. These results support recent dynamical models of the formation of the

  13. Amino acids in the Martian meteorite Nakhla.

    PubMed

    Glavin, D P; Bada, J L; Brinton, K L; McDonald, G D

    1999-08-03

    A suite of protein and nonprotein amino acids were detected with high-performance liquid chromatography in the water- and acid-soluble components of an interior fragment of the Martian meteorite Nakhla, which fell in Egypt in 1911. Aspartic and glutamic acids, glycine, alanine, beta-alanine, and gamma-amino-n-butyric acid (gamma-ABA) were the most abundant amino acids detected and were found primarily in the 6 M HCl-hydrolyzed, hot water extract. The concentrations ranged from 20 to 330 parts per billion of bulk meteorite. The amino acid distribution in Nakhla, including the D/L ratios (values range from <0.1 to 0.5), is similar to what is found in bacterially degraded organic matter. The amino acids in Nakhla appear to be derived from terrestrial organic matter that infiltrated the meteorite soon after its fall to Earth, although it is possible that some of the amino acids are endogenous to the meteorite. The rapid amino acid contamination of Martian meteorites after direct exposure to the terrestrial environment has important implications for Mars sample-return missions and the curation of the samples from the time of their delivery to Earth.

  14. Amino acids in the Martian meteorite Nakhla

    PubMed Central

    Glavin, Daniel P.; Bada, Jeffrey L.; Brinton, Karen L. F.; McDonald, Gene D.

    1999-01-01

    A suite of protein and nonprotein amino acids were detected with high-performance liquid chromatography in the water- and acid-soluble components of an interior fragment of the Martian meteorite Nakhla, which fell in Egypt in 1911. Aspartic and glutamic acids, glycine, alanine, β-alanine, and γ-amino-n-butyric acid (γ-ABA) were the most abundant amino acids detected and were found primarily in the 6 M HCl-hydrolyzed, hot water extract. The concentrations ranged from 20 to 330 parts per billion of bulk meteorite. The amino acid distribution in Nakhla, including the d/l ratios (values range from <0.1 to 0.5), is similar to what is found in bacterially degraded organic matter. The amino acids in Nakhla appear to be derived from terrestrial organic matter that infiltrated the meteorite soon after its fall to Earth, although it is possible that some of the amino acids are endogenous to the meteorite. The rapid amino acid contamination of Martian meteorites after direct exposure to the terrestrial environment has important implications for Mars sample-return missions and the curation of the samples from the time of their delivery to Earth. PMID:10430856

  15. Amino acids in the Martian meteorite Nakhla

    NASA Technical Reports Server (NTRS)

    Glavin, D. P.; Bada, J. L.; Brinton, K. L.; McDonald, G. D.

    1999-01-01

    A suite of protein and nonprotein amino acids were detected with high-performance liquid chromatography in the water- and acid-soluble components of an interior fragment of the Martian meteorite Nakhla, which fell in Egypt in 1911. Aspartic and glutamic acids, glycine, alanine, beta-alanine, and gamma-amino-n-butyric acid (gamma-ABA) were the most abundant amino acids detected and were found primarily in the 6 M HCl-hydrolyzed, hot water extract. The concentrations ranged from 20 to 330 parts per billion of bulk meteorite. The amino acid distribution in Nakhla, including the D/L ratios (values range from <0.1 to 0.5), is similar to what is found in bacterially degraded organic matter. The amino acids in Nakhla appear to be derived from terrestrial organic matter that infiltrated the meteorite soon after its fall to Earth, although it is possible that some of the amino acids are endogenous to the meteorite. The rapid amino acid contamination of Martian meteorites after direct exposure to the terrestrial environment has important implications for Mars sample-return missions and the curation of the samples from the time of their delivery to Earth.

  16. Amino Acids in the Martian Meteorite Nakhla

    NASA Astrophysics Data System (ADS)

    Glavin, Daniel P.; Bada, Jeffrey L.; Brinton, Karen L. F.; McDonald, Gene D.

    1999-08-01

    A suite of protein and nonprotein amino acids were detected with high-performance liquid chromatography in the water- and acid-soluble components of an interior fragment of the Martian meteorite Nakhla, which fell in Egypt in 1911. Aspartic and glutamic acids, glycine, alanine, β -alanine, and γ -amino-n-butyric acid (γ -ABA) were the most abundant amino acids detected and were found primarily in the 6 M HCl-hydrolyzed, hot water extract. The concentrations ranged from 20 to 330 parts per billion of bulk meteorite. The amino acid distribution in Nakhla, including the D/L ratios (values range from <0.1 to 0.5), is similar to what is found in bacterially degraded organic matter. The amino acids in Nakhla appear to be derived from terrestrial organic matter that infiltrated the meteorite soon after its fall to Earth, although it is possible that some of the amino acids are endogenous to the meteorite. The rapid amino acid contamination of Martian meteorites after direct exposure to the terrestrial environment has important implications for Mars sample-return missions and the curation of the samples from the time of their delivery to Earth.

  17. UV Raman imaging--a promising tool for astrobiology: comparative Raman studies with different excitation wavelengths on SNC Martian meteorites.

    PubMed

    Frosch, Torsten; Tarcea, Nicolae; Schmitt, Michael; Thiele, Hans; Langenhorst, Falko; Popp, Jürgen

    2007-02-01

    The great capabilities of UV Raman imaging have been demonstrated on the three Martian meteorites: Sayh al Uhaymir, Dar al Gani, and Zagami. Raman spectra without disturbing fluorescence and with high signal-to-noise-ratios and full of spectral features were derived. This result is of utmost importance for the development of powerful instruments for space missions. By point scanning the surfaces of the meteorite samples, it was possible for the first time to construct UV-Raman images out of the array of Raman spectra. Deep-UV Raman images are to the best of our knowledge presented for the first time. The images were used for a discussion of the chemical-mineralogical composition and texture of the meteorite surfaces. Comparative Raman studies applying visible and NIR Raman excitation wavelengths demonstrate a much better performance for UV Raman excitation. This comparative study of different Raman excitation wavelengths at the same sample spots was done by constructing a versatile, robust sample holder with a fixed micro-raster. The overall advantages of UV resonance Raman spectroscopy in terms of sensitivity and selectivity are demonstrated and discussed. Finally the application of this new technique for a UV Raman instrument for envisaged astrobiological focused space missions is suggested.

  18. Martian surface paleotemperatures from thermochronology of meteorites.

    PubMed

    Shuster, David L; Weiss, Benjamin P

    2005-07-22

    The temporal evolution of past martian surface temperatures is poorly known. We used thermochronology and published noble gas and petrographic data to constrain the temperature histories of the nakhlites and martian meteorite ALH84001. We found that the nakhlites have not been heated to more than 350 degrees C since they formed. Our calculations also suggest that for most of the past 4 billion years, ambient near-surface temperatures on Mars are unlikely to have been much higher than the present cold (<0 degrees C) state.

  19. Mapping the Iron Oxidation State in Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Martin, A. M.; Treimann, A. H.; Righter, K.

    2017-01-01

    Several types of Martian igneous meteorites have been identified: clinopyroxenites (nakhlites), basaltic shergottites, peridotitic shergottites, dunites (chassignites) and orthopyroxenites [1,2]. In order to constrain the heterogeneity of the Martian mantle and crust, and their evolution through time, numerous studies have been performed on the iron oxidation state of these meteorites [3,4,5,6,7,8,9]. The calculated fO2 values all lie within the FMQ-5 to FMQ+0.5 range (FMQ representing the Fayalite = Magnetite + Quartz buffer); however, discrepancies appear between the various studies, which are either attributed to the choice of the minerals/melts used, or to the precision of the analytical/calculation method. The redox record in volcanic samples is primarily related to the oxidation state in the mantle source(s). However, it is also influenced by several deep processes: melting, crystallization, magma mixing [10], assimilation and degassing [11]. In addition, the oxidation state in Martian meteorites is potentially affected by several surface processes: assimilation of sediment/ crust during lava flowing at Mars' surface, low temperature micro-crystallization [10], weathering at the surface of Mars and low temperature reequilibration, impact processes (i.e. high pressure phase transitions, mechanical mixing, shock degassing and melting), space weathering, and weathering on Earth (at atmospheric conditions different from Mars). Decoding the redox record of Martian meteorites, therefore, requires large-scale quantitative analysis methods, as well as a perfect understanding of oxidation processes.

  20. Biogenic Magnetite in Martian Meteorite ALH84001

    NASA Technical Reports Server (NTRS)

    Thomas-Keprta, Kathie L.; Bazylinski, Dennis; Wentworth, Susan J.; McKay, David S.; Kirschvink, Joseph L.; Clemett, Simon J.; Bell, Mary Sue; Golden, D. C.

    1999-01-01

    Fine-grained magnetite (Fe3O4) in martian meteorite ALH84001, generally less than 200 microns in size, is located primarily in the rims that surround the carbonate globules. There are two populations of ALH84001 magnets, which are likely formed at low temperature by inorganic and biogenic processes. Nearly 27/o of ALH84001 magnetite particles. also called elongated prisms, have characteristics which make them uniquely identifiable as biological precipitates.

  1. Biogenic Magnetite in Martian Meteorite ALH84001

    NASA Technical Reports Server (NTRS)

    Thomas-Keprta, K. L.; Bazylinski, Dennis; Wentworth, Susan J.; McKay, David S.; Kirschvink, Joseph L.; Clemett, SImon J.; Bell, Mary Sue; Golden, D. C.; Gibson, Everett K., Jr.

    1999-01-01

    Fine-grained magnetite (Fe3O4) in martian meteorite ALH84001, generally less than 200 nm in size, is located primarily in the rims that surround the carbonate globules. There are two populations of ALH84001 magnetites, which are likely formed at low temperature by inorganic and biogenic processes. Nearly 27% of ALH84001 magnetite particles, also called elongated prisms, have characteristics which make them uniquely identifiable as biological precipitates. Additional information is contained in the original extended abstract.

  2. Observations from a 4-year contamination study of a sample depth profile through Martian meteorite Nakhla.

    PubMed

    Toporski, Jan; Steele, Andrew

    2007-04-01

    Morphological, compositional, and biological evidence indicates the presence of numerous well-developed microbial hyphae structures distributed within four different sample splits of the Nakhla meteorite obtained from the British Museum (allocation BM1913,25). By examining depth profiles of the sample splits over time, morphological changes displayed by the structures were documented, as well as changes in their distribution on the samples, observations that indicate growth, decay, and reproduction of individual microorganisms. Biological staining with DNA-specific molecular dyes followed by epifluorescence microscopy showed that the hyphae structures contain DNA. Our observations demonstrate the potential of microbial interaction with extraterrestrial materials, emphasize the need for rapid investigation of Mars return samples as well as any other returned or impactor-delivered extraterrestrial materials, and suggest the identification of appropriate storage conditions that should be followed immediately after samples retrieved from the field are received by a handling/curation facility. The observations are further relevant in planetary protection considerations as they demonstrate that microorganisms may endure and reproduce in extraterrestrial materials over long (at least 4 years) time spans. The combination of microscopy images coupled with compositional and molecular staining techniques is proposed as a valid method for detection of life forms in martian materials as a first-order assessment. Time-resolved in situ observations further allow observation of possible (bio)dynamics within the system.

  3. Evidence for methane in Martian meteorites

    NASA Astrophysics Data System (ADS)

    Blamey, Nigel J. F.; Parnell, John; McMahon, Sean; Mark, Darren F.; Tomkinson, Tim; Lee, Martin; Shivak, Jared; Izawa, Matthew R. M.; Banerjee, Neil R.; Flemming, Roberta L.

    2015-06-01

    The putative occurrence of methane in the Martian atmosphere has had a major influence on the exploration of Mars, especially by the implication of active biology. The occurrence has not been borne out by measurements of atmosphere by the MSL rover Curiosity but, as on Earth, methane on Mars is most likely in the subsurface of the crust. Serpentinization of olivine-bearing rocks, to yield hydrogen that may further react with carbon-bearing species, has been widely invoked as a source of methane on Mars, but this possibility has not hitherto been tested. Here we show that some Martian meteorites, representing basic igneous rocks, liberate a methane-rich volatile component on crushing. The occurrence of methane in Martian rock samples adds strong weight to models whereby any life on Mars is/was likely to be resident in a subsurface habitat, where methane could be a source of energy and carbon for microbial activity.

  4. Evidence for methane in Martian meteorites.

    PubMed

    Blamey, Nigel J F; Parnell, John; McMahon, Sean; Mark, Darren F; Tomkinson, Tim; Lee, Martin; Shivak, Jared; Izawa, Matthew R M; Banerjee, Neil R; Flemming, Roberta L

    2015-06-16

    The putative occurrence of methane in the Martian atmosphere has had a major influence on the exploration of Mars, especially by the implication of active biology. The occurrence has not been borne out by measurements of atmosphere by the MSL rover Curiosity but, as on Earth, methane on Mars is most likely in the subsurface of the crust. Serpentinization of olivine-bearing rocks, to yield hydrogen that may further react with carbon-bearing species, has been widely invoked as a source of methane on Mars, but this possibility has not hitherto been tested. Here we show that some Martian meteorites, representing basic igneous rocks, liberate a methane-rich volatile component on crushing. The occurrence of methane in Martian rock samples adds strong weight to models whereby any life on Mars is/was likely to be resident in a subsurface habitat, where methane could be a source of energy and carbon for microbial activity.

  5. Evidence for methane in Martian meteorites

    PubMed Central

    Blamey, Nigel J. F.; Parnell, John; McMahon, Sean; Mark, Darren F.; Tomkinson, Tim; Lee, Martin; Shivak, Jared; Izawa, Matthew R. M.; Banerjee, Neil R.; Flemming, Roberta L.

    2015-01-01

    The putative occurrence of methane in the Martian atmosphere has had a major influence on the exploration of Mars, especially by the implication of active biology. The occurrence has not been borne out by measurements of atmosphere by the MSL rover Curiosity but, as on Earth, methane on Mars is most likely in the subsurface of the crust. Serpentinization of olivine-bearing rocks, to yield hydrogen that may further react with carbon-bearing species, has been widely invoked as a source of methane on Mars, but this possibility has not hitherto been tested. Here we show that some Martian meteorites, representing basic igneous rocks, liberate a methane-rich volatile component on crushing. The occurrence of methane in Martian rock samples adds strong weight to models whereby any life on Mars is/was likely to be resident in a subsurface habitat, where methane could be a source of energy and carbon for microbial activity. PMID:26079798

  6. Peology and Geochemistry of New Paired Martian Meteorites 12095 and LAR 12240

    NASA Technical Reports Server (NTRS)

    Funk, R. C.; Brandon, A. D.; Peslier, A.

    2015-01-01

    The meteorites LAR 12095 and LAR 12240 are believed to be paired Martian meteorites and were discovered during the Antarctic Search for Meteorites (ANSMET) 2012-2013 Season at Larkman Nunatak. The purpose of this study is to characterize these olivine-phyric shergottites by analyzing all mineral phases for major, minor and trace elements and examining their textural relationships. The goal is to constrain their crystallization history and place these shergottites among other Martian meteorites in order to better understand Martian geological history.

  7. Squeezing Meteorites to Reveal the Martian Mantle

    NASA Astrophysics Data System (ADS)

    Taylor, G. J.

    2006-12-01

    A piece of a Martian lava flow, Antarctic meteorite Yamato-980459, appears to represent the composition of a magma produced by partial melting of the Martian interior. That's the view of researchers Don Musselwhite, Walter Kiefer, and Allan Treiman (Lunar and Planetary Institute, Houston) and Heather Dalton (Arizona State University). Musselwhite and his colleagues determined that this basaltic Martian meteorite represented a primary melt from the mantle. This was an important discovery because magma produced inside a planet contains significant clues to the composition of the region of the interior in which it formed. The lava flows that decorate the surface of planets tell us about the mantle, the rocky region beneath the crust and above the metallic core. The researchers used apparatus at the Johnson Space Center to determine what minerals are present when samples with the composition of Y-980459 are heated to a range of temperatures and squeezed to a range of pressures like those that planetary scientists expect to exist in the interior of Mars. The results indicate that the magma represented by this special meteorite formed at a depth of about 100 kilometers and a temperature of about 1540 degrees C. From the high temperature and high ratio of magnesium to iron in the magma, Musselwhite and his colleagues infer that the amount of melting to produce the Y-980459 parent magma was high, which suggests that the temperature at the boundary between the metallic core and the rocky mantle was higher than previous estimates. This work gives us clues to the composition and dynamics of the Martian interior--all from a rock chipped off a lava flow on Mars and flung to Earth by an impact.

  8. Study of a possible magnetite biosignature in Martian meteorite ALH84001: Implications for the biological toxicology of Mars

    NASA Astrophysics Data System (ADS)

    Thomas-Keprta, Kathie Louise

    "Why do we have such a longstanding fascination with Mars? Very simply put, it's about life. The search for life elsewhere in our Solar System has been a major driver for exploring Mars, pretty much since we began seriously looking at that planet."1 The major objective of this work is to describe signs of possible life, that is biosignatures, in rocks from Mars if indeed they are present. Biosignatures are specific identifiable properties that result from living things; they may be implanted in the environment and may persist even if the living thing is no longer present. Over 100 mineral biosignatures have been discussed in the literature; however, only one, magnetite, is addressed by this study. Magnetite is found in many rock types on earth and in meteorites. Previous studies of terrestrial magnetite have used few properties, such as size and chemical composition, to determine one of the modes of origins for magnetite (e.g., biogenic, inorganic). This study has established a rigorous set of six criteria for the identification of intracellularly precipitated biogenic magnetite. These criteria have been applied to a subpopulation of magnetites embedded within carbonates in Martian meteorite ALH84001. These magnetites are found to be chemically and physically indistinguishable from those produced by magnetotactic bacteria strain MV-1, hence, they were likely formed by biogenic processes on ancient Mars. These criteria may be also used to distinguish origins for magnetites from terrestrial samples with complex or unknown histories. The presence of purported past life on early Mars suggests that, if life once began it may still exist today, possibly in oases in the Martian subsurface. Future manned missions should consider potential hazards of an extant biological environment(s) on Mars. 1 Quote attributed to Jack Farmer of Arizona State University in discussing NASA's program of Mars Exploration (see "Deciphering Mars: Follow the Water," Astrobiology Magazine Sept

  9. Geochemistry of Martian Meteorites and the Petrologic Evolution of Mars

    NASA Technical Reports Server (NTRS)

    Mittlefehldt, D. W.

    2002-01-01

    Mafic igneous rocks serve as probes of the interiors of their parent bodies - the compositions of the magmas contain an imprint of the source region composition and mineralogy, the melting and crystallization processes, and mixing and assimilation. Although complicated by their multifarious history, it is possible to constrain the petrologic evolution of an igneous province through compositional study of the rocks. Incompatible trace elements provide one means of doing this. I will use incompatible element ratios of martian meteorites to constrain the early petrologic evolution of Mars. Incompatible elements are strongly partitioned into the melt phase during igneous processes. The degree of incompatibility will differ depending on the mineral phases in equilibrium with the melt. Most martian meteorites contain some cumulus grains, but nevertheless, incompatible element ratios of bulk meteorites will be close to those of their parent magmas. ALH 84001 is an exception, and it will not be discussed. The martian meteorites will be considered in two groups; a 1.3 Ga group composed of the clinopyroxenites and dunite, and a younger group composed of all others.

  10. Cosmic-ray exposure histories of Martian meteorites studied from neutron capture reactions of Sm and Gd isotopes

    NASA Astrophysics Data System (ADS)

    Hidaka, Hiroshi; Yoneda, Shigekazu; Nishiizumi, Kunihiko

    2009-11-01

    The isotopic compositions of Sm and Gd in twelve Martian meteorites, ALH 77005, ALH 84001, DaG 735, Dhofar 019, EET 79001, Lafayette, Los Angeles, Nakhla, SaU 005, Y 000593, Y 000749 and Zagami, were determined to quantify the neutron capture records of individual meteorite specimens. Seven of these twelve samples, ALH 84001, Y 000749, DaG 735, Dhofar 019, EET 79001, SaU 005 and Zagami, showed significant isotopic shifts of 150Sm/ 149Sm and/or 158Gd/ 157Gd corresponding to neutron fluences of (0.7-3.4) × 10 15 n cm - 2 . Among these seven meteorites, the neutron fluences of ALH 84001, Y 000749, and Dhofar 019 apparently correlated with their cosmic-ray exposure ages, indicating that most of the irradiation took place while the meteoroids were small bodies in space after the ejection from Mars. However, our results suggest an accumulation of their inherited irradiation occurred on Mars. On the other hand, the exposure histories of the other four meteorites (basaltic shergottites), DaG 735, EET 79001, SaU 005, and Zagami, cannot be explained as single- or multistage irradiations in space, or as a single irradiation on the Martian surface. The mixing between basaltic lava with a significantly irradiated Martian regolith is a reasonable interpretation of the excess neutron capture records observed in these four basaltic shergottites.

  11. Hydrogen isotopic composition of the Martian mantle inferred from the newest Martian meteorite fall, Tissint

    NASA Astrophysics Data System (ADS)

    Mane, P.; Hervig, R.; Wadhwa, M.; Garvie, L. A. J.; Balta, J. B.; McSween, H. Y.

    2016-11-01

    The hydrogen isotopic composition of planetary reservoirs can provide key constraints on the origin and history of water on planets. The sources of water and the hydrological evolution of Mars may be inferred from the hydrogen isotopic compositions of mineral phases in Martian meteorites, which are currently the only samples of Mars available for Earth-based laboratory investigations. Previous studies have shown that δD values in minerals in the Martian meteorites span a large range of -250 to +6000‰. The highest hydrogen isotope ratios likely represent a Martian atmospheric component: either interaction with a reservoir in equilibrium with the Martian atmosphere (such as crustal water), or direct incorporation of the Martian atmosphere due to shock processes. The lowest δD values may represent those of the Martian mantle, but it has also been suggested that these values may represent terrestrial contamination in Martian meteorites. Here we report the hydrogen isotopic compositions and water contents of a variety of phases (merrillites, maskelynites, olivines, and an olivine-hosted melt inclusion) in Tissint, the latest Martian meteorite fall that was minimally exposed to the terrestrial environment. We compared traditional sample preparation techniques with anhydrous sample preparation methods, to evaluate their effects on hydrogen isotopes, and find that for severely shocked meteorites like Tissint, the traditional sample preparation techniques increase water content and alter the D/H ratios toward more terrestrial-like values. In the anhydrously prepared Tissint sample, we see a large range of δD values, most likely resulting from a combination of processes including magmatic degassing, secondary alteration by crustal fluids, shock-related fractionation, and implantation of Martian atmosphere. Based on these data, our best estimate of the δD value for the Martian depleted mantle is -116 ± 94‰, which is the lowest value measured in a phase in the

  12. Water in Pyroxene and Olivine from Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Peslier, A. H.

    2012-01-01

    Water in the interior of terrestrial planets can be dissolved in fluids or melts and hydrous phases, but can also be locked as protons attached to structural oxygen in lattice defects in nominally anhydrous minerals (NAM) like olivine, pyroxene, or feldspar [1-3]. Although these minerals contain only tens to hundreds of ppm H2O, this water can amount to at least one ocean in mass when added at planetary scales because of the modal dominance of NAM in the mantle and crust [4]. Moreover these trace amounts of water can have drastic effects on melting temperature, rheology, electrical and heat conductivity, and seismic wave attenuation [5]. There is presently a debate on how much water is present in the martian mantle. Secondary ionization mass spectrometry (SIMS) studies of NAM [6], amphiboles and glass in melt inclusions [7-10], and apatites [11, 12] from Martian meteorites report finding as much water as in the same phases from Earth's igneous rocks. Most martian hydrous minerals, however, generally have the relevant sites filled with Cl and F instead of H [13, 14], and experiments using Cl [15] in parent melts can reproduce Martian basalt compositions as well as those with water [16]. We are in the process of analyzing Martian meteorite minerals by Fourier transform infrared spectrometry (FTIR) in order to constrain the role of water in this planet s formation and magmatic evolution

  13. Terrestrial microbes in martian and chondritic meteorites

    NASA Astrophysics Data System (ADS)

    Airieau, S.; Picenco, Y.; Andersen, G.

    2007-08-01

    Introduction: The best extraterrestrial analogs for microbiology are meteorites. The chemistry and mineralogy of Asteroid Belt and martian (SNC) meteorites are used as tracers of processes that took place in the early solar system. Meteoritic falls, in particular those of carbonaceous chondrites, are regarded as pristine samples of planetesimal evolution as these rocks are primitive and mostly unprocessed since the formation of the solar system 4.56 billion years ago. Yet, questions about terrestrial contamination and its effects on the meteoritic isotopic, chemical and mineral characteristics often arise. Meteorites are hosts to biological activity as soon as they are in contact with the terrestrial biosphere, like all rocks. A wide biodiversity was found in 21 chondrites and 8 martian stones, and was investigated with cell culture, microscopy techniques, PCR, and LAL photoluminetry. Some preliminary results are presented here. The sample suite included carbonaceous chondrites of types CR, CV, CK, CO, CI, and CM, from ANSMET and Falls. Past studies documented the alteration of meteorites by weathering and biological activity [1]-[4]. Unpublished observations during aqueous extraction for oxygen isotopic analysis [5], noted the formation of biofilms in water in a matter of days. In order to address the potential modification of meteoritic isotopic and chemical signatures, the culture of microbial contaminating species was initiated in 2005, and after a prolonged incubation, some of the species obtained from cell culture were analyzed in 2006. The results are preliminary, and a systematic catalog of microbial contaminants is developing very slowly due to lack of funding. Methods: The primary method was cell culture and PCR. Chondrites. Chondritic meteorite fragments were obtained by breaking stones of approximately one gram in sterile mortars. The core of the rocks, presumably less contaminated than the surface, was used for the present microbial study, and the

  14. Curation of US Martian Meteorites Collected in Antarctica

    NASA Technical Reports Server (NTRS)

    Lindstrom, M.; Satterwhite, C.; Allton, J.; Stansbury, E.

    1998-01-01

    To date the ANSMET field team has collected five martian meteorites (see below) in Antarctica and returned them for curation at the Johnson Space Center (JSC) Meteorite Processing Laboratory (MPL). ne meteorites were collected with the clean procedures used by ANSMET in collecting all meteorites: They were handled with JSC-cleaned tools, packaged in clean bags, and shipped frozen to JSC. The five martian meteorites vary significantly in size (12-7942 g) and rock type (basalts, lherzolites, and orthopyroxenite). Detailed descriptions are provided in the Mars Meteorite compendium, which describes classification, curation and research results. A table gives the names, classifications and original and curatorial masses of the martian meteorites. The MPL and measures for contamination control are described.

  15. Curation of US Martian Meteorites Collected in Antarctica

    NASA Technical Reports Server (NTRS)

    Lindstrom, M.; Satterwhite, C.; Allton, J.; Stansbury, E.

    1998-01-01

    To date the ANSMET field team has collected five martian meteorites (see below) in Antarctica and returned them for curation at the Johnson Space Center (JSC) Meteorite Processing Laboratory (MPL). ne meteorites were collected with the clean procedures used by ANSMET in collecting all meteorites: They were handled with JSC-cleaned tools, packaged in clean bags, and shipped frozen to JSC. The five martian meteorites vary significantly in size (12-7942 g) and rock type (basalts, lherzolites, and orthopyroxenite). Detailed descriptions are provided in the Mars Meteorite compendium, which describes classification, curation and research results. A table gives the names, classifications and original and curatorial masses of the martian meteorites. The MPL and measures for contamination control are described.

  16. Possible Meteorites in the Martian Hills

    NASA Technical Reports Server (NTRS)

    2006-01-01

    From its winter outpost at 'Low Ridge' inside Gusev Crater, NASA's Mars Exploration Rover Spirit took this spectacular, color mosaic of hilly, sandy terrain and two potential iron meteorites. The two light-colored, smooth rocks about two-thirds of the way up from the bottom of the frame have been labeled 'Zhong Shan' and 'Allan Hills.'

    The two rocks' informal names are in keeping with the rover science team's campaign to nickname rocks and soils in the area after locations in Antarctica. Zhong Shang is an Antarctic base that the People's Republic of China opened on Feb. 26, 1989, at the Larsemann Hills in Prydz Bay in East Antarctica. Allan Hills is a location where researchers have found many Martian meteorites, including the controversial ALH84001, which achieved fame in 1996 when NASA scientists suggested that it might contain evidence for fossilized extraterrestrial life. Zhong Shan was the given name of Dr. Sun Yat-sen (1866-1925), known as the 'Father of Modern China.' Born to a peasant family in Guangdong, Sun moved to live with his brother in Honolulu at age 13 and later became a medical doctor. He led a series of uprisings against the Qing dynasty that began in 1894 and eventually succeeded in 1911. Sun served as the first provisional president when the Republic of China was founded in 1912.

    The Zhong Shan and Allan Hills rocks, at the left and right, respectively, have unusual morphologies and miniature thermal emission spectrometer signatures that resemble those of a rock known as 'Heat Shield' at the Meridiani site explored by Spirit's twin, Opportunity. Opportunity's analyses revealed Heat Shield to be an iron meteorite.

    Spirit acquired this approximately true-color image on the rover's 872nd Martian day, or sol (June 16, 2006), using exposures taken through three of the panoramic camera's filters, centered on wavelengths of 600 nanometers, 530 nanometers, and 480 nanometers.

  17. Possible Meteorites in the Martian Hills

    NASA Technical Reports Server (NTRS)

    2006-01-01

    From its winter outpost at 'Low Ridge' inside Gusev Crater, NASA's Mars Exploration Rover Spirit took this spectacular, color mosaic of hilly, sandy terrain and two potential iron meteorites. The two light-colored, smooth rocks about two-thirds of the way up from the bottom of the frame have been labeled 'Zhong Shan' and 'Allan Hills.'

    The two rocks' informal names are in keeping with the rover science team's campaign to nickname rocks and soils in the area after locations in Antarctica. Zhong Shang is an Antarctic base that the People's Republic of China opened on Feb. 26, 1989, at the Larsemann Hills in Prydz Bay in East Antarctica. Allan Hills is a location where researchers have found many Martian meteorites, including the controversial ALH84001, which achieved fame in 1996 when NASA scientists suggested that it might contain evidence for fossilized extraterrestrial life. Zhong Shan was the given name of Dr. Sun Yat-sen (1866-1925), known as the 'Father of Modern China.' Born to a peasant family in Guangdong, Sun moved to live with his brother in Honolulu at age 13 and later became a medical doctor. He led a series of uprisings against the Qing dynasty that began in 1894 and eventually succeeded in 1911. Sun served as the first provisional president when the Republic of China was founded in 1912.

    The Zhong Shan and Allan Hills rocks, at the left and right, respectively, have unusual morphologies and miniature thermal emission spectrometer signatures that resemble those of a rock known as 'Heat Shield' at the Meridiani site explored by Spirit's twin, Opportunity. Opportunity's analyses revealed Heat Shield to be an iron meteorite.

    Spirit acquired this approximately true-color image on the rover's 872nd Martian day, or sol (June 16, 2006), using exposures taken through three of the panoramic camera's filters, centered on wavelengths of 600 nanometers, 530 nanometers, and 480 nanometers.

  18. Amino Acids in the Antarctic Martian Meteorite MIL03346

    NASA Technical Reports Server (NTRS)

    Glavin, D. P.; Aubrey, A.; Dworkin, J. P.; Botta, O.; Bada, J. L.

    2005-01-01

    The report by McKay et al. that the Martian meteorite ALH84001 contains evidence for life on Mars remains controversial. Of central importance is whether ALH84001 and other Antarctic Martian meteorites contain endogenous organic compounds. In any investigation of organic compounds possibly derived from Mars it is important to focus on compounds that play an essential role in biochemistry as we know it and that have properties such as chirality which can be used to distinguish between biotic versus abiotic origins. Amino acids are one of the few compounds that fulfill these requirements. Previous analyses of the Antarctic Martian meteorites ALH84001 and EETA79001 have shown that these meteorites contain low levels of terrestrial amino acid contamination derived from Antarctic ice meltwater. Here we report preliminary amino acid investigations of a third Antarctic Martian meteorite MIL03346 which was discovered in Antarctica during the 2003-04 ANSMET season. Additional information is included in the original extended abstract

  19. Practicability of In Situ K-Ar Age Dating by Martian Landers; A Study of Mars Analogs and Meteorites

    NASA Astrophysics Data System (ADS)

    Park, Jisun; Ming, D. W.; Garrison, D. H.; Jones, J. H.; Bogard, D. D.

    2009-12-01

    Purpose of this noble gas investigation was to evaluate the feasibility of in situ K-Ar radiometric age dating of Martian surface rocks by future robotic missions, such as the Mars Science Laboratory(MSL), under constraints inherent to the Martian surface and lander design. The MSL Sample Analysis at Mars(SAM) instrument has the capability to measure noble gas compositions of Martain rocks and atmosphere. We evaluate requirements for SAM to obtain adequate noble gas abundances and compositions within the current instrumental operating conditions. In particular, maximum furnace temperature is limited to 1100ºC or lower due to power supply constraints. As a simulation experiment, we analyzed three Martian shergottites and terrestrial MORB, under the same conditions afforded SAM on the Martian surface. Our results suggest that SAM noble gas recoveries might be sufficient for K-Ar age determinations. Comparing these results with previous experiments performed on Martian meteorites at NASA-JSC, we can asses the capability of Mars lander designs with a variety of Martian rock types. The noble gas composition of Martian meteorites can be difficult to interpret due to the combined signals of in situ 40K decay, shock implanted 40Ar from Martian atmosphere[2,3], and 40Ar inherited from parent magma[4,5]. These components should also be considered in interpreting lander data. A possible advantage for landers is that K concentrations reported from the Martian surface are variable and possibly quite high, a desirable trait for K-Ar age dating. Spirit APXS reports 3000-7000ppm K for most locations but in some areas, concentrations as high as 25000ppm have been observed[6,7]. [1] Bogard (2009) MaPS44, 3-14; [2] Bogard and Johnson (1983) Science221,651-654 [3] Marti et al. (1995) Science267, 1981-1984; [4] Bogard and Park (2008) MAPS43, 1113-1126. [5] Bogard et al. (2009) MAPS44, 905-923. [6] Ming et al. (2006) JGR111, E02S12. [7] Ming D.W. et al. (2008) JGR113, E12S39.

  20. Maximizing the science return from 3.3 g of martian meteorite: A consortium study of olivine-phyric shergottite NorthWest Africa 6234

    NASA Astrophysics Data System (ADS)

    Filiberto, J.; Abernethy, F.; Butler, I. B.; Cartwright, J.; Chin, E. J.; Day, J. M.; Goodrich, C.; Grady, M.; Gross, J.; Franchi, I.; Herd, C. D.; Kelley, S. P.; Ott, U.; Penniston-Dorland, S. C.; Schwenzer, S. P.; Treiman, A. H.

    2011-12-01

    The ~382kg of sample returned from the lunar surface during the Apollo missions ranged from samples of gram to kilogram masses. However, any sample return mission from the martian surface will bring back small samples. Learning to get the most of each sample, while keeping enough material for future explorations, will require strategic planning and international consortium studies, as exemplified by studies of Apollo samples. Here we report on an international consortium study of 3.3 grams of olivine-phyric martian meteorite NWA 6234 as an example of what can be gleaned from a small martian sample. NWA 6234 was selected because its unusually fine grained texture suggests that it may approach a melt composition. To date, we have obtained bulk major and trace elements abundances (including highly siderophile elements; HSE), mineral compositions, Re-Os isotopes, and Li isotopes. A 100 mg slice from the interior of the sample containing an impact melt has also been scanned using high resolution X-ray computed tomography. Analyses of NWA 6234 in progress include: Ar isotopes ratios (including a separate of the impact melt vein); abundances and isotope ratios for all noble gases (for resolution of martian interior and atmosphere components using step heating); stepped combustion analyses of C and N to determine current residual and initial magmatic volatile components; melt inclusion mineralogy and chemistry to constrain original magma composition and crystallization sequence; and Sm-Nd isotope ratios to further elucidate the mantle source and age of the meteorite. So far we know that NWA 6234 has a bulk Mg# of 59 and phenocryst olivine of Fo 67. This suggests that the meteorite is more evolved than Yamato 980459 and NWA 1068. NWA 6234 has bulk REE abundances intermediate between the enriched end members (NWA 1068) and depleted (Yamato 980459) martian compositions, similar to those of basaltic shergottite Zagami. This similarity suggests another possible connection

  1. Evidence for life in a martian meteorite?

    PubMed

    McSween, H Y

    1997-07-01

    The controversial hypothesis that the ALH84001 meteorite contains relics of ancient martian life has spurred new findings, but the question has not yet been resolved. Organic matter probably results, at least in part, from terrestrial contamination by Antarctic ice meltwater. The origin of nanophase magnetites and sulfides, suggested, on the basis of their sizes and morphologies, to be biogenic remains contested, as does the formation temperature of the carbonates that contain all of the cited evidence for life. The reported nonfossils may be magnetite whiskers and platelets, probably grown from a vapor. New observations, such as the possible presence of biofilms and shock metamorphic effects in the carbonates, have not yet been evaluated. Regardless of the ultimate conclusion, this controversy continues to help define strategies and sharpen tools that will be required for a Mars exploration program focused on the search for life.

  2. Laboratory Simulations of Martian Meteorite Impacts and Their Seismic Signatures

    NASA Astrophysics Data System (ADS)

    Kedar, S.; Richardson, J. E.; Harvey, N. E.; Perry, D. C.; Bowling, T. J.; Kanamori, H.; Webb, F.; Li, M.; Garnero, E. J.

    2012-12-01

    Recent satellite images have revealed that meteorites regularly impact the Martian surface. Such impacts provide a constant background of planet-wide seismicity, and add a substantial number of seismic sources to an otherwise seismically quiet planet, with a natural quake rate estimated to be ~1000 times lower than on Earth. This is a potentially rich and relatively unexplored source of seismic activity that may be used to answer fundamental questions about the planet's internal structure, such as the size and nature of the core, the composition and layering of the mantle, and the planets crustal thickness and variability. Determining whether meteoritic impacts can be used as seismic sources for studying the Martian interior depends directly upon two fundamental parameters: (1) the rate of transfer of momentum to the elastic medium as defined by an impact's source-time function (or its power spectrum); and (2) the efficiency with which the kinetic energy of the impacting body is transferred to seismic energy. However, uncertainty of the impact source time function, combined with the wide range of impact seismic efficiency factors observed in various settings, makes it very difficult to determine the efficacy of natural impacts for seismic exploration. To overcome these challenges, we have begun a campaign combining impact laboratory experiments and numerical simulations with the goal of determining how well the observed meteoritic impact distribution on Mars can be used to resolve the Martian interior structure. To simulate the seismic signals expected from meteorite impacts on the Martian surface, we carried out a series of high velocity impact experiments at the NASA Ames Vertical Gun Range (AVGR) facility. The experiments spanned a variety of projectile impact velocities and angles, and were carried out in near vacuum conditions to mimic Martian atmospheric conditions. Seismic sensors were embedded in target material analogous to the Martian surface and were

  3. Shock-implanted noble gases - An experimental study with implications for the origin of Martian gases in shergottite meteorites

    NASA Technical Reports Server (NTRS)

    Bogard, Donald D.; Horz, Friedrich; Johnson, Pratt H.

    1986-01-01

    The shock-implantation of gases is studied by artificially shocking whole rock and power samples of terrestrial basalt to pressures of 2-40 GPa. Ar, Kr, Xe, and Ne were implanted into the silicate. It is observed that the amount of implanted gas is linearly proportional to its partial pressure over a pressure range of 0.0001 to 0.1 atmosphere. The fractionation effect in the implanted gas and the gas diffusion properties are examined. The amounts of gas that would have been implanted with 100 percent efficiency are calculated from the measured porosities of the power samples and are compared to observed abundances. It is determined that the implantation efficiencies are approximately 0.5 percent at 2 GPa, 7 percent at 5 GPa, and greater than 50 percent at both 20 and 35 GPa. The experimental data correlate with the shock implantation of Martian gases without mass fractionation into the shock-melted phase of meteorite EETA 79001.

  4. Shock-implanted noble gases - An experimental study with implications for the origin of Martian gases in shergottite meteorites

    NASA Technical Reports Server (NTRS)

    Bogard, Donald D.; Horz, Friedrich; Johnson, Pratt H.

    1986-01-01

    The shock-implantation of gases is studied by artificially shocking whole rock and power samples of terrestrial basalt to pressures of 2-40 GPa. Ar, Kr, Xe, and Ne were implanted into the silicate. It is observed that the amount of implanted gas is linearly proportional to its partial pressure over a pressure range of 0.0001 to 0.1 atmosphere. The fractionation effect in the implanted gas and the gas diffusion properties are examined. The amounts of gas that would have been implanted with 100 percent efficiency are calculated from the measured porosities of the power samples and are compared to observed abundances. It is determined that the implantation efficiencies are approximately 0.5 percent at 2 GPa, 7 percent at 5 GPa, and greater than 50 percent at both 20 and 35 GPa. The experimental data correlate with the shock implantation of Martian gases without mass fractionation into the shock-melted phase of meteorite EETA 79001.

  5. Report of the Workshop on Unmixing the SNCs: Chemical, Isotopic, and Petrologic Components of Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Treiman, Allan H. (Editor); Herd, Christopher D. K. (Editor)

    2002-01-01

    Geochemical and petrologic studies of the Martian meteorites (nicknamed the SNCs) have proliferated in the past few years, from a wealth of new samples and the perfection of new analytical methods. An intriguing result from these studies is that the chemical and isotopic compositions of the Martian meteorites, all basalts or derived from basaltic magma, can be modeled as mixtures of a limited number of components. These mixing components were the focus of the workshop.

  6. Identification of Iron-Bearing Phases on the Martian Surface and in Martian Meteorites and Analogue Samples by Moessbauer Spectroscopy

    NASA Technical Reports Server (NTRS)

    Klingelhoefer, G.; Agresti, D. G.; Schroeder, C.; Rodionov, D.; Yen, A.; Ming, Doug; Morris, Richard V.

    2007-01-01

    The Moessbauer spectrometers on the Mars Exploration Rovers (MER) Spirit (Gusev Crater) and Opportunity (Meridiani Planum) have each analyzed more than 100 targets during their ongoing missions (>1050 sols). Here we summarize the Fe-bearing phases identified to date and compare the results to Moessbauer analyses of martian meteorites and lunar samples. We use lunar samples as martian analogues because some, particularly the low-Ti Apollo 15 mare basalts, have bulk chemical compositions that are comparable to basaltic martian meteorites [1,2]. The lunar samples also provide a way to study pigeonite-rich samples. Pigeonite is a pyroxene that is not common in terrestrial basalts, but does often occur on the Moon and is present in basaltic martian meteorites

  7. Biogenic Activity in Selected Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Gibson, Everett K., Jr.; McKay, David S.; Thomas-Keprta, Kathie; Westall, Frances

    1999-01-01

    Criteria are well established within the scientific community for the acceptance of evidence for biogenic activity within samples from the early Earth. The eight criteria are: (1) geologic context, (2) age and stratigraphic location, (3) cellular morphology, (4) colonies, (v) biominerals, (6) isotope patterns, (7) organic biosignatures, and (8) features indigenous to sample. In the case of samples from Mars, we must also apply the same criteria. For the martian meteorite ALH84001, we have presented evidence which indicates possible biogenic activity associated with the 3.94 b.y. old, fracture-bound carbonate deposits. Subsequent major criticism of our hypothesis concerned the fact that many of the biogenic features could have been introduced during the time the meteorite was in Antarctica, prior to its collection. We address the possibility of Antarctic contamination and compare our evidence with accepted criteria for establishing the presence of past life. Although, we are close to matching some of the required criteria (likely biominerals, organic biomarkers, bacterial appendages, microfossils and indigenous features), there are others (well-documented geologic context, and evidence for colonies) which have not yet been met. It is not yet possible to come to a definitive conclusion concerning life on early Mars, but it is hoped that continued research will provide more relevant information.

  8. Biogenic Activity in Selected Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Gibson, Everett K., Jr.; McKay, David S.; Thomas-Keprta, Kathie; Westall, Frances

    1999-01-01

    Criteria are well established within the scientific community for the acceptance of evidence for biogenic activity within samples from the early Earth. The eight criteria are: (1) geologic context, (2) age and stratigraphic location, (3) cellular morphology, (4) colonies, (v) biominerals, (6) isotope patterns, (7) organic biosignatures, and (8) features indigenous to sample. In the case of samples from Mars, we must also apply the same criteria. For the martian meteorite ALH84001, we have presented evidence which indicates possible biogenic activity associated with the 3.94 b.y. old, fracture-bound carbonate deposits. Subsequent major criticism of our hypothesis concerned the fact that many of the biogenic features could have been introduced during the time the meteorite was in Antarctica, prior to its collection. We address the possibility of Antarctic contamination and compare our evidence with accepted criteria for establishing the presence of past life. Although, we are close to matching some of the required criteria (likely biominerals, organic biomarkers, bacterial appendages, microfossils and indigenous features), there are others (well-documented geologic context, and evidence for colonies) which have not yet been met. It is not yet possible to come to a definitive conclusion concerning life on early Mars, but it is hoped that continued research will provide more relevant information.

  9. Hydrogen Isotopic Systematics of Nominally Anhydrous Phases in Martian Meteorites

    NASA Astrophysics Data System (ADS)

    Tucker, Kera

    Hydrogen isotope compositions of the martian atmosphere and crustal materials can provide unique insights into the hydrological and geological evolution of Mars. While the present-day deuterium-to-hydrogen ratio (D/H) of the Mars atmosphere is well constrained (~6 times that of terrestrial ocean water), that of its deep silicate interior (specifically, the mantle) is less so. In fact, the hydrogen isotope composition of the primordial martian mantle is of great interest since it has implications for the origin and abundance of water on that planet. Martian meteorites could provide key constraints in this regard, since they crystallized from melts originating from the martian mantle and contain phases that potentially record the evolution of the H 2O content and isotopic composition of the interior of the planet over time. Examined here are the hydrogen isotopic compositions of Nominally Anhydrous Phases (NAPs) in eight martian meteorites (five shergottites and three nakhlites) using Secondary Ion Mass Spectrometry (SIMS). This study presents a total of 113 individual analyses of H2O contents and hydrogen isotopic compositions of NAPs in the shergottites Zagami, Los Angeles, QUE 94201, SaU 005, and Tissint, and the nakhlites Nakhla, Lafayette, and Yamato 000593. The hydrogen isotopic variation between and within meteorites may be due to one or more processes including: interaction with the martian atmosphere, magmatic degassing, subsolidus alteration (including shock), and/or terrestrial contamination. Taking into consideration the effects of these processes, the hydrogen isotope composition of the martian mantle may be similar to that of the Earth. Additionally, this study calculated upper limits on the H2O contents of the shergottite and nakhlite parent melts based on the measured minimum H2O abundances in their maskelynites and pyroxenes, respectively. These calculations, along with some petrogenetic assumptions based on previous studies, were subsequently used

  10. Magnesium isotope systematics in Martian meteorites

    NASA Astrophysics Data System (ADS)

    Magna, Tomáš; Hu, Yan; Teng, Fang-Zhen; Mezger, Klaus

    2017-09-01

    Magnesium isotope compositions are reported for a suite of Martian meteorites that span the range of petrological and geochemical types recognized to date for Mars, including crustal breccia Northwest Africa (NWA) 7034. The δ26Mg values (per mil units relative to DSM-3 reference material) range from -0.32 to -0.11‰; basaltic shergottites and nakhlites lie to the heavier end of the Mg isotope range whereas olivine-phyric, olivine-orthopyroxene-phyric and lherzolitic shergottites, and chassignites have slightly lighter Mg isotope compositions, attesting to modest correlation of Mg isotopes and petrology of the samples. Slightly heavier Mg isotope compositions found for surface-related materials (NWA 7034, black glass fraction of the Tissint shergottite fall; δ26Mg > -0.17‰) indicate measurable Mg isotope difference between the Martian mantle and crust but the true extent of Mg isotope fractionation for Martian surface materials remains unconstrained. The range of δ26Mg values from -0.19 to -0.11‰ in nakhlites is most likely due to accumulation of clinopyroxene during petrogenesis rather than garnet fractionation in the source or assimilation of surface material modified at low temperatures. The rather restricted range in Mg isotope compositions between spatially and temporally distinct mantle-derived samples supports the idea of inefficient/absent major tectonic cycles on Mars, which would include plate tectonics and large-scale recycling of isotopically fractionated surface materials back into the Martian mantle. The cumulative δ26Mg value of Martian samples, which are not influenced by late-stage alteration processes and/or crust-mantle interactions, is - 0.271 ± 0.040 ‰ (2SD) and is considered to reflect δ26Mg value of the Bulk Silicate Mars. This value is robust taking into account the range of lithologies involved in this estimate. It also attests to the lack of the Mg isotope variability reported for the inner Solar System bodies at current

  11. Searching for the Meteoritic Contribution to Martian Soils and Sediments

    NASA Astrophysics Data System (ADS)

    Clark, B. C.

    2015-07-01

    Martian soils and surface sediments will contain contributions from meteoritic (and IDP) input, with multiple important consequences. Determination of this input must interpret in situ measurements which focus on trace elements and evolved gases.

  12. Pyroxenes in Martian meteorites as petrogenetic indicators

    NASA Technical Reports Server (NTRS)

    McKay, Gordon; Le, L.; Mikouchi, T.; Makishima, J.; Schwandt, C.

    2006-01-01

    Pyroxenes in Martian meteorites are important recorders of petrogenetic processes. Understanding the details of pyroxene major and minor element compositional variations can provide important insights into those processes. A combination of careful petrographic analysis of natural samples and experimental crystallization studies can lead to better understanding of the processes that gave rise to these samples on Mars. In addition, experimentally determined major, minor and trace element partition coefficients are important for using natural pyroxenes to estimate the compositions of the melts from which they crystallized and the oxidation conditions that prevailed during crystallization. We will report on minor element (Al, Ti, Cr) zoning in nakhlite pyroxenes and in synthetic pyroxenes that we have grown for the purposes of determining pyroxene/melt partition coefficients for Sr and REE. The natural pyroxenes have patchy Al zoning that, by analogy with our experimental pyroxenes, we interpret as sector zoning. The irregular patchy nature of the zoning is probably the result of the vagaries of growth kinetics and local environment during crystal growth. More slowly cooled nakhlites have the most distinct bimodal zoning, with one mode having Al2O3 around 0.5-0.6 wt%, and the other around 0.9 %. Average Al content increases with increasing cooling rate. This feature is puzzling, since the cumulus pyroxenes were almost certainly present at the time of eruption. Al and Ti are strongly correlated, but Cr is completely decoupled from those elements. The synthetic pyroxenes are distinctly sector zoned in Al and Ti, and the sector-to-sector variation in Al within a single crystal has important effects on trace element partition coefficients. Trivalent REE are strongly correlated with Al, while divalent elements (Sr, Eu+2) show a significantly weaker correlation. For example, as the Al2O3 content varies from 0.3 to 0.6 wt % from one sector to another, D(Gd) increases by

  13. Tissint martian meteorite: a fresh look at the interior, surface, and atmosphere of Mars.

    PubMed

    Aoudjehane, H Chennaoui; Avice, G; Barrat, J-A; Boudouma, O; Chen, G; Duke, M J M; Franchi, I A; Gattacceca, J; Grady, M M; Greenwood, R C; Herd, C D K; Hewins, R; Jambon, A; Marty, B; Rochette, P; Smith, C L; Sautter, V; Verchovsky, A; Weber, P; Zanda, B

    2012-11-09

    Tissint (Morocco) is the fifth martian meteorite collected after it was witnessed falling to Earth. Our integrated mineralogical, petrological, and geochemical study shows that it is a depleted picritic shergottite similar to EETA79001A. Highly magnesian olivine and abundant glass containing martian atmosphere are present in Tissint. Refractory trace element, sulfur, and fluorine data for the matrix and glass veins in the meteorite indicate the presence of a martian surface component. Thus, the influence of in situ martian weathering can be unambiguously distinguished from terrestrial contamination in this meteorite. Martian weathering features in Tissint are compatible with the results of spacecraft observations of Mars. Tissint has a cosmic-ray exposure age of 0.7 ± 0.3 million years, consistent with those of many other shergottites, notably EETA79001, suggesting that they were ejected from Mars during the same event.

  14. Northwest Africa 8159: New Type of Martian Meteorite

    NASA Astrophysics Data System (ADS)

    Agee, C. B.; Muttik, N.; Ziegler, K. G.; Walton, E. L.; Herd, C. D. K.; McCubbin, F. M.; Santos, A. R.; Simon, J. I.

    2014-12-01

    Up until recently the orthopyroxenite ALH 84001 and basaltic breccia NWA 7034 were the only martian meteorites that did not fit within the common SNC types. However with the discovery of Northwest Africa (NWA) 8159, the diversity is expanded further with a third unique non-SNC meteorite type. The existence of meteorite types beyond the narrow range seen in SNCs is what might be expected from a random cratering sampling of a volcanically long-lived and geologically complex planet such as Mars. NWA 8159, a fine-grained, augite basalt, is a new type of martian meteorite, with SNC-like oxygen isotopes and Fe/Mn values, but having several characteristics that make it distinct from other known martian meteorite types. NWA 8159 is the only martian basalt type known to have augite as the sole pyroxene phase in its mineralogy. NWA 8159 is unique among martian meteorites in that it possesses both crystalline plagioclase and shock amorphized plagioclase, often observed within a single grain, the bracketing of plagioclase amorphization places the estimated peak shock pressures at >15 GPa and <23 GPa. Magnetite in NWA 8159 is exceptionally pure, whereas most martian meteorites contain solid-solution titano-magnetites, and this pure magnetite is a manifestation of the highest oxygen fugacity (fO2) yet observed in a martian meteorite. Although NWA 8159 has the highest fO2 of martian meteorites, it has a pronounced light rare earth (LREE) depletion pattern similar to that of very low fO2 basaltic shergottites such as QUE 94201. Thus NWA 8159 displays a striking exception to well documented correlation between fO2 and LREE patterns in SNC meteorites. Finally, NWA 8159 stands apart from other martian meteorites in that it has an an early Amazonian age that is not represented in the SNCs, ALH 84001, or the NWA 7034 pairing group. NWA 8159 appears to be from an eruptive flow or shallow intrusion that is petrologically distinct from shergottite basalts, and its crystallization age

  15. Comparison of Martian meteorites with earth composition: Study of effective atomic numbers in the energy range 1 keV-100 GeV

    NASA Astrophysics Data System (ADS)

    Ün, Adem; Han, Ibrahim; Ün, Mümine

    2016-04-01

    Effective atomic (Zeff) and electron numbers (Neff) for 24 Martian meteorites have been determined in the energy range from 1 keV to 100 GeV and also for sixteen significant energies of commonly used radioactive sources. The values of Zeff and Neff for all sample were obtained from the DirectZeff program. The obtained results for Martian meteorites have been compared with the results for Earth composition and similarities or differences also evaluated.

  16. Fe-Ti-Cr-Oxides in Martian Meteorite EETA79001 Studied by Point-counting Procedure Using Raman Spectroscopy

    NASA Technical Reports Server (NTRS)

    Wang, Alian; Kuebler, Karla E.; Jolliff, Bradley L.; Haskin, Larry A.

    2003-01-01

    Fe-Ti-Cr-Oxide minerals contain much information about rock petrogenesis and alteration. Among the most important in the petrology of common intrusive and extrusive rocks are those of the FeO-TiO2-Cr2O3 compositional system chromite, ulv spinel-magnetite, and ilmenite-hematite. These minerals retain memories of oxygen fugacity. Their exsolution into companion mineral pairs give constraints on formation temperature and cooling rate. Laser Raman spectroscopy is anticipated to be a powerful technique for characterization of materials on the surface of Mars. A Mars Microbeam Raman Spectrometer (MMRS) is under development. It combines a micro sized laser beam and an automatic point-counting mechanism, and so can detect minor minerals or weak Raman-scattering phases such as Fe- Ti-Cr-oxides in mixtures (rocks & soils), and provide information on grain size and mineral mode. Most Fe-Ti-Cr-oxides produce weaker Raman signals than those from oxyanionic minerals, e.g. carbonates, sulfates, phosphates, and silicates, partly because most of them are intrinsically weaker Raman scatters, and partly because their dark colors limit the penetration depth of the excitation laser beam (visible wavelength) and of the Raman radiation produced. The purpose of this study is to show how well the Fe-Ti-Cr-oxides can be characterized by on-surface planetary exploration using Raman spectroscopy. We studied the basic Raman features of common examples of these minerals using well-characterized individual mineral grains. The knowledge gained was then used to study the Fe-Ti-Cr-oxides in Martian meteorite EETA79001, especially effects of compositional and structural variations on their Raman features.

  17. Fe-Ti-Cr-Oxides in Martian Meteorite EETA79001 Studied by Point-counting Procedure Using Raman Spectroscopy

    NASA Technical Reports Server (NTRS)

    Wang, Alian; Kuebler, Karla E.; Jolliff, Bradley L.; Haskin, Larry A.

    2003-01-01

    Fe-Ti-Cr-Oxide minerals contain much information about rock petrogenesis and alteration. Among the most important in the petrology of common intrusive and extrusive rocks are those of the FeO-TiO2-Cr2O3 compositional system chromite, ulv spinel-magnetite, and ilmenite-hematite. These minerals retain memories of oxygen fugacity. Their exsolution into companion mineral pairs give constraints on formation temperature and cooling rate. Laser Raman spectroscopy is anticipated to be a powerful technique for characterization of materials on the surface of Mars. A Mars Microbeam Raman Spectrometer (MMRS) is under development. It combines a micro sized laser beam and an automatic point-counting mechanism, and so can detect minor minerals or weak Raman-scattering phases such as Fe- Ti-Cr-oxides in mixtures (rocks & soils), and provide information on grain size and mineral mode. Most Fe-Ti-Cr-oxides produce weaker Raman signals than those from oxyanionic minerals, e.g. carbonates, sulfates, phosphates, and silicates, partly because most of them are intrinsically weaker Raman scatters, and partly because their dark colors limit the penetration depth of the excitation laser beam (visible wavelength) and of the Raman radiation produced. The purpose of this study is to show how well the Fe-Ti-Cr-oxides can be characterized by on-surface planetary exploration using Raman spectroscopy. We studied the basic Raman features of common examples of these minerals using well-characterized individual mineral grains. The knowledge gained was then used to study the Fe-Ti-Cr-oxides in Martian meteorite EETA79001, especially effects of compositional and structural variations on their Raman features.

  18. Martian meteorite launch: high-speed ejecta from small craters.

    PubMed

    Head, James N; Melosh, H Jay; Ivanov, Boris A

    2002-11-29

    We performed high-resolution computer simulations of impacts into homogeneous and layered martian terrain analogs to try to account for the ages and characteristics of the martian meteorite collection found on Earth. We found that craters as small as approximately 3 kilometers can eject approximately 10(7) decimeter-sized fragments from Mars, which is enough to expect those fragments to appear in the terrestrial collection. This minimum crater diameter is at least four times smaller than previous estimates and depends on the physical composition of the target material. Terrain covered by a weak layer such as an impact-generated regolith requires larger, therefore rarer, impacts to eject meteorites. Because older terrain is more likely to be mantled with such material, we estimate that the martian meteorites will be biased toward younger ages, which is consistent with the meteorite collection.

  19. SNC meteorites and their implications for reservoirs of Martian volatiles

    NASA Technical Reports Server (NTRS)

    Jones, J. H.

    1993-01-01

    The SNC meteorites and the measurements of the Viking landers provide our only direct information about the abundance and isotopic composition of Martian volatiles. Indirect measurements include spectroscopic determinations of the D/H ratio of the Martian atmosphere. A personal view of volatile element reservoirs on Mars is presented, largely as inferred from the meteoritic evidence. This view is that the Martian mantle has had several opportunities for dehydration and is most likely dry, although not completely degassed. Consequently, the water contained in SNC meteorites was most likely incorporated during ascent through the crust. Thus, it is possible that water can be decoupled from other volatile/incompatible elements, making the SNC meteorites suspect as indicators of water inventories on Mars.

  20. Lunar and Planetary Science XXXV: Martian Meteorites: Petrology

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The session "Martian Meteorites: Petrology: included the following reports:Volatile Behavior in Lunar and Terrestrial Basalts During Shock: Implications for Martian Magmas; Problems with a Low-Pressure Tholeiitic Magmatic History for the Chassigny Dunite; Fast Cooling History of the Chassigny Martian Meteorite; Rehomogenized Interstitial and Inclusion Melts in Lherzolitic Shergottite ALH 77005: Petrologic Significance; Compositional Controls on the Formation of Kaersutite Amphibole in Shergottite Meteorites; Chemical Characteristics of an Olivine-Phyric Shergottite, Yamato 980459; Pb-Hf-Sr-Nd Isotopic Systematics and Age of Nakhlite NWA 998; Noble Gases in Two Samples of EETA 79001 (Lith. A); Experimental Constraints on the Iron Content of the Martian Mantle; and Mars as the Parent Body for the CI Carbonaceous Chondrites: New Data.

  1. Geochemistry and setting of Martian weathering: The Lafayette meteorite

    NASA Technical Reports Server (NTRS)

    Treiman, A. H.; Barrett, R. A.; Gooding, J. L.

    1992-01-01

    Lafayette, one of the SNC (martian) meteorites, contains preterrestrial alteration materials rich in smectite and ferric oxides. The compositions and textures of the veinlets suggest that they were formed in episodic alteration events by waters that contained a relatively small load of dissolved salts. The Lafayette achondrite, one of the nakhlites of probable martian origin, is an igneous rock consisting mostly of augite and olivine, with interstitial feldspar, sulfides (pyrite), high-Si glass, and other phases. Like Nakhla itself, Lafayette contains veinlets of hydrous alteration materials. We studied thin sections of sample ME2116 (Field Museum, Chicago), using scanning and transmission electron microscopy (SEM and TEM) with energy dispersive X-ray spectrometry (EDS).

  2. Geochemistry and setting of Martian weathering: The Lafayette meteorite

    NASA Astrophysics Data System (ADS)

    Treiman, A. H.; Barrett, R. A.; Gooding, J. L.

    1993-09-01

    Lafayette, one of the SNC (martian) meteorites, contains preterrestrial alteration materials rich in smectite and ferric oxides. The compositions and textures of the veinlets suggest that they were formed in episodic alteration events by waters that contained a relatively small load of dissolved salts. The Lafayette achondrite, one of the nakhlites of probable martian origin, is an igneous rock consisting mostly of augite and olivine, with interstitial feldspar, sulfides (pyrite), high-Si glass, and other phases. Like Nakhla itself, Lafayette contains veinlets of hydrous alteration materials. We studied thin sections of sample ME2116 (Field Museum, Chicago), using scanning and transmission electron microscopy (SEM and TEM) with energy dispersive X-ray spectrometry (EDS).

  3. Alteration Products and Secondary Minerals in Martian Meteorite Allan Hills 84001

    NASA Technical Reports Server (NTRS)

    Wentworth, S. J.; Thomas-Keprta, K. L.; McKay, D. S.

    1998-01-01

    The martian meteorites contain alteration products and secondary minerals that are a critical part of understanding their near-surface histories on both Mars and Earth. In some martian meteorites, suspected martian preterrestrial alteration products can be distinguished from terrestrial weathering effects Using scanning electron microscopy (SEM), field emission SEM (FE-SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray analysis (EDS), we are studying natural fracture surfaces of ALH 84001 chips, including samples from both the interior and the exterior of the meteorite. Exterior samples include fusion crust surfaces, which are important in determining the extent of terrestrial weathering of meteorites. The focus of this study is weathering features and secondary minerals other than the distinctive carbonate globules that continue to be studied by many researchers.

  4. Petrology of Martian meteorite Northwest Africa 998

    NASA Astrophysics Data System (ADS)

    Treiman, Allan H.; Irving, Anthony J.

    2008-05-01

    Nakhlite Northwest Africa (NWA) 998 is an augite-rich cumulate igneous rock with mineral compositions and oxygen isotopic composition consistent with an origin on Mars. This 456-gram, partially fusion-crusted meteorite consists of (by volume) ˜75% augite (core composition Wo39En39Fs22), ˜9% olivine (Fo35), ˜7% plagioclase (Ab61An35) as anhedra among augite and olivine, ˜3.5% low-calcium pyroxenes (pigeonite and orthopyroxene) replacing or forming overgrowths on olivine and augite, ˜1% titanomagnetite, and other phases including potassium feldspar, apatite, pyrrhotite, chalcopyrite, ilmenite, and fine-grained mesostasis material. Minor secondary alteration materials include "iddingsite" associated with olivine (probably Martian), calcite crack fillings, and iron oxide/hydroxide staining (both probably terrestrial). Shock effects are limited to minor cataclasis and twinning in augite. In comparison to other nakhlites, NWA 998 contains more low-calcium pyroxenes and its plagioclase crystals are blockier. The large size of the intercumulus feldspars and the chemical homogeneity of the olivine imply relatively slow cooling and chemical equilibration in the late- and post-igneous history of this specimen, and mineral thermometers give subsolidus temperatures near 730 °C. Oxidation state was near that of the QFM buffer, from about QFM-2 in earliest crystallization to near QFM in late crystallization, and to about QFM + 1.5 in some magmatic inclusions. The replacement or overgrowth of olivine by pigeonite and orthopyroxene (with or without titanomagnetite), and the marginal replacement of augite by pigeonite, are interpreted to result from late-stage reactions with residual melts (consistent with experimental phase equilibrium relationships). Apatite is concentrated in planar zones separating apatite-free domains, which suggests that residual magma (rich in P and REE) was concentrated in planar (fracture?) zones and possibly migrated through them. Loss of late magma

  5. 'Bounce' and Martian Meteorite of the Same Mold

    NASA Technical Reports Server (NTRS)

    2004-01-01

    These two sets of bar graphs compare the elemental compositions of six martian rocks: 'Bounce,' located at Meridiani Planum; EETA79001-B, a martian meteorite found in Antarctica in 1979; a rock found at the Mars Pathfinder landing site; Shergotty, a martian meteorite that landed in India in 1865; 'Adirondack,' located at Gusev Crater; and 'Humphrey,' also located at Gusev Crater. The graph on the left compares magnesium/iron ratios in the rocks, and the graph on the right compares aluminum/calcium ratios. The results illustrate the diversity of rocks on Mars and indicate that Bounce probably shares origins with the martian meterorite EETA79001-B. The Bounce data was taken on sol 68 by the alpha particle X-ray spectrometer on Mars Exploration Rover Opportunity.

  6. If a Meteorite of Martian Sandstone Hit You on the Head Would You Recognize It?

    NASA Astrophysics Data System (ADS)

    Ashley, G. M.; Delaney, J. S.

    1999-03-01

    Martian meteorites are igneous but Mars is Earthlike with sediments, igneous and maybe sedimentary rocks. Sedimentary meteorites should occur in proportion to the igneous/sedimentary ratio. Sedimentary meteorites would impact climatology and the search for life on Mars.

  7. LU-HF Age of Martian Meteorite Larkman Nunatek 06319

    NASA Technical Reports Server (NTRS)

    Shafer, J. T.; Brandon, A. D.; Lapen, T. J.; Righter, M.; Beard, B.; Peslier, A. H.

    2009-01-01

    Lu-Hf isotopic data were collected on mineral separates and bulk rock powders of LAR 06319, yielding an age of 197+/- 29 Ma. Sm-Nd isotopic data and in-situ LA-ICP-MS data from a thin section of LAR 06319 are currently being collected and will be presented at the 2009 LPSC. These new data for LAR 06319 extend the existing data set for the enriched shergottite group. Martian meteorites represent the only opportunity for ground truth investigation of the geochemistry of Mars [1]. At present, approximately 80 meteorites have been classified as Martian based on young ages and distinctive isotopic signatures [2]. LAR 06319 is a newly discovered (as part of the 2006 ANSMET field season) martian meteorite that represents an important opportunity to further our understanding of the geochemical and petrological constraints on the origin of Martian magmas. Martian meteorites are traditionally categorized into the shergottite, nakhlite, and chassignite groups. The shergottites are further classified into three distinct isotopic groups designated depleted, intermediate, and enriched [3,4] based on the isotope systematics and compositions of their source(s).

  8. Candidates source regions of martian meteorites as identified by OMEGA/MEx

    NASA Astrophysics Data System (ADS)

    Ody, A.; Poulet, F.; Quantin, C.; Bibring, J.-P.; Bishop, J. L.; Dyar, M. D.

    2015-09-01

    The objective of this study is to identify and map spectral analogues of some key martian meteorites (basaltic shergottites Los Angeles, Shergotty, QUE 94201, lherzolitic shergottite ALH A77005, Nakhla, Chassigny and the orthopyroxenite ALH 84001) in order to localize terrain candidates for their source regions. We develop a best fit procedure to reproduce the near-infrared (NIR) spectral properties of the martian surface as seen by the hyperspectral imaging spectrometer OMEGA/MEx from the NIR spectra of the martian meteorites. The fitting process is tested and validated, and Root Mean Square (RMS) global maps for each meteorite are obtained. It is found that basaltic shergottites have NIR spectral properties the most representative of the martian surface with the best spectral analogues found in early Hesperian volcanic provinces. Sites with spectral properties similar to those of ALH A77005 are scarce. They are mainly localized in olivine-bearing regions such as Nili Fossae and small Noachian/early Hesperian terrains. The only plausible source region candidate for Chassigny is the Nili Patera caldera dated to 1.6 Ga. Widespread spectral analogues for the ALH 84001 meteorite are found northeast of Syrtis Major and northwest of the Hellas basin. While this distribution is in agreement with the low-calcium-pyroxene-rich composition and old age (4.1 Ga) of this meteorite, the modal mineralogy of these candidates is not consistent with that of this meteorite. No convincing spectral analogue is found for the Amazonian-aged Nakhla meteorite suggesting that its olivine/high-calcium-pyroxene-rich composition could be representative of the Amazonian terrains buried under dust. Finally, some young rayed craters are proposed as possible candidates for source craters of the studied martian meteorites.

  9. Volatile/mobile trace elements in meteoritic, non-lunar basalts: Guides to Martian sample contents

    NASA Technical Reports Server (NTRS)

    Lipschutz, M. E.; Paul, R. L.

    1988-01-01

    A variety of genetic processes on or in extraterrestrial objects can be examined by study of volatile/mobile trace elements. Doubtless, considerable efforts will be expended on determining these elements in returned Martian samples. The purpose is to estimate levels of such elements expected to be present in returned Martian samples. Some ideas about Martian genesis were already advanced from the volatile/mobile element contents in SNC meteorites, assuming that Mars was their parent body. Even is Mars and the SNC meteorite parent body are identical, compositional ranges for returned Martian samples should exceed those of SNC meteorites. It is expected, therefore, that Martian samples returned from locations other than Polar regions will have indigenous volatile/mobile element contents within howardite-diogenite ranges. Elements with strong lithophile tendences may be more abundant, as they are in many lunar samples. Most of these elements should be at ppb levels except for Co, Ga, Zn, and Rb, which should lie at ppm levels. If Martian volcanism was accompanied by fumarolic emanations, it should be reflected in occasional huge enrichments of mobile trance elements, as in lunar meteorite Y 791197. During collection and transport Earthward, samples must be contained under conditions appropriate to ppb concentrations. Materials must be used that will not cause contamination which occurred during the Apollo program, where indium from seals contaminated many samples.

  10. Volatile/mobile trace elements in meteoritic, non-lunar basalts: Guides to Martian sample contents

    NASA Technical Reports Server (NTRS)

    Lipschutz, M. E.; Paul, R. L.

    1988-01-01

    A variety of genetic processes on or in extraterrestrial objects can be examined by study of volatile/mobile trace elements. Doubtless, considerable efforts will be expended on determining these elements in returned Martian samples. The purpose is to estimate levels of such elements expected to be present in returned Martian samples. Some ideas about Martian genesis were already advanced from the volatile/mobile element contents in SNC meteorites, assuming that Mars was their parent body. Even is Mars and the SNC meteorite parent body are identical, compositional ranges for returned Martian samples should exceed those of SNC meteorites. It is expected, therefore, that Martian samples returned from locations other than Polar regions will have indigenous volatile/mobile element contents within howardite-diogenite ranges. Elements with strong lithophile tendences may be more abundant, as they are in many lunar samples. Most of these elements should be at ppb levels except for Co, Ga, Zn, and Rb, which should lie at ppm levels. If Martian volcanism was accompanied by fumarolic emanations, it should be reflected in occasional huge enrichments of mobile trance elements, as in lunar meteorite Y 791197. During collection and transport Earthward, samples must be contained under conditions appropriate to ppb concentrations. Materials must be used that will not cause contamination which occurred during the Apollo program, where indium from seals contaminated many samples.

  11. Ne-20/Ne-22 in the Martian Atmosphere: New Evidence from Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Park, J.; Nyquist, L. E.; Herzog, G. F.; Nagao, K.; Mikouchi, T.; Kusakabe, M.

    2017-01-01

    Analyses of Ne trapped in "pods" of impact melt in the Elephant Moraine 79001 (EET 79001) Martian meteorite led to suggest (Ne-20/Ne-22) approx.10 in the Martian atmosphere (MA). In contrast, obtained trapped (Ne-20/Ne-22)Tr approx.7 from an impact melt vein in Yamato 793605 (Y-793605) and concluded that the isotopic composition of Martian Ne remained poorly defined. A "pyroxene-rich" separate from Dhofar 378 (Dho 378) analyzed gave a comparatively high trapped Ne concentration and (Ne-20/Ne-22) = 7.3+/-0.2 in agreement with the Y-793605 value. We explore the hypothesis that Martian Ne was trapped in the Dho 378 meteorite in a manner similar to entrapment of terrestrial Ne in tektites strengthening the "Martian atmosphere" interpretation. We also report new data for Northwest Africa 7034 (NWA 7034) that are consistent with the Ne data for Dho 378.

  12. Comparison of Martian meteorites with earth composition: Study of effective atomic numbers in the energy range 1 keV-100 GeV

    SciTech Connect

    Ün, Adem Han, İbrahim; Ün, Mümine

    2016-04-18

    Effective atomic (Z{sub eff}) and electron numbers (N{sub eff}) for 24 Martian meteorites have been determined in the energy range from 1 keV to 100 GeV and also for sixteen significant energies of commonly used radioactive sources. The values of Z{sub eff} and N{sub eff} for all sample were obtained from the DirectZeff program. The obtained results for Martian meteorites have been compared with the results for Earth composition and similarities or differences also evaluated.

  13. Life on Mars: chemical arguments and clues from Martian meteorites.

    PubMed

    Brack, A; Pillinger, C T

    1998-08-01

    Primitive terrestrial life-defined as a chemical system able to transfer its molecular information via self-replication and to evolve-probably originated from the evolution of reduced organic molecules in liquid water. Several sources have been proposed for the prebiotic organic molecules: terrestrial primitive atmosphere (methane or carbon dioxide), deep-sea hydrothermal systems, and extraterrestrial meteoritic and cometary dust grains. The study of carbonaceous chondrites, which contain up to 5% by weight of organic matter, has allowed close examination of the delivery of extraterrestrial organic material. Eight proteinaceous amino acids have been identified in the Murchison meteorite among more than 70 amino acids. Engel reported that L-alanine was surprisingly more abundant than D-alanine in the Murchison meteorite. Cronin also found excesses of L-enantiomers for nonprotein amino acids. A large collection of micrometeorites has been recently extracted from Antarctic old blue ice. In the 50- to 100-micron size range, carbonaceous micrometeorites represent 80% of the samples and contain 2% of carbon, on average. They might have brought more carbon than that involved in the present surficial biomass. The early histories of Mars and Earth clearly show similarities. Liquid water was once stable on the surface of Mars, attesting the presence of an atmosphere capable of deccelerating C-rich micrometeorites. Therefore, primitive life may have developed on Mars as well and fossilized microorganisms may still be present in the near subsurface. The Viking missions to Mars in 1976 did not find evidence of either contemporary or past life, but the mass spectrometer on the lander aeroshell determined the atmospheric composition, which has allowed a family of meteorites to be identified as Martian. Although these samples are essentially volcanic in origin, it has been recognized that some of them contain carbonate inclusions and even veins that have a carbon isotopic

  14. Determining the source locations of martian meteorites: Hapke mixture models applied to CRISM simulated data of igneous mineral mixtures and martian meteorites

    NASA Astrophysics Data System (ADS)

    Harris, Jennifer; Grindrod, Peter

    2017-04-01

    At present, martian meteorites represent the only samples of Mars available for study in terrestrial laboratories. However, these samples have never been definitively tied to source locations on Mars, meaning that the fundamental geological context is missing. The goal of this work is to link the bulk mineralogical analyses of martian meteorites to the surface geology of Mars through spectral mixture analysis of hyperspectral imagery. Hapke radiation transfer modelling has been shown to provide accurate (within 5 - 10% absolute error) mineral abundance values from laboratory derived hyperspectral measurements of binary [1] and ternary [2] mixtures of plagioclase, pyroxene and olivine. These three minerals form the vast bulk of the SNC meteorites [3] and the bedrock of the Amazonian provinces on Mars that are inferred to be the source regions for these meteorites based on isotopic aging. Spectral unmixing through the Hapke model could be used to quantitatively analyse the Martian surface and pinpoint the exact craters from which the SNC meteorites originated. However the Hapke model is complex with numerous variables, many of which are determinable in laboratory conditions but not from remote measurements of a planetary surface. Using binary and tertiary spectral mixtures and martian meteorite spectra from the RELAB spectral library, the accuracy of Hapke abundance estimation is investigated in the face of increasing constraints and simplifications to simulate CRISM data. Constraints and simplifications include reduced spectral resolution, additional noise, unknown endmembers and unknown particle physical characteristics. CRISM operates in two spectral resolutions, the Full Resolution Targeted (FRT) with which it has imaged approximately 2% of the martian surface, and the lower spectral resolution MultiSpectral Survey mode (MSP) with which it has covered the vast majority of the surface. On resampling the RELAB spectral mixtures to these two wavelength ranges it was

  15. Atomic force microscopy imaging of fragments from the Martian meteorite ALH84001

    NASA Technical Reports Server (NTRS)

    Steele, A.; Goddard, D.; Beech, I. B.; Tapper, R. C.; Stapleton, D.; Smith, J. R.

    1998-01-01

    A combination of scanning electron microscopy (SEM) and environmental scanning electron microscopy (ESEM) techniques, as well as atomic force microscopy (AFM) methods has been used to study fragments of the Martian meteorite ALH84001. Images of the same areas on the meteorite were obtained prior to and following gold/palladium coating by mapping the surface of the fragment using ESEM coupled with energy-dispersive X-ray analysis. Viewing of the fragments demonstrated the presence of structures, previously described as nanofossils by McKay et al. (Search for past life on Mars--possible relic biogenic activity in martian meteorite ALH84001. Science, 1996, pp. 924-930) of NASA who used SEM imaging of gold-coated meteorite samples. Careful imaging of the fragments revealed that the observed structures were not an artefact introduced by the coating procedure.

  16. Atomic force microscopy imaging of fragments from the Martian meteorite ALH84001

    NASA Technical Reports Server (NTRS)

    Steele, A.; Goddard, D.; Beech, I. B.; Tapper, R. C.; Stapleton, D.; Smith, J. R.

    1998-01-01

    A combination of scanning electron microscopy (SEM) and environmental scanning electron microscopy (ESEM) techniques, as well as atomic force microscopy (AFM) methods has been used to study fragments of the Martian meteorite ALH84001. Images of the same areas on the meteorite were obtained prior to and following gold/palladium coating by mapping the surface of the fragment using ESEM coupled with energy-dispersive X-ray analysis. Viewing of the fragments demonstrated the presence of structures, previously described as nanofossils by McKay et al. (Search for past life on Mars--possible relic biogenic activity in martian meteorite ALH84001. Science, 1996, pp. 924-930) of NASA who used SEM imaging of gold-coated meteorite samples. Careful imaging of the fragments revealed that the observed structures were not an artefact introduced by the coating procedure.

  17. Atomic force microscopy imaging of fragments from the Martian meteorite ALH84001.

    PubMed

    Steele, A; Goddard, D; Beech, I B; Tapper, R C; Stapleton, D; Smith, J R

    1998-01-01

    A combination of scanning electron microscopy (SEM) and environmental scanning electron microscopy (ESEM) techniques, as well as atomic force microscopy (AFM) methods has been used to study fragments of the Martian meteorite ALH84001. Images of the same areas on the meteorite were obtained prior to and following gold/palladium coating by mapping the surface of the fragment using ESEM coupled with energy-dispersive X-ray analysis. Viewing of the fragments demonstrated the presence of structures, previously described as nanofossils by McKay et al. (Search for past life on Mars--possible relic biogenic activity in martian meteorite ALH84001. Science, 1996, pp. 924-930) of NASA who used SEM imaging of gold-coated meteorite samples. Careful imaging of the fragments revealed that the observed structures were not an artefact introduced by the coating procedure.

  18. Isotopic Evidence for a Martian Regolith Component in Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Rao, M. N.; Nyquist, L. E.; Bogard, D. D.; Garrison, D. H.; Sutton, S.

    2009-01-01

    Noble gas measurements in gas-rich impact-melt (GRIM) glasses in EET79001 shergottite showed that their elemental and isotopic composition is similar to that of the Martian atmosphere [1-3]. The GRIM glasses contain large amounts of Martian atmospheric gases. Those measurements further suggested that the Kr isotopic composition of Martian atmosphere is approximately similar to that of solar Kr. The (80)Kr(sub n) - (80)Kr(sub M) mixing ratio in the Martian atmosphere reported here is approximately 3%. These neutron-capture reactions presumably occurred in the glass-precursor regolith materials containing Sm- and Br- bearing mineral phases near the EET79001/ Shergotty sites on Mars. The irradiated materials were mobilized into host rock voids either during shock-melting or possibly by earlier aeolian / fluvial activity.

  19. Magnetic tests for magnetosome chains in Martian meteorite ALH84001.

    PubMed

    Weiss, Benjamin P; Kim, Soon Sam; Kirschvink, Joseph L; Kopp, Robert E; Sankaran, Mohan; Kobayashi, Atsuko; Komeili, Arash

    2004-06-01

    Transmission electron microscopy studies have been used to argue that magnetite crystals in carbonate from Martian meteorite ALH84001 have a composition and morphology indistinguishable from that of magnetotactic bacteria. It has even been claimed from scanning electron microscopy imaging that some ALH84001 magnetite crystals are aligned in chains. Alignment of magnetosomes in chains is perhaps the most distinctive of the six crystallographic properties thought to be collectively unique to magnetofossils. Here we use three rock magnetic techniques, low-temperature cycling, the Moskowitz test, and ferromagnetic resonance, to sense the bulk composition and crystallography of millions of ALH84001 magnetite crystals. The magnetic data demonstrate that although the magnetite is unusually pure and fine-grained in a manner similar to terrestrial magnetofossils, most or all of the crystals are not arranged in chains.

  20. Magnetic tests for magnetosome chains in Martian meteorite ALH84001

    PubMed Central

    Weiss, Benjamin P.; Kim, Soon Sam; Kirschvink, Joseph L.; Kopp, Robert E.; Sankaran, Mohan; Kobayashi, Atsuko; Komeili, Arash

    2004-01-01

    Transmission electron microscopy studies have been used to argue that magnetite crystals in carbonate from Martian meteorite ALH84001 have a composition and morphology indistinguishable from that of magnetotactic bacteria. It has even been claimed from scanning electron microscopy imaging that some ALH84001 magnetite crystals are aligned in chains. Alignment of magnetosomes in chains is perhaps the most distinctive of the six crystallographic properties thought to be collectively unique to magnetofossils. Here we use three rock magnetic techniques, low-temperature cycling, the Moskowitz test, and ferromagnetic resonance, to sense the bulk composition and crystallography of millions of ALH84001 magnetite crystals. The magnetic data demonstrate that although the magnetite is unusually pure and fine-grained in a manner similar to terrestrial magnetofossils, most or all of the crystals are not arranged in chains. PMID:15155900

  1. Evidence of atmospheric sulphur in the martian regolith from sulphur isotopes in meteorites.

    PubMed

    Farquhar, J; Savarino, J; Jackson, T L; Thiemens, M H

    2000-03-02

    Sulphur is abundant at the martian surface, yet its origin and evolution over time remain poorly constrained. This sulphur is likely to have originated in atmospheric chemical reactions, and so should provide records of the evolution of the martian atmosphere, the cycling of sulphur between the atmosphere and crust, and the mobility of sulphur in the martian regolith. Moreover, the atmospheric deposition of oxidized sulphur species could establish chemical potential gradients in the martian near-surface environment, and so provide a potential energy source for chemolithoautotrophic organisms. Here we present measurements of sulphur isotopes in oxidized and reduced phases from the SNC meteorites--the group of related achondrite meteorites believed to have originated on Mars--together with the results of laboratory photolysis studies of two important martian atmospheric sulphur species (SO2 and H2S). The photolysis experiments can account for the observed sulphur-isotope compositions in the SNC meteorites, and so identify a mechanism for producing large abiogenic 34S fractionations in the surface sulphur reservoirs. We conclude that the sulphur data from the SNC meteorites reflects deposition of oxidized sulphur species produced by atmospheric chemical reactions, followed by incorporation, reaction and mobilization of the sulphur within the regolith.

  2. The source crater of martian shergottite meteorites.

    PubMed

    Werner, Stephanie C; Ody, Anouck; Poulet, François

    2014-03-21

    Absolute ages for planetary surfaces are often inferred by crater densities and only indirectly constrained by the ages of meteorites. We show that the <5 million-year-old and 55-km-wide Mojave Crater on Mars is the ejection source for the meteorites classified as shergottites. Shergottites and this crater are linked by their coinciding meteorite ejection ages and the crater formation age and by mineralogical constraints. Because Mojave formed on 4.3 billion-year-old terrain, the original crystallization ages of shergottites are old, as inferred by Pb-Pb isotope ratios, and the much-quoted shergottite ages of <600 million years are due to resetting. Thus, the cratering-based age determination method for Mars is now calibrated in situ, and it shifts the absolute age of the oldest terrains on Mars backward by 200 million years.

  3. Evolution of water reservoirs on Mars: Constraints from hydrogen isotopes in martian meteorites

    NASA Astrophysics Data System (ADS)

    Kurokawa, H.; Sato, M.; Ushioda, M.; Matsuyama, T.; Moriwaki, R.; Dohm, J. M.; Usui, T.

    2014-05-01

    Martian surface morphology implies that Mars was once warm enough to maintain persistent liquid water on its surface. While the high D/H ratios (˜6 times the Earth's ocean water) of the current martian atmosphere suggest that significant water has been lost from the surface during martian history, the timing, processes, and the amount of the water loss have been poorly constrained. Recent technical developments of ion-microprobe analysis of martian meteorites have provided accurate estimation of hydrogen isotope compositions (D/H) of martian water reservoirs at the time when the meteorites formed. Based on the D/H data from the meteorites, this study demonstrates that the water loss during the pre-Noachian (>41-99 m global equivalent layers, GEL) was more significant than in the rest of martian history (>10-53 m GEL). Combining our results with geological and geomorphological evidence for ancient oceans, we propose that undetected subsurface water/ice (≃100-1000 m GEL) should exist, and it exceeds the observable present water inventory (≃20-30 m GEL) on Mars.

  4. Hosts of hydrogen in ALH 84001: Evidence for hydrous martian salts in the oldest martian meteorite?

    NASA Astrophysics Data System (ADS)

    Eiler, John M.; Kitchen, Nami; Leshin, Lauri; Strausberg, Melissa

    2002-03-01

    The Martian meteorite, ALH84001, contains D-rich hydrogen of plausible Martian origin (Leshin et al. 1996). The phase identity of the host(s) of this hydrogen are not well known and could include organic matter (McKay et al., 1996), phlogopite (Brearley 2000), glass (Mittlefehldt 1994) and/or other, unidentified components of this rock. Previous ion microprobe studies indicate that much of the hydrogen in ALH84001 as texturally associated with concretions of nominally anhydrous carbonates, glass and oxides (Boctor et al., 1998; Sugiura and Hoshino, 2000). We examined the physical and chemical properties of the host(s) of this hydrogen by stepped pyrolysis of variously pre-treated sub-samples. A continuous-flow method of water reduction and mass spectrometry (Eiler and Kitchen 2001) was used to permit detailed study of the small amounts of this hydrogen-poor sample available for study. We find that the host(s) of D-rich hydrogen released from ALH84001 at relatively low temperatures (~500 deg C) is soluble in orthophosphoric and dilute hydrochloric acids and undergoes near-complete isotopic exchange with water within hours at temperatures of 200 to 300 deg C. These characteristics are most consistent with the carrier phase(s) being a hydrous salt (e.g., carbonate, sulfate or halide); the thermal stability of this material is inconsistent with many examples of such minerals (e.g., gypsum) and instead suggests one or more relatively refractory hydrous carbonates (e.g., hydromagnesite). Hydrous salts (particularly hydrous carbonates) are common on the earth only in evaporite, sabkha, and hydrocryogenic-weathering environments; we suggest that much (if not all) of the 'Martian' hydrogen in ALH84001 was introduced in analogous environments on or near the martian surface rather than through biological activity or hydrothermal alteration of silicates in the crust.

  5. The age of the carbonates in martian meteorite ALH84001

    NASA Technical Reports Server (NTRS)

    Borg, L. E.; Connelly, J. N.; Nyquist, L. E.; Shih, C. Y.; Wiesmann, H.; Reese, Y.

    1999-01-01

    The age of secondary carbonate mineralization in the martian meteorite ALH84001 was determined to be 3.90 +/- 0.04 billion years by rubidium-strontium (Rb-Sr) dating and 4.04 +/- 0.10 billion years by lead-lead (Pb-Pb) dating. The Rb-Sr and Pb-Pb isochrons are defined by leachates of a mixture of high-graded carbonate (visually estimated as approximately 5 percent), whitlockite (trace), and orthopyroxene (approximately 95 percent). The carbonate formation age is contemporaneous with a period in martian history when the surface is thought to have had flowing water, but also was undergoing heavy bombardment by meteorites. Therefore, this age does not distinguish between aqueous and impact origins for the carbonates.

  6. The age of the carbonates in martian meteorite ALH84001

    NASA Technical Reports Server (NTRS)

    Borg, L. E.; Connelly, J. N.; Nyquist, L. E.; Shih, C. Y.; Wiesmann, H.; Reese, Y.

    1999-01-01

    The age of secondary carbonate mineralization in the martian meteorite ALH84001 was determined to be 3.90 +/- 0.04 billion years by rubidium-strontium (Rb-Sr) dating and 4.04 +/- 0.10 billion years by lead-lead (Pb-Pb) dating. The Rb-Sr and Pb-Pb isochrons are defined by leachates of a mixture of high-graded carbonate (visually estimated as approximately 5 percent), whitlockite (trace), and orthopyroxene (approximately 95 percent). The carbonate formation age is contemporaneous with a period in martian history when the surface is thought to have had flowing water, but also was undergoing heavy bombardment by meteorites. Therefore, this age does not distinguish between aqueous and impact origins for the carbonates.

  7. Formation and Evolution of Mars Inferred from Martian Meteorites

    NASA Astrophysics Data System (ADS)

    Borg, L. E.; Symes, S.

    2011-12-01

    The return of samples from Mars has been a long standing NASA objective that, if achieved, would dramatically change our view of the formation and evolution of the terrestrial planets, as well as the physical and chemical conditions in the solar system at the time when life formed on Earth. Significant insight into Mars has been gleaned from the >50 martian meteorites that have landed on Earth. These meteorites fall into 3 categories: First, 165 to 570 Ma basalts and basaltic cumulates, second 1.3 Ga clinopyroxenites and dunites, and third a >4 Ga orthopyroxenite. The basaltic meteorites form a continuum between those with geochemical and isotopic characteristics indicating derivation from depleted and enriched sources. This is most easily explained as mixing between a depleted mantle reservoir and a poorly constrained enriched reservoir in the mantle or crust. Like some basalts. the clinopyroxenites/dunites are slightly enriched in incompatible elements relative to chondrites, but cannot be related to the basaltic meteorites by any simple process. This is most clearly supported by their vastly different short-lived isotopic compositions (e.g. 182W and 142Nd) compared to the basalts. Although all samples have undergone some low temperature alteration on Mars, the orthopyroxenite has undergone significantly more. These observations led to several fundamental conclusions: (1) the young ages indicate the planet is geologically active at present, (2) non-chondritic 182W and 142Nd suggest core formation and silicate differentiation occurred <5 Ma and <25Ma after CAIs, respectively, (3) preservation of isotopic anomalies in short-lived isotopic systems requires geochemical reservoirs on Mars to remain isolated for much of Mars history, (4) basalt geochemical relationships indicate these reservoirs mixed recently during basalt genesis and that these samples are closely related, and (5) water based alteration present in the meteorites occurred throughout martian history

  8. New Martian Meteorite Is One of the Most Oxidized Found to Date

    NASA Technical Reports Server (NTRS)

    Hui, Hejiu; Peslier, Anne; Lapen, Thomas J.; Shafer, John T.; Brandon, Alan D.; Irving, Anthony J.

    2014-01-01

    As of 2013, about 60 meteorites from the planet Mars have been found and are being studied. Each time a new Martian meteorite is found, a wealth of new information comes forward about the red planet. The most abundant type of Martian meteorite is a shergottite; its lithologies are broadly similar to those of Earth basalts and gabbros; i.e., crustal igneous rocks. The entire suite of shergottites is characterized by a range of trace element, isotopic ratio, and oxygen fugacity values that mainly reflect compositional variations of the Martian mantle from which these magmas came. A newly found shergottite, NWA 5298, was the focus of a study performed by scientists within the Astromaterials Research and Exploration Science (ARES) Directorate at the Johnson Space Center (JSC) in 2012. This sample was found in Morocco in 2008. Major element analyses were performed in the electron microprobe (EMP) laboratory of ARES at JSC, while the trace elements were measured at the University of Houston by laser inductively coupled plasma mass spectrometry (ICPMS). A detailed analysis of this stone revealed that this meteorite is a crystallized magma that comes from the enriched end of the shergottite spectrum; i.e., trace element enriched and oxidized. Its oxidation comes in part from its mantle source and from oxidation during the magma ascent. It represents a pristine magma that did not mix with any other magma or see crystal accumulation or crustal contamination on its way up to the Martian surface. NWA 5298 is therefore a direct, albeit evolved, melt from the Martian mantle and, for its lithology (basaltic shergottite), it represents the oxidized end of the shergottite suite. It is thus a unique sample that has provided an end-member composition for Martian magmas.

  9. Martian Pyroxenes in the Shergottite Meteorites; Zagami, SAU005, DAG476 and EETA79001

    NASA Astrophysics Data System (ADS)

    Stephen, N.; Benedix, G. K.; Bland, P.; Hamilton, V. E.

    2010-12-01

    The geology and surface mineralogy of Mars is characterised using remote sensing techniques such as thermal emission spectroscopy (TES) from instruments on a number of spacecraft currently orbiting Mars or gathered from roving missions on the Martian surface. However, the study of Martian meteorites is also important in efforts to further understand the geological history of Mars or to interpret mission data as they are believed to be the only available samples that give us direct clues as to Martian igneous processes [1]. We have recently demonstrated that the spectra of Martian-specific minerals can be determined using micro-spectroscopy [2] and that these spectra can be reliably obtained from thin sections of Martian meteorites [3]. Accurate modal mineralogy of these meteorites is also important [4]. In this study we are using a variety of techniques to build upon previous studies of these particular samples in order to fully characterise the nature of the 2 common pyroxenes found in Martian Shergottites; pigeonite and augite [5], [6]. Previous studies have shown that the Shergottite meteorites are dominated by pyroxene (pigeonite and augite in varying quantities) [4], [5], commonly but not always olivine, plagioclase or maskelynite/glass and also hydrous minerals, which separate the Martian meteorites from other achondrites [7]. Our microprobe study of meteorites Zagami, EETA79001, SAU005 and DAG476 in thin-section at the Natural History Museum, London shows a chemical variability within both the pigeonite and augite composition across individual grains in all thin sections; variation within either Mg or Ca concentration varies from core to rim within the grains. This variation can also be seen in modal mineralogy maps using SEM-derived element maps and the Photoshop® technique previously described [4], and in new micro-spectroscopy data, particularly within the Zagami meteorite. New mineral spectra have been gathered from the Shergottite thin-sections by

  10. Origins of Magnetite Nanocrystals in Martian Meteorite ALH84001

    NASA Technical Reports Server (NTRS)

    Thomas-Keprta, Kathie L.; Clemett, Simon J.; Mckay, David S.; Gibson, Everett K.; Wentworth, Susan J.

    2009-01-01

    The Martian meteorite ALH84001 preserves evidence of interaction with aqueous fluids while on Mars in the form of microscopic carbonate disks. These carbonate disks are believed to have precipitated 3.9 Ga ago at beginning of the Noachian epoch on Mars during which both the oldest extant Martian surfaces were formed, and perhaps the earliest global oceans. Intimately associated within and throughout these carbonate disks are nanocrystal magnetites (Fe3O4) with unusual chemical and physical properties, whose origins have become the source of considerable debate. One group of hypotheses argues that these magnetites are the product of partial thermal decomposition of the host carbonate. Alternatively, the origins of mag- netite and carbonate may be unrelated; that is, from the perspective of the carbonate the magnetite is allochthonous. For example, the magnetites might have already been present in the aqueous fluids from which the carbonates were believed to have been deposited. We have sought to resolve between these hypotheses through the detailed characterized of the compo- sitional and structural relationships of the carbonate disks and associated magnetites with the orthopyroxene matrix in which they are embedded. Extensive use of focused ion beam milling techniques has been utilized for sample preparation. We then compared our observations with those from experimental thermal decomposition studies of sideritic carbonates under a range of plausible geological heating scenarios. We conclude that the vast majority of the nanocrystal magnetites present in the car- bonate disks could not have formed by any of the currently proposed thermal decomposition scenarios. Instead, we find there is considerable evidence in support of an alternative allochthonous origin for the magnetite unrelated to any shock or thermal processing of the carbonates.

  11. Origins of Magnetite Nanocrystals in Martian Meteorite ALH84001

    NASA Technical Reports Server (NTRS)

    Thomas-Keprta, Kathie L.; Clemett, Simon J.; Mckay, David S.; Gibson, Everett K.; Wentworth, Susan J.

    2009-01-01

    The Martian meteorite ALH84001 preserves evidence of interaction with aqueous fluids while on Mars in the form of microscopic carbonate disks. These carbonate disks are believed to have precipitated 3.9 Ga ago at beginning of the Noachian epoch on Mars during which both the oldest extant Martian surfaces were formed, and perhaps the earliest global oceans. Intimately associated within and throughout these carbonate disks are nanocrystal magnetites (Fe3O4) with unusual chemical and physical properties, whose origins have become the source of considerable debate. One group of hypotheses argues that these magnetites are the product of partial thermal decomposition of the host carbonate. Alternatively, the origins of mag- netite and carbonate may be unrelated; that is, from the perspective of the carbonate the magnetite is allochthonous. For example, the magnetites might have already been present in the aqueous fluids from which the carbonates were believed to have been deposited. We have sought to resolve between these hypotheses through the detailed characterized of the compo- sitional and structural relationships of the carbonate disks and associated magnetites with the orthopyroxene matrix in which they are embedded. Extensive use of focused ion beam milling techniques has been utilized for sample preparation. We then compared our observations with those from experimental thermal decomposition studies of sideritic carbonates under a range of plausible geological heating scenarios. We conclude that the vast majority of the nanocrystal magnetites present in the car- bonate disks could not have formed by any of the currently proposed thermal decomposition scenarios. Instead, we find there is considerable evidence in support of an alternative allochthonous origin for the magnetite unrelated to any shock or thermal processing of the carbonates.

  12. Mineral Biomarkers in Martian Meteorite Allan Hills 84001?

    NASA Technical Reports Server (NTRS)

    Thomas-Keprta, K. L.; Bazylinski, D. A.; Wentworth, S. J.; McKay, D. S.; Golden, D. C.; Gibson, E. K., Jr.; Romanek, C. S.

    1998-01-01

    The occurrence of fine-grained magnetite in the Fe-rich rims surrounding carbonate globules in the martian meteorite ALH84001, originally described in , have been proposed as fossil remains of primitive martian organisms. Here we report observations on size and shape distributions of magnetites from ALH84001 and compare them to biogenic and inorganic magnetite crystals of terrestrial origin. While some magnetite morphology is not unequivocally diagnostic for its biogenicity, such as cubodial forms of magnetite, which are common in inorganically formed magnetites, other morphologies of magnetite (parallel-epiped or elongated prismatic and arrowhead forms) are more likely signatures of biogenic activity. Some ALH 84001 magnetite particles described below have unique morphology and length-to-width ratios that are indistinguishable from a variety of terrestrial biogenic magnetite and distinct from all known inorganic forms of magnetite.

  13. Water in SNC meteorites - Evidence for a Martian hydrosphere

    NASA Technical Reports Server (NTRS)

    Karlsson, Haraldur R.; Clayton, Robert N.; Gibson, Everett K., Jr.; Mayeda, Toshiko K.

    1992-01-01

    The Shergotty-Nakhla-Chassigny (SNC) meteorites, purportedly of Martian origin, contain 0.04 to 0.4 percent water by weight. Oxygen isotopic analysis can be used to determine whether this water is extraterrestrial or terrestrial. Such analysis reveals that a portion of the water is extraterrestrial and furthermore was not in oxygen isotopic equilibrium with the host rock. Lack of equilibrium between water and host rock implies that the lithosphere and hydrosphere of the SNC parent body formed two distinct oxygen isotopic reservoirs. If Mars was the parent body, the maintenance of two distinct reservoirs may result from the absence of plate tectonics on the planet.

  14. Water in SNC meteorites: evidence for a martian hydrosphere.

    PubMed

    Karlsson, H R; Clayton, R N; Gibson, E K; Mayeda, T K

    1992-03-13

    The Shergotty-Nakhla-Chassigny (SNC) meteorites, purportedly of martian origin, contain 0.04 to 0.4 percent water by weight. Oxygen isotopic analysis can be used to determine whether this water is extraterrestrial or terrestrial. Such analysis reveals that a portion of the water is extraterrestrial and furthermore was not in oxygen isotopic equilibrium with the host rock. Lack of equilibrium between water and host rock implies that the lithosphere and hydrosphere of the SNC parent body formed two distinct oxygen isotopic reservoirs. If Mars was the parent body, the maintenance of two distinct reservoirs may result from the absence of plate tectonics on the planet.

  15. Workshop on the Issue Martian Meteorites: Where do we Stand and Where are we Going?

    NASA Technical Reports Server (NTRS)

    1998-01-01

    The presentations in this workshop discuss the composition of Martian meteorites. Many of the talks were on a specific meteorite, i.e., Allan Hills 84001 (ALH84001). The discovery earlier of carbonates in ALH84001 lead some researchers to suggest that there was evidence of martian life. Other possible explanations for this phenomena are given. Other papers discuss methods to sterilize martian samples, the existence of water on Mars, the facilities of the Meteorite Processing Laboratory at Johnson Space Center, comparative analyses of geologic processes and the gathering of meteorites.

  16. Alteration of Meteorite-Derived Kamacite in Martian Regolith: A new Insight of Chemical Processes in Martian Soils

    NASA Astrophysics Data System (ADS)

    Berger, G.

    2014-07-01

    We experimented the idea that the martian regolith, which is assumed to be contaminated by meteoritic inputs, may have contained kamacite (Fe-Ni). The reactivity of an iron-based metal offers new perspectives for the alteration mechanisms.

  17. Rare-Earth minerals in Martian Meteorite NWA 7034/7533: Evidence for Fluid-Rock Interaction in Martian Crust

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Ma, C.; Chen, Y.; Beckett, J.; Guan, Y.

    2015-07-01

    Previously, we reported finding of monazite, chevikinite-perrierite and xenotime in the ‘Black Beauty’ meteorite (NWA 7034/7533). Here, we show textural and compositional evidence of these minerals that suggest hydrothermal fluids in martian crust.

  18. The provenance, formation, and implications of reduced carbon phases in Martian meteorites

    NASA Astrophysics Data System (ADS)

    Steele, Andrew; McCubbin, Francis M.; Fries, Marc D.

    2016-11-01

    This review is intended to summarize the current observations of reduced carbon in Martian meteorites, differentiating between terrestrial contamination and carbon that is indigenous to Mars. Indeed, the identification of Martian organic matter is among the highest priority targets for robotic spacecraft missions in the next decade, including the Mars Science Laboratory and Mars 2020. Organic carbon compounds are essential building blocks of terrestrial life, so the occurrence and origin (biotic or abiotic) of organic compounds on Mars is of great significance; however, not all forms of reduced carbon are conducive to biological systems. This paper discusses the significance of reduced organic carbon (including methane) in Martian geological and astrobiological systems. Specifically, it summarizes current thinking on the nature, sources, and sinks of Martian organic carbon, a key component to Martian habitability. Based on this compilation, reduced organic carbon on Mars, including detections of methane in the Martian atmosphere, is best described through a combination of abiotic organic synthesis on Mars and infall of extraterrestrial carbonaceous material. Although conclusive signs of Martian life have yet to be revealed, we have developed a strategy for life detection on Mars that can be utilized in future life-detection studies.

  19. Iddingsite in the Nakhla meteorite: TEM study of mineralogy and texture of pre-terrestrial (Martian?) alterations

    NASA Technical Reports Server (NTRS)

    Treiman, Allan H.; Gooding, James L.

    1991-01-01

    Rusty-colored veinlets and patches in the Nakhla meteorite, identified as iddingsite, are pre-terrestrial. The rusty material is iddingsite (smectites + hematite + ferrihydrite); like terrestrial iddingsites, it probably formed during low-temperature interaction of olivine and water. Fragments of rusty material with host olivine were removed from thin sections of Nakhla with a tungsten needle. Fragments were embedded in epoxy, microtomed to 100 nanometers thickness, and mounted on Cu grids. Phase identifications were by Analytical Electron Microscopy/Energy Dispersive X-ray Analysis (EM/EDX) standardless chemical analyses (for silicates), electron diffraction (hematite and ferrihydrite), and lattice fringe imaging. This iddingsite in Nakhla is nearly identical to some formed on Earth, suggesting similar conditions of formation on the Shergottites-Nakhlites-Chassigny (SNC) meteorite parent planet. A more detailed account of the results is presented.

  20. Search for Past Life on Mars: Possible Relict Biogenic Activity in Martian Meteorite ALH84001

    NASA Technical Reports Server (NTRS)

    McKay, David S.; Gibson, Everett K., Jr.; Thomas-Keprta, Kathie L.; Vali, Hojatollah; Romanek, Christopher S.; Clemett, Simon J.; Chillier, Xavier D. F.; Maechling, Claude R.; Zare, Richard N.

    1996-01-01

    Fresh fracture surfaces of the martian meteorite ALH84001 contain abundant polycyclic aromatic hydrocarbons (PAHs). These fresh fracture surfaces also display carbonate globules. Contamination studies suggest the PAHs are indigenous to the meteorite. High resolution scanning and transmission electron microscopy study of surface textures and internal structures of selected carbonate globules show that the globules contain fine-grained, secondary phases of single-domain magnetite and Fe-monosulfides. The carbonate globules are similar in texture and size to some terrestrial bacterially induced carbonate precipitates. Although inorganic formation is possible, formation of the globules by biogenic processes could explain many of the observed features including the PAHs. The PAHs, the carbonate globules, and their associated secondary mineral phases and textures could thus be fossil remains of a past martian biota.

  1. MN Carbonates in the Martian Meteorite Nakhla: Possible Evidence of Brine Evaporation

    NASA Technical Reports Server (NTRS)

    Bailey, J. V.; McKay, D. S.; Wentworth, S. J.

    2003-01-01

    The importance of secondary phases in martian meteorites lies in their potential to provide clues about the martian environments responsible for their formation. During this study, we analyzed a number of carbonate-bearing fracture surfaces from the Nakhla meteorite. Here we describe the physical and chemical properties of several manganese-calcium-rich siderites. Additionally, we describe a potential model for the formation and alteration of these carbonates, and we suggest constraints on the conditions responsible for their precipitation. Nakhla is an olivine-bearing clinopyroxenite with minor amounts of feldspar, FeS, and Fe oxides. Secondary mineral assemblages include vein filling clay with embedded iron oxides, a calcium sulfate, amorphous silica, chlorapatite, halite and carbonates. Bridges and Grady suggested that the carbonates in Nakhla formed from brine evaporation. Isotope studies of the Mn rich siderite are also consistent with formation from hydrothermal fluids with an upper T constraint of 170 C.

  2. PYTi-NiCr Signatures in the Columbia Hills are Present in Certain Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Clark, B. C.; Gellert, R.; Ming, D. W.; Morris, R. V.; Mittlefehldt, D. W.; Squyres, S. W.

    2006-01-01

    Uniquely high levels of phosphorus and titanium were observed in several samples [1-3] by the APXS x-ray fluorescence measurements as the MER Spirit rover climbed Husband Hill (Columbia Hills, Gusev crater, Mars). A careful study of many such samples and their geochemical variability has revealed additional elements in this pattern, and that the derived multi-element signature is also unambiguously manifested in several martian meteorites.

  3. Ferric saponite and serpentine in the nakhlite martian meteorites

    NASA Astrophysics Data System (ADS)

    Hicks, L. J.; Bridges, J. C.; Gurman, S. J.

    2014-07-01

    Transmission electron microscopy and Fe-K X-ray absorption spectroscopy have been used to determine structure and ferric content of the secondary phase mineral assemblages in the nakhlite martian meteorites, NWA 998, Lafayette, Nakhla, GV, Y 000593, Y 000749, MIL 03346, NWA 817, and NWA 5790. The secondary phases are a rapidly cooled, metastable assemblage that has preserved Mg# and Ca fractionation related to distance from the fluid source, for most of the nakhlites, though one, NWA 5790, appears not to have experienced a fluid pathway. All nine nakhlite samples have also been analysed with scanning electron microscopy, electron probe micro analysis, Bright Field high-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction. By measuring the energy position of the Fe-K XANES 1s → 3d pre-edge transition centroid we calculate the ferric content of the minerals within the nakhlite meteorites. The crystalline phyllosilicates and amorphous silicate of the hydrothermal deposits filling the olivine fractures are found to have variable Fe3+/ΣFe values ranging from 0.4 to 0.9. In Lafayette, the central silicate gel parts of the veins are more ferric than the phyllosilicates around it, showing that the fluid became increasingly oxidised. The mesostasis of Lafayette and NWA 817 also have phyllosilicate, which have a higher ferric content than the olivine fracture deposits, with Fe3+/ΣFe values of up to 1.0. Further study, via TEM analyses, reveal the Lafayette and NWA 817 olivine phyllosilicates to have 2:1 T-O-T lattice structure with a the d001-spacing of 0.96 nm, whereas the Lafayette mesostasis phyllosilicates have 1:1 T-O structure with d001-spacings of 0.7 nm. Based on our analyses, the phyllosilicate found within the Lafayette olivine fractures is trioctahedral ferric saponite (Ca0.2K0.1)∑0.3(Mg2.6Fe2+1.3Fe3+1.7Mn0.1)∑5.7[(Si6.7AlIV0.9Fe3+0.4)∑8.0O20](OH)4·nH2O, and that found in the mesostasis fractures is an Fe

  4. Habitability Conditions Constrained by Martian Meteorites: Implications for Microbial Colonization and Mars Sample Return

    NASA Astrophysics Data System (ADS)

    Shivak, J. N.; Banerjee, N.; Flemming, R. L.

    2013-12-01

    We report the results of a comparative study of the crustal environmental conditions recorded by several Martian meteorites (Nakhla, Los Angeles, and Zagami). Though no samples have yet been returned from Mars, numerous meteorites are known and these provide the only samples of the Martian crust currently available for study. Terrestrial basalts and other mafic igneous rocks are analogous in many ways to much of the Martian crust, as evidenced by the composition of known Martian meteorites and measurements from planetary missions [1]. Microorganisms are known to thrive in the terrestrial geosphere and make use of many different substrates within rock in the subsurface of the Earth [2]. The action of aqueous solutions in the Martian crust has been well established through the study of alteration mineral assemblages present in many Martian meteorites, such as the nakhlites [3]. Aqueous activity in terrestrial chemolithoautotrophic habitats provides numerous energy and nutrient sources for microbes [4], suggesting the potential for habitable endolithic environments in Martian rocks. Fayalite in Nakhla has experienced extensive aqueous alteration to reddish-brown 'iddingsite' material within a pervasive fracture system. Textural imaging shows the replacement of primary olivine with various alteration phases and infiltration of this alteration front into host grains. Geochemical analysis of the alteration material shows the addition of iron and silica and removal of magnesium during alteration. Novel In situ Micro-XRD and Raman Spectroscopy of this material reveals a new assemblage consisting of iron oxides, smectite clays, carbonates, and a minor serpentine component. The alteration mineral assemblage here differs from several that have been previously reported [4] [5], allowing for a reevaluation of the environmental conditions during fluid action. Los Angeles and Zagami show no evidence of aqueous activity, though their primary basaltic mineralogies show many

  5. Amphibole in Martian Meteorites: Composition and Implication for Volatile Content of Parental Magma

    NASA Astrophysics Data System (ADS)

    Williams, K. B.; Sonzogni, Y.; Treiman, A. H.

    2013-12-01

    Titanium-rich amphibole is present in melt inclusions in many martian (SNC) meteorites, suggesting that martian magmas contained water. Amphibole has been reported in melt inclusions within olivine grains in chassignites [1-3], and occurs in melt inclusions within pigeonite grains in most shergottites [4-10]. This study focuses on a comparison of amphibole compositions in two olivine-phyric shergottites: Tissint and Elephant Moraine (EETA) 79001, Lithology A. While amphibole (commonly of kaersutitic composition) is rare in martian meteorites, the mineral is widespread and may be useful in constraining volatile abundances in the martian mantle. Amphibole incorporates hydroxyl into its mineral structure on its O(3) site, which can also contain F-, Cl-, and O2-. Previous chemical analyses of amphiboles in martian meteorites show low halogen abundances, implying high proportions of OH- and/or O2- in the O(3) site [6, 11]. Presence of O2- on O(3) is not considered in this study, even though oxy-kaersutite can be stable at 1 bar pressure [11, 12]. Our chemical data on amphibole in martian meteorites will expand the current compositional database and provide amphibole water content estimates that can then be used to constrain the water content of the parental magma. Amphiboles were identified in polished thin sections of Tissint and EETA79001A by their yellow-orange to light brown pleochroism. Consistent with previous observations of amphibole in shergottites [4-10], the amphiboles are present only in melt inclusions in the cores of pigeonite grains, and never in augite, olivine, or mesostasis. The amphibole grains are subhedral, and range up to 15 μm in diameter. Amphibole formulae were calculated from chemical analyses by normalizing to 23 O, assuming that all iron is ferrous, and assuming that halogens and hydroxyl fully occupy the O(3) site (i.e., F-+Cl-+OH-= 2). Variability in iron oxidation and the possibility of internal amphibole dehydrogenation provide

  6. Chemical Alterations in Martian Meteorites from Cold and Hot Deserts

    NASA Astrophysics Data System (ADS)

    Dreibus, G.; Huisl, W.; Spettel, B.; Haubold, R.; Jagoutz, E.

    2003-04-01

    Martian meteorites (SNC) provide evidence of the magmatic fractionation processes of their parent body. As 23 of the total of 27 meteorites are finds, the influence of chemical alterations during their residence time on Earth must be considered, when interpreting the mineralogical, chemical, or isotopic features. Many basaltic shergottites and nakhlites were collected both in the cold desert, Antarctica, and in hot deserts of North Africa and Asia. To detect alteration processes in the finds we have to compare their analytical data with those obtained from the very scarce falls. In this way, we find an overabundance of iodine in meteorites from Antarctica. The iodine contamination is caused by aerosols adhering to the ice. Therefore, iodine can penetrate into the meteorite during its residence in Antarctica. The iodine content measured in the Antarctic shergottites varies from 0.060 to 4.6 ppm and seems to depend on their residence time on ice. The paired Yamato nakhlites Y-000593 and Y-000749 recently discovered in Antarctica also reveal an iodine overabundance compared to Nakhla, which is the only fall among the nakhlites. However, in Nakhla we have another problem of alteration. Nakhla has unusually high Br and Cl concentrations which could originate from terrestrial or parent body alterations. As Cl and Br are readily extracted during water leaching experiments we favor a terrestrial contamination. A Br overabundance was also found in many olivine-rich shergottite finds from hot deserts, DaG 476, Dhofar 019, and SaU 005. However, in the basaltic shergottite Dhofar 378 and in the nakhlite NWA 817 [1] no Br contamination was observed. The olivine phases of the shergottites seem to be preferably attacked by weathering reactions in the hot deserts. In the shergottites from hot deserts, the subchondritic La/U ratios are remarkable, indicating a U contamination. All these meteorites are covered with an evaporation product, caliche. Caliche has a high content of

  7. Organic Carbon Features Identified in the Nakhla Martian Meteorite

    NASA Technical Reports Server (NTRS)

    Mckay, D. S.; Thomas-Keprta, K. L.; Clemett, S. J.; Gibson, E. K., Jr.; Le, L.; Rahman, Z.; Wentworth, S. J.

    2011-01-01

    We report, for the first time, the identification of specific carbonaceous phases, present within iddingsite alteration zones of the Nakhla meteorite that possess discrete, well defined, structurally coherent morphologies. These structures bear superficial similarity to the carbonaceous nanoglobules [1] found in primitive chondrites interplanetary dust particles, although they are an order-of-magnitude larger in size. Introduction: It has been known for many years that some members of the Martian meteorite clan contain organic matter [e.g., 2-4]. Based on both isotopic measurements [5] and circumstantial observations [4] (e.g., the similarity organic signatures present in both Antarctic finds and non-Antarctic falls) a credible argument has been made for a preterrestrial origin for the majority of these organics. The Nakhla meteorite is of particular interest in that it has been shown to contain both an acid-labile organic fraction as well as an acid-insoluble high molecular weight organic component [4]. Pyrolysis-gas chromatography-mass spectrometry of the latter component indicates it to be composed of aromatic and alkyl-aromatic functionalities bound into a macromolecule phase through ether linkages [4]. However, the spatial, textural and mineralogical associations of this carbonaceous macromolecular material have remained elusive [6].

  8. A Younger Age for the Oldest Martian Meteorite

    NASA Astrophysics Data System (ADS)

    Taylor, G. J.

    2010-05-01

    The Allan Hills (ALH) 84001 Martian meteorite is famous for containing fiercely-disputed evidence for fossil life. Equally important to many cosmochemists, the meteorite also contains important information about the construction of the Martian crust by magmas derived from the interior, and the subsequent modification of those igneous rocks by large impacts and circulating water. A surprising feature of ALH 84001 has been its extremely ancient age, 4.50 billion years, as determined by samarium-neodymium (Sm-Nd) and rubidium-strontium (Rb-Sr) isotopic dating. If correct, the ancient age implies that the magma in which ALH 84001 formed intruded the primordial crust, perhaps forming in a deep ocean of magma that surrounded Mars during its initial differentiation into metallic core, rocky mantle, and primary crust. New age determinations by Thomas Lapen (University of Houston) and colleagues there and at the Johnson Space Center, the Lunar and Planetary Institute, the University of Wisconsin, and the University of Brussels, Belgium, indicate that the rock crystallized in a magma 4.091 billion years ago. They used lutetium-hafnium (Lu-Hf) isotopes in determining the new age. This isotopic system has the advantage of not being affected as readily by impact heating and water alteration as are Sm-Nd and Rb-Sr. The new age is consistent with igneous activity throughout Martian history and with a period of heavy bombardment between 4.2 and 4.1 billion years as inferred from the ages of large impact basins on Mars.

  9. Evaporite mineral assemblages in the nakhlite (martian) meteorites

    NASA Astrophysics Data System (ADS)

    Bridges, J. C.; Grady, M. M.

    2000-03-01

    A mineralogical study of the three nakhlite (martian) meteorites has revealed that they contain evaporite mineral assemblages. Lafayette has Ca-siderite and clay minerals (smectite/illite) along fractures within olivine; Governador Valadares contains clay mineral veins in olivine, with siderite, gypsum and anhydrite in interstitial areas; Nakhla has clay and gypsum veins in olivine, with Mg-, Mn-rich siderite, anhydrite and halite in interstitial sites. Minor goethite is also present in the three meteorites. Lafayette siderite has the range of compositions (mol%) CaCO 3 21.6-36.8, MnCO 3 4.2-35.3, MgCO 3 0.1-1.6, FeCO 3 27.4-67.0; Governador Valadares has CaCO 3 3.6-11.1, MnCO 3 1.1-2.1, MgCO 3 9.0-29.2, FeCO 3 64.3-77.8; Nakhla has CaCO 3 0.1-5.7, MnCO 3 1.0-39.9, MgCO 3 2.0-40.9, FeCO 3 23.2-87.0. Trace element abundances for clay, siderite and gypsum are all similar with LREE, Y>HREE, Zr, Nb and La 0.9-95×CI; Y 0.2-2.4×CI. This pattern of abundances reflects the trace element contents of the parent fluid, which in turn were derived through dissolution of LREE-enriched feldspathic mesostasis. The close similarities in silicate petrography and radiometric ages determined by other workers for these olivine clinopyroxenites suggests that the parent rocks were close to one another on Mars and therefore the same fluid may have been responsible for the precipitation of the evaporite mineral assemblages. Lafayette contains the mineral assemblage and siderite composition which are least soluble in water and Nakhla contains the most soluble minerals and carbonate composition. On the basis of our new data we consider a new model of progressive evaporation from a Na-Mg-Fe-Ca-SO 4-Cl-H 2O-HCO 3- acidic brine in an area of enclosed drainage (e.g. crater or low-lying flood plain) on Mars. Partial dissolution of near-surface rocks by the acidic brine released Fe, Mg and trace elements from mesostasis and olivine into the fluid. The Lafayette assemblage was formed where >25

  10. Characterization of Martian Soil Fines Fraction in SNC Meteorites

    NASA Technical Reports Server (NTRS)

    Rao, M. N.; McKay, D. S.

    2003-01-01

    Some impact-melt glasses in shergottite meteorites contain large abundances of martian atmospheric noble gases with high (129)Xe/(132)Xe ratios, accompanied by varying (87)Sr/(86)Sr (initial) ratios. These glasses contain Martian Soil Fines (MSF) probably from young volcanic terrains such as Tharsis or Elysium Mons. The composition of the MSF bearing samples is different from the average bulk composition of the host rock. These samples show the following charecteristics: a) simultaeneous enrichment of the felsic component and depletion of the mafic component relative to the host phase and b) significant secondary sulfur/sulfate excesses over the host material. The degree of enrichment and associated depletion varies from one sample to another. Earlier, we found large enrichments of felsic (Al, Ca, Na and K) component and depletion of mafic (Fe, Mg, Mn and Ti) component in several impact melt glass veins and pods of samples ,77 ,78 , 18, and ,20A in EET79001 accompanied by large sulfur/sulfate excesses. Based on these results, we proposed a model where the comminution of basaltic rocks takes place by meteoroid bombardment on the martian surface, leading to the generation of fine-grained soil near the impact sites. This fine-grained soil material is subsequently mobilized by saltation and deflation processes on Mars surface due to pervasive aeolian activity. This movement results in mechanical fractionation leading to the felsic enrichment and mafic depletion in the martian dust. We report, here, new data on an impact-melt inclusion ,507 (PAPA) from EET79001, Lith B and ,506 (ALPHA) from EET79001, Lith A and compare the results with those obtained on Shergotty impact melt glass (DBS).

  11. Characterization of Martian Soil Fines Fraction in SNC Meteorites

    NASA Technical Reports Server (NTRS)

    Rao, M. N.; McKay, D. S.

    2003-01-01

    Some impact-melt glasses in shergottite meteorites contain large abundances of martian atmospheric noble gases with high (129)Xe/(132)Xe ratios, accompanied by varying (87)Sr/(86)Sr (initial) ratios. These glasses contain Martian Soil Fines (MSF) probably from young volcanic terrains such as Tharsis or Elysium Mons. The composition of the MSF bearing samples is different from the average bulk composition of the host rock. These samples show the following charecteristics: a) simultaeneous enrichment of the felsic component and depletion of the mafic component relative to the host phase and b) significant secondary sulfur/sulfate excesses over the host material. The degree of enrichment and associated depletion varies from one sample to another. Earlier, we found large enrichments of felsic (Al, Ca, Na and K) component and depletion of mafic (Fe, Mg, Mn and Ti) component in several impact melt glass veins and pods of samples ,77 ,78 , 18, and ,20A in EET79001 accompanied by large sulfur/sulfate excesses. Based on these results, we proposed a model where the comminution of basaltic rocks takes place by meteoroid bombardment on the martian surface, leading to the generation of fine-grained soil near the impact sites. This fine-grained soil material is subsequently mobilized by saltation and deflation processes on Mars surface due to pervasive aeolian activity. This movement results in mechanical fractionation leading to the felsic enrichment and mafic depletion in the martian dust. We report, here, new data on an impact-melt inclusion ,507 (PAPA) from EET79001, Lith B and ,506 (ALPHA) from EET79001, Lith A and compare the results with those obtained on Shergotty impact melt glass (DBS).

  12. Martian carbon dioxide: Clues from isotopes in SNC meteorites

    NASA Technical Reports Server (NTRS)

    Karlsson, H. R.; Clayton, R. N.; Mayeda, T. K.; Jull, A. J. T.; Gibson, E. K., Jr.

    1993-01-01

    Attempts to unravel the origin and evolution of the atmosphere and hydrosphere on Mars from isotopic data have been hampered by the impreciseness of the measurements made by the Viking Lander and by Earth-based telescopes. The SNC meteorites which are possibly pieces of the Martian surface offer a unique opportunity to obtain more precise estimates of the planet's volatile inventory and isotopic composition. Recently, we reported results on oxygen isotopes of water extracted by pyrolysis from samples of Shergotty, Zagami, Nakhla, Chassigny, Lafayette, and EETA-79001. Now we describe complementary results on the stable isotopic composition of carbon dioxide extracted simultaneously from those same samples. We will also report on C-14 abundances obtained by accelerator mass spectrometry (AMS) for some of these CO2 samples.

  13. Lead in Martian Meteorites-- Observations and Inconsistencies: I. Chassigny

    NASA Technical Reports Server (NTRS)

    Jones, J. H.; Simon, J. I.; Usui, T.

    2017-01-01

    The history of Pb isotope analyses of the martian meteorites (SNC) and their interpretations is laden with difficulties. Two different analytical groups have interpreted their ancient (= 4 Ga) shergottite Pb ages as primary [1-5]. A Nakhla age of approximately 4.3 Ga has been interpreted to be primary as well [2]. This is in stark contrast to the young (= 1.4 Ga) crystallization ages defined by the Rb-Sr, Sm-Nd, Lu-Hf, and KAr systems [6]. Possibly, a better interpretation for the ancient Pb ages is that they reflect the formation times of the various SNC source regions [7]. A difficulty in dealing with Pb is that terrestrial contamination is ubiquitous, unlike the other chronometer systems noted above. This issue is complicated by the fact that radioactive decay causes localized mineral damage. So washing and leaching to remove Pb contamination tends to remove in situ radiogenic Pb. This issue is further compounded because U and Th are often concentrated in phosphates and other minor phases, so the leaching process tends to remove these, especially phosphates. Another difficulty is that it is not clear whether the observed Pb isotopic variation in leachates, residues, and ion-microprobe analyses is due to terrestrial or to indigenous martian Pb contamination [e.g., 8]. A third difficulty is that the shergottites on the one hand, and the nakhlites and chassignites on the other, appear to have come from separate source regions with different chemical compositions [e.g., 7]. Thus, it is expected that their Pb isotopic characteristics would be different. And even if all these meteorite types came from the same source region, their igneous ages differ considerably. The nakhlites and chassignites are 1.4 Ga and the shergottites are = 600 Ma [e.g., 6]. This age difference alone should assure that the two distinct SNC groups have differing Pb isotopic signatures.

  14. Los Angeles: The Most Differentiated Basaltic Martian Meteorite

    NASA Technical Reports Server (NTRS)

    Rubin, Alan E.; Warren, Paul H.; Greenwood, James P.; Verish, Robert S.; Leshin, Laurie A.; Hervig, Richard L.; Clayton, Robert N.; Mayeda, Toshiko K.

    2000-01-01

    Los Angeles is a new martian meteorite that expands the compositional range of basaltic shergottites. Compared to Shergotty, Zagami, QUE94201, and EET79001-B, Los Angeles is more differentiated, with higher concentrations of incompatible elements (e.g., La) and a higher abundance of late-stage phases such as phosphates and K-rich feldspathic glass. The pyroxene crystallization trend starts at compositions more ferroan than in other martian basaits. Trace elements indicate a greater similarity to Shergotty and Zagami than to QUE94201 or EET79001-B, but the Mg/Fe ratio is low even compared to postulated parent melts of Shergotty and Zagami. Pyroxene in Los Angeles has 0.7-4-microns-thick exsolution lamellae, approx. 10 times thicker than those in Shergotty and Zaganii. Opaque oxide compositions suggest a low equilibration temperature at an oxygen fugacity near the fayafite-magnetitequartz buffer. Los Angeles cooled more slowly than Shergotty and Zagami. Slow cooling, coupled with the ferroan bulk composition, produced abundant fine-grained intergrowths of fayalite, hedenbergite, and silica, by the breakdown of pyroxferroite. Shock effects in Los Angeles include maskelynitized plagioclase, pyroxene with mosaic extinction, and rare fault zones. One such fault ruptured a previously decomposed zone of pyroxferroite. Although highly differentiated, the bulk composition of Los Angeles is not close to the low-Ca/Si composition or the globally wind-stirred soil of Mars.

  15. A combined electron microprobe (EMP) and Raman spectroscopic study of the alteration products in Martian meteorite MIL 03346

    NASA Astrophysics Data System (ADS)

    Kuebler, K. E.

    2013-03-01

    We examine the secondary alteration products in MIL 03346 using Raman spectroscopic and electron microprobe traverses. Discussion focuses on the single olivine in ,177 supplemented with observations from ,168 and ,169. Traverses start at the rim and progress into the interior. Dark brown, nearly opaque, laihunite [Fe2+Fe3+2(SiO4)2] is present as overgrowths, and 20-50 µm veins of reddish-brown stilpnomelane [(K,Na,Ca)4(Ti0.1,Al2.3,Fe3+35.5,Mn0.8,Mg9.3) (Si63Al9)(O,OH)206∗n(H2O)] occur inside the olivine. Stilpnomelane crosscuts and postdates the laihunite; veins are in sharp contact with the host olivine but lined by ~5 µm films of jarosite [KFe3+3(SO4)2(OH)6] from a later generation of alteration. An interstitial laihunite also hosts stilpnomelane. The most recent secondary phases are gypsum and bassanite in our X-ray maps of ,168 and ,169. Ca-sulfates were not observed in X-ray maps of ,177 but were detected in our Raman point count. All sulfates are believed to be Martian. The groundmass of MIL indicates rapid cooling from elevated temperatures with fO2 near QFM. Reports of laihunite synthesis by olivine oxidation at elevated temperatures (100-800°C) suggest the overgrowths formed during consolidation. In terrestrial rocks, stilpnomelane is a product of late diagenesis to garnet-grade metamorphism. In MIL, stilpnomelane appears to be a secondary phase formed at the lower end of this stability range, at conditions akin to diagenesis. Raman spectra indicate that the stilpnomelane, jarosite, and Ca-sulfates are hydrated. The stilpnomelane contains Cl- and was followed by jarosite, a product of acid alteration, and the deposition of Ca-sulfates and halide salts from more neutral chloride solutions.

  16. New Bulk Sulfur Measurements of Martian Meteorites - Implications for Sulfur Cycle on Mars

    NASA Astrophysics Data System (ADS)

    Ding, S.; Dasgupta, R.; Lee, C.; Wadhwa, M.

    2013-12-01

    Magmatic degassing was likely critical in giving rise to a thick atmosphere of ancient Mars and SO2 and H2S could have been key greenhouse gases. How much S was released depends on (1) the S content of the mantle-derived magma and (2) the magmatic sulfur budget of the basaltic crust. While the former is estimated by S content of basaltic melts at sulfide saturation (SCSS) [1,2], assuming mantle-derived magma is sulfide saturated, it is unclear how much S gets trapped during crystallization of basalts in the crust versus how much is released to the atmosphere. S content of the martian crust can be estimated from martian meteorites, yet bulk S concentration data of martian meteorites is limited [3]. Further, most martian meteorites contain cumulus minerals and some have experienced secondary alteration (weathering/ impact effects), which could either deplete or enrich S in these samples. To better constrain the degassing of S from the martian interior, we measured bulk S contents of 7 martian meteorites via high mass-resolution solution ICP-MS [4]. Basaltic shergottites Los Angeles, Zagami and NWA 856 have S contents of 2865×224, 1954×91 and 1584×10 ppm, respectively while clinopyroxenites Nakhla and NWA 998 give values of 690×60 and 253×42 ppm S. Olivine-phyric shergottites NWA 1068 and Tissint have intermediate S contents of 1280×48 and 2120×68 ppm. The meteorites have lower S contents than the predicted SCSS of ~3500-4500 ppm [2] along liquid line of descent for a liquid similar to Yamato 980459 at 1 GPa, estimated using alphaMELTS. Taking into account the possible proportion of inter-cumulus liquid (f= 6-70 wt.%) in the analyzed meteorites estimated by previous studies, the degassed S could be as low as ~300-1900 ppm (estimated by the difference between the SCSS×f and the S in the meteorites). However, nakhlite Nakhla and basaltic shergottites NWA 856 and Zagami show higher S than the calculated SCSS×f. In these two meteorites, sulfides occur as

  17. Petrology and Geochemistry of New Paired Martian Meteorites Larkman Nunatak 12240 and Larkman Nunatak 12095

    NASA Astrophysics Data System (ADS)

    Funk, R. C.; Peslier, A. H.; Brandon, A. D.; Humayun, M.

    2016-08-01

    Two of the latest Martian meteorites found in Antarctica, paired olivine-phyric shergottites LAR 12240 and LAR 12095, are described in order to decipher their petrological context, and place constraints on the geological history of Mars.

  18. Raman Spectroscopy of Opaque Minerals and Applications to EETA79001 Martian Meteorite

    NASA Technical Reports Server (NTRS)

    Wang, A.; Kuebler, K. E.; Jollif, B. L.

    2001-01-01

    Martian meteorite EETA79001 contains abundant Fe-Ti oxides, which yield Raman spectra useful for the assignment of their structural and compositional features. Additional information is contained in the original extended abstract.

  19. Possible Meteorites in the Martian Hills (False Color)

    NASA Technical Reports Server (NTRS)

    2006-01-01

    From its winter outpost at 'Low Ridge' inside Gusev Crater, NASA's Mars Exploration Rover Spirit took this spectacular, color mosaic of hilly, sandy terrain and two potential iron meteorites. The two light-colored, smooth rocks about two-thirds of the way up from the bottom of the frame have been labeled 'Zhong Shan' and 'Allan Hills.'

    The two rocks' informal names are in keeping with the rover science team's campaign to nickname rocks and soils in the area after locations in Antarctica. Zhong Shang is an Antarctic base that the People's Republic of China opened on Feb. 26, 1989, at the Larsemann Hills in Prydz Bay in East Antarctica. Allan Hills is a location where researchers have found many Martian meteorites, including the controversial ALH84001, which achieved fame in 1996 when NASA scientists suggested that it might contain evidence for fossilized extraterrestrial life. Zhong Shan was the given name of Dr. Sun Yat-sen (1866-1925), known as the 'Father of Modern China.' Born to a peasant family in Guangdong, Sun moved to live with his brother in Honolulu at age 13 and later became a medical doctor. He led a series of uprisings against the Qing dynasty that began in 1894 and eventually succeeded in 1911. Sun served as the first provisional president when the Republic of China was founded in 1912.

    The Zhong Shan and Allan Hills rocks, at the left and right, respectively, have unusual morphologies and miniature thermal emission spectrometer signatures that resemble those of a rock known as 'Heat Shield' at the Meridiani site explored by Spirit's twin, Opportunity. Opportunity's analyses revealed Heat Shield to be an iron meteorite.

    Spirit acquired this false-color image on the rover's 872nd Martian day, or sol (June 16, 2006), using exposures taken through three of the panoramic camera's filters, centered on wavelengths of 750 nanometers, 530 nanometers, and 430 nanometers. The image is presented in false color to emphasize differences among

  20. Possible Meteorites in the Martian Hills (False Color)

    NASA Technical Reports Server (NTRS)

    2006-01-01

    From its winter outpost at 'Low Ridge' inside Gusev Crater, NASA's Mars Exploration Rover Spirit took this spectacular, color mosaic of hilly, sandy terrain and two potential iron meteorites. The two light-colored, smooth rocks about two-thirds of the way up from the bottom of the frame have been labeled 'Zhong Shan' and 'Allan Hills.'

    The two rocks' informal names are in keeping with the rover science team's campaign to nickname rocks and soils in the area after locations in Antarctica. Zhong Shang is an Antarctic base that the People's Republic of China opened on Feb. 26, 1989, at the Larsemann Hills in Prydz Bay in East Antarctica. Allan Hills is a location where researchers have found many Martian meteorites, including the controversial ALH84001, which achieved fame in 1996 when NASA scientists suggested that it might contain evidence for fossilized extraterrestrial life. Zhong Shan was the given name of Dr. Sun Yat-sen (1866-1925), known as the 'Father of Modern China.' Born to a peasant family in Guangdong, Sun moved to live with his brother in Honolulu at age 13 and later became a medical doctor. He led a series of uprisings against the Qing dynasty that began in 1894 and eventually succeeded in 1911. Sun served as the first provisional president when the Republic of China was founded in 1912.

    The Zhong Shan and Allan Hills rocks, at the left and right, respectively, have unusual morphologies and miniature thermal emission spectrometer signatures that resemble those of a rock known as 'Heat Shield' at the Meridiani site explored by Spirit's twin, Opportunity. Opportunity's analyses revealed Heat Shield to be an iron meteorite.

    Spirit acquired this false-color image on the rover's 872nd Martian day, or sol (June 16, 2006), using exposures taken through three of the panoramic camera's filters, centered on wavelengths of 750 nanometers, 530 nanometers, and 430 nanometers. The image is presented in false color to emphasize differences among

  1. Prospects for Chronological Studies of Martian Rocks and Soils

    NASA Technical Reports Server (NTRS)

    Nyquist, L. E.; Shih, C-Y.; Reese, Y. D.

    2008-01-01

    Chronological information about Martian processes comes from two sources: Crater-frequency studies and laboratory studies of Martian meteorites. Each has limitations that could be overcome by studies of returned Martian rocks and soils. Chronology of Martian volcanism: The currently accepted chronology of Martian volcanic surfaces relies on crater counts for different Martian stratigraphic units [1]. However, there is a large inherent uncertainty for intermediate ages near 2 Ga ago. The effect of differing preferences for Martian cratering chronologies [1] is shown in Fig. 1. Stoeffler and Ryder [2] summarized lunar chronology, upon which Martian cratering chronology is based. Fig. 2 shows a curve fit to their data, and compares to it a corresponding lunar curve from [3]. The radiometric ages of some lunar and Martian meteorites as well as the crater-count delimiters for Martian epochs [4] also are shown for comparison to the craterfrequency curves. Scaling the Stoeffler-Ryder curve by a Mars/Moon factor of 1.55 [5] places Martian shergottite ages into the Early Amazonian to late Hesperian epochs, whereas using the lunar curve of [3] and a Mars/Moon factor 1 consigns the shergottites to the Middle-to-Late Amazonian, a less probable result. The problem is worsened if a continually decreasing cratering rate since 3 Ga ago is accepted [6]. We prefer the adjusted St ffler-Ryder curve because it gives better agreement with the meteorite ages (Fig.

  2. Evidence for exclusively inorganic formation of magnetite in Martian meteorite ALH84001

    NASA Technical Reports Server (NTRS)

    Golden, D. C.; Ming, D. W.; Morris, R. V.; Brearley, A. J.; Lauer, H. V., Jr.; Treiman, A. H.; Zolensky, M. E.; Schwandt, C. S.; Lofgren, G. E.

    2004-01-01

    Magnetite crystals produced by terrestrial magnetotactic bacterium MV-1 are elongated on a [111] crystallographic axis, in a so-called truncated hexa-Octahedral shape. This morphology has been proposed to constitute a biomarker (i.e., formed only in biogenic processes). A subpopulation of magnetite crystals associated with carbonate globules in Martian meteorite ALH84001 is reported to have this morphology, and the observation has been taken as evidence for biological activity on Mars. In this study, we present evidence for the exclusively inorganic origin of [111]-elongated magnetite crystals in ALH84001. We report three-dimensional(3-D) morphologies for approx.1000 magnetite crystals extracted from: (1) thermal decomposition products of Fe-rich carbonate produced by inorganic hydrothermal precipitation in laboratory experiments; (2) carbonate globules in Martian meteoriteeALH84001; and (3) cells of magnetotactic bacterial strain MV-1. The 3-D morphologies were derived by fitting 3-D shape models to two-dimensional bright-field transmission-electron microscope (TEAM) images obtained at a series of viewing angles. The view down the {110} axes closest to the [111] elongation axis of magnetite crystals ([111]x{110) not equal to 0) provides a 2-D projection that uniquely discriminates among the three [111]-elongated magnetite morphologies found in these samples: [111]-elongated truncated hexaoctahedron ([111]-THO), [111]-elongated cubo-octahedron ([111]-ECO), and [111]-elongated simple octahedron ([111]-ESO). All [111] -elongated morphologies are present in the three types of sample, but in different proportions. In the ALH84001 Martian meteorite and in our inorganic laboratory products, the most common [111]-elongated magnetite crystal morphology is [111]-ECO. In contrast, the most common morphology for magnetotactic bacterial strain MV-1 is [111]-THO. These results show that: (1) the morphology of [111]-elongated magnetite crystals associated with the carbonate

  3. Evidence for exclusively inorganic formation of magnetite in Martian meteorite ALH84001

    NASA Technical Reports Server (NTRS)

    Golden, D. C.; Ming, D. W.; Morris, R. V.; Brearley, A. J.; Lauer, H. V., Jr.; Treiman, A. H.; Zolensky, M. E.; Schwandt, C. S.; Lofgren, G. E.

    2004-01-01

    Magnetite crystals produced by terrestrial magnetotactic bacterium MV-1 are elongated on a [111] crystallographic axis, in a so-called truncated hexa-Octahedral shape. This morphology has been proposed to constitute a biomarker (i.e., formed only in biogenic processes). A subpopulation of magnetite crystals associated with carbonate globules in Martian meteorite ALH84001 is reported to have this morphology, and the observation has been taken as evidence for biological activity on Mars. In this study, we present evidence for the exclusively inorganic origin of [111]-elongated magnetite crystals in ALH84001. We report three-dimensional(3-D) morphologies for approx.1000 magnetite crystals extracted from: (1) thermal decomposition products of Fe-rich carbonate produced by inorganic hydrothermal precipitation in laboratory experiments; (2) carbonate globules in Martian meteoriteeALH84001; and (3) cells of magnetotactic bacterial strain MV-1. The 3-D morphologies were derived by fitting 3-D shape models to two-dimensional bright-field transmission-electron microscope (TEAM) images obtained at a series of viewing angles. The view down the {110} axes closest to the [111] elongation axis of magnetite crystals ([111]x{110) not equal to 0) provides a 2-D projection that uniquely discriminates among the three [111]-elongated magnetite morphologies found in these samples: [111]-elongated truncated hexaoctahedron ([111]-THO), [111]-elongated cubo-octahedron ([111]-ECO), and [111]-elongated simple octahedron ([111]-ESO). All [111] -elongated morphologies are present in the three types of sample, but in different proportions. In the ALH84001 Martian meteorite and in our inorganic laboratory products, the most common [111]-elongated magnetite crystal morphology is [111]-ECO. In contrast, the most common morphology for magnetotactic bacterial strain MV-1 is [111]-THO. These results show that: (1) the morphology of [111]-elongated magnetite crystals associated with the carbonate

  4. Estimating different eruptive style volcanic areas of Mars from NASA Martian Meteorites Compendium data

    NASA Astrophysics Data System (ADS)

    Mari, Nicola; Verrino, Miriam

    2016-04-01

    The geomorphological characteristics of the Martian surface suggest that both effusive and explosive eruptive behaviour occurred. We investigated whether data about magma viscosity could be extrapolated from Mars SNCs (Shergotty, Nakhla, and Chassigny classes) meteorites, by using available geochemical and petrographic data from the NASA Martian Meteorites Compendium. Viscosity was used to characterize how eruptive style could change in different volcanic regions of planet Mars. Data about composition and crystallinity of 41 SNCs meteorites were used and classified, avoiding meteorites with poor/incomplete database. We assumed Mars as a one-plate planet, fO2 = QFM, and H2O wt% = 0 for each sample. Collected data from the Mars Global Surveyor Thermal Emission Spectrometer (MGS TES) identified the source regions for almost all the studied SNCs meteorites. As input for thermodynamic simulations we first needed to find the depth and pressure of the magmatic source for each meteorite sample through available Thermal Emission Imaging System (THEMIS). Data about average surface temperatures was used to establish whether a magmatic source is shallow or deep. Successively, we found the magma source depth (and pressure) by using the relationship with the heights of the volcanic edifice. The subsolidus equilibration temperatures found through petrologic softwares were used to calculate viscosity. Results indicate a crystallization temperature in a range from 1,120°C to 843°C, follow by a variation in viscosity from 101,43 to 105,97 Pa s. Viscosity seems to be higher in Tharsis, Elysium, Amazonis, and Syrtis Major regions than the remnant areas. According to past experimental studies about magma viscosity, we classified the eruptive style into effusive (101-103,5 Pa s), intermediate (103,5-104,5 Pa s), and explosive (104,5-106 Pa s). The Hellas Basin, Argyre Basin, Ganges Chasma, Eos Chasma, and Nili Fossae regions show an eruptive behaviour between effusive and intermediate

  5. The temperature of formation of carbonate in Martian meteorite ALH84001: constraints from cation diffusion

    SciTech Connect

    Hutcheon, I D; Kent, A; Phinney, D L; Ryerson, F J

    1999-08-13

    An important test of the hypothesis that Martian meteorite ALH84001 contains fossil remnants of an ancient Martian biota is the thermal history of the carbonate rosettes associated with the proposed biomarkers. If carbonates formed at temperatures over {approximately} 110 C (the limit for terrestrial life), it is unlikely that these minerals are associated with a terrestrial-like biota.

  6. Geochemical modeling of the Martian mantle reservoir: Upwelling plume origin for SNC meteorites

    NASA Astrophysics Data System (ADS)

    Shimoda, G.; Ikeda, Y.; Kita, N. T.; Morishita, Y.; Imae, N.

    2003-12-01

    SNC meteorites (shergottites, nakhlites and chassignite) are widely accepted as their origin from Mars. Although individual SNC meteorites have been studied intensively to understand their petrogenesis, a question of how the parental magma was generated in Martian mantle has never been answered. Considering the absence of plate tectonics in Martian mantle, upwelling plume could be the only way to generate magma in Martian mantle. In addition, SNC meteorites have initial 143Nd/144Nd and 87Sr/86Sr ratios of which range is wider than all terrestrial basalts. Their strongly depleted and enriched isotopic compositions suggest the existence of terrestrial-mantle like depleted reservoir and crust-like enriched reservoir in Mars. In this study, we propose a new geochemical model involving upwelling plume from the deep Martian mantle, based on the results of high-pressure experiments and the geochemical analyses from the literatures. Our model successfully explains the early evolution of Martian mantle reservoirs in relation to the isotopic and trace element characteristics of later generated SNC source magmas. Our model assumes basically three steps, (1) the early mantle differentiation by magma ocean (~4.5Ga) to produce the deep mantle reservoir, (2) the first stage melting of a plume to produce nakhlites magma (~1.3Ga), and (3) the second stage melting of the same plume to produce shergottites magma (<600Ma). We examine plausible physical and chemical conditions (pressure, temperature, mineral assemblages and melting degree) at each step to estimate rare earth element (REE) compositions of magmas. These estimated REE compositions are well agreement with the parental magma compositions of nakhlites and shergottites which are estimated from the pyroxene core compositions. For the further examination of this model, initial 143Nd/144Nd and 87Sr/86Sr ratios of the nakhlite and shergottite are calculated with our model assuming the bulk-silicate Mars initial 143Nd/144Nd and 87

  7. Martian Meteorite Chronology and Effects of Impact Metamorphism (Invited)

    NASA Astrophysics Data System (ADS)

    Bouvier, A.; Blichert-Toft, J.; Albarede, F.

    2009-12-01

    Martian (SNC) meteorites provide important clues to processes of alteration or shock at the surface of the planet as many of them contain secondary phases and/or high-pressure assemblages, which are the products of aqueous alteration and impact events, respectively. They include gabbros (shergottites), pyroxenites (nakhlites), and dunites (chassignites), and a single orthopyroxenite, ALH 84001. Pb-Pb isotope systematics of Martian meteorites favor three groups of formation ages: 4.3 Ga for depleted shergottites, 4.1 Ga for ALH 84001 and intermediate and enriched shergottites, and 1.3 Ga for nakhlites and Chassigny [1]. This contrasts with the young mineral isochron ages obtained by Ar-Ar dating or phosphate-based chronometers (e.g., U-Pb, Sm-Nd). In addition to Pb-Pb isotope systematics [1], we have obtained preliminary Sm-Nd and Lu-Hf mineral isochron data for the shergottite NWA 480 and find an age of ~345 Ma in contrast to its ~4.1 Ga Pb-Pb age. For the nakhlites MIL 03346 and Yamato-000593, we find Sm-Nd and Lu-Hf ages at ~1335 Ma, consistent with their ~1.3 Ga Pb-Pb age. Hence, all shergottites unambiguously show evidence of resetting events, which is not the case for nakhlites. We interpret the young ages indicated by shergottite Rb-Sr, Sm-Nd, Lu-Hf, and U-Pb internal isochrons as recent resetting by fluids, impacts, or both. Internal isochrons date the last closure, whether initial cooling or late resetting, of the chronometric system in coexisting minerals. Problems arise in part because the carriers of the parent and daughter nuclides have been wrongly assigned to major rather than accessory minerals, and in part because, with the exception of the Pb-Pb chronometer, the rock samples have been strongly leached and, hence, the parent and daughter nuclides became fractionated in the process. The Rb-Sr, U-Pb, Sm-Nd, and Lu-Hf mineral isochrons of shergottites show young age clusters around 180, 350, 475, and 575 Ma. Each cluster of young mineral isochron ages

  8. Nakhla: a Martian Meteorite with Indigenous Organic Carbonaceous Features

    NASA Technical Reports Server (NTRS)

    McKay, D. S.; Gibson, E. K.; Thomas-Keprta, K. L.; Clemett, S. J.; Le, L.; Rahman, Z.; Wentworth, S. J.

    2011-01-01

    The Nakhla meteorite possesses discrete, well defined, structurally coherent morphologies of carbonaceous phases present within iddingsite alteration zones. Based upon both isotopic measurements and analysis of organic phases the presence of pre-terrestrial organics is now recognized. Within the microcrystalline layers of Nakhla s iddingsite, discrete clusters of salt crystals are present. These salts are predominantly halite (NaCl) with minor MgCl2 crystals. Some CaSO4, likely gypsum, appears to be partially intergrown with some of the halite. EDX mapping shows discrete C-rich features are interspersed among these crystals. A hollow semi-spherical bowl structure ( 3 m ) has been identified and analyzed after using a focused ion beam (FIB) to cut a transverse TEM thin section of the feature and the underlying iddingsite. TEM/EDX analysis reveals that the feature is primarily carbonaceous containing C with lesser amounts of Si, S, Ca, Cl, F, Na, and minor Mn and Fe; additionally a small peak consistent with N, which has been previously seen in Nakhla carbonaceous matter, is also present. Selected area electron diffraction (SAED) shows that this C-rich material is amorphous (lacking any long-range crystallographic order) and is not graphite or carbonate. Micro-Raman spectra acquired from the same surface from which the FIB section was extracted demonstrate a typical kerogen-like D and G band structure with a weak absorption peak at 1350 and a stronger peak at 1600/cm. The C-rich feature is intimately associated with both the surrounding halite and underlying iddingsite matrix. Both iddingsite and salts are interpreted as having formed as evaporate assemblages from progressive evaporation of water bodies on Mars. This assemblage, sans the carbonaceous moieties, closely resembles iddingsite alteration features previously described which were interpreted as indigenous Martian assemblages. These distinctive macromolecular carbonaceous structures in Nakhla may represent

  9. Electron Microscopy Studies, Surface Analysis and Microbial Culturing Experiments on a Depth Profile Through Martian Meteorite Nakhla

    NASA Technical Reports Server (NTRS)

    Toporski, J. K. W.; Steele, A.; Westall, F.; Griffin, C.; Whitby, C.; Avci, R.; McKay, D. S.

    2000-01-01

    Combined electron microscopy studies and culturing experiments have shown that Nakhla became contaminated with recent terrestrial microorganisms. Additional surface analysis detected an as yet unknown organic species which may represent a biomarker.

  10. Electron Microscopy Studies, Surface Analysis and Microbial Culturing Experiments on a Depth Profile Through Martian Meteorite Nakhla

    NASA Technical Reports Server (NTRS)

    Toporski, J. K. W.; Steele, A.; Westall, F.; Griffin, C.; Whitby, C.; Avci, R.; McKay, D. S.

    2000-01-01

    Combined electron microscopy studies and culturing experiments have shown that Nakhla became contaminated with recent terrestrial microorganisms. Additional surface analysis detected an as yet unknown organic species which may represent a biomarker.

  11. Nanophase Magnetite and Pyrrhotite in ALH84001 Martian Meteorite: Evidence for an Abiotic Origin

    NASA Technical Reports Server (NTRS)

    Golden, D. C.; Lauer, H. V., Jr. III; Ming, D. W.; Morris, R. V.

    2006-01-01

    The nanophase magnetite crystals in the black rims of pancake-shaped carbonate globules of the Martian meteorite ALH84001 have been studied extensively because of the claim by McKay et al.that they are biogenic in origin. A subpopulation of these magnetite crystals are reported to conform to a unique elongated shape called "truncated hexa-octahedral" or "THO" by Thomas-Keprta et al. They claim these THO magnetite crystals can only be produced by living bacteria thus forming a biomarker in the meteorite. In contrast, thermal decomposition of Fe-rich carbonate has been suggested as an alternate hypothesis for the elongated magnetite formation in ALH84001 carbonates. The experimental and observational evidence for the inorganic formation of nanophase magnetite and pyrrhotite in ALH84001 by decomposition of Fe-rich carbonate in the presence of pyrite are provided.

  12. Soil Components in Heterogeneous Impact Glass in Martian Meteorite EETA79001

    NASA Technical Reports Server (NTRS)

    Schrader, C. M.; Cohen, B. A.; Donovan, J. J.; Vicenzi, E. P.

    2010-01-01

    Martian soil composition can illuminate past and ongoing near-surface processes such as impact gardening [2] and hydrothermal and volcanic activity [3,4]. Though the Mars Exploration Rovers (MER) have analyzed the major-element composition of Martian soils, no soil samples have been returned to Earth for detailed chemical analysis. Rao et al. [1] suggested that Martian meteorite EETA79001 contains melted Martian soil in its impact glass (Lithology C) based on sulfur enrichment of Lithology C relative to the meteorite s basaltic lithologies (A and B) [1,2]. If true, it may be possible to extract detailed soil chemical analyses using this meteoritic sample. We conducted high-resolution (0.3 m/pixel) element mapping of Lithology C in thin section EETA79001,18 by energy dispersive spectrometry (EDS). We use these data for principal component analysis (PCA).

  13. Evidence From Hydrogen Isotopes in Meteorites for a Martian Permafrost

    NASA Technical Reports Server (NTRS)

    Usui, T.; Alexander, C. M. O'D.; Wang, J.; Simon, J. I.; Jones, J. H.

    2014-01-01

    Fluvial landforms on Mars suggest that it was once warm enough to maintain persistent liquid water on its surface. The transition to the present cold and dry Mars is closely linked to the history of surface water, yet the evolution of surficial water is poorly constrained. We have investigated the evolution of surface water/ ice and its interaction with the atmosphere by measurements of hydrogen isotope ratios (D/H: deuterium/ hydrogen) of martian meteorites. Hydrogen is a major component of water (H2O) and its isotopes fractionate significantly during hydrological cycling between the atmosphere, surface waters, ground ice, and polar cap ice. Based on in situ ion microprobe analyses of three geochemically different shergottites, we reported that there is a water/ice reservoir with an intermediate D/H ratio (delta D = 1,000?2500 %) on Mars. Here we present the possibility that this water/ice reservoir represents a ground-ice/permafrost that has existed relatively intact over geologic time.

  14. Remote Laser Induced Breakdown Spectroscopy (LIBS) of Martian Meteorites and Other Basaltic Samples

    NASA Astrophysics Data System (ADS)

    Clegg, S. M.; Thompson, J. R.; Wiens, R. C.; Barefield, J. E.; Vaniman, D. T.; Newsom, H. E.

    2005-12-01

    Laser Induced Breakdown Spectroscopy (LIBS) is a rapid and quantitative analytical tool for elemental analysis in terrestrial1 and Martian environments. LIBS is one of two instruments comprising the "ChemCam" package recently selected for the Mars Science Laboratory (MSL) Rover Mission scheduled to launch in 2009. LIBS will be the first active remote sensing instrument to fly on a NASA rover, designed to interrogate samples to a distance of 9 m. In preparation for the MSL mission, we are working to improve our ability to extract quantitative results under the Martian environment. We recently completed a study in which we extracted quantitative elemental concentrations and calculated the oxide concentrations from two Martian basaltic shergottite meteorites, Dar al Gani (DaG) 476 and Zagami. The current LIBS laboratory setup involves ablating some material from the sample surface with a focused Nd:YAG (1064nm) laser. The ablated material produces a supersonically expanding plasma of electronically excited atoms. A dispersive spectrometer and an ICCD camera are used to record the spectral signatures emitted from the electronically excited atoms. In our experimental set-up, samples were placed at a distance of 5.4 m from the instrument in a vacuum chamber filled with 7 Torr CO2 to simulate the Martian atmosphere. Terrestrial basalt standards were used to generate calibration curves for all of the major elements and some of the minor and trace species including Si, Fe, Mg, Ca, Ti, Al, and Na. First, two blind basalt standards were analyzed and their compositions were found to match the actual compositions within the uncertainty of the measurement, being correctly distinguished from other available basalt standards. Next, LIBS was used to distinguish between two different basaltic Martian meteorites. Using 14 analysis spots of ~400 μm diameter on DaG 476 and 9 analysis spots on Zagami, LIBS distinguished the olivine-phyric (DaG 476) from the basaltic (Zagami

  15. Chemical Weathering Records of Martian Soils Preserved in the Martian Meteorite EET79001

    NASA Technical Reports Server (NTRS)

    Rao, M. N.; Wentworth, S. J.; McKay, D. S.

    2004-01-01

    Impact-melt glasses, rich in Martian atmospheric gases, contain Martian soil fines (MSF) mixed with other coarse-grained regolith fractions which are produced during impact bombardment on Mars surface. An important characteristic of the MSF fraction is the simultaneous enrichment of felsic component accompanied by the depletion of mafic component relative to the host phase in these glasses. In addition, these glasses yield large sulfur abundances due to the occurrence of secondary mineral phases such as sulfates produced during acid-sulfate weathering of the regolith material near the Martian surface. Sulfurous gases released into atmosphere by volcanoes on Mars are oxidized to H2SO4 which deposit back on the surface of Mars as aerosol particles. Depending on the water availability, sulfuric acids dissolve into solutions which aggressively decompose the Fe-Mg silicates in the Martian regolith. During chemical weathering, structural elements such as Fe, Mg and Ca (among others) are released into the transgressing solutions. These solutions leach away the soluble components of Mg, Ca and Na, leaving behind insoluble iron as Fe3(+) hydroxysulfate mixed with poorly crystalline hydroxide- precipitates under oxidizing conditions. In this study, we focus on the elemental distribution of FeO and SO3 in the glass veins of EET79001, 507 sample, determined by Electron Microprobe and FE SEM measurements at JSC. This glass sample is an aliquot of a bigger glass inclusion ,104 analysed by where large concentrations of Martian atmospheric noble gases are found.

  16. Chemical Weathering Records of Martian Soils Preserved in the Martian Meteorite EET79001

    NASA Technical Reports Server (NTRS)

    Rao, M. N.; Wentworth, S. J.; McKay, D. S.

    2004-01-01

    Impact-melt glasses, rich in Martian atmospheric gases, contain Martian soil fines (MSF) mixed with other coarse-grained regolith fractions which are produced during impact bombardment on Mars surface. An important characteristic of the MSF fraction is the simultaneous enrichment of felsic component accompanied by the depletion of mafic component relative to the host phase in these glasses. In addition, these glasses yield large sulfur abundances due to the occurrence of secondary mineral phases such as sulfates produced during acid-sulfate weathering of the regolith material near the Martian surface. Sulfurous gases released into atmosphere by volcanoes on Mars are oxidized to H2SO4 which deposit back on the surface of Mars as aerosol particles. Depending on the water availability, sulfuric acids dissolve into solutions which aggressively decompose the Fe-Mg silicates in the Martian regolith. During chemical weathering, structural elements such as Fe, Mg and Ca (among others) are released into the transgressing solutions. These solutions leach away the soluble components of Mg, Ca and Na, leaving behind insoluble iron as Fe3(+) hydroxysulfate mixed with poorly crystalline hydroxide- precipitates under oxidizing conditions. In this study, we focus on the elemental distribution of FeO and SO3 in the glass veins of EET79001, 507 sample, determined by Electron Microprobe and FE SEM measurements at JSC. This glass sample is an aliquot of a bigger glass inclusion ,104 analysed by where large concentrations of Martian atmospheric noble gases are found.

  17. Exsolution and shock microstructures of igneous pyroxene clasts in the Northwest Africa 7533 Martian meteorite

    NASA Astrophysics Data System (ADS)

    Leroux, Hugues; Jacob, Damien; Marinova, Maya; Hewins, Roger H.; Zanda, Brigitte; Pont, Sylvain; Lorand, Jean-Pierre; Humayun, Munir

    2016-05-01

    Northwest Africa (NWA) 7533 is a Martian regolith breccia. This meteorite (and its pairings) offers a good opportunity to study (near-) surface processes that occurred on early Mars. Here, we have conducted a transmission electron microscope study of medium- and coarse-grained (a few tens to hundreds of micrometers) Ca-rich pyroxene clasts in order to define their thermal and shock histories. The pyroxene grains have a high-temperature (magmatic) origin as revealed by the well-developed pigeonite-augite exsolution microstructure. Exsolution lamella characteristics (composition, thickness, and spacing) indicate a moderately slow cooling. Some of the pyroxene clasts display evidence for local decomposition into magnetite and silica at the submicron scale. This phase decomposition may have occurred at high temperature and occurred at high oxygen fugacity at least 2-3 log units above the QFM buffer, after the formation of the exsolution lamellae. This corresponds to oxidizing conditions well above typical Martian magmatic conditions. These oxidizing conditions seem to have prevailed early and throughout most of the history of NWA 7533. The shock microstructure consists of (100) mechanical twins which have accommodated plastic deformation. Other pyroxene shock indicators are absent. Compared with SNC meteorites that all suffered significant shock metamorphism, NWA 7533 appears only mildly shocked. The twin microstructure is similar from one clast to another, suggesting that the impact which generated the (100) twins involved the compacted breccia and that the pyroxene clasts were unshocked when they were incorporated into the NWA 7533 breccia.

  18. Light lithophile elements in pyroxenes of Northwest Africa (NWA) 817 and other Martian meteorites: Implications for water in Martian magmas

    NASA Astrophysics Data System (ADS)

    Treiman, Allan H.; Musselwhite, Donald S.; Herd, Christopher D. K.; Shearer, Charles K.

    2006-06-01

    Zoning patterns of light lithophile elements (the LLE: Li, Be, and B) in pyroxenes of some Martian basaltic meteorites have been used to suggest that the parent basalts were saturated in water and exsolved an aqueous fluid phase. Here, we examine LLE zoning in the augites of a quickly cooled Martian basalt that was not water-saturated—the Northwest Africa (NWA) 817 nakhlite. Analyses for LLE were by secondary ion mass spectrometry (SIMS), supported by EMP analyses of major and minor elements. In NWA 817, zoning of Be and B is consistent with igneous fractionations while Li abundances are effectively constant across wide ranges in abundance of other incompatible elements (Be, B, Ti, and Fe*). The lack of strong zoning in Li can be ascribed to intracrystalline diffusion, despite the rapid cooling of NWA 817. Most other nakhlites, notably Nakhla and Lafayette, cooled more slowly than did NWA 817 [Treiman, A.H., 2005. The nakhlite Martian meteorites: augite-rich igneous rock from Mars. Chem. Erde65, 203-270]. In them Li abundances are constant across augite, as are abundances of other elements. In Nakhla pyroxenes, all the LLE have effectively constant abundances across significant ranges in Fe* and Ti abundance. Lafayette is more equilibrated still, and shows constant abundances of LLE and nearly constant Fe*. A pyroxene in the NWA480 shergottite has constant Li abundances, and was interpreted to represent mineral fractionation coupled with exsolution of aqueous fluid. A simple quantitative model of this process requires that the partitioning of Li between basalt and aqueous fluid, LiDaq/bas, be 15 times larger than its experimentally determined value. Thus, its seems unlikely that the Li zoning pattern in NWA480 augite represents exsolution of aqueous fluid. Late igneous or sub-solidus diffusion seems more likely as is suggested by Li isotopic studies [Beck, P., Chaussidon, M., Barrat, J.-A., Gillet, Ph., Bohn, M., 2005. An ion-microprobe study of lithium isotopes

  19. Noble gas contents of shergottites and implications for the Martian origin of SNC meteorites

    NASA Astrophysics Data System (ADS)

    Bogard, D. D.; Nyquist, L. E.; Johnson, P.

    1984-09-01

    Three meteorites belonging to the rare group of SNC achondrites, which may have originated in the planet Mars, have been subjected to noble gas isotopic concentration measurements. The elemental and isotopic ratios obtained are unlike those for any other noble gas components except those obtained in analyses of the Martian atmosphere by Viking spacecraft. It is hypothesized that the Kr and Xe gases represent a portion of the Martian atmosphere which was shock-implanted in the case of Elephant Moraine A79001, and that they constitute direct evidence of a Martian origin for the shergottite meteorites. If the SNC meteorites were ejected from Mars at the shergottite shock age of about 180 My ago, they must have been objects more than 6 m in diameter which experienced at least three space collisions to initiate cosmic ray exposure.

  20. Noble gas contents of shergottites and implications for the Martian origin of SNC meteorites

    NASA Technical Reports Server (NTRS)

    Bogard, D. D.; Nyquist, L. E.; Johnson, P.

    1984-01-01

    Three meteorites belonging to the rare group of SNC achondrites, which may have originated in the planet Mars, have been subjected to noble gas isotopic concentration measurements. The elemental and isotopic ratios obtained are unlike those for any other noble gas components except those obtained in analyses of the Martian atmosphere by Viking spacecraft. It is hypothesized that the Kr and Xe gases represent a portion of the Martian atmosphere which was shock-implanted in the case of Elephant Moraine A79001, and that they constitute direct evidence of a Martian origin for the shergottite meteorites. If the SNC meteorites were ejected from Mars at the shergottite shock age of about 180 My ago, they must have been objects more than 6 m in diameter which experienced at least three space collisions to initiate cosmic ray exposure.

  1. Investigations into an unknown organism on the martian meteorite Allan Hills 84001

    NASA Technical Reports Server (NTRS)

    Steele, A.; Goddard, D. T.; Stapleton, D.; Toporski, J. K.; Peters, V.; Bassinger, V.; Sharples, G.; Wynn-Williams, D. D.; McKay, D. S.

    2000-01-01

    Examination of fracture surfaces near the fusion crust of the martian meteorite Allan Hills (ALH) 84001 have been conducted using scanning electron microscopy (SEM) and atomic force microscopy (AFM) and has revealed structures strongly resembling mycelium. These structures were compared with similar structures found in Antarctic cryptoendolithic communities. On morphology alone, we conclude that these features are not only terrestrial in origin but probably belong to a member of the Actinomycetales, which we consider was introduced during the Antarctic residency of this meteorite. If true, this is the first documented account of terrestrial microbial activity within a meteorite from the Antarctic blue ice fields. These structures, however, do not bear any resemblance to those postulated to be martian biota, although they are a probable source of the organic contaminants previously reported in this meteorite.

  2. Scanning Electron Microscopy Investigation of a Sample Depth Profile Through the Martian Meteorite Nakhla

    NASA Technical Reports Server (NTRS)

    Toporski, Jan; Steele, Andrew; Westall, Frances; McKay, David S.

    2000-01-01

    The ongoing scientific debate as to whether or not the Martian meteorite ALH84001 contained evidence of possible biogenic activities showed the need to establish consistent methods to ascertain the origin of such evidence. To distinguish between terrestrial organic material/microbial contaminants and possible indigenous microbiota within meteorites is therefore crucial. With this in mind a depth profile consisting of four samples from a new sample allocation of Martian meteorite Nakhla was investigated using scanning electron microscopy (SEM) and energy dispersive X-ray analysis. SEM imaging of freshly broken fractured chips revealed structures strongly recent terrestrial microorganisms, in some cases showing evidence of active growth. This conclusion was supported by EDX analysis, which showed the presence of carbon associated with these structures, we concluded that these structures represent recent terrestrial contaminants rather than structures indigenous to the meteorite. Page

  3. Investigations into an unknown organism on the martian meteorite Allan Hills 84001

    NASA Technical Reports Server (NTRS)

    Steele, A.; Goddard, D. T.; Stapleton, D.; Toporski, J. K.; Peters, V.; Bassinger, V.; Sharples, G.; Wynn-Williams, D. D.; McKay, D. S.

    2000-01-01

    Examination of fracture surfaces near the fusion crust of the martian meteorite Allan Hills (ALH) 84001 have been conducted using scanning electron microscopy (SEM) and atomic force microscopy (AFM) and has revealed structures strongly resembling mycelium. These structures were compared with similar structures found in Antarctic cryptoendolithic communities. On morphology alone, we conclude that these features are not only terrestrial in origin but probably belong to a member of the Actinomycetales, which we consider was introduced during the Antarctic residency of this meteorite. If true, this is the first documented account of terrestrial microbial activity within a meteorite from the Antarctic blue ice fields. These structures, however, do not bear any resemblance to those postulated to be martian biota, although they are a probable source of the organic contaminants previously reported in this meteorite.

  4. Investigations into an unknown organism on the martian meteorite Allan Hills 84001.

    PubMed

    Steele, A; Goddard, D T; Stapleton, D; Toporski, J K; Peters, V; Bassinger, V; Sharples, G; Wynn-Williams, D D; McKay, D S

    2000-03-01

    Examination of fracture surfaces near the fusion crust of the martian meteorite Allan Hills (ALH) 84001 have been conducted using scanning electron microscopy (SEM) and atomic force microscopy (AFM) and has revealed structures strongly resembling mycelium. These structures were compared with similar structures found in Antarctic cryptoendolithic communities. On morphology alone, we conclude that these features are not only terrestrial in origin but probably belong to a member of the Actinomycetales, which we consider was introduced during the Antarctic residency of this meteorite. If true, this is the first documented account of terrestrial microbial activity within a meteorite from the Antarctic blue ice fields. These structures, however, do not bear any resemblance to those postulated to be martian biota, although they are a probable source of the organic contaminants previously reported in this meteorite.

  5. The chlorine isotopic composition of Martian meteorites 1: Chlorine isotope composition of Martian mantle and crustal reservoirs and their interactions

    NASA Astrophysics Data System (ADS)

    Williams, J. T.; Shearer, C. K.; Sharp, Z. D.; Burger, P. V.; McCubbin, F. M.; Santos, A. R.; Agee, C. B.; McKeegan, K. D.

    2016-11-01

    The Martian meteorites record a wide diversity of environments, processes, and ages. Much work has been done to decipher potential mantle sources for Martian magmas and their interactions with crustal and surface environments. Chlorine isotopes provide a unique opportunity to assess interactions between Martian mantle-derived magmas and the crust. We have measured the Cl-isotopic composition of 17 samples that span the range of known ages, Martian environments, and mantle reservoirs. The 37Cl of the Martian mantle, as represented by the olivine-phyric shergottites, NWA 2737 (chassignite), and Shergotty (basaltic shergottite), has a low value of approximately -3.8‰. This value is lower than that of all other planetary bodies measured thus far. The Martian crust, as represented by regolith breccia NWA 7034, is variably enriched in the heavy isotope of Cl. This enrichment is reflective of preferential loss of 35Cl to space. Most basaltic shergottites (less Shergotty), nakhlites, Chassigny, and Allan Hills 84001 lie on a continuum between the Martian mantle and crust. This intermediate range is explained by mechanical mixing through impact, fluid interaction, and assimilation-fractional crystallization.

  6. Fractionated Noble Gases in Martian Meteorite ALH 84001 — An Indicator for Water-Rock Interaction, or a Sample of Ancient Atmosphere?

    NASA Astrophysics Data System (ADS)

    Schwenzer, S. P.; Bart, G.; Bridges, J. C.; Crowther, S. A.; Filiberto, J.; Gilmour, J. D.; Herrmann, S.; Hicks, L. J.; Kelley, S. P.; Miller, M. A.; Ott, U.; Steer, E. D.; Swindle, T. D.; Treiman, A. H.

    2017-10-01

    Noble gases in the nakhlite and ALH84001 Martian meteorites are still a mystery, but could tell us about either the history of the Martian atmosphere, Martian water rock interaction or - likely - both!

  7. Fractionated (Martian) Noble Gases — EFA, Experiments and Meteorites

    NASA Astrophysics Data System (ADS)

    Schwenzer, S. P.; Barnes, G.; Bridges, J. C.; Bullock, M. A.; Chavez, C. L.; Filiberto, J.; Herrmann, S.; Hicks, L. J.; Kelley, S. P.; Miller, M. A.; Moore, J. M.; Ott, U.; Smith, H. D.; Steer, E. D.; Swindle, T. D.; Treiman, A. H.

    2016-08-01

    Noble gases are tracers for physical processes, including adsorption, dissolution and secondary mineral formation. We examine the Martian fractionated atmosphere through literature, terrestrial analogs and experiments.

  8. (U-Th)/He ages of phosphates from Zagami and ALHA77005 Martian meteorites: Implications to shock temperatures

    NASA Astrophysics Data System (ADS)

    Min, Kyoungwon; Farah, Annette E.; Lee, Seung Ryeol; Lee, Jong Ik

    2017-01-01

    Shock conditions of Martian meteorites provide crucial information about ejection dynamics and original features of the Martian rocks. To better constrain equilibrium shock temperatures (Tequi-shock) of Martian meteorites, we investigated (U-Th)/He systematics of moderately-shocked (Zagami) and intensively shocked (ALHA77005) Martian meteorites. Multiple phosphate aggregates from Zagami and ALHA77005 yielded overall (U-Th)/He ages 92.2 ± 4.4 Ma (2σ) and 8.4 ± 1.2 Ma, respectively. These ages correspond to fractional losses of 0.49 ± 0.03 (Zagami) and 0.97 ± 0.01 (ALHA77005), assuming that the ejection-related shock event at ∼3 Ma is solely responsible for diffusive helium loss since crystallization. For He diffusion modeling, the diffusion domain radius is estimated based on detailed examination of fracture patterns in phosphates using a scanning electron microscope. For Zagami, the diffusion domain radius is estimated to be ∼2-9 μm, which is generally consistent with calculations from isothermal heating experiments (1-4 μm). For ALHA77005, the diffusion domain radius of ∼4-20 μm is estimated. Using the newly constrained (U-Th)/He data, diffusion domain radii, and other previously estimated parameters, the conductive cooling models yield Tequi-shock estimates of 360-410 °C and 460-560 °C for Zagami and ALHA77005, respectively. According to the sensitivity test, the estimated Tequi-shock values are relatively robust to input parameters. The Tequi-shock estimates for Zagami are more robust than those for ALHA77005, primarily because Zagami yielded intermediate fHe value (0.49) compared to ALHA77005 (0.97). For less intensively shocked Zagami, the He diffusion-based Tequi-shock estimates (this study) are significantly higher than expected from previously reported Tpost-shock values. For intensively shocked ALHA77005, the two independent approaches yielded generally consistent results. Using two other examples of previously studied Martian meteorites

  9. A Search for Amino Acids and Nucleobases in the Martian Meteorite Roberts Massif 04262 Using Liquid Chromatography-Mass Spectrometry

    NASA Technical Reports Server (NTRS)

    Callahan, Michael P.; Burton, Aaron S.; Elsila, Jamie E.; Baker, Eleni M.; Smith, Karen E.; Glavin, Daniel P.; Dworkin, Jason P.

    2013-01-01

    The investigation into whether Mars contains signatures of past or present life is of great interest to science and society. Amino acids and nucleobases are compounds that are essential for all known life on Earth and are excellent target molecules in the search for potential Martian biomarkers or prebiotic chemistry. Martian meteorites represent the only samples from Mars that can be studied directly in the laboratory on Earth. Here, we analyzed the amino acid and nucleobase content of the shergottite Roberts Massif (RBT) 04262 using liquid chromatography-mass spectrometry. We did not detect any nucleobases above our detection limit in formic acid extracts; however, we did measure a suite of protein and nonprotein amino acids in hot-water extracts with high relative abundances of beta-alanine and gamma-amino-eta-butyric acid. The presence of only low (to absent) levels of several proteinogenic amino acids and a lack of nucleobases suggest that this meteorite fragment is fairly uncontaminated with respect to these common biological compounds. The distribution of straight-chained amine-terminal eta-omega-amino acids in RBT 04262 resembled those previously measured in thermally altered carbonaceous meteorites. A carbon isotope ratio of -24(0/00) +/- 6(0/00) for beta-alanine in RBT 04262 is in the range of reduced organic carbon previously measured in Martian meteorites (Steele et al. 2012). The presence of eta-omega-amino acids may be due to a high temperature Fischer-Tropschtype synthesis during igneous processing on Mars or impact ejection of the meteorites from Mars, but more experimental data are needed to support these hypotheses.

  10. A search for amino acids and nucleobases in the Martian meteorite Roberts Massif 04262 using liquid chromatography-mass spectrometry

    NASA Astrophysics Data System (ADS)

    Callahan, Michael P.; Burton, Aaron S.; Elsila, Jamie E.; Baker, Eleni M.; Smith, Karen E.; Glavin, Daniel P.; Dworkin, Jason P.

    2013-05-01

    The investigation into whether Mars contains signatures of past or present life is of great interest to science and society. Amino acids and nucleobases are compounds that are essential for all known life on Earth and are excellent target molecules in the search for potential Martian biomarkers or prebiotic chemistry. Martian meteorites represent the only samples from Mars that can be studied directly in the laboratory on Earth. Here, we analyzed the amino acid and nucleobase content of the shergottite Roberts Massif (RBT) 04262 using liquid chromatography-mass spectrometry. We did not detect any nucleobases above our detection limit in formic acid extracts; however, we did measure a suite of protein and nonprotein amino acids in hot-water extracts with high relative abundances of β-alanine and γ-amino-n-butyric acid. The presence of only low (to absent) levels of several proteinogenic amino acids and a lack of nucleobases suggest that this meteorite fragment is fairly uncontaminated with respect to these common biological compounds. The distribution of straight-chained amine-terminal n-ω-amino acids in RBT 04262 resembled those previously measured in thermally altered carbonaceous meteorites (Burton et al. 2012; Chan et al. 2012). A carbon isotope ratio of -24‰ ± 6‰ for β-alanine in RBT 04262 is in the range of reduced organic carbon previously measured in Martian meteorites (Steele et al. 2012). The presence of n-ω-amino acids may be due to a high temperature Fischer-Tropsch-type synthesis during igneous processing on Mars or impact ejection of the meteorites from Mars, but more experimental data are needed to support these hypotheses.

  11. Unmixing the SNCs: Chemical, Isotopic, and Petrologic Components of the Martian Meteorites

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This volume contains abstracts that have been accepted for presentation at the conference on Unmixing the SNCs: Chemical, Isotopic, and Petrologic Components of Martian Meteorites, September 11-12, 2002, in Houston, Texas. Administration and publications support for this meeting were provided by the staff of the Publications and Program Services Department at the Lunar and Planetary Institute.

  12. Natural bridgmanite-periclase aggregates in Martian meteorites

    NASA Astrophysics Data System (ADS)

    Tschauner, O. D.; Ma, C.; Prescher, C.; Prakapenka, V.

    2014-12-01

    We use a combination of in-house- and synchrotron-based micro-mapping techniques to identify and characterize natural parageneseis of bridgmanite (MgSiO3 in the perovskite structure, IMA 2014-017) and periclase in shocked meteorites. The goal is to evaluate if shock-generated bridgmanite-melt, bridgmanite-periclase intergrowths provide information on element partitioning and rock-deformation that complement experimental studies. As in case of any natural rock recovered from high P-T conditions, chemical and physical changes during release require careful assessment. Major- and minor element concentrations are measured quantitatively with EPMA. Phase identification,-distribution, as well as internal structural parameters are evaluated based on micro-diffraction mappings. Laue diffraction peak profile analysis permits examination of dislocations active during deformation of bridgmanite-periclase aggregates.

  13. The Tissint Martian meteorite as evidence for the largest impact excavation.

    PubMed

    Baziotis, Ioannis P; Liu, Yang; DeCarli, Paul S; Melosh, H Jay; McSween, Harry Y; Bodnar, Robert J; Taylor, Lawrence A

    2013-01-01

    High-pressure minerals in meteorites provide clues for the impact processes that excavated, launched and delivered these samples to Earth. Most Martian meteorites are suggested to have been excavated from 3 to 7 km diameter impact craters. Here we show that the Tissint meteorite, a 2011 meteorite fall, contains virtually all the high-pressure phases (seven minerals and two mineral glasses) that have been reported in isolated occurrences in other Martian meteorites. Particularly, one ringwoodite (75 × 140 μm(2)) represents the largest grain observed in all Martian samples. Collectively, the ubiquitous high-pressure minerals of unusually large sizes in Tissint indicate that shock metamorphism was widely dispersed in this sample (~25 GPa and ~2,000 °C). Using the size and growth kinetics of the ringwoodite grains, we infer an initial impact crater with ~90 km diameter, with a factor of 2 uncertainty. These energetic conditions imply alteration of any possible low-T minerals in Tissint.

  14. Insights into the Martian Regolith from Martian Meteorite Northwest Africa 7034

    NASA Technical Reports Server (NTRS)

    McCubbin, Francis M.; Boyce, Jeremy W.; Szabo, Timea; Santos, Alison R.; Domokos, Gabor; Vazquez, Jorge; Moser, Desmond E.; Jerolmack, Douglas J.; Keller, Lindsay P.; Tartese, Romain

    2015-01-01

    Everything we know about sedimentary processes on Mars is gleaned from remote sensing observations. Here we report insights from meteorite Northwest Africa (NWA) 7034, which is a water-rich martian regolith breccia that hosts both igneous and sedimentary clasts. The sedimentary clasts in NWA 7034 are poorly-sorted clastic siltstones that we refer to as protobreccia clasts. These protobreccia clasts record aqueous alteration process that occurred prior to breccia formation. The aqueous alteration appears to have occurred at relatively low Eh, high pH conditions based on the co-precipitation of pyrite and magnetite, and the concomitant loss of SiO2 from the system. To determine the origin of the NWA 7034 breccia, we examined the textures and grain-shape characteristics of NWA 7034 clasts. The shapes of the clasts are consistent with rock fragmentation in the absence of transport. Coupled with the clast size distribution, we interpret the protolith of NWA 7034 to have been deposited by atmospheric rainout resulting from pyroclastic eruptions and/or asteroid impacts. Cross-cutting and inclusion relationships and U-Pb data from zircon, baddelleyite, and apatite indicate NWA 7034 lithification occurred at 1.4-1.5 Ga, during a short-lived hydrothermal event at 600-700 C that was texturally imprinted upon the submicron groundmass. The hydrothermal event caused Pb-loss from apatite and U-rich metamict zircons, and it caused partial transformation of pyrite to submicron mixtures of magnetite and maghemite, indicating the fluid had higher Eh than the fluid that caused pyrite-magnetite precipitation in the protobreccia clasts. NWA 7034 also hosts ancient 4.4 Ga crustal materials in the form of baddelleyites and zircons, providing up to a 2.9 Ga record of martian geologic history. This work demonstrates the incredible value of sedimentary basins as scientific targets for Mars sample return missions, but it also highlights the importance of targeting samples that have not been

  15. Evidence for a Second Generation of Magnesite in Martian Meteorite Allan Hills 84001

    NASA Technical Reports Server (NTRS)

    Corrigan, C. M.; Harvey, R. P.

    2003-01-01

    Single-stage formation mechanisms for carbonate and other secondary minerals in ALH84001 are rapidly being revised to include multiple stages of carbonate growth and later thermal and mechanical events including alteration. In an effort to confirm some of these more complex histories we have been studying carbonate-bearing regions within this meteorite. Magnesitic carbonates found in contact with unique 'slab' carbonates in two thin sections of ALH84001 show indications of being of a later generation. The results of our observations help clarify the origins of the carbonate and related minerals in ALH84001, and how these minerals can be used to understand the history of interactions between the martian crust and its volatile inventory.

  16. The Nakhla Martian Meteorite is a Cumulate Igenous Rock. Comment on "Glass-Bearing Inclusions in Nakhla (SNC Meteorite) Augite: Heterogeneously Trapped Phases"

    NASA Technical Reports Server (NTRS)

    Treiman, A. H.

    2003-01-01

    All the properties of the Nakhla Martian meteorite suggest that it is a cumulate igneous rock, formed from a basaltic parental magma. Anomalous magmatic inclusions in Nakhla s augite grains can be explained by disequilibrium processes during crystal growth, and have little significance in the geological history of the meteorite.

  17. The Nakhla Martian Meteorite is a Cumulate Igenous Rock. Comment on "Glass-Bearing Inclusions in Nakhla (SNC Meteorite) Augite: Heterogeneously Trapped Phases"

    NASA Technical Reports Server (NTRS)

    Treiman, A. H.

    2003-01-01

    All the properties of the Nakhla Martian meteorite suggest that it is a cumulate igneous rock, formed from a basaltic parental magma. Anomalous magmatic inclusions in Nakhla s augite grains can be explained by disequilibrium processes during crystal growth, and have little significance in the geological history of the meteorite.

  18. Petrogenesis of Igneous-Textured Clasts in Martian Meteorite Northwest Africa 7034

    NASA Technical Reports Server (NTRS)

    Santos, A. R.; Agee, C. B.; Humayun, M.; McCubbin, F. M.; Shearer, C. K.

    2016-01-01

    The martian meteorite Northwest Africa 7034 (and pairings) is a breccia that samples a variety of materials from the martian crust. Several previous studies have identified multiple types of igneous-textured clasts within the breccia [1-3], and these clasts have the potential to provide insight into the igneous evolution of Mars. One challenge presented by studying these small rock fragments is the lack of field context for this breccia (i.e., where on Mars it formed), so we do not know how many sources these small rock fragments are derived from or the exact formation his-tory of these sources (i.e., are the sources mantle de-rived melt or melts contaminated by a meteorite impactor on Mars). Our goal in this study is to examine specific igneous-textured clast groups to determine if they are petrogenetically related (i.e., from the same igneous source) and determine more information about their formation history, then use them to derive new insights about the igneous history of Mars. We will focus on the basalt clasts, FTP clasts (named due to their high concentration of iron, titanium, and phosphorous), and mineral fragments described by [1] (Fig. 1). We will examine these materials for evidence of impactor contamination (as proposed for some materials by [2]) or mantle melt derivation. We will also test the petrogenetic models proposed in [1], which are igneous processes that could have occurred regardless of where the melt parental to the clasts was formed. These models include 1) derivation of the FTP clasts from a basalt clast melt through silicate liquid immiscibility (SLI), 2) derivation of the FTP clasts from a basalt clast melt through fractional crystallization, and 3) a lack of petrogenetic relationship between these clast groups. The relationship between the clast groups and the mineral fragments will also be explored.

  19. Ultraviolet-radiation-induced methane emissions from meteorites and the Martian atmosphere.

    PubMed

    Keppler, Frank; Vigano, Ivan; McLeod, Andy; Ott, Ulrich; Früchtl, Marion; Röckmann, Thomas

    2012-05-30

    Almost a decade after methane was first reported in the atmosphere of Mars there is an intensive discussion about both the reliability of the observations--particularly the suggested seasonal and latitudinal variations--and the sources of methane on Mars. Given that the lifetime of methane in the Martian atmosphere is limited, a process on or below the planet's surface would need to be continuously producing methane. A biological source would provide support for the potential existence of life on Mars, whereas a chemical origin would imply that there are unexpected geological processes. Methane release from carbonaceous meteorites associated with ablation during atmospheric entry is considered negligible. Here we show that methane is produced in much larger quantities from the Murchison meteorite (a type CM2 carbonaceous chondrite) when exposed to ultraviolet radiation under conditions similar to those expected at the Martian surface. Meteorites containing several per cent of intact organic matter reach the Martian surface at high rates, and our experiments suggest that a significant fraction of the organic matter accessible to ultraviolet radiation is converted to methane. Ultraviolet-radiation-induced methane formation from meteorites could explain a substantial fraction of the most recently estimated atmospheric methane mixing ratios. Stable hydrogen isotope analysis unambiguously confirms that the methane released from Murchison is of extraterrestrial origin. The stable carbon isotope composition, in contrast, is similar to that of terrestrial microbial origin; hence, measurements of this signature in future Mars missions may not enable an unambiguous identification of biogenic methane.

  20. Magmatic carbon in Martian meteorites: attempts to constrain the carbon cycle on Mars

    NASA Astrophysics Data System (ADS)

    Grady, M. M.; Verchovsky, A. B.; Wright, I. P.

    2004-04-01

    One of the current goals of Martian exploration is to find evidence for extinct (or even extant) life. Carbon (an essential ingredient of life on Earth) is known to occur on Mars as CO2 in the atmosphere and frozen in the polar caps; it is inferred to be present as carbonates in the Martian crust and soils. We are attempting to define and quantify the different carbon reservoirs on Mars, so that we can follow Mars' carbon cycle. This paper discusses a primordial magmatic component that could be the starting point of such a cycle. The nature, distribution and isotopic composition of carbon was measured in a suite of Martian meteorites, comprising Chassigny and 11 shergottites. Other Martian meteorites were not included, as they sample rocks that have been altered by fluids at Mars' surface. Our results, obtained by high-resolution stepped combustion and mass spectrometry, show that the magmatic component has a very variable abundance of 1 100 ppm, with [delta]13C~[minus sign]20±4‰. This value is close to magmatic carbon determined for Moon and for Vesta (the parent body of the HED basaltic meteorites), but very different from that of Earth.

  1. An assessment of the meteoritic contribution to the Martian soil

    SciTech Connect

    Flynn, G.J. ); McKay, D.S. )

    1990-08-30

    The addition of meteoritic material to the Mars soils should perturb their chemical compositions, as has been detected for soils on the Moon and sediments on Earth. Using the measured mass influx at Earth and estimates of the Mars/Earth flux ratio, the authors estimate the continuous, planet-wide meteoritic mass influx on Mars to be between 2,700 and 59,000 t/yr. If distributed uniformly into a soil with a mean planetary production rate of 1 m/b.y., consistent with radar estimates of the soil depth overlaying a bouldered terrain in the Tharsis region, their estimated mass influx would produce a meteoritic concentration in the Mars soil ranging from 2 to 29% by mass. Analysis of the Viking X ray fluorescence data indicates that the Mars soil composition is inconsistent with typical basaltic rock fragments but can be fit by a mixture of 60% basaltic rock fragments and 40% meteoritic material. The meteoritic influx they calculate is sufficient to provide most or all of the material required by the Clark and Baird model. Particles in the mass range from 10{sup {minus}7} to 10{sup {minus}3} g, about 60-1,200 {mu}m in diameter, contribute 80% of the total mass flux of meteoritic material in the 10{sup {minus}13} to 10{sup 6} g mass range at Earth. On Earth atmospheric entry all but the smallest particles (generally {le} 50 {mu}m in diameter) in the 10{sup {minus}7} to 10{sup {minus}3} g mass range are heated sufficiently to melt or vaporize. Mars, because of its lower escape velocity and larger atmospheric scale height, is a much more favorable site for unmelted survival of micrometeorites on atmospheric deceleration. They calculate that a significant fraction of particles throughout the 60-1,200 {mu}m diameter range will survive Mars atmospheric entry unmelted.

  2. Comparison of Martian Meteorites and Martian Regolith as Shield Materials for Galactic Cosmic Rays

    NASA Technical Reports Server (NTRS)

    Kim, Myung-Hee Y.; Thibeault, Sheila A.; Simonsen, Lisa C.; Wilson, John W.

    1998-01-01

    Theoretical calculations of radiation attenuation due to energetic galactic cosmic rays behind Martian rock and Martian regolith material have been made to compare their utilization as shields for advanced manned missions to Mars because the detailed chemical signature of Mars is distinctly different from Earth. The modified radiation fields behind the Martian rocks and the soil model were generated by solving the Boltzmann equation using a HZETRN system with the 1977 Solar Minimum environmental model. For the comparison of the attenuation characteristics, dose and dose equivalent are calculated for the five different subgroups of Martian rocks and the Martian regolith. The results indicate that changes in composition of subgroups of Martian rocks have negligible effects on the overall shielding properties because of the similarity of their constituents. The differences for dose and dose equivalent of these materials relative to those of Martian regolith are within 0.5 and 1 percent, respectively. Therefore, the analysis of Martian habitat construction options using in situ materials according to the Martian regolith model composition is reasonably accurate. Adding an epoxy to Martian regolith, which changes the major constituents of the material, enhances shielding properties because of the added hydrogenous constituents.

  3. In Situ Mars Compositions Determined by Alpha Particle X-Ray Spectrometry (APXS): Overview and Comparison with Martian Meteorite Dataset

    NASA Astrophysics Data System (ADS)

    Thompson, L. M.; Gellert, R.; Spray, J. G.; Schmidt, M. E.; Izawa, M.; MSL APXS Team

    2016-08-01

    APXS instruments have flown on every rover mission to Mars. This work provides an overview of the diverse in situ chemistry encountered, with emphasis on MSL Curiosity mission results, and compares this with the martian meteorite data set.

  4. The Shergottite Age Paradox and the Relative Probabilities of Ejecting Martian Meteorites of Differing Ages

    NASA Technical Reports Server (NTRS)

    Borg, L. E.; Shih, C.-Y.; Nyquist, L. E.

    1998-01-01

    The apparent paradox that the majority of impacts yielding Martian meteorites appear to have taken place on only a few percent of the Martian surface can be resolved if all the shergottites were ejected in a single event rather than in multiple events as expected from variations in their cosmic ray exposure and crystallization ages. If the shergottite-ejection event is assigned to one of three craters in the vicinity of Olympus Mons that were previously identified as candidate source craters for the SNC (Shergottites, Nakhlites, Chassigny) meteorites, and the nakhlite event to another candidate crater in the vicinity of Ceraunius Tholus, the implied ages of the surrounding terranes agree well with crater density ages. EN,en for high cratering rates (minimum ages), the likely origin of the shergottites is in the Tharsis region, and the paradox of too many meteorites from too little terrane remains for multiple shergottite-ejection events. However, for high cratering rates it is possible to consider sources for the nakhlltes which are away from the Tharsis region. The meteorite-yielding impacts may have been widely dispersed with sources of the young SNC meteorites in the northern plains, and the source of the ancient orthopyroxenite, ALH84001, in the ancient southern uplands. Oblique-impact craters can be identified with the sources of the nakhlites and the orthopyroxenite,, respectively, in the nominal cratering rate model, and with the shergottites and orthopyroxenite, respectively, in the high cratering rate model. Thus, oblique impacts deserve renewed attention as an ejection mechanism for Martian meteorites.

  5. Comparison of the LEW88516 and ALHA77005 martian meteorites: Similar but distinct

    NASA Astrophysics Data System (ADS)

    Treiman, A. H.; McKay, G. A.; Bogard, D. D.; Mittlefehldt, D. W.; Wang, M.-S.; Keller, L.; Lipschutz, M. E.; Lindstrom, M. M.; Garrison, D.

    1994-09-01

    By mineral and bulk compositions, the Lewis Cliff (LEW) 88516 meteorite is quite similar to the ALHA77005 martian meteorite. These two meteorites are not paired because their mineral compositions are distinct, they were found 500 km apart in ice fields with different sources for meteorites, and their terrestrial residence ages are different. Minerals in LEW88516 include: olivine, pyroxenes (low- and high-Ca), and maskelynite (ater plagioclase); and the minor minerals chromite, whitlockite, ilmenite, and pyrrhotite. Mineral grains in LEW88516 range up to a few mm. Texturally, the meteorite is complex, with regions of olivine and chromite poikilitically enclosed in pyroxene, regions of interstitial basaltic texture, and glass-rich (shock) veinlets. Olivine compositions range from Fo64 to Fo70, (avg. Fo67), more ferroan and with more variation than in ALHA77005 (Fo69 to Fo73). Pyroxene compositions fall between En77Wo4 and En65Wo15 and in clusters near En63Wo9 and En53Wo33, on average more magnesian and with more variation than in ALHA77005. Shock features in LEW88516 range from weak deformation through complete melting. Bulk chemical analyses by modal recombination of electron microprobe analyses, instrumental neutron activation, and radiochemical neutron activation confirm that LEW88516 is more closely related to ALHA77005 than to other known martian meteorites. Key element abundance ratios are typical of martian meteorites, as is it nonchondritic rare earth pattern. Differences between the chemical compositions of LEW88516 and ALHA77005 are consistent with slight differences in the proportions of their constituent minerals and not from fundamental petrogenetic differences. Noble gas abundances in LEW88516, like those in ALHA77005, show modest excesses of Ar-40 and Xe-129 from trapped (shock-implanted) gas. As with other ALHA77005 and the shergottite martian meteorites (except EETA79001), noble gas isotope abundances in LEW88516 are consistent with exposure to

  6. Comparison of the LEW88516 and ALHA77005 martian meteorites: Similar but distinct

    NASA Technical Reports Server (NTRS)

    Treiman, A. H.; Mckay, G. A.; Bogard, D. D.; Mittlefehldt, D. W.; Wang, M.-S.; Keller, L.; Lipschutz, M. E.; Lindstrom, M. M.; Garrison, D.

    1994-01-01

    By mineral and bulk compositions, the Lewis Cliff (LEW) 88516 meteorite is quite similar to the ALHA77005 martian meteorite. These two meteorites are not paired because their mineral compositions are distinct, they were found 500 km apart in ice fields with different sources for meteorites, and their terrestrial residence ages are different. Minerals in LEW88516 include: olivine, pyroxenes (low- and high-Ca), and maskelynite (ater plagioclase); and the minor minerals chromite, whitlockite, ilmenite, and pyrrhotite. Mineral grains in LEW88516 range up to a few mm. Texturally, the meteorite is complex, with regions of olivine and chromite poikilitically enclosed in pyroxene, regions of interstitial basaltic texture, and glass-rich (shock) veinlets. Olivine compositions range from Fo(sub 64) to Fo(sub 70), (avg. Fo(sub 67)), more ferroan and with more variation than in ALHA77005 (Fo(sub 69) to Fo(sub 73)). Pyroxene compositions fall between En(sub 77)Wo(sub 4) and En(sub 65)Wo(sub 15) and in clusters near En(sub 63)Wo(sub 9) and En(sub 53)Wo(sub 33), on average more magnesian and with more variation than in ALHA77005. Shock features in LEW88516 range from weak deformation through complete melting. Bulk chemical analyses by modal recombination of electron microprobe analyses, instrumental neutron activation, and radiochemical neutron activation confirm that LEW88516 is more closely related to ALHA77005 than to other known martian meteorites. Key element abundance ratios are typical of martian meteorites, as is it nonchondritic rare earth pattern. Differences between the chemical compositions of LEW88516 and ALHA77005 are consistent with slight differences in the proportions of their constituent minerals and not from fundamental petrogenetic differences. Noble gas abundances in LEW88516, like those in ALHA77005, show modest excesses of Ar-40 and Xe-129 from trapped (shock-implanted) gas. As with other ALHA77005 and the shergottite martian meteorites (except EETA79001

  7. Testing the survival of microfossils in an artificial martian sedimentary meteorite: the STONE 6 Experiment

    NASA Astrophysics Data System (ADS)

    Foucher, Frédéric; Westall, Frances; Brandstaetter, Franz; Demets, Rene; Parnell, John; Cockell, Charles; Edwards, Howell; Jean-Michel, B.; Brack, André; Kurat, Gero

    Conditions on early Mars during the Noachian (-4.5 to -3.5 Ga) were possibly suitable for the emergence of life [1,3] even though water bodies were probably not permanent and could have been destroyed by frequent impacts. Since Mars does not appear to have had plate tectonics, the remains of this hypothetic life could be found within Noachian sediments. In addition to proving the existence of extraterrestrial life, such a discovery would be very helpful for studies related to the origin and early evolution of life on Earth. Indeed, although life most likely appeared on Earth before 4 Ga ago, no suitable (i.e. well-preserved) rocks containing traces of life older than 3.5 billion years exist; older rocks are either too metamorphosed or have been destroyed by plate tectonics. Because of the harsh conditions on Noachian Mars compared to those of the early Earth, the martian organisms are likely to have remained in a very primitive state of evolution and will thus be very difficult to observe in situ. One way to investigate potential traces of life in martian rocks would be to study sedimentary meteorites from Mars. However, all the 54 martian meteorites found so far are volcanic rocks [4]. Is this because sedimentary rocks do not survive the original impact to escape Mars, or the stresses of entry into the Earth's atmosphere? In order to test the latter effects, a series of experiments were devised to test the survivability of different types of sediments during Earth atmosphere entry, the STONE experiments. In particular, the present experiment STONE 6 tested a Noachian sedimentary analogue that consisted of a 3.45 Ga-old silicified volcanic sand containing ancient traces of life [5]. The volcanic sand (chert) from the Pilbara, Australia, containing organic microfossils [6] was embedded in the heat shield of a FOTON space capsule that underwent atmospheric entry on the 26th September, 2007. After landing, the first observation was the white colour of the fusion crust

  8. Micro-Spectroscopy as a Tool for Detecting Micron-Scale Mineral Variations Across a Rock Surface: An Example Using a Thin Section of Martian Meteorite ALH 84001

    NASA Technical Reports Server (NTRS)

    Dalton, J. Brad; Bishop, Janice L.

    2003-01-01

    Imaging spectroscopy is a powerful tool for mineral detection across broad spatial regions. A prototype micro-imaging spectrometer at NASA Ames is tested in this study on a scale of tens to hundreds of microns across rock surfaces. Initial measurements were performed in the visible spectral region on a thin section of martian meteorite ALH 84001.

  9. Micro-Spectroscopy as a Tool for Detecting Micron-Scale Mineral Variations Across a Rock Surface: An Example Using a Thin Section of Martian Meteorite ALH 84001

    NASA Technical Reports Server (NTRS)

    Dalton, J. Brad; Bishop, Janice L.

    2003-01-01

    Imaging spectroscopy is a powerful tool for mineral detection across broad spatial regions. A prototype micro-imaging spectrometer at NASA Ames is tested in this study on a scale of tens to hundreds of microns across rock surfaces. Initial measurements were performed in the visible spectral region on a thin section of martian meteorite ALH 84001.

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

    NASA Technical Reports Server (NTRS)

    Thomas-Keprta, K. L.; McKay, D. S.; Wentworth, S. J.; Stevens, T. O.; Taunton, A. E.; Allen, C. C.; Gibson, E. K., Jr.; Romanek, C. S.

    1998-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

    Thomas-Keprta, K. L.; McKay, D. S.; Wentworth, S. J.; Stevens, T. O.; Taunton, A. E.; Allen, C. C.; Gibson, E. K., Jr.; Romanek, C. S.

    1998-01-01

    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.

  12. Ar-Ar Dating of Martian Meteorite, Dhofar 378: An Early Shock Event?

    NASA Technical Reports Server (NTRS)

    Park, J.; Bogard, D. D.

    2006-01-01

    Martian meteorite, Dhofar 378 (Dho378) is a basaltic shergottite from Oman, weighing 15 g, and possessing a black fusion crust. Chemical similarities between Dho378 and the Los Angeles 001 shergottite suggests that they might have derived from the same Mars locale. The plagioclase in other shergottites has been converted to maskelenite by shock, but Dho378 apparently experienced even more intense shock heating, estimated at 55-75 GPa. Dho378 feldspar (approximately 43 modal %) melted, partially flowed and vesiculated, and then partially recrystallized. Areas of feldspathic glass are appreciably enriched in K, whereas individual plagioclases show a range in the Or/An ratio of approximately 0.18-0.017. Radiometric dating of martian shergottites indicate variable formation times of 160-475 Myr, whereas cosmic ray exposure (CRE) ages of shergottites indicate most were ejected from Mars within the past few Myr. Most determined Ar-39-Ar-40 ages of shergottites appear older than other radiometric ages because of the presence of large amounts of martian atmosphere or interior Ar-40. Among all types of meteorites and returned lunar rocks, the impact event that initiated the CRE age very rarely reset the Ar-Ar age. This is because a minimum time and temperature is required to facilitate Ar diffusion loss. It is generally assumed that the shock-texture characteristics in martian meteorites were produced by the impact events that ejected the rocks from Mars, although the time of these shock events (as opposed to CRE ages) are not directly dated. Here we report Ar-39-Ar-40 dating of Dho378 plagioclase. We suggest that the determined age dates the intense shock heating event this meteorite experienced, but that it was not the impact that initiated the CRE age.

  13. Origin and age of the earliest Martian crust from meteorite NWA 7533.

    PubMed

    Humayun, M; Nemchin, A; Zanda, B; Hewins, R H; Grange, M; Kennedy, A; Lorand, J-P; Göpel, C; Fieni, C; Pont, S; Deldicque, D

    2013-11-28

    The ancient cratered terrain of the southern highlands of Mars is thought to hold clues to the planet's early differentiation, but until now no meteoritic regolith breccias have been recovered from Mars. Here we show that the meteorite Northwest Africa (NWA) 7533 (paired with meteorite NWA 7034) is a polymict breccia consisting of a fine-grained interclast matrix containing clasts of igneous-textured rocks and fine-grained clast-laden impact melt rocks. High abundances of meteoritic siderophiles (for example nickel and iridium) found throughout the rock reach a level in the fine-grained portions equivalent to 5 per cent CI chondritic input, which is comparable to the highest levels found in lunar breccias. Furthermore, analyses of three leucocratic monzonite clasts show a correlation between nickel, iridium and magnesium consistent with differentiation from impact melts. Compositionally, all the fine-grained material is alkalic basalt, chemically identical (except for sulphur, chlorine and zinc) to soils from Gusev crater. Thus, we propose that NWA 7533 is a Martian regolith breccia. It contains zircons for which we measured an age of 4,428 ± 25 million years, which were later disturbed 1,712 ± 85 million years ago. This evidence for early crustal differentiation implies that the Martian crust, and its volatile inventory, formed in about the first 100 million years of Martian history, coeval with earliest crust formation on the Moon and the Earth. In addition, incompatible element abundances in clast-laden impact melt rocks and interclast matrix provide a geochemical estimate of the average thickness of the Martian crust (50 kilometres) comparable to that estimated geophysically.

  14. Petrology and Geochemistry of New Paired Martian Meteorites Larkman Nunatak 12240 and Larkman Nunatak 12095

    NASA Technical Reports Server (NTRS)

    Funk, R. C.; Peslier, A. H.; Brandon, A. D.; Humayun, M.

    2016-01-01

    Two of the latest Martian meteorites found in Antarctica, paired olivine-phyric shergottites LAR 12240 and LAR 12095, are described in order to decipher their petrological context, and place constraints on the geological history of Mars. This project identifies all phases found in LAR 12240 and 12095 and analyzes them for major and trace elements. The textural relationships among these phases are examined in order to develop a crystallization history of the magma(s) that formed these basalts.

  15. Putative indigenous carbon-bearing alteration features in martian meteorite Yamato 000593.

    PubMed

    White, Lauren M; Gibson, Everett K; Thomas-Keprta, Kathie L; Clemett, Simon J; McKay, David S

    2014-02-01

    We report the first observation of indigenous carbonaceous matter in the martian meteorite Yamato 000593. The carbonaceous phases are heterogeneously distributed within secondary iddingsite alteration veins and present in a range of morphologies including areas composed of carbon-rich spheroidal assemblages encased in multiple layers of iddingsite. We also observed microtubular features emanating from iddingsite veins penetrating into the host olivine comparable in shape to those interpreted to have formed by bioerosion in terrestrial basalts.

  16. Distinctive Carbonates in Five Martian Meteorites: Search for Water on Mars

    NASA Technical Reports Server (NTRS)

    Wentworth, Susan J.; Bailey, Jake; McKay, David S.; Thomas-Keprta, Kathie L.; Velbel, Michael

    2003-01-01

    Recently published results from Mars orbital data strongly support both the idea that large bodies of water were present at the surface in the past and the possibility that significant amounts of water ice are currently present in the regolith just below the planet's surface. These new findings increase the significance of the evidence in martian meteorites that some low-temperature aqueous alteration and secondary mineral deposition occurred on Mars.

  17. Polycyclic Aromatic Hydrocarbons in the Martian (SNC) Meteorite ALH 84001: Hydrocarbons from Mars, Terrestrial Contaminants, or Both?

    NASA Astrophysics Data System (ADS)

    Thomas, K. L.; Clemett, S. J.; Romanek, C. S.; Macheling, C. R.; Gibson, E. K.; McKay, D. S.; Score, R.; Zare, R. N.

    1995-09-01

    Previous work has shown that pre-terrestrial polycyclic aromatic hydrocarbons (PAHs) exist in interplanetary dust particles (IDPs) and certain meteorites [1-3]. We previously reported the first observation of PAHs in the newest member of the SNC group, Allan Hills 84001 [4] and determined that particular types of organic compounds are indigenous to ALH 84001 because they are associated with certain mineralogical features [4]. We also analyzed two diogenites from Antarctica: one showed no evidence for aromatic hydrocarbons while the other contained PAHs with the same major peaks as those in ALH 84001[4]. PAHs in the diogenite meteorite are not associated with mineral features on the analyzed surface and the most abundant PAHs in the diogenite are lower by a factor of 3 than those in ALH 84001. Furthermore, ALH 84001 contains a number of minor PAHs not found in the diogenite or typical terrestrial soils [4]. In this study we are analyzing a more complete group of Antarctic and non-Antarctic meteorites, including SNCs, to determine: (1) PAHs abundance and diversity in Antarctic meteorites and (2) the contribution of PAHs in SNCs from martian and, possibly, terrestrial sources. ALH 84001 is an unusual orthopyroxenite which contains abundant carbonate spheroids which are ~100-200 micrometers in diameter and range in composition from magnesite to ferroan magnesite [5-7]. These spheroids are not the result of terrestrial contamination: oxygen isotopic compositions indicate that the carbonates probably precipitated from a low-temperature fluid within the martian crust [5] and carbon isotopic abundances are consistent with martian atmospheric CO2 as the carbon source [5]. PAHs may coexist with other low-temperature carbon-bearing phases in a subsurface martian environment. Samples: We are analyzing freshly-fractured meteorite samples, or chips, which have been extracted from the internal regions of the following meteorites: ALH 84001 (crush and uncrush zones), EETA79001

  18. Trace Element Geochemistry of Martian Iddingsite in the Lafayette Meteorite

    NASA Technical Reports Server (NTRS)

    Treiman, Allan H.; Lindstrom, David J.

    1997-01-01

    The Lafayette meteorite contains abundant iddingsite, a fine-grained intergrowth of smectite clay, ferrihydrite, and ionic salt minerals. Both the meteorite and iddingsite formed on Mars. Samples of iddingsite, olivine, and augite pyroxene were extracted from Lafayette and analyzed for trace elements by instrumental neutron activation. Our results are comparable to independent analyses by electron and ion microbeam methods. Abundances of most elements in the iddingsite do not covary significantly. The iddingsite is extremely rich in Hg, which is probably terrestrial contamination. For the elements Si, Al, Fe, Mn, Ni, Co, and Zn, the composition of the iddingsite is close to a mixture of approximately 50% Lafayette olivine + approximately 40% Lafayette siliceous glass + approximately 1O% water. Concordant behavior among these elements is not compatible with element fractionations between smectite and water, but the hydrous nature and petrographic setting of the iddingsite clearly suggest an aqueous origin. These inferences are both consistent, however, with deposition of the iddingsite originally as a silicate gel, which then crystallized (neoformed) nearly isochemically. The iddingsite contains significantly more magnesium than implied by the model, which may suggest that the altering solutions were rich in Mg(2+).

  19. Origin of carbonate-magnetite-sulfide assemblages in Martian meteorite ALH84001

    NASA Astrophysics Data System (ADS)

    Scott, Edward R. D.

    1999-02-01

    A review of the mineralogical, isotopic, and chemical properties of the carbonates and associated submicrometer iron oxides and sulfides in Martian meteorite ALH84001 provides minimal evidence for microbial activity. Some magnetites resemble those formed by magnetotactic microorganisms but cubic crystals <50 nm in size and elongated grains <25 nm long are too small to be single-domain magnets and are probably abiogenic. Magnetites with shapes that are clearly unique to magnetotactic bacteria appear to be absent in ALH84001. Magnetosomes have not been reported in plutonic rocks and are unlikely to have been transported in fluids through fractures and uniformly deposited where abiogenic magnetite was forming epitaxially on carbonate. Submicrometer sulfides and magnetites probably formed during shock heating. Carbonates have correlated variations in Ca, Mg, and 18O/16O, magnetite-rich rims, and they appear to be embedded in pyroxene and plagioclase glass. Carbonates with these features have not been identified in carbonaceous chondrites and terrestrial rocks, suggesting that the ALH84001 carbonates have a unique origin. Carbonates and hydrated minerals in ALH84001, like secondary phases in other Martian meteorites, have O and H isotopic ratios favoring formation from fluids that exchanged with the Martian atmosphere. I propose that carbonates originally formed in ALH84001 from aqueous fluids and were subsequently shock heated and vaporized. The original carbonates were probably dolomite-magnesite-siderite assemblages that formed in pores at interstitial sites with minor sulfate, chloride, and phyllosilicates. These phases, like many other volatile-rich phases in Martian meteorites, may have formed as evaporite deposits from intermittent floods.

  20. Carbonates in fractures of Martian meteorite Allan Hills 84001: petrologic evidence for impact origin

    NASA Technical Reports Server (NTRS)

    Scott, E. R.; Krot, A. N.; Yamaguchi, A.

    1998-01-01

    Carbonates in Martian meteorite Allan Hills 84001 occur as grains on pyroxene grain boundaries, in crushed zones, and as disks, veins, and irregularly shaped grains in healed pyroxene fractures. Some carbonate disks have tapered Mg-rich edges and are accompanied by smaller, thinner and relatively homogeneous, magnesite microdisks. Except for the microdisks, all types of carbonate grains show the same unique chemical zoning pattern on MgCO3-FeCO3-CaCO3 plots. This chemical characteristic and the close spatial association of diverse carbonate types show that all carbonates formed by a similar process. The heterogeneous distribution of carbonates in fractures, tapered shapes of some disks, and the localized occurrence of Mg-rich microdisks appear to be incompatible with growth from an externally derived CO2-rich fluid that changed in composition over time. These features suggest instead that the fractures were closed as carbonates grew from an internally derived fluid and that the microdisks formed from a residual Mg-rich fluid that was squeezed along fractures. Carbonate in pyroxene fractures is most abundant near grains of plagioclase glass that are located on pyroxene grain boundaries and commonly contain major or minor amounts of carbonate. We infer that carbonates in fractures formed from grain boundary carbonates associated with plagiociase that were melted by impact and dispersed into the surrounding fractured pyroxene. Carbonates in fractures, which include those studied by McKay et al. (1996), could not have formed at low temperatures and preserved mineralogical evidence for Martian organisms.

  1. Carbonates in fractures of Martian meteorite Allan Hills 84001: petrologic evidence for impact origin

    NASA Technical Reports Server (NTRS)

    Scott, E. R.; Krot, A. N.; Yamaguchi, A.

    1998-01-01

    Carbonates in Martian meteorite Allan Hills 84001 occur as grains on pyroxene grain boundaries, in crushed zones, and as disks, veins, and irregularly shaped grains in healed pyroxene fractures. Some carbonate disks have tapered Mg-rich edges and are accompanied by smaller, thinner and relatively homogeneous, magnesite microdisks. Except for the microdisks, all types of carbonate grains show the same unique chemical zoning pattern on MgCO3-FeCO3-CaCO3 plots. This chemical characteristic and the close spatial association of diverse carbonate types show that all carbonates formed by a similar process. The heterogeneous distribution of carbonates in fractures, tapered shapes of some disks, and the localized occurrence of Mg-rich microdisks appear to be incompatible with growth from an externally derived CO2-rich fluid that changed in composition over time. These features suggest instead that the fractures were closed as carbonates grew from an internally derived fluid and that the microdisks formed from a residual Mg-rich fluid that was squeezed along fractures. Carbonate in pyroxene fractures is most abundant near grains of plagioclase glass that are located on pyroxene grain boundaries and commonly contain major or minor amounts of carbonate. We infer that carbonates in fractures formed from grain boundary carbonates associated with plagiociase that were melted by impact and dispersed into the surrounding fractured pyroxene. Carbonates in fractures, which include those studied by McKay et al. (1996), could not have formed at low temperatures and preserved mineralogical evidence for Martian organisms.

  2. Isotopic Composition of Trapped and Cosmogenic Noble Gases in Several Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Garrison, Daniel H.; Bogard, Donald D.

    1997-01-01

    Isotopic abundances of the noble gases were measured in the following Martian meteorites: two shock glass inclusions from EET79001, shock vein glass from Shergotty and Y793605, and whole rock samples of ALH84001 and QUE94201. These glass samples, when combined with literature data on a separate single glass inclusion from EET79001 and a glass vein from Zagami, permit examination of the isotopic composition of Ne, Ar, Kr, and Xe trapped from the Martian atmosphere in greater detail. The isotopic composition of Martian Ne, if actually present in these glasses, remains poorly defined. The Ar-40/Ar-36 ratio of Martian atmospheric Ar may be much less than the ratio measured by Viking and possibly as low as approx. 1900. The atmospheric Ar-36/Ar-38 ratio is less than or equal to 4.0. Martian atmospheric Kr appears to be enriched in lighter isotopes by approx. 0.4%/amu compared to both solar wind Kr and to the Martian composition previously reported. The Martian atmospheric Ar-36/Xe-132 and Kr-84/Xe-132 Xe elemental ratios are higher than those reported by Viking by factors of approx. 3.3 and approx. 2.5, respectively. Cosmogenic gases indicate space exposure ages of 13.9 +/- 1 Myr for ALH84001 and 2.7 +/- 0.6 Myr for QUE94201. Small amounts of Ne-21 produced by energetic solar protons may be present in QUE94201, but are not present in ALH84001 or Y793605. The space exposure age for Y793605 is 4.9 +/- 0.6 Myr and appears to be distinctly older than the ages for basaltic shergottites.

  3. The Martian sources of the SNC meteorites (two, not one), and what can and can't be learned from the SNC meteorites

    NASA Technical Reports Server (NTRS)

    Treiman, A. H.

    1993-01-01

    The SNC meteorites, which almost certainly originate in the Martian crust, have been inferred to come from a single impact crater site, but no known crater fits all criteria. Formation at two separate sites (S from one, NC from the other) is more consistent with the sum of petrologic, geochronologic, and cosmochronologic data. If the source craters for the SNC meteorites can be located, Mars science will advance considerably. However, many significant questions cannot be answered by the SNC meteorites. These questions await a returned sample.

  4. Isotope Geochemistry of Possible Terrestrial Analogue for Martian Meteorite ALH84001

    NASA Technical Reports Server (NTRS)

    Mojzsis, Stephen J.

    2000-01-01

    We have studied the microdomain oxygen and carbon isotopic compositions by SIMS of complex carbonate rosettes from spinel therzolite xenoliths, hosted by nepheline basanite, from the island of Spitsbergen (Norway). The Quaternary volcanic rocks containing the xenoliths erupted into a high Arctic environment and through relatively thick continental crust containing carbonate rocks. We have attempted to constrain the sources of the carbonates in these rocks by combined O-18/O-16 and C-13/C-12 ratio measurements in 25 micron diameter spots of the carbonate and compare them to previous work based primarily on trace-element distributions. The origin of these carbonates can be interpreted in terms of either contamination by carbonate country rock during ascent of the xenoliths in the host basalt, or more probably by hydrothermal processes after emplacement. The isotopic composition of these carbonates from a combined delta.18O(sub SMOW) and delta.13C(sub PDB) standpoint precludes a primary origin of these minerals from the mantle. Here a description is given of the analysis procedure, standardization of the carbonates, major element compositions of the carbonates measured by electron microprobe, and their correlated C and O isotope compositions as measured by ion microprobe. Since these carbonate rosettes may represent a terrestrial analogue to the carbonate "globules" found in the martian meteorite ALH84001 interpretations for the origin of the features found in the Spitsbergen may be of interest in constraining the origin of these carbonate minerals on Mars.

  5. Origin of Magnetite Crystals in Martian Meteorite ALH84001 Carbonate Disks

    NASA Technical Reports Server (NTRS)

    Thomas-Keprta, K.L.; Clemett, S.J.; McKay, D.S.; Gibson, E. K.; Wentworth, S. J.

    2010-01-01

    Martian meteorite ALH84001 preserves evidence of interaction with aqueous fluids while on Mars in the form of microscopic carbonate disks which are believed to have precipitated approx.3.9 Ga ago at beginning of the Noachian epoch. Intimately associated within and throughout these carbonate disks are nanocrystal magnetites (Fe3O4) with unusual chemical and physical properties, whose origins have become the source of considerable debate. One group of hypotheses argues that these Fe3O4 are the product of partial thermal decomposition of the host carbonate. Alternatively, the origins of Fe3O4 and carbonate may be unrelated; that is, from the perspective of the carbonate the magnetite is allochthonous. We have sought to resolve between these hypotheses through the detailed characterized of the compositional and structural relationships of the carbonate disks and associated magnetites with the orthopyroxene matrix in which they are embedded [1]. We focus this discussion on the composition of ALH84001 magnetites and then compare these observations with those from our thermal decomposition studies of sideritic carbonates under a range of plausible geological heating scenarios.

  6. Detailed Raman Spectroscopic Study of the Tissint Meteorite: Extraordinary Occurrence of High Pressure Polymorphs in a Single Fresh Piece of Martian Shergottite

    NASA Astrophysics Data System (ADS)

    Baziotis, Ioannis; Liu, Yang; Taylor, Lawrence

    2013-04-01

    A recent (July 2011) witnessed fall of a Martian Shergottite, Tissint, has generated great excitement for its pristine nature and its great scientific potential owing to its minimum terrestrial contamination. In recent work, using detailed petrography, electron microprobe method, micro-Raman Spectroscopy on serial sections, we investigated the presence of high-pressure (Hi-P) polymorphs occurring in impact-melt pockets throughout our 10 gm sample. Based upon the static and dynamic phase experimentation, we reconstructed the P-T-t conditions for the formation of these many polymorphs (Baziotis et al., 2012, Nature Comm.). Tissint is an olivine-phyric shergottite, with large olivine grains (2000 ° C. Furthermore, the large size of ringwoodite in Tissint likely reflects prolonged shock durations. After heating, rapid cooling was achieved in ~50 ms for the center of the melt pocket and ~20 ms for the rim of the pocket, rendering conditions capable of preserving the high-P minerals observed.

  7. Solving the Martian meteorite age conundrum using micro-baddeleyite and launch-generated zircon

    NASA Astrophysics Data System (ADS)

    Moser, D. E.; Chamberlain, K. R.; Tait, K. T.; Schmitt, A. K.; Darling, J. R.; Barker, I. R.; Hyde, B. C.

    2013-07-01

    Invaluable records of planetary dynamics and evolution can be recovered from the geochemical systematics of single meteorites. However, the interpreted ages of the ejected igneous crust of Mars differ by up to four billion years, a conundrum due in part to the difficulty of using geochemistry alone to distinguish between the ages of formation and the ages of the impact events that launched debris towards Earth. Here we solve the conundrum by combining in situ electron-beam nanostructural analyses and U-Pb (uranium-lead) isotopic measurements of the resistant micromineral baddeleyite (ZrO2) and host igneous minerals in the highly shock-metamorphosed shergottite Northwest Africa 5298 (ref. 8), which is a basaltic Martian meteorite. We establish that the micro-baddeleyite grains pre-date the launch event because they are shocked, cogenetic with host igneous minerals, and preserve primary igneous growth zoning. The grains least affected by shock disturbance, and which are rich in radiogenic Pb, date the basalt crystallization near the Martian surface to 187 +/- 33 million years before present. Primitive, non-radiogenic Pb isotope compositions of the host minerals, common to most shergottites, do not help us to date the meteorite, instead indicating a magma source region that was fractionated more than four billion years ago to form a persistent reservoir so far unique to Mars. Local impact melting during ejection from Mars less than 22 +/- 2 million years ago caused the growth of unshocked, launch-generated zircon and the partial disturbance of baddeleyite dates. We can thus confirm the presence of ancient, non-convecting mantle beneath young volcanic Mars, place an upper bound on the interplanetary travel time of the ejected Martian crust, and validate a new approach to the geochronology of the inner Solar System.

  8. Solving the Martian meteorite age conundrum using micro-baddeleyite and launch-generated zircon.

    PubMed

    Moser, D E; Chamberlain, K R; Tait, K T; Schmitt, A K; Darling, J R; Barker, I R; Hyde, B C

    2013-07-25

    Invaluable records of planetary dynamics and evolution can be recovered from the geochemical systematics of single meteorites. However, the interpreted ages of the ejected igneous crust of Mars differ by up to four billion years, a conundrum due in part to the difficulty of using geochemistry alone to distinguish between the ages of formation and the ages of the impact events that launched debris towards Earth. Here we solve the conundrum by combining in situ electron-beam nanostructural analyses and U-Pb (uranium-lead) isotopic measurements of the resistant micromineral baddeleyite (ZrO2) and host igneous minerals in the highly shock-metamorphosed shergottite Northwest Africa 5298 (ref. 8), which is a basaltic Martian meteorite. We establish that the micro-baddeleyite grains pre-date the launch event because they are shocked, cogenetic with host igneous minerals, and preserve primary igneous growth zoning. The grains least affected by shock disturbance, and which are rich in radiogenic Pb, date the basalt crystallization near the Martian surface to 187 ± 33 million years before present. Primitive, non-radiogenic Pb isotope compositions of the host minerals, common to most shergottites, do not help us to date the meteorite, instead indicating a magma source region that was fractionated more than four billion years ago to form a persistent reservoir so far unique to Mars. Local impact melting during ejection from Mars less than 22 ± 2 million years ago caused the growth of unshocked, launch-generated zircon and the partial disturbance of baddeleyite dates. We can thus confirm the presence of ancient, non-convecting mantle beneath young volcanic Mars, place an upper bound on the interplanetary travel time of the ejected Martian crust, and validate a new approach to the geochronology of the inner Solar System.

  9. A search for endogenous amino acids in martian meteorite ALH84001

    NASA Technical Reports Server (NTRS)

    Bada, J. L.; Glavin, D. P.; McDonald, G. D.; Becker, L.

    1998-01-01

    Trace amounts of glycine, serine, and alanine were detected in the carbonate component of the martian meteorite ALH84001 by high-performance liquid chromatography. The detected amino acids were not uniformly distributed in the carbonate component and ranged in concentration from 0.1 to 7 parts per million. Although the detected alanine consists primarily of the L enantiomer, low concentrations (<0.1 parts per million) of endogenous D-alanine may be present in the ALH84001 carbonates. The amino acids present in this sample of ALH84001 appear to be terrestrial in origin and similar to those in Allan Hills ice, although the possibility cannot be ruled out that minute amounts of some amino acids such as D-alanine are preserved in the meteorite.

  10. Modern atmospheric signatures in 4.4 Ga Martian meteorite NWA 7034

    NASA Astrophysics Data System (ADS)

    Cartwright, J. A.; Ott, U.; Herrmann, S.; Agee, C. B.

    2014-08-01

    The NWA 7034 Martian basaltic breccia, dated at ˜4.4 Ga, represents an entirely new type of Martian meteorite. However, due to the unique make-up of NWA 7034 compared to other Martian meteorite types (including its anomalous oxygen isotope ratios), noble gas analyses - a key tool for Martian meteorite identification - are important to confirm its Martian origin. Here, we report the first noble gas results for NWA 7034, which show the presence of a trapped component that resembles the current Martian atmosphere. This trapped component is also similar in composition to trapped gases found in the much younger shergottites (˜150-600 Ma). Our formation ages for the sample suggest events at ˜1.6 Ga (K-Ar), and ˜170 Ma (U-Th/He), which are considerably younger than those observed by Rb-Sr (2.1 Ga), and Sm-Nd (4.4 Ga; zircons ˜4.4 Ga). However, our K-Ar age is similar to a disturbance in the U-Pb zircon data at ˜1.7 Ga, which could hint that both chronometers have been subjected to disturbance by a common process or event. The U-Th/He age of ˜170 Ma could relate to complete loss of radiogenic 4He at this time, and is a similar age to the crystallisation age of most shergottites. While this may be coincidental, it could indicate that a single event is responsible for both shergottite formation and NWA 7034 thermal metamorphism. As for cosmic ray exposure ages, our favoured age is ˜5 Ma, which is outside the ranges for other Martian meteorite groups, and may suggest a distinct ejection event. NWA 7034 shows evidence for neutron capture on Br, which has caused elevations in Kr isotopes 80Kr and 82Kr. These elevated abundances indicate significant shielding, and could relate to either a large meteoroid size, and/or shielding in relation to a regolithic origin. We have also applied similar neutron capture corrections to Ar and Xe data, which further refine the likelihood of a modern atmospheric component, though such corrections remain speculative. Cosmogenic production

  11. Modern terrestrial analogues for the carbonate globules in Martian meteorite ALH84001.

    PubMed

    Kazmierczak, Józef; Kempe, Stephan

    2003-04-01

    Modern carbonate globules, located in cracks of submerged volcanic rocks and in calcareous pinnacles in alkaline (sodic) Lake Van, Turkey, appear to be analogues for the approximately 3.9 billion-year-old carbonate globules in Martian meteorite ALH84001. These terrestrial globules have similar diameters and are chemically and mineralogically zoned. Furthermore, they display surface and etching structures similar to those described from ALH84001, which were interpreted as fossilized microbial forms. These terrestrial carbonates formed at low temperatures where Ca-rich groundwaters enter the lake. Chemical, mineralogical, microbiological, and biomolecular methods were used in an attempt to decipher the process responsible for the genesis of these structures. Although the exact mode of formation of Lake Van carbonates remains an enigma, their similarity to the Martian globules indicates that the ALH84001 carbonates may have formed in similar setting on ancient Mars.

  12. Effect of Shock on the Magnetic Properties of Pyrrhotite, the Martian Crust, and Meteorites

    NASA Technical Reports Server (NTRS)

    Louzad, Karin L.; Stewart, Sarah T.; Weiss, Benjamin P.

    2007-01-01

    We performed planar shock recovery experiments on natural pyrrhotite at pressures up to 6.9 GPa. We find that high-field isothermal remanent magnetization in pyrrhotite is demagnetized up to 90% by shock due to preferential removal of low coercivity components of magnetization. Contrary to static experiments, we do not observe complete demagnetization. Post shock permanent changes in magnetic properties include increasing saturation isothermal remanent magnetization, bulk coercivity and lowtemperature memory, and changes in squareness of hysteresis. These changes are consistent with an increase in the volume fraction of single domain grains. The lack of magnetic anomalies over large Martian impact basins is not expected to be solely due to shock demagnetization of the crust. We find that pyrrhotite-bearing rocks and meteorites can retain records of Martian magnetic fields even if shocked to pressures approaching 7 GPa. However, some paleointensity techniques may underestimate this field.

  13. Putative Indigenous Carbon-Bearing Alteration Features in Martian Meteorite Yamato 000593

    PubMed Central

    Gibson, Everett K.; Thomas-Keprta, Kathie L.; Clemett, Simon J.; McKay, David S.

    2014-01-01

    Abstract We report the first observation of indigenous carbonaceous matter in the martian meteorite Yamato 000593. The carbonaceous phases are heterogeneously distributed within secondary iddingsite alteration veins and present in a range of morphologies including areas composed of carbon-rich spheroidal assemblages encased in multiple layers of iddingsite. We also observed microtubular features emanating from iddingsite veins penetrating into the host olivine comparable in shape to those interpreted to have formed by bioerosion in terrestrial basalts. Key Words: Meteorite—Yamato 000593—Mars—Carbon. Astrobiology 14, 170–181. PMID:24552234

  14. Bacterial mineralization patterns in basaltic aquifers: implications for possible life in martian meteorite ALH84001

    NASA Technical Reports Server (NTRS)

    Thomas-Keprta, K. L.; McKay, D. S.; Wentworth, S. J.; Stevens, T. O.; Taunton, A. E.; Allen, C. C.; Coleman, A.; Gibson, E. K. Jr; Romanek, C. S.

    1998-01-01

    To explore the formation and preservation of biogenic features in igneous rocks, we have examined the organisms in experimental basaltic microcosms using scanning and transmission electron microscopy. Four types of microorganisms were recognized on the basis of size, morphology, and chemical composition. Some of the organisms mineralized rapidly, whereas others show no evidence of mineralization. Many mineralized cells are hollow and do not contain evidence of microstructure. Filaments, either attached or no longer attached to organisms, are common. Unattached filaments are mineralized and are most likely bacterial appendages (e.g., prosthecae). Features similar in size and morphology to unattached, mineralized filaments are recognized in martian meteorite ALH84001.

  15. Bacterial mineralization patterns in basaltic aquifers: implications for possible life in martian meteorite ALH84001

    NASA Technical Reports Server (NTRS)

    Thomas-Keprta, K. L.; McKay, D. S.; Wentworth, S. J.; Stevens, T. O.; Taunton, A. E.; Allen, C. C.; Coleman, A.; Gibson, E. K. Jr; Romanek, C. S.

    1998-01-01

    To explore the formation and preservation of biogenic features in igneous rocks, we have examined the organisms in experimental basaltic microcosms using scanning and transmission electron microscopy. Four types of microorganisms were recognized on the basis of size, morphology, and chemical composition. Some of the organisms mineralized rapidly, whereas others show no evidence of mineralization. Many mineralized cells are hollow and do not contain evidence of microstructure. Filaments, either attached or no longer attached to organisms, are common. Unattached filaments are mineralized and are most likely bacterial appendages (e.g., prosthecae). Features similar in size and morphology to unattached, mineralized filaments are recognized in martian meteorite ALH84001.

  16. Polycyclic aromatic hydrocarbons (PAHs) in Antarctic Martian meteorites, carbonaceous chondrites, and polar ice

    SciTech Connect

    Becker, L. |; Glavin, D.P.; Bada, J.L.

    1997-01-01

    Recent analyses of the carbonate globules present in the Martian meteorite ALH84001 have detected polycyclic aromatic hydrocarbons (PAHs) at the ppm level. The distribution of PAHs observed in ALH84001 was interpreted as being inconsistent with a terrestrial origin and were claimed to be indigenous to the meteorite, perhaps derived from an ancient martian biota. We have examined PAHs in the Antarctic shergottite EETA79001, which is also considered to be from Mars, as well as several Antarctic carbonaceous chondrites. We have found that many of the same PAHs detected in the ALH84001 carbonate globules are present in Antarctic carbonaceous chondrites and in both the matrix and carbonate (druse) component of EETA79001. We also investigated PAHs in polar ice and found that carbonate is an effective scavenger of PAHs in ice meltwater. Moreover, the distribution of PAHs in the carbonate extract of Antarctic Allan Hills ice is remarkably similar to that found in both EETA79001 and ALH84001. The reported presence of L-amino acids of apparent terrestrial origin in the EETA79001 druse material suggests that this meteorite is contaminated with terrestrial organics probably derived from Antarctic ice meltwater that had percolated through the meteorite. Our data suggests that the PAHs observed in both ALH84001 and EETA79001 are derived from either the exogenous delivery of organics to Mars or extraterrestrial and terrestrial PAHs present in the ice meltwater or, more likely, from a mixture of these sources. It would appear that PAHs are not useful biomarkers in the search for extinct or extant life on Mars. 33 refs., 3 figs., 1 tab.

  17. Spatial distributions of secondary minerals in the Martian meteorite MIL 03346,168 determined by Raman spectroscopic imaging

    NASA Astrophysics Data System (ADS)

    Ling, Zongcheng; Wang, Alian

    2015-06-01

    Miller Range (MIL) 03346 is a nakhlite meteorite that has been extensively studied due to its unique complex secondary mineral phases and their potential implications for the hydrologic history of Mars. We conducted a set of Raman spectroscopic and Raman imaging studies of MIL 03346,168, focusing on the secondary mineral phases and their spatial distributions, with a goal to better understand the possible processes by which they were generated on Mars. This study revealed three types of calcium sulfates, a solid solution of (K, Na)-jarosite and two groups of hydrated species with low crystallinity (HSLC) in the veins and/or mesostasis areas of the meteorite. The most abundant Ca-sulfate is bassanite that suggests two possible paths for its direct precipitation from a Ca-S-H2O brine, either having low water activity or with incomplete development (producing bassanite with gypsum microcrystals) on Mars. The second most abundant Ca-sulfate is soluble γ-CaSO4 which raises a new question on the origins of this phase in the Martian meteorite, since γ-CaSO4 readily hydrates in the laboratory but is apparently stable in Atacama Desert. The close spatial relationship of (K, Na)-jarosite solid solutions with rasvumite (KFe2S3), magnetite, HSLC, and fine-grained low-crystallinity alkali feldspar in mesostasis suggests a potential in situ formation of mesostasis jarosite from these Fe-K,Na-S-O-H2O species.

  18. Evidence for shock heating and constraints on Martian surface temperatures revealed by 40Ar/ 39Ar thermochronometry of Martian meteorites

    NASA Astrophysics Data System (ADS)

    Cassata, William S.; Shuster, David L.; Renne, Paul R.; Weiss, Benjamin P.

    2010-12-01

    The thermal histories of Martian meteorite are important for the interpretation of petrologic, geochemical, geochronological, and paleomagnetic constraints that they provide on the evolution of Mars. In this paper, we quantify 40Ar/ 39Ar ages and Ar diffusion kinetics of Martian meteorites Allan Hills (ALH) 84001, Nakhla, and Miller Range (MIL) 03346. We constrain the thermal history of each meteorite and discuss the resulting implications for their petrology, paleomagnetism, and geochronology. Maskelynite in ALH 84001 yields a 40Ar/ 39Ar isochron age of 4163 ± 35 Ma, which is indistinguishable from recent Pb-Pb ( Bouvier et al., 2009a) and Lu-Hf ages ( Lapen et al., 2010). The high precision of this result arises from clear resolution of a reproducible trapped 40Ar/ 36Ar component in maskelynite in ALH 84001 ( 40Ar/ 36Ar = 632 ± 90). The maskelynite 40Ar/ 39Ar age predates the Late Heavy Bombardment and likely represents the time at which the original natural remanent magnetization (NRM) component observed in ALH 84001 was acquired. Nakhla and MIL 03346 yield 40Ar/ 39Ar isochron ages of 1332 ± 24 and 1339 ± 8 Ma, respectively, which we interpret to date crystallization. Multi-phase, multi-domain diffusion models constrained by the observed Ar diffusion kinetics and 40Ar/ 39Ar age spectra suggest that localized regions within both ALH 84001 and Nakhla were intensely heated for brief durations during shock events at 1158 ± 110 and 913 ± 9 Ma, respectively. These ages may date the marginal melting of pyroxene in each rock, mobilization of carbonates and maskelynite in ALH 84001, and NRM overprints observed in ALH 84001. The inferred peak temperatures of the shock heating events (>1400 °C) are sufficient to mobilize Ar, Sr, and Pb in constituent minerals, which may explain some of the dispersion observed in 40Ar/ 39Ar, Rb-Sr, and U-Th-Pb data toward ages younger than ˜4.1 Ga. The data also place conservative upper bounds on the long-duration residence

  19. Morphological Evidence for an Exclusively Inorganic Origin for Magnetite in Martian Meteorite ALH84001

    NASA Technical Reports Server (NTRS)

    Golden, D. C.; Ming, D. W.; Morris, R. V.; Brearley, A. J.; Lauer, H. V., Jr.; Treiman, A.; Zolensky, M. E.; Schwandt, C. S.; Lofgren, G. E.; McKay, G. A.

    2003-01-01

    The origin of magnetite crystals in Martian Meteorite ALH84001 is the focus of a debate about the possibility of past (and present) life on Mars. McKay et al. originally suggested that some of the magnetite crystals associated with carbonate globules in Martian Meteorite ALH84001 are biogenic in ori-gin, because they are single magnetic domain, free of crystalline defects, chemically pure, and coexist with other metastable phases in apparent disequilibrium. Thomas-Keprta et al. reported that a subpopulation of magnetite crystals (approx. 25%) associated with carbonate globules in ALH84001 and magnetite crystals produced by magnetotactic bacterial strain MV-1 have similar morphologies with crystal elongation along the [111] crystallographic axis that they describe as "truncated hexa-octahedral" ([111-THO]) magnetite. Along with several other properties, the [111]-THO morphology has been proposed to constitute a biomarker (i.e., formed only in biogenic processes), so that the presence of [111]-THO magnetite in ALH84001 may be evidence for past life on Mars.

  20. Morphological Evidence for an Exclusively Inorganic Origin for Magnetite in Martian Meteorite ALH84001

    NASA Technical Reports Server (NTRS)

    Golden, D. C.; Ming, D. W.; Morris, R. V.; Brearley, A. J.; Lauer, H. V., Jr.; Treiman, A.; Zolensky, M. E.; Schwandt, C. S.; Lofgren, G. E.; McKay, G. A.

    2003-01-01

    The origin of magnetite crystals in Martian Meteorite ALH84001 is the focus of a debate about the possibility of past (and present) life on Mars. McKay et al. originally suggested that some of the magnetite crystals associated with carbonate globules in Martian Meteorite ALH84001 are biogenic in ori-gin, because they are single magnetic domain, free of crystalline defects, chemically pure, and coexist with other metastable phases in apparent disequilibrium. Thomas-Keprta et al. reported that a subpopulation of magnetite crystals (approx. 25%) associated with carbonate globules in ALH84001 and magnetite crystals produced by magnetotactic bacterial strain MV-1 have similar morphologies with crystal elongation along the [111] crystallographic axis that they describe as "truncated hexa-octahedral" ([111-THO]) magnetite. Along with several other properties, the [111]-THO morphology has been proposed to constitute a biomarker (i.e., formed only in biogenic processes), so that the presence of [111]-THO magnetite in ALH84001 may be evidence for past life on Mars.

  1. Organic Carbon Exists in Mars Meteorites: where is it on the Martian Surface?

    NASA Astrophysics Data System (ADS)

    McKay, David; Clemett, Simon; Gibson, Everett; Thomas-Keprta, Kathie; Wentworth, Susan

    The search for organic carbon on Mars has been a major challenge. The first attempt was the Viking GC-MS in situ experiment which gave inconclusive results at two sites on Mars [1]. After the discovery that the SNC meteorites were from Mars [2], [3-5] reported C isotopic compositional information which suggested a reduced C component present in the Martian meteorites. [6 7] reported the presence of reduced C components (i.e., polycyclic aromatic hydrocarbons) associated with the carbonate globules in ALH84001. Jull et al. [8] noted in Nakhla there was an acid insoluble C component present with more than 75% of its C lacking any 14 C, which is modern-day terrestrial carbon. This C fraction was believed to be either indigenous martian or ancient meteoritic carbon. Fisk et al. [9, 10] have shown textural evidence along with C-enriched areas within fractures in Nakhla and ALH84001. Westall et al. [11] have shown the presence of a large irregular fragment of organic material completely embedded within a chip of ALH84001. Interior samples from the Nakhla SNC made available by the British Museum of Natural His-tory, were analyzed. Petrographic examination [12] of Nakhla showed evidence of fractures ( 0.5 m wide) filled with dark brown to black dendritic material with characteristics similar to those observed by [10]. Iddingsite is also present along fractures in olivine. Fracture filling and dendritic material was examined by SEM-EDX, TEM-EDX, Focused Electron Beam mi-croscopy, Laser Raman Spectroscopy, Nano-SIMS Ion Micro-probe, and Stepped-Combustion Static Mass Spectrometry. Observations from the first three techniques are discussed in [12 and 13]. Nano-SIMS Ion Microprobe studies of the C-bearing fractures, containing the optically dark dendritic material, show direct correlation between C- and CN- abundances. Ion abun-dances for epoxy are distinct from those of the dendritic material[12] . Laser Raman Spectrometry was utilized to examine the optically dark dendritic

  2. Implications of noble gases in a recently recognized Martian meteorite (ALH84001) for the degassing history of Mars

    NASA Technical Reports Server (NTRS)

    Swindle, T. D.

    1994-01-01

    For terrestrial planets, atmospheric compositions are not static, but evolve with time, in part due to degassing of the interior. Unfortunately, the evolution is slow enough that it is usually not observable on human timescales, or even on the timescales of rocks that preserve samples of Earth's ancient atmosphere. Preliminary results on a recently recognized Martian meteorite, ALH84001, indicate that it is a very old rock, and has a relatively high noble gas content suggestive of atmospheric incorporation, but with an isotopic composition slightly inconsistent with currently known Martian reservoirs. Hence, this rock may provide a sample of ancient Martian atmosphere, which can be used to test models of volatile evolution (in particular, degassing) on Mars. ALH84001 is a cumulate orthopyroxenite. Although originally classified as a diogenite, its oxygen isotopes, and several chemical and petrographic features, strong suggest that it is, like the SNC meteorites, Martian. A Sm-Nd crystallization age of 4.5 Ga has been reported. The meteorite is rich in noble gases, compared to most SNC's. In many respects the noble gases are typical of SNC meteorites. However, there are some subtle differences. In particular, the Xe isotopes in SNC meteorites can be explained as a mixture of Martian atmospheric Xe (as represented by glass in EETA 79001), the Xe in the dunite Chassigny (usually assumed to be representative of the Martian interior, and with lower (129)Xe/(132)Xe, (134)Xe/(132)Xe and (136)Xe/(132)Xe ratios), and later additions from known processes like fission, spallation and terrestrial contamination. The isotopic composition of ALH84001 is inconsistent (at greater than 2-3 sigma) with any mixture of those components. Even if no accumulation of fission Xe during the age of the rock is assumed, there is too little (136)Xe and (134)Xe for the amount of (129)Xe measured.

  3. ALH84001, a cumulate orthopyroxenite member of the Martian meteorite clan

    NASA Technical Reports Server (NTRS)

    Mittlefehldt, David W.

    1994-01-01

    ALH84001, originally classified as a diogenite, is a coarse-grained, cataclastic, orthopyroxenite meteorite related to the martian (SNC) meteorites. The orthopyroxene is relatively uniform in composition, with a mean composition of Wo3.3En69.4Fs27.3. Minor phases are euhedral to subhedral chromite and interstitial maskelynite, An31.1Ab63.2Or5.7, with accessory augite, Wo42.2En45.1Fs12.7, apatite, pyrite and carbonates, Cc11.5Mg58.0Sd29.4Rd1.1. The pyroxenes and chromites in ALH84001 are similar in composition to these phases in EETA79001 lithology a megacrysts but are more homogeneous. Maskelynite is similar in composition to feldspars in the nakhlites and Chassigny. Two generations of carbonates are present, early (pre-shock) strongly zoned carbonates and late (post-shock) carbonates. The high Ca content of both types of carbonates indicates that they were formed at moderately high temperature, possibly approximately 700 C. ALH84001 has a slightly LREE-depleted pattern with La 0.67x and Lu 1.85x CI abundances and with a negative Eu anomaly (Eu/Sm 0.56x CI). The uniform pyroxene composition is unusual for martian meteorites, and suggests that ALH84001 cooled more slowly than did the shergottites, nakhlites of Chassigny. The nearly monomineralic composition, coarse-grain size, homogeneous orthopyroxene and chromite compositions, the interstitial maskelynite and apatite, and the REE pattern suggest that ALH84001 is a cumulate orthopyroxenite containing minor trapped, intercumulus material.

  4. Organic Carbon Exists in Mars Meteorites: Where is it on the Martian Surface?

    NASA Technical Reports Server (NTRS)

    McKay, D. S.; Clemett, S. J.; Gibson, E. K., Jr.; Thomas-Keprta, K. L.; Wentworth, S. J.

    2010-01-01

    The search for organic carbon on Mars has been a major challenge. The first attempt was the Viking GC-MS in situ experiment which gave inconclusive results at two sites oil. After the discovery that the SNC meteorites were from Mars, reported C isotopic compositional information which suggested a reduced C component present in the Martian meteorites reported the presence of reduced C components (i.e., polycyclic aromatic hydrocarbons) associated with the carbonate globules in ALH84001. Jull et al. noted in Nakhla there was acid insoluble C component present with more than 75% of its C lacking any C-14, which is modern-day terrestrial carbon. This C fraction was believed to be either indigenous martian or ancient meteoritic carbon. Fisk et al. have shown textural evidence along with C-enriched areas within fractures in Nakhla and ALH84001. Westall et al. have shown the presence of a large irregular fragment of organic material completely embedded within a chip of ALH84001. Interior samples from the Naklnla SNC made available by the British Museum of Natural History, were analyzed. Petrographic examination of Nakhla showed evidence of fractures (approx.0.5 microns wide) filled with dark brown to black dendritic material with characteristics similar to those observed by. Iddingsite is also present along fractures in olivine. Fracture filling and dendritic material was examined by SEM-EDX, TEM-EDX, Focused Electron Beam microscopy, Laser Raman Spectroscopy, Nano-SIMS Ion Micro-probe, and Stepped-Combustion Static Mass Spectrometry. Observations from the first three techniques are discussed.

  5. The origin of organic matter in the Martian meteorite ALH84001.

    PubMed

    Becker, L; Popp, B; Rust, T; Bada, J L

    1999-03-30

    Stable carbon isotope measurements of the organic matter associated with the carbonate globules and the bulk matrix material in the ALH84001 Martian meteorite indicate that two distinct sources are present in the sample. The delta 13C values for the organic matter associated with the carbonate globules averaged -26% and is attributed to terrestrial contamination. In contrast, the delta 13C values for the organic matter associated with the bulk matrix material yielded a value of -15%. The only common sources of carbon on the Earth that yield similar delta 13C values, other then some diagenetically altered marine carbonates, are C4 plants. A delta 13C value of -15%, on the other hand, is consistent with a kerogen-like component, the most ubiquitous form of organic matter found in carbonaceous chondrites such as the Murchison meteorite. Examination of the carbonate globules and bulk matrix material using laser desorption mass spectrometry (LDMS) indicates the presence of a high molecular weight organic component which appears to be extraterrestrial in origin, possibly derived from the exogenous delivery, of meteoritic or cometary debris to the surface of Mars.

  6. Comparing Meteorite and Spacecraft Noble Gas Measurements to Trace Processes in the Martian Crust and Atmosphere

    NASA Astrophysics Data System (ADS)

    Swindle, T. D.

    2014-12-01

    Our knowledge of the noble gas abundances and isotopic compositions in the Martian crust and atmosphere come from two sources, measurements of meteorites from Mars and in situ measurements by spacecraft. Measurements by the Viking landers had large uncertainties, but were precise enough to tie the meteorites to Mars. Hence most of the questions we have are currently defined by meteorite measurements. Curiosity's SAM has confirmed that the Ar isotopic composition of the atmosphere is highly fractionated, presumably representing atmospheric loss that can now be modeled with more confidence. What turns out to be a more difficult trait to explain is the fact that the ratio of Kr/Xe in nakhlites, chassignites and ALH84001 is distinct from the atmospheric ratio, as defined by measurements from shergottites. This discrepancy has been suggested to be a result of atmosphere/groundwater/rock interaction, polar clathrate formation, or perhaps local temperature conditions. More detailed atmospheric measurements, along with targeted simulation experiments, will be needed to make full use of this anomaly.

  7. Noble gases and nitrogen in Martian meteorites Dar al Gani 476, Sayh al Uhaymir 005 and Lewis Cliff 88516: EFA and extra neon

    NASA Astrophysics Data System (ADS)

    Mohapatra, Ratan K.; Schwenzer, Susanne P.; Herrmann, Siegfried; Murty, S. V. S.; Ott, Ulrich; Gilmour, Jamie D.

    2009-03-01

    that vice-versa, via noble gases and nitrogen in meteorites and other relevant samples from terrestrial deserts, Martian secondary processes can be studied.

  8. Calcium carbonate and calcium sulfate in Martian meteorite EETA79001

    NASA Technical Reports Server (NTRS)

    Gooding, J. L.; Wentworth, S. J.

    1987-01-01

    Chips of glassy Lithology C of EETA79001 were studied by scanning electron microscopy and energy dispersive X-ray spectroscopy to determine the mineralogy and petrogenesis of the glass that was shown by others to contain trapped Mars-like gases. Calcium carbonite was identified as massive to acicular crystals for which Ca, C, and O were the major elements. Calcium sulfate was identified as prismatic-acicular crystals with Ca and S as the major elements.

  9. Magnetite Formation from Thermal Decomposition of Siderite: Implications for Inorganic Magnetite Formation in Martian Meteorite ALH84001

    NASA Technical Reports Server (NTRS)

    Morris, RIchard V.

    2002-01-01

    A biogenic mechanism for formation of a subpopulation magnetite in Martian meteorite ALH84001 has been suggested [McKay et al., 1996; Thomas-Keprta, et al., 2000]. We are developing experimental evidence for an alternating working hypothesis, that the subpopulation was produced inorganically by the thermal decomposition of siderite [Golden et al., 2000].

  10. Martian polar geological studies

    NASA Technical Reports Server (NTRS)

    Cutts, J. A. J.

    1977-01-01

    Multiple arcs of rugged mountains and adjacent plains on the surface of Mars were examined. These features, located in the southern polar region were photographed by Mariner 9. Comparisons are made with characteristics of a lunar basin and mare; Mare imbrium in particular. The martian feature is interpreted to have originated in the same way as its lunar analog- by volcanic flooding of a large impact basin. Key data and methodology leading to this conclusion are cited.

  11. Cosmochemical Studies: Meteorites and their Parent Asteroids

    NASA Technical Reports Server (NTRS)

    Wasson, John T.

    2003-01-01

    This a final technical report that focuses on cosmochemical studies of meteorites and their parent asteroids. The topics include: 1) Formation of iron meteorites and other metal rich meteorites; 2) New perspectives on the formation of chondrules; and 3) Consequences of large aerial bursts. Also a list of seven papers that received significant support from this research are included.

  12. The role of sulfides in the fractionation of highly siderophile and chalcophile elements during the formation of martian shergottite meteorites

    NASA Astrophysics Data System (ADS)

    Baumgartner, Raphael J.; Fiorentini, Marco L.; Lorand, Jean-Pierre; Baratoux, David; Zaccarini, Federica; Ferrière, Ludovic; Prašek, Marko K.; Sener, Kerim

    2017-08-01

    The shergottite meteorites are ultramafic to mafic igneous rocks whose parental magmas formed from partial melting of the martian mantle. This study reports in-situ laser ablation inductively coupled plasma mass spectrometry analyses for siderophile and chalcophile major and trace elements (i.e., Co, Ni, Cu, As, Se, Ag, Sb, Te, Pb, Bi, and the highly siderophile platinum-group elements, PGE: Os, Ir, Ru, Rh, Pt and Pd) of magmatic Fe-Ni-Cu sulfide assemblages from four shergottite meteorites. They include three geochemically similar incompatible trace element- (ITE-) depleted olivine-phyric shergottites (Yamato-980459, Dar al Gani 476 and Dhofar 019) that presumably formed from similar mantle and magma sources, and one distinctively ITE-enriched basaltic shergottite (Zagami). The sulfides in the shergottites have been variably modified by alteration on Earth and Mars, as well as by impact shock-shock related melting/volatilization during meteorite ejection. However, they inherit and retain their magmatic PGE signatures. The CI chondrite-normalized PGE concentration patterns of sulfides reproduce the whole-rock signatures determined in previous studies. These similarities indicate that sulfides exerted a major control on the PGE during shergottite petrogenesis. However, depletions of Pt (and Ir) in sulfide relative to the other PGE suggest that additional phases such discrete Pt-Fe-Ir alloys have played an important role in the concentration of these elements. These alloys are expected to have enhanced stability in reduced and FeO-rich shergottite magmas, and could be a common feature in martian igneous systems. A Pt-rich PGM was found to occur in a sulfide assemblage in Dhofar 019. However, its origin may be related to impact shock-related sulfide melting and volatilisation during meteorite ejection. In the ITE-depleted olivine-phyric shergottites, positive relationships exist between petrogenetic indicators (e.g., whole-rock Mg-number) and most moderately to

  13. Alteration Assemblages in Martian Meteorites: Implications for Near-Surface Processes

    NASA Astrophysics Data System (ADS)

    Bridges, J. C.; Catling, D. C.; Saxton, J. M.; Swindle, T. D.; Lyon, I. C.; Grady, M. M.

    2001-04-01

    The SNC (Shergotty-Nakhla-Chassigny) meteorites have recorded interactions between martian crustal fluids and the parent igneous rocks. The resultant secondary minerals - which comprise up to ~1 vol.% of the meteorites - provide information about the timing and nature of hydrous activity and atmospheric processes on Mars. We suggest that the most plausible models for secondary mineral formation involve the evaporation of low temperature (25 - 150 °C) brines. This is consistent with the simple mineralogy of these assemblages - Fe-Mg-Ca carbonates, anhydrite, gypsum, halite, clays - and the chemical fractionation of Ca-to Mg-rich carbonate in ALH84001 "rosettes". Longer-lived, and higher temperature, hydrothermal systems would have caused more silicate alteration than is seen and probably more complex mineral assemblages. Experimental and phase equilibria data on carbonate compositions similar to those present in the SNCs imply low temperatures of formation with cooling taking place over a short period of time (e.g. days). The ALH84001 carbonate also probably shows the effects of partial vapourisation and dehydration related to an impact event post-dating the initial precipitation. This shock event may have led to the formation of sulphide and some magnetite in the Fe-rich outer parts of the rosettes. Radiometric dating (K-Ar, Rb-Sr) of the secondary mineral assemblages in one of the nakhlites (Lafayette) suggests that they formed between 0 and 670 Myr, and certainly long after the crystallisation of the host igneous rocks. Crystallisation of ALH84001 carbonate took place 0.5 Gyr after the parent rock. These age ranges and the other research on these assemblages suggest that environmental conditions conducive to near-surface liquid water have been present on Mars periodically over the last ~1 Gyr. This fluid activity cannot have been continuous over geological time because in that case much more silicate alteration would have taken place in the meteorite parent

  14. Accretion timescale and impact history of Mars deduced from the isotopic systematics of martian meteorites

    SciTech Connect

    Borg, Lars E.; Brennecka, Gregory A.; Symes, Steven J. K.

    2015-12-12

    High precision Sm-Nd isotopic analyses have been completed on a suite of 11 martian basaltic meteorites in order to better constrain the age of silicate differentiation on Mars associated with the formation of their mantle sources. Our data is used to evaluate the merits and disadvantages of various mathematical approaches that have been employed in previous work on this topic. Ages determined from the Sm-Nd isotopic systematics of individual samples are strongly dependent on the assumed Nd isotopic composition of the bulk planet. This assumption is problematic given differences observed between the Nd isotopic composition of Earth and chondritic meteorites and the fact that these materials are both commonly used to represent bulk planetary Nd isotopic compositions. Ages determined from the slope of Sm-146-Nd-142 whole rock isochrons are not dependent on the assumed Nd-142/Nd-144 ratio of the planet, but require the sample suite to be derived from complementary, contemporaneously-formed reservoirs. In this work, we present a mathematical expression that defines the age of formation of the source regions of such a suite of samples that is based solely on the slope of a Nd-143-Nd-142 whole rock isochron and is also independent of any a priori assumptions regarding the bulk isotopic composition of the planet. This expression is also applicable to mineral isochrons and has been used to successfully calculate Nd-143-Nd-142 model crystallization ages of early refractory solids as well as lunar samples. This permits ages to be obtained using only Nd isotopic measurements without the need for Sm-147/Nd-144 isotope dilution determinations. When used in conjunction with high-precision Nd isotopic measurements completed on martian meteorites this expression yields an age of formation of the martian basaltic meteorite source regions of 4504 +/- 6 Ma. Because the Sm-Nd model ages for the formation of martian source regions are commonly interpreted to record the age at which

  15. Accretion timescale and impact history of Mars deduced from the isotopic systematics of martian meteorites

    NASA Astrophysics Data System (ADS)

    Borg, Lars E.; Brennecka, Gregory A.; Symes, Steven J. K.

    2016-02-01

    High precision Sm-Nd isotopic analyses have been completed on a suite of 11 martian basaltic meteorites in order to better constrain the age of silicate differentiation on Mars associated with the formation of their mantle sources. These data are used to evaluate the merits and disadvantages of various mathematical approaches that have been employed in previous work on this topic. Ages determined from the Sm-Nd isotopic systematics of individual samples are strongly dependent on the assumed Nd isotopic composition of the bulk planet. This assumption is problematic given differences observed between the Nd isotopic composition of Earth and chondritic meteorites and the fact that these materials are both commonly used to represent bulk planetary Nd isotopic compositions. Ages determined from the slope of 146Sm-142Nd whole rock isochrons are not dependent on the assumed 142Nd/144Nd ratio of the planet, but require the sample suite to be derived from complementary, contemporaneously-formed reservoirs. In this work, we present a mathematical expression that defines the age of formation of the source regions of such a suite of samples that is based solely on the slope of a 143Nd-142Nd whole rock isochron and is also independent of any a priori assumptions regarding the bulk isotopic composition of the planet. This expression is also applicable to mineral isochrons and has been used to successfully calculate 143Nd-142Nd model crystallization ages of early refractory solids as well as lunar samples. This permits ages to be obtained using only Nd isotopic measurements without the need for 147Sm/144Nd isotope dilution determinations. When used in conjunction with high-precision Nd isotopic measurements completed on martian meteorites this expression yields an age of formation of the martian basaltic meteorite source regions of 4504 ± 6 Ma. Because the Sm-Nd model ages for the formation of martian source regions are commonly interpreted to record the age at which large scale

  16. First evidence for infiltration metasomatism in a martian meteorite, ALH 84001

    NASA Astrophysics Data System (ADS)

    Wadhwa, M.; Crozaz, G.

    1994-07-01

    ALH 84001, originally classified as a diogenite, was recently recognized by Mittlefehldt as a new member of the clan of martian meteorites. It is a coarse-grained orthopyroxenite with same O isotopic composition as the nakhlites. Most of this meteorite consists of orthopyroxene grains; it also contains maskelynite, chromite, and accessory minerals including apatite, augite, pyrite, and Mg-Ca-Mn-Fe carbonates. With the ion microprobe, we measured the concentrations of Rare Earth Elements (REEs) and other selected minor and trace elements in individual grains of orthopyroxene, maskelynite, and apatite. Although in all SNCs phosphate is the mineral with the highest REE concentrations, it is not the major REE carrier in ALH 84001. Using the most appropriate partition coefficients for these minerals in SNCs, we estimated the compositions of the metals that may have been in equilibrium with the 'average' orthopyroxene, the apatite, and the maskelynite. The orthopyroxene equilibrium melt is slightly LREE depleted, whereas the apatite and maskelynite equilibrium melts have higher REE concentrations and are strikingly LREE enriched. We tried unsuccessfully to derive the apatite and maskelynite melts from the orthopyroxene melt by fractional crystallization. We therefore suggest that an infiltrating fluid enriched in LREE is responsible for the formation of the apatite and maskelynite that occur as interstitial grains in ALH 84001. The similarity of REE patterns for the parent melts of ALH 84001, Shergotty, and Zagami seems to indicate that the new SNC meteorite is more closely related to these two shergottites than to any of the other meteorites thought to have come from Mars.

  17. A Petrographic History of Martian Meteorite ALH84001: Two Shocks and an Ancient Age

    NASA Technical Reports Server (NTRS)

    Treiman, Allan H.

    1995-01-01

    ALH84001 is an igneous meteorite, an orthopyroxenite of martian origin. It contains petrographic evidence of two shock metamorphic events, separated by thermal and chemical events. The evidence for two shock events suggests that ALH84001 is ancient and perhaps a sample of the martian highlands. From petrography and mineral chemistry, the history of ALH84001 must include: crystallization from magma, a first shock (impact) metamorphism, thermal metamorphism, low-temperature chemical alteration, and a second shock (impact) metamorphism. Originally, ALH84001 was igneous, an orthopyroxene-chromite cumulate. In the first shock event, the igneous rock was cut by melt-breccia or cataclastic veinlets, now bands of equigranular fine-grained pyroxene and other minerals (crush zones). Intact fragments of the cumulate were fractured and strained (now converted to polygonized zones). The subsequent thermal metamorphism (possibly related to the first shock) annealed the melt-breccia or cataclastic veinlets to their present granoblastic texture and permitted chemical homogenization of all mineral species present. The temperature of metamorphism was at least 875 C, based on mineral thermometers. Next, Mg-Fe-Ca carbonates and pyrite replaced plagioclase in both clasts and granular bands, producing ellipsoidal carbonate globules with sub-micron scale compositional stratigraphy, repeated identically in all globules, The second shock event produced microfault offsets of carbonate stratigraphy and other mineral contacts, radial fractures around chromite and maskelynite, and strain birefringence in pyroxene. Maskelynite could not have been preserved from the first shock event, because it would have crystallized back to plagioclase. The martian source area for ALH84001 must permit this complex, multiple impact history. Very few craters on young igneous surfaces are on or near earlier impact features. It is more likely that ALH84001 was ejected from an old igneous unit (Hesperian or

  18. Hydrothermal Origin for Carbonate Globules in Martian Meteorite ALH84001: A Terrestrial Analogue from Spitsbergen (Norway)

    NASA Technical Reports Server (NTRS)

    Treiman, Allan H.; Amundsen, Hans E. F.; Blake, David F.; Bunch, Ted

    2002-01-01

    Carbonate minerals in the ancient Martian meteorite ALH84001 are the only known solid phases that bear witness to the processing of volatile and biologically critical compounds (CO2, H2O) on early Mars. Similar carbonates have been found in xenoliths and their host basalts from Quaternary volcanic centers in northern Spitsbergen (Norway). These carbonates were deposited by hot (i.e., hydrothermal) waters associated with the volcanic activity. By analogy with the Spitsbergen carbonates, the ALH84001 carbonates were probably also deposited by hot water. Hydrothermal activity was probably common and widespread on Early Mars, which featured abundant basaltic rocks, water as ice or liquid, and heat from volcanos and asteroid impacts. On Earth, descendants of the earliest life forms still prefer hydrothermal environments, which are now shown to have been present on early Mars.

  19. Hydrothermal Origin for Carbonate Globules in Martian Meteorite ALH84001: A Terrestrial Analogue from Spitsbergen (Norway)

    NASA Technical Reports Server (NTRS)

    Treiman, Allan H.; Amundsen, Hans E. F.; Blake, David F.; Bunch, Ted

    2002-01-01

    Carbonate minerals in the ancient Martian meteorite ALH84001 are the only known solid phases that bear witness to the processing of volatile and biologically critical compounds (CO2, H2O) on early Mars. Similar carbonates have been found in xenoliths and their host basalts from Quaternary volcanic centers in northern Spitsbergen (Norway). These carbonates were deposited by hot (i.e., hydrothermal) waters associated with the volcanic activity. By analogy with the Spitsbergen carbonates, the ALH84001 carbonates were probably also deposited by hot water. Hydrothermal activity was probably common and widespread on Early Mars, which featured abundant basaltic rocks, water as ice or liquid, and heat from volcanos and asteroid impacts. On Earth, descendants of the earliest life forms still prefer hydrothermal environments, which are now shown to have been present on early Mars.

  20. Experimental Shock Decomposition of Siderite and the Origin of Magnetite in Martian Meteorite ALH84001

    NASA Technical Reports Server (NTRS)

    Bell, Mary Sue

    2007-01-01

    Shock recovery experiments to determine whether magnetite could be produced by the decomposition of iron-carbonate were initiated. Naturally occurring siderite was first characterized by electron microprobe (EMP), transmission electron microscopy (TEM), Mossbauer spectroscopy, and magnetic susceptibility measurements to be sure that the starting material did not contain detectable magnetite. Samples were shocked in tungsten-alloy holders (W=90%, Ni=6%, Cu=4%) to further insure that any iron phases in the shock products were contributed by the siderite rather than the sample holder. Each sample was shocked to a specific pressure between 30 to 49 GPa. Previously reported results of TEM analyses on 49 GPa experiments indicated the presence of nano-phase spinel-structured iron oxide. Transformation of siderite to magnetite as characterized by TEM was found in the 49 GPa shock experiment. Compositions of most magnetites are greater than 50% Fe sup(+2) in the octahedral site of the inverse spinel structure. Magnetites produced in shock experiments display the same range of single-domain, superparamagnetic sizes (approx. 50 100 nm), compositions (100% magnetite to 80% magnetite-20% magnesioferrite), and morphologies (equant, elongated, euhedral to subhedral) as magnetites synthesized by Golden et al. (2001) or magnetites grown naturally by MV1 magnetotactic bacteria, and as the magnetites in Martian meteorite ALH84001. Fritz et al. (2005) previously concluded that ALH84001 experienced approx. 32 GPa pressure and a resultant thermal pulse of approx. 100 - 110 C. However, ALH84001 contains evidence of local temperature excursions high enough to 1 melt feldspar, pyroxene, and a silica-rich phase. This 49 GPa experiment demonstrates that magnetite can be produced by the shock decomposition of siderite as a result of local heating to greater than 470 C. Therefore, magnetite in the rims of carbonates in Martian meteorite ALH84001 could be a product of shock devolatilization of

  1. Accretion timescale and impact history of Mars deduced from the isotopic systematics of martian meteorites

    DOE PAGES

    Borg, Lars E.; Brennecka, Gregory A.; Symes, Steven J. K.

    2015-12-12

    High precision Sm-Nd isotopic analyses have been completed on a suite of 11 martian basaltic meteorites in order to better constrain the age of silicate differentiation on Mars associated with the formation of their mantle sources. Our data is used to evaluate the merits and disadvantages of various mathematical approaches that have been employed in previous work on this topic. Ages determined from the Sm-Nd isotopic systematics of individual samples are strongly dependent on the assumed Nd isotopic composition of the bulk planet. This assumption is problematic given differences observed between the Nd isotopic composition of Earth and chondritic meteoritesmore » and the fact that these materials are both commonly used to represent bulk planetary Nd isotopic compositions. Ages determined from the slope of Sm-146-Nd-142 whole rock isochrons are not dependent on the assumed Nd-142/Nd-144 ratio of the planet, but require the sample suite to be derived from complementary, contemporaneously-formed reservoirs. In this work, we present a mathematical expression that defines the age of formation of the source regions of such a suite of samples that is based solely on the slope of a Nd-143-Nd-142 whole rock isochron and is also independent of any a priori assumptions regarding the bulk isotopic composition of the planet. This expression is also applicable to mineral isochrons and has been used to successfully calculate Nd-143-Nd-142 model crystallization ages of early refractory solids as well as lunar samples. This permits ages to be obtained using only Nd isotopic measurements without the need for Sm-147/Nd-144 isotope dilution determinations. When used in conjunction with high-precision Nd isotopic measurements completed on martian meteorites this expression yields an age of formation of the martian basaltic meteorite source regions of 4504 +/- 6 Ma. Because the Sm-Nd model ages for the formation of martian source regions are commonly interpreted to record the age at

  2. Martian surface weathering studies

    NASA Technical Reports Server (NTRS)

    Calvin, M.

    1973-01-01

    The nature of the Martian surface was characterized by means of its reflectance properties. The Mariner 9 photography was used to establish terrain units which were crossed by the Mariner 6 and 7 paths. The IR reflectance measured by the IR spectrometers on these spacecraft was to be used to indicate the nature of the surface within these units. There is an indication of physical size and/or compositional variation between units but too many natural parameters can vary (size, shape, composition, adsorbed phases, reradiation, atmospheric absorbtion, temperature gradients, etc.) to be certain what effect is causing those variations observed. It is suggested that the characterization could be fruitfully pursued by a group which was dedicated to peeling back the layers of minutia affecting IR reflectance.

  3. EBSD analysis of the Shergottite Meteorites: New developments within the technique and their implication on what we know about the preferred orientation of Martian minerals

    NASA Astrophysics Data System (ADS)

    Stephen, N.; Benedix, G. K.; Bland, P.; Berlin, J.; Salge, T.; Goran, D.

    2011-12-01

    What we know about the geology and mineralogy of the Martian surface has been characterised by both the use of remote sensing techniques and the analysis of Martian meteorites. Various techniques are employed to conduct these analyses including crystallographic, geochemical and spectral measurements, all of which enable us to infer a geological history for these rocks. Several references have been made to the potential for preferred orientation of crystals within the Shergottites [1] and their implication for the cooling history of the respective magmas on Mars [2]. We have already shown that a preferred orientation of the two pyroxenes, augite and pigeonite, can be seen in the Zagami meteorite using electron back-scatter diffraction (EBSD) analysis [3]. However, when compared to previous modal studies of the same meteorites [4], it becomes apparent that the current EBSD datasets for Martian meteorites are incomplete. Indexing of some minerals can be hampered by the lack of available matches within library databases for EBSD, or become difficult to resolve between minerals where crystallographic differences between similar minerals fall below the technical limitations of the instrument [3]. Recent advances in EBSD technologies combined with the simultaneous acquisition of energy-dispersive spectra (EDS) however now allow us to determine a more comprehensive set of analyses in a much shorter period of time, fully resolving even similar minerals where areas have been left with no indexing previously [5]. Preliminary investigations suggest that the new technology can successfully index >90% of the sample. The most recent EBSD analyses potentially reveals previously unseen fabrics in the meteorites alongside the EDS hyper-spectral imaging helping to resolve any unknown or questionable phases within them. In this study we will present new data from an investigation using EDS alongside EBSD analysis on 2 Shergottite meteorites, SAU 005 and Zagami, to further resolve

  4. The age of the martian meteorite Northwest Africa 1195 and the differentiation history of the shergottites

    SciTech Connect

    Symes, S; Borg, L; Shearer, C; Irving, A

    2007-04-05

    Samarium-neodymium isotopic analyses of unleached and acid-leached mineral fractions from the recently identified olivine-bearing shergottite Northwest Africa 1195 yield a crystallization age of 348 {+-} 19 Ma and an {var_epsilon}{sub Nd}{sup 143} value of +40.1 {+-} 1.3. Maskelynite fractions do not lie on the Sm-Nd isochron and appear to contain a martian surface component with low {sup 147}Sm/{sup 144}Nd and {sup 143}Nd/{sup 144}Nd ratios that was added during shock. The Rb-Sr system is disturbed and does not yield an isochron. Terrestrial Sr appears to have affected all of the mineral fractions, although a maximum initial {sup 87}Sr/{sup 86}Sr ratio of 0.701614 {+-} 16 is estimated by passing a 348 Ma reference isochron through the maskelynite fraction that is least affected by contamination. The high initial {var_epsilon}{sub Nd}{sup 143} value and the low initial {sup 87}Sr/{sup 86}Sr ratio, combined with the geologically young crystallization age, indicate that Northwest Africa 1195 is derived from a source region characterized by a long-term incompatible element depletion. The age and initial Sr and Nd isotopic compositions of Northwest Africa 1195 are very similar to those of Queen Alexandra Range 94201, indicating these samples were derived from source regions with nearly identical Sr-Nd isotopic systematics. These similarities suggest that these two meteorites share a close petrogenetic relationship and might have been erupted from a common volcano. The meteorites Yamato 980459, Dar al Gani 476, Sayh al Uhaymir 005/008, and Dhofar 019 also have relatively old ages between 474-575 Ma and trace element and/or isotopic systematics that are indicative of derivation from incompatible-element-depleted sources. This suggests that the oldest group of meteorites is more closely related to one another than they are to the younger meteorites that are derived from less incompatible-element-depleted sources. Closed-system fractional crystallization of this suite of

  5. Meteorites

    NASA Astrophysics Data System (ADS)

    Jenniskens, Peter

    2015-08-01

    Meteorites have long been known to offer a unique window into planetary formation processes at the time of solar system formation and into the materials that rained down on Earth at the time of the origin of life. Their material properties determine the impact hazard of Near Earth Asteroids. Some insight into how future laboratory studies of meteorites and laboratory astrophysics simulations of relevant physical processes can help address open questions in these areas and generate new astronomical observations, comes from what was learned from the recent laboratory studies of freshly fallen meteorites. The rapid recovery of Almahata Sitta (a polymict Ureilite), Sutter's Mill (a CM chondrite regolith breccia), Novato (an L6 chondrite), and Chelyabinsk (an LL5 chondrite) each were followed by the creation of a meteorite consortium, which grew to over 50 researchers in the case of Chelyabinsk. New technologies were used to probe the organic content of the meteorites as well as their magnetic signatures, isotopic abundances, trapped noble gasses, and cosmogenic radio nucleides, amongst others. This has resulted in fascinating insight into the nature of the Ureilite parent body, the likely source region of the CM chondrites in the main asteroid belt, and the collisional environment of the CM parent body. This work has encouraged follow-up in the hope of catching more unique materials. Rapid response efforts are being developed that aim to recover meteorites as pristinely as possible from falls for which the approach orbit was measured. A significant increase in the number of known approach orbits for different meteorite types will help tie meteorite types to their asteroid family source regions. Work so far suggests that future laboratory studies may recognize multiple source regions for iron-rich ordinary chondrites, for example. Hope is that these source regions will give insight into the material properties of impacting asteroids. At least some future laboratory

  6. Carbonaceous structures in the Tissint Martian Meteorite: evidence of a biogenetic origin

    NASA Astrophysics Data System (ADS)

    Wallis, Jamie; Wickramasinghe, N. C.; Wallis, Daryl H.; Miyake, Nori; Wallis, M. K.; Hoover, Richard B.

    2015-09-01

    We report for the first time in situ observations of 5-50μm spherical carbonaceous structures in the Tissint Martian meteorite comprising of pyrite (FeS2) cores and carbonaceous outer coatings. The structures are characterized as smooth immiscible spheres with curved boundaries occasionally following the contours of the pyrite inclusion. The structures bear striking resemblance to similar-sized immiscible carbonaceous spheres found in hydrothermal calcite vein deposits in the Mullaghwornia Quarry in central Ireland. Similar structures have been reported in Proterozoic and Ordovician sandstones from Canada as well as in a variety of astronomical sources including carbonaceous chondrites, chondritic IDPs and primitive chondritic meteorites. SEM and X-Ray elemental mapping confirmed the presence of organic carbon filling the crack and cleavage space in the pyroxene substrate, with further evidence of pyrite acting as an attractive substrate for the collection of organic matter. The detection of precipitated carbon collecting around pyrite grains is at variance with an igneous origin as proposed for the reduced organic component in Tissint, and is more consistent with a biogenetic origin.

  7. Geochronology of the Martian meteorite Zagami revealed by U-Pb ion probe dating of accessory minerals

    NASA Astrophysics Data System (ADS)

    Zhou, Qin; Herd, Christopher D. K.; Yin, Qing-Zhu; Li, Xian-Hua; Wu, Fu-Yuan; Li, Qiu-Li; Liu, Yu; Tang, Guo-Qiang; McCoy, Timothy J.

    2013-07-01

    The precise chronology of geological events on Mars is hampered by the lack of absolute ages for the Martian timescale, and the significant uncertainties that result from the extrapolation of the lunar timescale to Mars (Hartmann and Neukum, 2001). Martian meteorites represent the only samples of Mars currently available. Attempts to identify source craters for the meteorites have thus far proven inconclusive (Hamilton et al., 2003; Lang et al., 2009; Mouginis-Mark and Boyce, 2012>), precluding their use in constraining the absolute Martian timescale. The majority of the known Martian meteorites are basalts ("shergottites"); all dated shergottites have mineral separate (Rb-Sr or Sm-Nd) ages of <600 Ma (Borg et al., 2005). Here we report a 238U/206Pb age of 182.7±6.9 Ma by ion microprobe analysis of baddeleyite (ZrO2) grains in the Zagami shergottite. There is no correlation between discordancy and baddeleyite grain location relative to shock metamorphism. Mineral petrography demonstrates that baddeleyite is the result of late-stage igneous crystallization, and Raman spectroscopy shows that baddeleyite has not been transformed by shock into preservable high-pressure polymorphs. Supported by an age of 153±81 Ma for phosphate grains, obtained using the same method, we conclude that Zagami crystallized at ~180 Ma, in agreement with previous results from mineral separate geochronology. Therefore, the shergottites represent igneous rocks preferentially ejected from young terrains on Mars in a small number of ejection events.

  8. Field Emission Gun Scanning Electron (FEGSEM) and Transmission Electron (TEM) Microscopy of Phyllosilicates in Martian Meteorites ALH84001, Nakhla, and Shergotty

    NASA Technical Reports Server (NTRS)

    Thomas-Keprta, Kathie L.; Wentworth, Susan J.; McKay, David S.; Gibson, Everett K.

    2000-01-01

    Here we document the occurrence of phyllosilicates and alteration phases in three martian meteorites, suggest formation conditions required for phyllosilicate formation and speculate on the extent of fluid:rock interactions during the past history of Mars.

  9. Field Emission Gun Scanning Electron (FEGSEM) and Transmission Electron (TEM) Microscopy of Phyllosilicates in Martian Meteorites ALH84001, Nakhla, and Shergotty

    NASA Technical Reports Server (NTRS)

    Thomas-Keprta, Kathie L.; Wentworth, Susan J.; McKay, David S.; Gibson, Everett K.

    2000-01-01

    Here we document the occurrence of phyllosilicates and alteration phases in three martian meteorites, suggest formation conditions required for phyllosilicate formation and speculate on the extent of fluid:rock interactions during the past history of Mars.

  10. Sayh al Uhaymir 094 a new martian meteorite from the Oman desert

    NASA Astrophysics Data System (ADS)

    Gnos, E.; Hofmann, B.; Franchi, I. A.; Al-Kathiri, A.; Hauser, M.; Moser, L.

    2003-04-01

    The new martian meteorite Sayh al Uhaymir 094 was found in february 2001 during a joint meteorite search campaign of the University of Berne, the Natural History Museum Bern, and the Ministry of Commerce and Industry, Sultanate of Oman. The martian meteorite is a 223.3 g partially crusted, strongly to very strongly shocked melanocratic olivine-porphyric rock of the shergottite group showing a microgabbroic texture. The rock consists of 52.0 58.2 vol% prismatic pigeonite (En60-68Fs20-27Wo7-9) and augite (En46-49Fs15-16Wo28-31), oxydized olivine (Fo65-69;22.1 31%), completely isotropic interstitial plagioclase glass (maskelynite; 8.6 13.0%), chromite and titanian magnesian chromite (0.9 1.0%), traces of ilmenite (ilm80-86), pyrrhotite (Fe92-100; 0.1 0.2%), merrillite, Ca9Na(Mg,Fe)(PO4)7, (<< 0.1%). Shock melt pockets (4.8 6.7%) consist of green basaltic to basaltic andesite glass that is devitrified into a brown to black product along the boundaries to the primary minerals. The average maximum dimensions of minerals are: olivine (1.5 mm), pyroxene (0.3 mm) and maskelynite (0.3 mm). Melt inclusions in olivine are common and account for 0.1 0.6% of the rock. X-ray tomography revealed that the specimen contains approximately 0.4 vol% of shock-melt associated vesicles, up to 3 mm in size, which show a preferred orientation. Fluidization of the maskelynite, melting and recrystallization of pyroxene, olivine and pyrrhotite indicate shock stage S6. Terrestrial weathering resulted in calcite-veining and minor oxidation of sulfides. The modal composition is similar to some basaltic shergottites, with the exception that neither mesostasis nor titanomagnetite nor apatite are present and that all phases show little zonation. The restricted mineral composition, predominance of chromite among the oxides, and abundance of olivine indicate affinities to the ultramafic shergottites.

  11. Ni/S/Cl systematics and the origin of impact-melt glasses in Martian meteorite Elephant Moraine 79001

    NASA Astrophysics Data System (ADS)

    Schrader, Christian M.; Cohen, Barbara A.; Donovan, John J.; Vicenzi, Edward P.

    2016-04-01

    Martian meteorite Elephant Moraine A79001 (EET 79001) has received considerable attention for the unusual composition of its shock melt glass, particularly its enrichment in sulfur relative to the host shergottite. It has been hypothesized that Martian regolith was incorporated into the melt or, conversely, that the S-enrichment stems from preferential melting of sulfide minerals in the host rock during shock. We present results from an electron microprobe study of EET 79001 including robust measurements of major and trace elements in the shock melt glass (S, Cl, Ni, Co, V, and Sc) and minerals in the host rock (Ni, Co, and V). We find that both S and major element abundances can be reconciled with previous hypotheses of regolith incorporation and/or excess sulfide melt. However, trace element characteristics of the shock melt glass, particularly Ni and Cl abundances relative to S, cannot be explained either by the incorporation of regolith or sulfide minerals. We therefore propose an alternative hypothesis whereby, prior to shock melting, portions of EET 79001 experienced acid-sulfate leaching of the mesostasis, possibly groundmass feldspar, and olivine, producing Al-sulfates that were later incorporated into the shock melt, which then quenched to glass. Such activity in the Martian near-surface is supported by observations from the Mars Exploration Rovers and laboratory experiments. Our preimpact alteration model, accompanied by the preferential survival of olivine and excess melting of feldspar during impact, explains the measured trace element abundances better than either the regolith incorporation or excess sulfide melting hypothesis does.

  12. Bulk and Stable Isotopic Compositions of Carbonate Minerals in Martian Meteorite Allan Hills 84001: No Proof of High Formation Temperature

    NASA Technical Reports Server (NTRS)

    Treiman, Allan H.; Romanek, Christopher S.

    1998-01-01

    Understanding the origin of carbonate minerals in the Martian meteorite Allan Hills (ALH) 84001 is crucial to evaluating the hypothesis that they contain traces of ancient Martian life. Using arguments based on chemical equilibria among carbonates and fluids, an origin at greater than 650 C (inimical to life) has been proposed. However, the bulk and stable isotopic compositions of the carbonate minerals are open to multiple interpretations and so lend no particular support to a high-temperature origin. Other methods (possibly less direct) will have to be used to determine the formation temperature of the carbonates in ALH 84001.

  13. The Microbiological Contamination of Meteorites: A Null Hypothesis

    NASA Technical Reports Server (NTRS)

    Steele, A.; Toporski, J. K. W.; Westall, F. W.; Thomas-Keprta, K.; Gibson, E. K.; Avci, R.; Whitby, C.; McKay, D. S.; Griffin, C.

    2000-01-01

    Using 4 different techniques we have studied 9 meteorites including the Martian meteorites ALH84001 and Nakhla for terrestrial contamination in all 9 we have found evidence of terrestrial microorganisms.

  14. Chalcophile elements in Martian meteorites indicate low sulfur content in the Martian interior and a volatile element-depleted late veneer

    NASA Astrophysics Data System (ADS)

    Wang, Zaicong; Becker, Harry

    2017-04-01

    It is generally believed that the Martian mantle and core are rich in sulfur and that shergottites originated from sulfide-saturated magma. However, recent work suggests that the high FeO contents would require very high S concentrations in shergottite parent magmas at sulfide saturation. Here we combine new and published data on chalcophile elements in shergottites, nakhlites and ALH84001 to constrain the sulfide saturation state of the parent magmas and the chalcophile element concentrations in their mantle sources. Regardless of the MgO content and the long-term depletion history of incompatible lithophile elements as indicated by initial ε143Nd, different groups of shergottites display limited variations in ratios of Pt, Pd, Re, Cu, S, Se and Te. The emplacement of most shergottites within the crust and limited variations of ratios of chalcophile elements with substantial differences in volatility during eruption (e.g., Cu/S, Cu/Se and Pt/Re) indicate little degassing losses of S, Se, Te and Re from shergottites. Limited variations in ratios of elements with very different sulfide-silicate melt partition coefficients and negative correlations of chalcophile elements with MgO require a sulfide-undersaturated evolution of the parent magmas from mantle source to emplacement in the crust, consistent with the FeO-based argument. Sulfide petrography and the komatiite-like fractionation of platinum group elements (PGE) in shergottites also support this conclusion. The absence of accumulated sulfides in the ancient Martian cumulate ALH84001 results in very low contents of PGE, Re, Cu, Se and Te in this meteorite, hinting that sulfide-undersaturated magmas may have occurred throughout the Martian geological history. The negative correlation of Cu and MgO contents in shergottites suggests approximately 2 ± 0.4 (1s) μg/g Cu in the Martian mantle. The ratios of Cu, S, Se and Te indicate 360 ± 120 μg/g (1s) S, 100 ± 27 ng/g (1s) Se and 0.50 ± 0.25 ng/g (1s) Te in the

  15. Oxygen Isotopic Constraints on the Genesis of Carbonates from Martian Meteorite ALH84001

    NASA Technical Reports Server (NTRS)

    Leshin, Laurie A.; McKeegan, Kevin D.; Carpenter, Paul K.; Harvey, Ralph P.

    1998-01-01

    Ion microprobe oxygen isotopic measurements of a chemically diverse suite of carbonates from Martian meteorite ALH84001 are reported. The delta(sup 18)O values are highly variable, ranging from +5.4 to + 25.3%, and are correlated with major element compositions of the carbonate. The earliest forming (Ca-rich) carbonates have the lowest delta(sup 18)O values and the late-forming (Mg-rich) carbonates have the highest delta(sup 18)O values. Two models are presented which can explain the isotopic variations. The carbonates could have formed in a water rich environment at relatively low, but highly variable temperatures. In this open-system case the lower limit to the temperature variation is approx. 125 C, with fluctuations of over 250 C possible within the constraints of the model. Alternatively, the data can be explained by a closed-system model in which the carbonates precipitated from a limited amount of CO2-rich fluid. This scenario can reproduce the isotopic variations observed at a range of temperatures, including relatively high temperatures (less than 500 C). Thus the oxygen isotopic compositions do not provide unequivocal evidence for formation of the carbonates at low temperature. Although more information is needed in order to distinguish between the models, neither of the implied environments is consistent with biological activity. Thus, we suggest that features associated with the carbonates which have been interpreted to be the result of biological activity were most probably formed by inorganic processes.

  16. P Isotope Data of SNC Meteorites and Implications on the Age of the Martian Surface

    NASA Astrophysics Data System (ADS)

    Jagoutz, E.; Jotter, R.; Kubny, A.; Zartman, R.

    SNC meteorites might originate from the Martian surface. However, these meteorites have experienced a relative young metamorphosis which obscures their origin. Pb isotopes seem to be the best way to look through these young disturbances. A major fraction of the U and Th in the SNCs is not a primary constituent but was introduced at the time of disturbance and resides in the phosphates. By contrast, the Pb in the silicate minerals seems to have remained essentially in isotopic equilibration with the U and Th in the mineral since the time of original crystallization. The main cause of any scatter in the determined initial composition is probably due to the addition of terrestrial Pb, although some minor in situ isotopic disturbance cannot be ruled out. Our best values for the initial isotopic ratios of Shergotty, Zagami, and Los Angeles will be shown. The parent body formed and differentiated at 4.55 Ga, and the various meteorite source lithologies evolved isotopically undisturbed until 0.45 Ga (Los Angeles with a µ =238 U/204 Pb of ˜4, Zagami with a µ of ˜4.5, and Shergotty with a µ of ˜5). At ˜0.45 Ga the "young event" affected each of these meteorites and the initial Pb ratios, after being corrected for subsequent in situ growth of radiogenic Pb, are scattering on a fossilized 0.45 Ga geochron. Additional insight is gained from isotopic data for the Nakhlites, including several that have been newly found and analyzed. All Nakhlites appear to have been derived from an isotopic uniform reservoir, and share a well-defined "young event" age of 1.25 Ga. Of particular note is the fact that their initial Pb isotopic composition does not plot on the modern geochron, but instead to the right of it. If experiencing only a single stage evolution prior to 1.25 Ga, its initial Pb should actually plot on a fossilized 1.25 Ga geochron considerably to the left of the modern geochron. Only a relatively recent increase of the U/Pb ratio in the Nakhlite reservoir could

  17. Constraints on the Martian cratering rate imposed by the SNC meteorites and Vallis Marineris layered deposits

    NASA Technical Reports Server (NTRS)

    Brandenburg, J. E.

    1993-01-01

    Following two independent lines of evidence -- estimates of the age and formation time of a portion of the Martian geologic column exposed in the layered deposits and the crystallization and ejection ages of the SNC meteorites -- it appears that the Martian cratering rate must be double the lunar rate or even higher. This means models such as NHII or NHIII (Neukum and Hiller models II and III), which estimate the Martian cratering rate as being several times lunar are probably far closer to reality on Mars than lunar rates. The effect of such a shift is profound: Mars is transformed from a rather Moon-like place into a planet with vigorous dynamics, multiple large impacts, erosion, floods, and volcanism throughout its history. A strong shift upward in cratering rates on Mars apparently solves some glaring problems; however, it creates others. The period of time during which Earth-like atmospheric conditions existed, the liquid water era on Mars, persists in NHIII up to only 0.5 b.y. ago. Scenarios of extended Earth-like conditions on Mars have been discounted in the past because they would have removed many of the craters from the early bombardment era found in the south. It does appear that some process of crater removal was quite vigorous in the north during Mars' past. Evidence exists that the northern plains may have been the home of long-lived seas or perhaps even a paleo-ocean, so models exist for highly localized destruction of craters in the north. However, the question of how the ancient crater population could be preserved in the south under a long liquid-water era found in any high-cratering-rate models is a serious question that must be addressed. It does appear to be a higher-order problem because it involves low-energy dynamics acting in localized areas, i.e., erosion of craters in the south of Mars, whereas the two problems with the low-cratering-rate models involve high-energy events acting over large areas: the formation of the Vallis Marineris

  18. Constraints on the Martian cratering rate imposed by the SNC meteorites and Vallis Marineris layered deposits

    NASA Astrophysics Data System (ADS)

    Brandenburg, J. E.

    Following two independent lines of evidence -- estimates of the age and formation time of a portion of the Martian geologic column exposed in the layered deposits and the crystallization and ejection ages of the SNC meteorites -- it appears that the Martian cratering rate must be double the lunar rate or even higher. This means models such as NHII or NHIII (Neukum and Hiller models II and III), which estimate the Martian cratering rate as being several times lunar are probably far closer to reality on Mars than lunar rates. The effect of such a shift is profound: Mars is transformed from a rather Moon-like place into a planet with vigorous dynamics, multiple large impacts, erosion, floods, and volcanism throughout its history. A strong shift upward in cratering rates on Mars apparently solves some glaring problems; however, it creates others. The period of time during which Earth-like atmospheric conditions existed, the liquid water era on Mars, persists in NHIII up to only 0.5 b.y. ago. Scenarios of extended Earth-like conditions on Mars have been discounted in the past because they would have removed many of the craters from the early bombardment era found in the south. It does appear that some process of crater removal was quite vigorous in the north during Mars' past. Evidence exists that the northern plains may have been the home of long-lived seas or perhaps even a paleo-ocean, so models exist for highly localized destruction of craters in the north. However, the question of how the ancient crater population could be preserved in the south under a long liquid-water era found in any high-cratering-rate models is a serious question that must be addressed. It does appear to be a higher-order problem because it involves low-energy dynamics acting in localized areas, i.e., erosion of craters in the south of Mars, whereas the two problems with the low-cratering-rate models involve high-energy events acting over large areas: the formation of the Vallis Marineris

  19. A new Martian meteorite from Morocco: the nakhlite North West Africa 817

    NASA Astrophysics Data System (ADS)

    Sautter, V.; Barrat, J. A.; Jambon, A.; Lorand, J. P.; Gillet, Ph.; Javoy, M.; Joron, J. L.; Lesourd, M.

    2002-02-01

    North West Africa (NWA 817) is a single stone of 104 g found in the Sahara (Morocco) by meteorite hunters in November 2000. The meteorite is an unbrecciated, medium-grained olivine-bearing clinopyroxenite with a cumulate texture. It consists of zoned euhedral subcalcic augite (Wo 42En 38-22Fs 20-36), olivine spanning a wide range of compositions (from Fa 56 in the core to Fa 86) with rare magmatic inclusions and an intercumulus mesostasis made of Fe-bearing albitic plagioclase, Si-rich glass, Ti-magnetite with unusual skeletal growth morphologies containing ilmenite exsolutions, acicular pyroxene, olivine and cristobalite. Trace minerals are sulfide droplets and Cl-apatite. Mineral modes (in vol%) are augite 69%, olivine 10%, mesostasis 20% and Fe-Ti oxides 1%. Pervasive alteration produced a reddish clay mineral (hydrous ferrous silicate) in both olivine crystals and the mesostasis. The major element composition of NWA 817 is very similar to that of the other nakhlites: high FeO, MgO and CaO concentrations reflect the abundance of cumulus augite and olivine. Key element ratios such as FeO/MnO (=37), Na/Al (=0.40), K/La (=449), Ga/Al (=3.9×10 -4) and oxygen isotopic composition (Δ 17O=+0.37‰) are clear evidence for a Martian origin. The incompatible trace element pattern as in Nakhla displays a strong light rare earth element enrichment relative to chondrite (La n/Yb n=4.89). However, when compared to the other nakhlites, NWA 817 has specific features: (1) a higher modal proportion of mesostasis; (2) quench textures of Ti-magnetite and Fe-rich clinopyroxene; (3) more Mg-rich olivine core compositions whereas the augite core composition is identical for all nakhlites; (4) a stronger Fe enrichment toward crystal rims of these cumulus minerals. The intercumulus minerals (Ti-magnetite with skeletal growth morphology, acicular chains of clinopyroxene and Fe 3+-rich feldspar) indicate rapid crystallization in response to a high degree of undercooling at the end of

  20. Northwest Africa 4797: A strongly shocked ultramafic poikilitic shergottite related to compositionally intermediate Martian meteorites

    NASA Astrophysics Data System (ADS)

    Walton, E. L.; Irving, A. J.; Bunch, T. E.; Herd, C. D. K.

    2012-09-01

    Northwest Africa (NWA) 4797 is an ultramafic Martian meteorite composed of olivine (40.3 vol%), pigeonite (22.2%), augite (11.9%), plagioclase (9.1%), vesicles (1.6%), and a shock vein (10.3%). Minor phases include chromite (3.4%), merrillite (0.8%), and magmatic inclusions (0.4%). Olivine and pyroxene compositions range from Fo66-72,En58-74Fs19-28Wo6-15, and En46-60Fs14-22Wo34-40, respectively. The rock is texturally similar to "lherzolitic" shergottites. The oxygen fugacity was QFM-2.9 near the liquidus, increasing to QFM-1.7 as crystallization proceeded. Shock effects in olivine and pyroxene include strong mosaicism, grain boundary melting, local recrystallization, and pervasive fracturing. Shock heating has completely melted and vesiculated igneous plagioclase, which upon cooling has quench-crystallized plagioclase microlites in glass. A mm-size shock melt vein transects the rock, containing phosphoran olivine (Fo69-79), pyroxene (En44-51Fs14-18Wo30-42), and chromite in a groundmass of alkali-rich glass containing iron sulfide spheres. Trace element analysis reveals that (1) REE in plagioclase and the shock melt vein mimics the whole rock pattern; and (2) the reconstructed NWA 4797 whole rock is slightly enriched in LREE relative to other intermediate ultramafic shergottites, attributable to local mobilization of melt by shock. The shock melt vein represents bulk melting of NWA 4797 injected during pressure release. Calculated oxygen fugacity for NWA 4797 indicates that oxygen fugacity is decoupled from incompatible element concentrations. This is attributed to subsolidus re-equilibration. We propose an alternative nomenclature for "lherzolitic" shergottites that removes genetic connotations. NWA 4797 is classified as an ultramafic poikilitic shergottite with intermediate trace element characteristics.

  1. Significance of the cosmogenic argon correction in deciphering the 40Ar/39Ar ages of the Nakhlite (Martian) meteorites

    NASA Astrophysics Data System (ADS)

    Cohen, B. E.; Cassata, W.; Mark, D. F.; Tomkinson, T.; Lee, M. R.; Smith, C. L.

    2015-12-01

    All meteorites contain variable amounts of cosmogenic 38Ar and 36Ar produced during extraterrestrial exposure, and in order to calculate reliable 40Ar/39Ar ages this cosmogenic Ar must be removed from the total Ar budget. The amount of cosmogenic Ar has usually been calculated from the step-wise 38Ar/36Ar, minimum 36Ar/37Ar, or average 38Arcosmogenic/37Ar from the irradiated meteorite fragment. However, if Cl is present in the meteorite, then these values will be disturbed by Ar produced during laboratory neutron irradiation of Cl. Chlorine is likely to be a particular issue for the Nakhlite group of Martian meteorites, which can contain over 1000 ppm Cl [1]. An alternative method for the cosmogenic Ar correction uses the meteorite's exposure age as calculated from an un-irradiated fragment and step-wise production rates based on the measured Ca/K [2]. This calculation is independent of the Cl concentration. We applied this correction method to seven Nakhlites, analyzed in duplicate or triplicate. Selected samples were analyzed at both Lawrence Livermore National Laboratory and SUERC to ensure inter-laboratory reproducibility. We find that the cosmogenic argon correction of [2] has a significant influence on the ages calculated for individual steps, particularly for those at lower temperatures (i.e., differences of several tens of million years for some steps). The lower-temperature steps are more influenced by the alternate cosmogenic correction method of [2], as these analyses yielded higher concentrations of Cl-derived 38Ar. As a result, the Nakhlite data corrected using [2] yields step-heating spectra that are flat or nearly so across >70% of the release spectra (in contrast to downward-stepping spectra often reported for Nakhlite samples), allowing for the calculation of precise emplacement ages for these meteorites. [1] Cartwright J. A. et al. (2013) GCA, 105, 255-293. [2] Cassata W. S., and Borg L. E. (2015) 46th LPSC, Abstract #2742.

  2. Cosmogenic Nuclides Study of Large Iron Meteorites

    NASA Astrophysics Data System (ADS)

    Hutzler, A.; Smith, T.; Rochette, P.; Bourles, D. L.; Leya, I.; Gattacceca, J.

    2014-09-01

    Six large iron meteorites were selected (Saint-Aubin, Mont-Dieu, Caille, Morasko, Agoudal, and Gebel Kamil). We measured stable and radiogenic cosmogenic nuclides, to study pre-atmospheric size, cosmic-ray exposure ages and terrestrial ages.

  3. What Were the Major Factors That Controlled Mineralogical Similarities and Differences of Basaltic, Lherzolitic and Clinopyroxentic Martian Meteorites Within Each Group

    NASA Technical Reports Server (NTRS)

    Mikouchi, T.; Miyamoto, M.; McKay, G. A.

    1998-01-01

    Twelve martian meteorites that have been re- covered so far are classified into five groups (basalt, lherzolite, clinopyroxenite, dunite, and orthopyroxenite) mainly from petrology and chemistry. Among them, the dunite and orthopyroxenite groups consist of only one meteorite each (dunite: Chassigny, orthopyroxenite: ALH 84001). The basalt group is the largest group and consists of four meteorites (Shergotty, Zagani, EETA 79001, and QUE 94201). The lherzolitic and clinopyroxenitic groups include three meteorites each (Lherzolite: ALH 77005, LEW 88516, and Y793605, clinopyroxenite: Nakhla, Governador Valadares, and Lafayette). These meteorites within each group are generally similar to the others, but none of them is paired with the others. In this abstract, we discuss the major factors that controlled mineralogical similarities and differences of basaltic, lherzolitic, and clinopyroxenitic meteorites within each group. This may help in understanding their petrogenesis and original locations on Mars in general.

  4. The Northwest Africa (NWA) 5790 meteorite: A mesostasis-rich nakhlite with little or no Martian aqueous alteration

    NASA Astrophysics Data System (ADS)

    Tomkinson, Tim; Lee, Martin R.; Mark, Darren F.; Dobson, Katherine J.; Franchi, Ian A.

    2015-02-01

    Northwest Africa (NWA) 5790 is the most recently discovered member of the nakhlite group. Its mineralogy differs from the other nakhlites with a high abundance mesostasis (38.1 ± 3.6 vol%) and scarcity of olivine (4.0 ± 2.2 vol%). Furthermore, zoning of augite phenocrysts, and other petrographic and chemical characteristics suggest that NWA 5790 samples the chilled margin of its parent lava flow/sill. NWA 5790 contains calcite and rare clay minerals that are evidence for its exposure to liquid water. The calcite forms a cement to coatings of dust on the outer surface of the find and extends into the interior of the meteorite within veins. The presence of microbial remains within the coating confirms that the dust and its carbonate cement are terrestrial in origin, consistent with the carbon and oxygen isotope composition of the calcite. The clay minerals are finely crystalline and comprise ~0.003 vol% of the meteorite. δD values of the clay minerals range from -212 ± 109‰ to -96 ± 132‰, and cannot be used to distinguish between a terrestrial or Martian origin. As petrographic results are also not definitive, we conclude that secondary minerals produced by Martian groundwaters are at best very rare within NWA 5790. The meteorite has therefore sampled a region of the lava flow/sill with little or no exposure to the aqueous solutions that altered other nakhlites. This isolation could relate to the scarcity of olivine in NWA 5790 because dissolution of olivine in other nakhlites by Martian groundwaters enhanced their porosity and permeability, and provided solutes for secondary minerals.

  5. Gypsum, jarosite, and hydrous iron-phosphate in Martian meteorite Roberts Massif 04262: Implications for sulfate geochemistry on Mars.

    NASA Astrophysics Data System (ADS)

    Greenwood, J. P.

    2008-12-01

    Gypsum has been identified on Mars by MEX OMEGA [1] and jarosite identified via MER-B lander [2] and both minerals are examples of the importance of calcium and iron sulfates in Martian weathering processes. The weathering of Martian basalt to form Ca and iron sulfates should be an important process on Mars. Martian jarosite has been identified in MIL 03346 [3] and Ca-sulfate has been identified in EETA 79001 [4], but both phases have yet to be identified in the same Martian sample. In Roberts Massif 04262, an olivine-phyric shergottite, iron-sulfide and calcium-phosphate minerals are undergoing reaction (dissolution and reprecipitation?) to form gypsum, jarosite, and an iron-phosphate phase, presumably during the meteorite's residence in Antarctica. If true, then an acidic and oxidizing fluid was present in this meteorite, due to the formation of jarosite which requires fluid of this type to form [5]. The weathering of iron-sulfides on Earth to form acidic and oxidizing fluids is common, thus this can be reconciled with the formation of an acidic fluid in a basic rock. Presumably, under more extensive weathering of silicate minerals in Martian basalt, the pH would be raised to values where jarosite would not be stable. While the weathering of RBT 04262 is likely occurring in Antarctica, a similar susceptibility of the apatite and pyrrhotite to incipient weathering on Mars may be expected. Oxidizing crustal fluids on Mars may attack iron- sulfides first in Martian basalts. The weathering of iron-sulfides leads to increasing acidity of fluids, which would enhance the dissolution of the calcium-phosphate minerals [6]. The formation of jarosite, gypsum, and iron-phosphate minerals during the early stages of weathering of Martian basalts may be an important process on Mars globally. [1] Gendrin, A. et al. (2005) Science, 307, 1587-1591. [2] Klingelhöfer et al. (2004) Science, 306, 1740- 1745. [3] Vicenzi E. P. et al. (2007) LPSC XXXVIII, Abstract 2335. [4] Gooding J

  6. The variability of ruthenium in chromite from chassignite and olivine-phyric shergottite meteorites: New insights into the behavior of PGE and sulfur in Martian magmatic systems

    NASA Astrophysics Data System (ADS)

    Baumgartner, Raphael J.; Fiorentini, Marco L.; Baratoux, David; Ferrière, Ludovic; Locmelis, Marek; Tomkins, Andrew; Sener, Kerim A.

    2017-02-01

    The Martian meteorites comprise mantle-derived mafic to ultramafic rocks that formed in shallow intrusions and/or lava flows. This study reports the first in situ platinum-group element data on chromite and ulvöspinel from a series of dunitic chassignites and olivine-phyric shergottites, determined using laser-ablation ICP-MS. As recent studies have shown that Ru has strongly contrasting affinities for coexisting sulfide and spinel phases, the precise in situ analysis of this element in spinel can provide important insights into the sulfide saturation history of Martian mantle-derived melts. The new data reveal distinctive differences between the two meteorite groups. Chromite from the chassignites Northwest Africa 2737 (NWA 2737) and Chassigny contained detectable concentrations of Ru (up to 160 ppb Ru) in solid solution, whereas chromite and ulvöspinel from the olivine-phyric shergottites Yamato-980459 (Y-980459), Tissint, and Dhofar 019 displayed Ru concentrations consistently below detection limit (<42 ppb). The relatively elevated Ru signatures of chromite from the chassignites suggest a Ru-rich ( 1-4 ppb) parental melt for this meteorite group, which presumably did not experience segregation of immiscible sulfide liquids over the interval of mantle melting, melt ascent, and chromite crystallization. The relatively Ru-depleted signature of chromite and ulvöspinel from the olivine-phyric shergottites may be the consequence of relatively lower Ru contents (<1 ppb) in the parental melts, and/or the presence of sulfides during the crystallization of the spinel phases. The results of this study illustrate the significance of platinum-group element in situ analysis on spinel phases to decipher the sulfide saturation history of magmatic systems.

  7. Truncated Hexa-Octahedral Magnetite Crystals in Martian Meteorite ALH84001: Evidence of Biogenic Activity on Early Mars

    NASA Technical Reports Server (NTRS)

    Thomas-Keprta, K.; Clemett, S. J.; Schwartz, C.; McIntosh, J. R.; Bazylinski, D. A.; Kirschvink, J.; McKay, D. S.; Gibson, E. K.; Vali, H.; Romanek, C. S.

    2004-01-01

    The landmark paper by McKay et al. [1] cited four lines of evidence associated with the Martian meteorite ALH84001 to support the hypothesis that life existed on Mars approximately 4 Ga ago. Now, more than five years later, attention has focused on the ALH84001 magnetite grains embedded within carbonate globules in the ALH84001 meteorite. We have suggested that up to approx.25% of the ALH84001 magnetite crystals are products of biological activity [e.g., 2]. The remaining magnetites lack sufficient characteristics to constrain their origin. The papers of Thomas Keprta et al. were criticized arguing that the three dimensional structure of ALH84001 magnetite crystals can only be unambiguously determined using electron tomographic techniques. Clemett et al. [3] confirmed that magnetites produced by magnetotactic bacteria strain MV-I display a truncated hexa-octahedral geometry using electron tomography and validated the use of the multi-tilt classical transmission microscopy technique used by [2]. Recently the geometry of the purported martian biogenic magnetites was shown be identical to that for MV-1 magnetites using electron tomography [6].

  8. Hydrogeological Interpretation of Candidate Origin Sites for Martian Meteorite ALH84001

    NASA Technical Reports Server (NTRS)

    Gulick, Virginia C.; McKay, Chris; Cuzzi, Jeffrey N. (Technical Monitor)

    1996-01-01

    Barlow (this meeting) has identified two potential source craters for the martian meteorite ALH84001. The craters are at 11.7 deg S, 243.3 deg W (Mare Tyrrhenum site) and 14.0 deg S, 343.5 deg W (Sinus Sabaeus site). As noted by Barlow, both craters lie in the heavily cratered terrain (HCT) and are adjacent to fluvial valleys, Here I explore the fluvial history of these areas based upon the surrounding valley morphology. The most prominent valley network at the Sabaeus site is Evros Vallis. This wide, flat-floored valley is approximately 600 km long with an average width of 2.5 km and a depth of 220 m. The eroded volume of the entire Evros network is approximately 6 x 10(exp 11) cc. This is typical for networks located in the heavily cratered terrain (e.g. Warrego and Parana Valles). Evros is also an isolated valley system. No similar networks are found in the surrounding terrain. Thus it is unlikely that Evros formed as a result of widespread rainfall. A localized water source, such as discharge of a hydrothermal system or localized melting of snowfall, seems more consistent Previous modeling has demonstrated that only hydrothermal systems associated with high permeability subsurfaces can discharge sufficient water to form a valley network. The bulk of the discharge from such systems is consequently low temperature, slightly heated water Precipitation of calcium carbonate by low temperature fluids is consistent with most interpretations of the geochemistry of ALH84001. Available imagery at the Tyrrhenum site is of lesser quality. While eroded units of the HCT are nearby, there are no comparable well developed valley networks at this site. Erosion is instead manifested predominantly as gullies on slopes. This style of erosion suggests that water was not present at this site for the length of time as at the more integrated Sabaeus site. The superposition of fluidized ejecta blankets suggests however that ground water or ground ice was still present at this locality

  9. Smectite Formation in Gale Crater, Mars and in the Nakhlite Martian Meteorites

    NASA Astrophysics Data System (ADS)

    Bridges, J.; Schwenzer, S. P.; Leveille, R. J.; Westall, F.; Wiens, R. C.; Mangold, N.; Bristow, T.; Edwards, P.

    2014-12-01

    Recent, detailed analyses of the nakhlite martian meteorites have enabled characterization of a ferric saponite and ferric serpentine (Hicks et al. 2014 10.1016/j.gca.2014.04.010). This nakhlite assemblage is part of a rapidly cooled, hydrothermal assemblage, cooled from ~150 oC, with the clay forming at ~50 oC (Bridges and Schwenzer 2012 10.1016/j.epsl.2012.09.044). Although there are differences between the overall secondary assemblage in the nakhlites and that identified in the Yellowknife Bay mudstones by CheMin (Vaniman et al. 2014 10.1126/science1243480), the trioctahedral iron-rich saponite is probably the closest analogue known to the smectite found in Gale Crater. MSL analysed mudstones at the Yellowknife Bay, deposited in a fluvio-lacustrine setting followed by diagenesis ~50 oC (Grotzinger et al. 2014 10.1126/science.1242777). The mineralogical information provides allows us to constrain mineral reactions, W/R, pH, and redox associated using thermochemical modelling, and comparisons to the nakhlites. We use a 2 stage fluid model, with an initial Deccan-type brine composition (Minissale et al. 2000 10.1016/S0012-821X(00)00200-4) which reacts with the known rock compositions - using ChemCam and APXS data to produce a pore fluid. CHIM-XPT was used for the modelling. Initial reaction of the early brine with olivine in the mudstone produces relatively Mg-rich phyllosilicate. This early diagenesis may correspond to the formation of Mg-Fe rich ridges (Leveille et al. 10.1002/2014JE004620). Subsequent reaction of the resultant fluid separated at a W/R of 100, produced a fluid that we then reacted with a range of different mineral and amorphous mixtures, T, W/R conditions. A mixture of 70% amorphous, 20% olivine, 10% host rock produced a clay-Fe oxide dominated assemblage, similar to that in Sheepbed. The clay has a similar composition to ferric saponite and gel in the nakhlites (Bridges et al. JGR, subm.).

  10. Martian Volatiles and Isotopic Signatures

    NASA Technical Reports Server (NTRS)

    Bogard, Donald D.

    1997-01-01

    Data on martian volatiles gathered from Viking atmosphere measurements, modest groundbased spectra, shock-implanted atmospheric gases in martian (SNC) meteorites, trapped mantle gases in martian meteorites, and volatile-rich solid phases in martian meteorites, are presented. Atmospheric volatiles, surface volatiles, and isotopic chronologies are discussed, along with energetic particle interactions.

  11. Methane Emission from the Murchison Meteorite Induced by Ultraviolet Radiation and its Potential Impact on the Martian Atmosphere

    NASA Astrophysics Data System (ADS)

    Keppler, F.; Vigano, I.; McLeod, A.; Ott, U.; Roeckmann, T.

    2011-12-01

    Almost a decade ago three independent groups of scientists announced the discovery of methane in the atmosphere of Mars at concentrations up to several tens of parts per billion (Mumma et al., 2003; Krasnopolsky et al., 2004; Formisano et al., 2004). Since then there has been an ongoing debate as to whether the formation processes are of geological or biological origin because methane is considered to be unstable in the Martian atmosphere, with a lifetime of a few hundred years or even less (Lefèvre and Forget 2009). Thus a process on or below the planet surface must be continuously replacing it. Furthermore methane release appears to be non-uniform over the planet because it was observed as plumes over certain regions in Northern Summer (Mumma et al. 2009). A biological origin would provide support for the theory of some form of life or potential life on the planet, whereas a geological origin would imply that there is unusual geological activity occurring on it. Almost ten possible mechanisms may be involved in the production of methane on Mars (Schürger et al. 2011) including subsurface clathrates and serpentinization of olivine, geothermal outgassing or biological methanogenic processes. However, all hypotheses explaining methane formation on Mars also have shortcomings. For example, methane release from meteorites as a product of ablation and pyrolysis upon atmospheric entry of carbonaceous chondrites was estimated to account only for a negligible fraction of Martian methane (Court and Sephton 2009). In this presentation we show that methane is produced in significant quantities from the carbonaceous chondrite Murchison (CM2) when exposed to ultraviolet radiation similar to Martian surface conditions. Emission rates depend on temperature and atmospheric pressure. Stable carbon and hydrogen isotope analyses of methane released from Murchison were also determined and confirm that the methane emitted from Murchison is of extraterrestrial origin. Our results

  12. Degradation studies of Martian impact craters

    NASA Technical Reports Server (NTRS)

    Barlow, N. G.

    1991-01-01

    The amount of obliteration suffered by Martian impact craters is quantified by comparing measurable attributes of the current crater shape to those values expected for a fresh crater of identical size. Crater diameters are measured from profiles obtained using photoclinometry across the structure. The relationship between the diameter of a fresh crater and a crater depth, floor width, rim height, central peak height, etc. was determined by empirical studies performed on fresh Martian impact craters. We utilized the changes in crater depth and rim height to judge the degree of obliteration suffered by Martian impact craters.

  13. A Parent Magma for the Nakhla Martian Meteorite: Reconciliation of Estimates from 1-Bar Experiments, Magmatic Inclusions in Olivine, and Magmatic Inclusions in Augite

    NASA Technical Reports Server (NTRS)

    Treiman, Allan H.; Goodrich, Cyrena Anne

    2001-01-01

    The composition of the parent magma for the Nakhla (martian) meteorite has been estimated from mineral-melt partitioning and from magmatic inclusions in olivine and in augite. These independent lines of evidence have converged on small range of likely compositions. Additional information is contained in the original extended abstract.

  14. A Parent Magma for the Nakhla Martian Meteorite: Reconciliation of Estimates from 1-Bar Experiments, Magmatic Inclusions in Olivine, and Magmatic Inclusions in Augite

    NASA Technical Reports Server (NTRS)

    Treiman, Allan H.; Goodrich, Cyrena Anne

    2001-01-01

    The composition of the parent magma for the Nakhla (martian) meteorite has been estimated from mineral-melt partitioning and from magmatic inclusions in olivine and in augite. These independent lines of evidence have converged on small range of likely compositions. Additional information is contained in the original extended abstract.

  15. Evidence of martian perchlorate, chlorate, and nitrate in Mars meteorite EETA79001: Implications for oxidants and organics

    NASA Astrophysics Data System (ADS)

    Kounaves, Samuel P.; Carrier, Brandi L.; O'Neil, Glen D.; Stroble, Shannon T.; Claire, Mark W.

    2014-02-01

    The results from the Viking mission in the mid 1970s provided evidence that the martian surface contained oxidants responsible for destroying organic compounds. In 2008 the Phoenix Wet Chemistry Lab (WCL) found perchlorate (ClO4-) in three soil samples at concentrations from 0.5 to 0.7 wt%. The detection of chloromethane (CH3Cl) and dichloromethane (CH2Cl2) by the Viking pyrolysis gas chromatograph-mass spectrometer (GC-MS) may have been a result of ClO4- at that site oxidizing either terrestrial organic contaminates or, if present, indigenous organics. Recently, the Sample Analysis at Mars (SAM) instrument on the Mars Science Laboratory (MSL) Curiosity directly measured the presence of CH3Cl, CH2Cl2 and, along with measurements of HCl and oxygen, indirectly indicate the presence of ClO4-. However, except for Phoenix, no other direct measurement of the ClO4- anion in martian soil or rock has been made. We report here ion chromatographic (IC) and isotopic analyses of a unique sawdust portion of the martian meteorite EETA79001 that show the presence by mass of 0.6 ± 0.1 ppm ClO4-, 1.4 ± 0.1 ppm ClO3-, and 16 ± 0.2 ppm NO3- at a quantity and location within the meteorite that is difficult to reconcile with terrestrial contamination. The sawdust sample consists of basaltic material with a minor salt-rich inclusion in a mass ratio of ∼300:1, thus the salts may be 300 times more concentrated within the inclusion than the whole sample. The molar ratios of NO3-:ClO4- and Cl:ClO4-, are very different for EETA79001 at ∼40:1 and 15:1, respectively, than the Antarctic soils and ice near where the meteorite was recovered at ∼10,000:1 and 5000:1, respectively. In addition, the isotope ratios for EETA79001 with δ15N = -10.48 ± 0.32‰ and δ18O = +51.61 ± 0.74‰ are significantly different from that of the nearby Miller Range blue ice with δ15N = +102.80 ± 0.14‰ and δ18O = +43.11 ± 0.64‰. This difference is notable, because if the meteorite had been

  16. Thirteen Iron Meteorites Found at Gale Crater, Meridiani Planum, and Gusev Crater — Exogenic Witnesses to Weathering Processes Near the Martian Equator

    NASA Astrophysics Data System (ADS)

    Ashley, J.

    2014-12-01

    At least 20 meteorites and meteorite candidates have now been found by science teams at three Mars rover landing sites, all within 15 degrees of the martian equator. Thirteen of these are iron meteorites, comprising 65% of the population — an order of magnitude greater abundance than found among witnessed iron falls in Earth-based collections (~6%). Chondritic meteorites, which comprise some 86% of Earth-based falls, are conspicuously absent from the Mars inventory. The reasons for this disproportion may involve a) post-fall environmental resistance differences favoring iron survivability; b) fragmentation from impact shock (and possibly internal weathering stresses associated with oxide production in desert environments [1]); combined with c) selection biases arising from residual chondritic fragments appearing less conspicuous. Impact features along rover traverses often show evidence of dark materials likely to be impactor fragments [e.g., 2], which could represent the missing chondritic fraction. The reactivity of reduced (metallic) iron to aqueous alteration, combined with the near equatorial and widely distributed locations of these rocks, makes them particularly useful to the assessment of climate models arguing for geologically recent ice at the martian equator. Exposure histories involving alternating wind/water cycles are imprinted on several Meridiani irons, for example [3]. Evidence for oxide coating removal demonstrates the current epoch to be one of coating destruction, not production, showing that atmospheric exposure alone is insufficient to produce the coating. Cavernous weathering is likely associated with acidic corrosion, while evidence of aeolian scouring is found in Widmanstätten patterns, sharp-crested scallops, regmaglypt enlargement, and abundant pitting. Further study of these features could help constrain wind direction and velocity during epochs of sculpting [e.g., 4], and assist in exposure age estimation. References: [1] Ashley J. W

  17. The chlorine isotope composition of Martian meteorites 2. Implications for the early solar system and the formation of Mars

    NASA Astrophysics Data System (ADS)

    Sharp, Zachary; Williams, Jeffrey; Shearer, Charles; Agee, Carl; McKeegan, Kevin

    2016-11-01

    We determined the chlorine isotope composition of 16 Martian meteorites using gas source mass spectrometry on bulk samples and in situ secondary ion microprobe analysis on apatite grains. Measured δ37Cl values range from -3.8 to +8.6‰. The olivine-phyric shergottites are the isotopically lightest samples, with δ37Cl mostly ranging from -4 to -2‰. Samples with evidence for a crustal component have positive δ37Cl values, with an extreme value of 8.6‰. Most of the basaltic shergottites have intermediate δ37Cl values of -1 to 0‰, except for Shergotty, which is similar to the olivine-phyric shergottites. We interpret these data as due to mixing of a two-component system. The first component is the mantle value of -4 to -3‰. This most likely represents the original bulk Martian Cl isotope value. The other endmember is a 37Cl-enriched crustal component. We speculate that preferential loss of 35Cl to space has resulted in a high δ37Cl value for the Martian surface, similar to what is seen in other volatile systems. The basaltic shergottites are a mixture of the other two endmembers. The low δ37Cl value of primitive Mars is different from Earth and most chondrites, both of which are close to 0‰. We are not aware of any parent-body process that could lower the δ37Cl value of the Martian mantle to -4 to -3‰. Instead, we propose that this low δ37Cl value represents the primordial bulk composition of Mars inherited during accretion. The higher δ37Cl values seen in many chondrites are explained by later incorporation of 37Cl-enriched HCl-hydrate.

  18. Martian low-temperature alteration materials in shock-melt pockets in Tissint: Constraints on their preservation in shergottite meteorites

    NASA Astrophysics Data System (ADS)

    Kuchka, C. R.; Herd, C. D. K.; Walton, E. L.; Guan, Y.; Liu, Y.

    2017-08-01

    We apply an array of in situ analytical techniques, including electron and Raman microscopy, electron and ion probe microanalysis, and laser ablation mass spectrometry to the Tissint martian meteorite in order to find and elucidate a geochemical signature characteristic of low-temperature alteration at or near the martian surface. Tissint contains abundant shock-produced quench-crystallized melt pockets containing water in concentrations ranging from 73 to 1730 ppm; water content is positively correlated with Cl content. The isotopic composition of hydrogen in the shock-produced glass ranges from δD = 2559 to 4422‰. Water is derived from two distinct hydrogen reservoirs: the martian near-surface (>500‰) and the martian mantle (-100‰). In one shock melt pocket comprising texturally homogeneous vesiculated glass, the concentration of H in the shock melt decreases while simultaneously becoming enriched in D, attributable to the preferential loss of H over D to the vesicle while the pocket was still molten. While igneous sulfides are pyrrhotite in composition (Fe0.88-0.90S), the iron to sulfur ratios of spherules in shock melt pockets are elevated, up to Fe1.70S, which we attribute to shock-oxidation of igneous pyrrhotite and the formation of hematite at high temperature. The D- and Cl-enrichment, and higher oxidation of the pockets (as indicated by hematite) support a scenario in which alteration products formed within fractures or void spaces within the rock; the signature of these alteration products is preserved within shock melt (now glass) which formed upon collapse of these fractures and voids during impact shock. Thermal modeling of Tissint shock melt pockets using the HEAT program demonstrates that the shock melt pockets with the greatest potential to preserve a signature of aqueous alteration are small, isolated from other regions of shock melt, vesicle-free, and glassy.

  19. Extraterrestrial water of possible Martian origin in SNC meteorites: Constraints from oxygen isotopes

    NASA Technical Reports Server (NTRS)

    Karlsson, H. R.; Clayton, R. N.; Gibson, E. K.; Mayeda, T. K.; Socki, R. A.

    1991-01-01

    Many lines of evidence suggest that the SNC group of meteorites (Shergotty-Nakhla-Chassigny) are derived from the planet Mars. Because SNC meteorites have water, they may contain information on the origin and fate of water on the planet Mars. The first measurements are presented of delta O-18 and delta O-17 of water extracted from SNC's. The water analyses are displayed with each meteorite designated. The isotopic composition is shown of the SNC waters relative to the SNC whole rocks and the terrestrial line. The O-17 excess is shown of the SNC water as a function of pyrolysis temperature. And delta O-18 values are displayed of the water as a function of pyrolysis temperature for the four SNC meteorites. The analyses are briefly examined.

  20. Reassessing the cooling rate and geologic setting of Martian meteorites MIL 03346 and NWA 817

    NASA Astrophysics Data System (ADS)

    Richter, Frank; Chaussidon, Marc; Mendybaev, Ruslan; Kite, Edwin

    2016-06-01

    Lithium concentration and isotopic fractionation profiles across augite grains from two Martian meteorites - MIL 03346 and NWA 817 - were used to determine their thermal history and implications for their geologic setting. The iron-magnesium zoning and associated magnesium isotopic fractionation of olivine grains from NWA 817 were also measured and provide a separate estimate of the cooling rate. The observed correlation of concentration with isotopic fractionation provides the essential evidence that the zoning of these grains was in fact due to diffusion and thus can be used as a measure of their cooling rate. The diffusion rate of lithium in augite depends on the oxygen fugacity, which has to be taken into account when determining a cooling rate based on the lithium zoning. The Fe-Mg exchange in olivine is much less sensitive to oxygen fugacity, but it is significantly anisotropic and for this reason we determined the direction relative to crystallographic axes of the line along which the Fe-Mg zoning was measured. We found that the cooling rate of NWA 817 determined from the lithium zoning in augite grains and that based on the Fe-Mg zoning of olivines are in good agreement at an oxygen fugacity close to that of quartz-fayalite-magnetite oxygen buffer. The cooling rate of MIL 03346 was found to be resolvably faster than that of NWA 817 - of the order of 1 °C/h for the former and of the order of 0.2 °C/h for the latter. An important observation regarding the history of MIL 03346 and NWA 817 is that the lithium and Fe-Mg zoning are only observed where the augite or olivine is in contact with the mesostasis, which implies that they were already about 80% crystallized at the time diffusion began. The augite and olivine core compositions while very homogeneous are not in equilibrium with each other, which we interpret to imply that prior to the rapid cooling there must have been a protracted period of the order of years above the solidus, during which the much

  1. Formation of Carbonate Minerals in Martian Meteorite ALH 84001 from Cool Water Near the Surface of Mars

    NASA Astrophysics Data System (ADS)

    Taylor, G. J.

    2011-12-01

    Carbonate minerals in the Allan Hills 84001 meteorite are important because they ought to contain information about the chemistry and temperature of the water they formed in. They are also an important part of testing the idea that the meteorite contains evidence of past life on Mars. Hypotheses for the origin of the carbonates are impressively varied. A key test of the ideas is to determine the temperature at which the carbonates formed. Estimates up to now range from a bit below freezing to 700 oC, too big a range to test anything! To address the problem Itay Halevy, Woodward Fischer, and John Eiler (Caltech) used an approach that involves "clumped" isotope thermometry, which makes comparisons among different isotopic compositions of extracted CO2. This allowed the investigators to use the isotopic abundances of both carbon and oxygen. The results indicate that the carbonates formed at 18 ± 4 oC from a shallow subsurface (upper few meters to tens of meters) pool of water that was gradually evaporating. The wet episode did not last long, leading Halevy and his colleagues to conclude that the environment may have been too transient for life to have emerged here from scratch. On the other hand, if life already existed on the Martian surface this wet near-surface environment would have provided a happy home. An impact blasted the Martian home of ALH 84001, causing a transient heating event, perhaps disturbing the isotopic record...or perhaps not because the event was so short. In any case, the clumped isotope thermometry approach seems to have given a good measurement of the temperature at which the carbonate minerals formed.

  2. Metal-saturated sulfide assemblages in NWA 2737: Evidence for impact-related sulfur devolatilization in Martian meteorites

    NASA Astrophysics Data System (ADS)

    Lorand, Jean-Pierre; Barrat, Jean-Alix; Chevrier, Vincent; Sautter, Violaine; Pont, Sylvain

    2012-11-01

    Abstract-NWA 2737, a <span class="hlt">Martian</span> <span class="hlt">meteorite</span> from the Chassignite subclass, contains minute amounts (0.010 ± 0.005 vol%) of metal-saturated Fe-Ni sulfides. These latter bear evidence of the strong shock effects documented by abundant Fe nanoparticles and planar defects in Northwest Africa (NWA) 2737 olivine. A Ni-poor troilite (Fe/S = 1.0 ± 0.01), sometimes Cr-bearing (up to 1 wt%), coexists with micrometer-sized taenite/tetrataenite-type native Ni-Fe alloys (Ni/Fe = 1) and Fe-Os-Ir-(Ru) alloys a few hundreds of nanometers across. The troilite has exsolved flame-like pentlandite (Fe/Fe + Ni = 0.5-0.6). Chalcopyrite is almost lacking, and no pyrite has been found. As a hot desert find, NWA 2737 shows astonishingly fresh sulfides. The composition of troilite coexisting with Ni-Fe alloys is completely at odds with Chassigny and Nahkla sulfides (pyrite + metal-deficient monoclinic-type pyrrhotite). It indicates strongly reducing crystallization conditions (close to IW), several log units below the fO2 conditions inferred from chromites compositions and accepted for Chassignites (FMQ-1 log unit). It is proposed that reduction in sulfides into base and precious metal alloys is operated via sulfur degassing, which is supported by the highly resorbed and denticulated shape of sulfide blebs and their spongy textures. Shock-related S degassing may be responsible for considerable damages in magmatic sulfide structures and sulfide assemblages, with concomitant loss of magnetic properties as documented in some other <span class="hlt">Martian</span> <span class="hlt">meteorites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995Metic..30R.580S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995Metic..30R.580S"><span>Stable Isotope Enrichment of Carbonate from the <span class="hlt">Martian</span> <span class="hlt">Meteorite</span> ALH84001: Test of a Hypothesis at Wright Valley, Antarctica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Socki, R. A.; Gibson, E. K., Jr.; Romanek, C. S.</p> <p>1995-09-01</p> <p>We report here the stable isotope composition of carbonate measured from a suite of desert soils from the Dry Valleys of Antarctica [1] to determine the 13C enrichments attributed to cryogenic freezing in terrestrial environments. These data are then used to gauge whether cryogenic freezing is a viable aqueous process that can produce extreme 13C enrichments observed in <span class="hlt">Martian</span> carbonates (e.g., ALH 84001 [2]). Analyses of ALH 84001 have shown that the delta^(13)C of carbonate is the most-positive yet recorded for an SNC <span class="hlt">meteorite</span> (ca. 42 per mil)[2]. The source of carbon is thought to be <span class="hlt">Martian</span> atmospheric CO2, which has been recycled through an aqueous medium into the solid phase. The delta^(13)C of the carbonate is consistent with a precipitation temperature below ~300 degrees C [3], assuming the delta^(13)C of <span class="hlt">Martian</span> CO2 lies somewhere between 26 and 46 per mil [4, 5]. An equilibrium temperature of formation near 0 degrees C is difficult to reconcile if the atmospheric source of carbon is <26 per mil, despite the fact that equilbrium isotope enrichments are large at this temperature (12-14 per mil) [6-8]. Low delta^(13)C for atmospheric CO2 is only compatible with high delta^(13)C for carbonate when non-equilibrium processes are the primary mechanism of isotopic fractionation. An inorganic surficial process known to enrich carbonate by >15 per mil over ambient atmospheric CO2 is cryogenic freezing [9]. Carbonate-bearing soils from Wright Valley, Antarctica were <span class="hlt">studied</span> as a terrestrial analog to the carbonates in ALH 84001 to characterize isotopic "fingerprints" associated with cryogenic freezing. delta^(13)C and delta^(18)O carbonate values from Prospect Mesa Soil Pit range from +0.89 per mil to -20.46 per mil (PDB) within the "permanently frozen zone" (below 0.4 m), and +4.20 per mil to -11.87 per mil at the surface. The most enriched 13C and 18O tend to occur at the surface where seasonal variations in temperature or precipitation have imposed cyclical</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013M%26PS...48..165H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013M%26PS...48..165H"><span>Alteration assemblages in the Miller Range and Elephant Moraine regions of Antarctica: Comparisons between terrestrial igneous rocks and <span class="hlt">Martian</span> <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hallis, L. J.</p> <p>2013-02-01</p> <p>The weathering products present in igneous terrestrial Antarctic samples were analyzed, and compared with those found in the four Miller Range nakhlite <span class="hlt">Martian</span> <span class="hlt">meteorites</span>. The aim of these comparisons was to determine which of the alteration phases in the Miller Range nakhlites are produced by terrestrial weathering, and what effect rock composition has on these phases. Antarctic terrestrial samples MIL 05031 and EET 96400, along with the Miller Range nakhlites MIL 03346 and 090032, were found to contain secondary alteration assemblages at their externally exposed surfaces. Despite the difference in primary mineralogy, the assemblages of these rocks consist mostly of sulfates (jarosite in MIL 05031, jarosite and gypsum in EET 96400) and iddingsite-like Fe-clay. As neither of the terrestrial samples contains sulfur-bearing primary minerals, and these minerals are rare in the Miller Range nakhlites, it appears that SO42-, possibly along with some of the Na+, K+, and Ca+ in these phases, was sourced from wind-blown sea spray and biogenic emissions from the southern ocean. Cl enrichment in the terrestrially derived "iddingsite" of MIL 05031 and MIL 03346, and the presence of halite at the exterior edge of MIL 090032, can also be explained by this process. However, jarosite within and around the olivine-bound melt inclusions of MIL 090136 is present in the interior of the <span class="hlt">meteorite</span> and, therefore, is probably the product of preterrestrial weathering on Mars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040191778','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040191778"><span>The First Billion Years of <span class="hlt">Martian</span> History as Seen from the SNC <span class="hlt">Meteorites</span>: A Review</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jones, J. H.</p> <p>2004-01-01</p> <p>There are currently 28 known, distinct samples of Mars that have been liberated from that planet by impacts and subsequently delivered to the Earth. The formation ages of these samples range from 4.5 b.y. to 180 m.y. Collectively, these samples are called SNC <span class="hlt">meteorites</span> after the major petrologic subdivisions: Shergottite, Nakhlite, Chassigny. Texturally, most of these <span class="hlt">meteorites</span> are cumulates or partial cumulates. However, a few may represent real melt compositions: EET79001B, Y9800459, QUE94201, and the groundmass of EET79001A.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980055128','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980055128"><span>Natural thermoluminescence of Antarctic <span class="hlt">meteorites</span> and related <span class="hlt">studies</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Benoit, Paul H.; Sears, Derek W. G.</p> <p>1998-01-01</p> <p>The natural thermoluminescence (TL) laboratory's primary purpose is to provide data on newly recovered Antarctic <span class="hlt">meteorites</span> that can be included in discovery announcements and to investigate the scientific implications of the data. Natural TL levels of <span class="hlt">meteorites</span> are indicators of recent thermal history and terrestrial history, and the data can be used to <span class="hlt">study</span> the orbital/radiation history of groups of <span class="hlt">meteorites</span> (e.g., H chondrites) or to <span class="hlt">study</span> the processes leading to the concentration of <span class="hlt">meteorites</span> at certain sites in Antarctica. An important application of these data is the identification of fragments, or "pairs" of <span class="hlt">meteorites</span> produced during atmospheric passage or during terrestrial weathering. Thermoluminescence data are particularly useful for pairing within the most common <span class="hlt">meteorite</span> classes, which typically exhibit very limited petrographic and chemical diversity. Although not originally part of the laboratory's objectives, TL data are also useful in the identification and classification of petrographically or mineralogically unusual <span class="hlt">meteorites</span>, including unequilibrated ordinary chondrites and some basaltic achondrites. In support of its primary mission, the laboratory also engages in TL <span class="hlt">studies</span> of modern falls, finds from hot deserts, and terrestrial analogs and conducts detailed <span class="hlt">studies</span> of the TL properties of certain classes of <span class="hlt">meteorites</span>. These <span class="hlt">studies</span> include the measurement of TL profiles in <span class="hlt">meteorites</span>, the determination of TL levels of finds from the Sahara and the Nullarbor region of Australia, and comparison of TL data to other indicators of irradiation or terrestrial history, such as cosmogenic noble gas and radionuclide abundances. Our current work can be divided into five subcategories, (a) TL survey of Antarctic <span class="hlt">meteorites</span>, (b) pairing and field relations of Antarctic <span class="hlt">meteorites</span>, (c) characterization of TL systematics of <span class="hlt">meteorites</span>, (d) comparison of natural TL and other terrestrial age indicators for Antarctic <span class="hlt">meteorites</span>, and for <span class="hlt">meteorites</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040056051&hterms=nC&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DnC','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040056051&hterms=nC&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DnC"><span>Signatures in <span class="hlt">Martian</span> Volatiles and the Magma Sources of NC <span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Marti, K.; Mathew, K. J.</p> <p>2004-01-01</p> <p>We report nitrogen and xenon isotopic signatures in Yamato nakhlites and use the data to assess properties of the magma source of NC <span class="hlt">meteorites</span> in planet Mars. The Chassigny <span class="hlt">meteorite</span> was investigated by Floran et al, who classified it as a cumulate dunite with hydrous amphibole-bearing melt inclusions with no preferred orientation of the olivines. Their inferred composition of the parent magma, which was based on electron microprobe analyses, has been questioned. The trace and minor elements in minerals were analyzed in nakhlites and in Chassigny and the authors conclude that nakhlites may represent samples from different horizons of the same lithologic unit, but that Chassigny was not co-magmatic with the nakhlites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016E%26PSL.451..251L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016E%26PSL.451..251L"><span>Rare-earth-element minerals in <span class="hlt">martian</span> breccia <span class="hlt">meteorites</span> NWA 7034 and 7533: Implications for fluid-rock interaction in the <span class="hlt">martian</span> crust</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Yang; Ma, Chi; Beckett, John R.; Chen, Yang; Guan, Yunbin</p> <p>2016-10-01</p> <p>Paired <span class="hlt">martian</span> breccia <span class="hlt">meteorites</span>, Northwest Africa (NWA) 7034 and 7533, are the first <span class="hlt">martian</span> rocks found to contain rare-earth-element (REE) phosphates and silicates. The most common occurrence is as clusters of anhedral monazite-(Ce) inclusions in apatite. Occasionally, zoned, irregular merrillite inclusions are also present in apatite. Monazite-bearing apatite is sometimes associated with alkali-feldspar and Fe-oxide. Apatite near merrillite and monazite generally contains more F and OH (F-rich region) than the main chlorapatite host and forms irregular boundaries with the main host. Locally, the composition of F-rich regions can reach pure fluorapatite. The chlorapatite hosts are similar in composition to isolated apatite without monazite inclusions, and to euhedral apatite in lithic clasts. The U-Th-total Pb ages of monazite in three apatite are 1.0 ± 0.4Ga (2σ), 1.1 ± 0.5Ga (2σ), and 2.8 ± 0.7Ga (2σ), confirming a <span class="hlt">martian</span> origin. The texture and composition of monazite inclusions are mostly consistent with their formation by the dissolution of apatite and/or merrillite by fluid at elevated temperatures (>100 °C). In NWA 7034, we observed a monazite-chevkinite-perrierite-bearing benmoreite or trachyandesite clast. Anhedral monazite and chevkinite-perrierite grains occur in a matrix of sub-micrometer REE-phases and silicates inside the clast. Monazite-(Ce) and -(Nd) and chevkinite-perrierite-(Ce) and -(Nd) display unusual La and Ce depletion relative to Sm and Nd. In addition, one xenotime-(Y)-bearing pyrite-ilmenite-zircon clast with small amounts of feldspar and augite occurs in NWA 7034. One xenotime crystal was observed at the edge of an altered zircon grain, and a cluster of xenotime crystals resides in a mixture of alteration materials. Pyrite, ilmenite, and zircon in this clast are all highly altered, zircon being the most likely source of Y and HREE now present in xenotime. The association of xenotime with zircon, low U and Th contents, and the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20060013610&hterms=burial&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dburial','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20060013610&hterms=burial&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dburial"><span>Mineralogy of nakhlite <span class="hlt">Martian</span> <span class="hlt">meteorites</span>: Implications for their relative burial depths</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mikouchi, T.; McKay, Gordon; Miyamoto, M.</p> <p>2006-01-01</p> <p>Nakhlites are <span class="hlt">Martian</span> cumulate rocks mainly composed of augite with variable amounts of olivine and groundmass (mesostasis). Currently seven samples are known: Nakhla (Nak), Governador Valadares (GV), Lafayette (Laf), NWA817, Y000593 (Y), NWA998 and MIL03346 (MIL). All the nakhlites show a similar unbrecciated cumulate texture, and their identical crystallization and exposure ages suggest that they originated from the same igneous body on Mars and were ejected by the same impact event. It is important to <span class="hlt">study</span> difference of their mineralogy to reconstruct the igneous body from which nakhlites originated. Augite grains in all nakhlites have a nearly identical core composition (En39Fs22Wo39) and have thin Fe-rich rims. These Fe-rich rims are zoned to Ca-poor pyroxene compositions and the degree of chemical zoning varies from one sample to another. NWA998 has the most Mg-rich edge composition. The edge composition becomes more Fe-rich in the order of Laf, Nak/GV, Y and NWA817. Unlike other samples, the Fe-rich edge of MIL augite is zoned to the hedenbergite composition. Olivine grains in all samples except Laf and NWA998 show extensive chemical zoning whose degree is clearly related to the chemical zoning of pyroxenes. MIL and NWA817 have the widest compositional ranges (Fa54-93). Y has a slightly narrower compositional range of Fa58-85. Nak and GV have even narrower ranges (Fa58-72). In contrast to these samples, olivines in Laf and NWA998 are homogeneous (Fa66-67 and Fa61-62, respectively). Such chemical zoning (Fa and Ca) can be used to quantitatively estimate their cooling rates (burial depths) because it was clearly formed by interaction with the intercumulus melt. The obtained burial depths are 1-2 m for NWA817, 4 m for MIL, 7 m for Y, approx.10 m for Nak and GV, and >30 m for Laf and NWA998. This order is clearly related to the degree of pyroxene chemical zoning. The abundance and mineralogy of nakhlite groundmass are also consistent with this order. In Nak, GV</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/289430','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/289430"><span>Bacterial mineralization patterns in basaltic aquifers: Implications for possible life in <span class="hlt">Martian</span> <span class="hlt">meteorite</span> ALH84001</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Thomas-Keprta, K.L.; Wentworth, S.J.; Allen, C.C.; McKay, D.S.; Gibson, E.K. Jr.; Stevens, T.O.; Taunton, A.E.; Coleman, A.; Romanek, C.S.</p> <p>1998-11-01</p> <p>To explore the formation and preservation of biogenic features in igneous rocks, the authors have examined the organisms in experimental basaltic microcosms using scanning and transmission electron microscopy. Four types of microorganisms were recognized on the basis of size, morphology, and chemical composition. Some of the organisms mineralized rapidly, whereas others show no evidence of mineralization. Many mineralized cells are hollow and do not contain evidence of microstructure. Filaments, either attached or no longer attached to organisms, are common. Unattached filaments are mineralized and are most likely bacterial appendages (e.g., prosthecae). Features similar in size and morphology to unattached, mineralized filaments are recognized in martial <span class="hlt">meteorite</span> ALH84001.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995Metic..30R.567R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995Metic..30R.567R"><span>Carbon- and Sulfur-bearing Minerals in the <span class="hlt">Martian</span> <span class="hlt">Meteorite</span> ALH 84001</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Romanek, C. S.; Thomas, K. L.; Gibson, E. K., Jr.; McKay, D. S.; Socki, R. A.</p> <p>1995-09-01</p> <p>Unusual carbonate minerals in ALH 84001 [1] provide insights into surficial processes that may have occurred on Mars, but despite detailed geochemical <span class="hlt">studies</span> [2-4] carbonate petrogenesis has yet to be fully-characterized. High-resolution TEM and SEM analyses were performed on C- and S-bearing mineral grains to better constrain the nature and timing of carbonate mineralization events. Morphological elements: C- and S-bearing minerals in ALH 84001 commonly occur as spheroidal aggregates or fine-grained vug-filling structures. Spheroids are either orange or black, ~150 micrometers (+/- 50 micrometers) in diameter and highly-flattened (10-30 micrometers thick). Orange spheroids have limpid amber-colored cores and white to translucent mantles which are sometimes bound by thin black rims (< 10 micrometers). When viewed under cathodoluminescence, cores are non-luminescent while mantles luminesce a uniform bright-orange color. Black spheroids are less frequently observed; while they are similar in dimension to the orange spheroids they are chemically more heterogeneous. Black irregular aggregates fill residual pore-space between mineral grains. These structures are comprised of extremely fine-grained (< 2 micrometers) material that occasionally forms lenticular stringers up to 50 micrometers in length. Chemistry and Mineralogy: Small grains (30 micrometers dia.) were removed from C- and S-bearing aggregates, microtomed (~100 nm thick) and examined by TEM for imaging, electron diffraction, and elemental analysis. The orange spheroids have cores composed of Fe-Mg-Ca carbonate, with the centers having the highest concentration of Fe (45 mol%) and Ca (15 mol%). The concentration of Mg increases outward to almost pure MgCO3. TEM results support previous analyses of carbonate chemistry [1-4] and clearly indicate that a wide range of Mg-Fe-Ca solid solution exists in carbonate at a scale of ~10 nm. White mantles of the orange spheroids are composed of nearly pure MgCO3 (<5 mol</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940028733','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940028733"><span>Carbonates, surfates, phosphates, nitrates, and organic materials: Their association in a <span class="hlt">Martian</span> <span class="hlt">meteorite</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wright, I. P.; Grady, M. M.; Pillinger, C. T.</p> <p>1993-01-01</p> <p>The debate concerning the evolution of CO2 on Mars continues. It would appear that in order to explain the valley networks and other relict fluvial landforms it is necessary to accept that liquid water was once present at the surface of Mars. This in turn requires, at some point in the planet's history, a higher surface temperature than exists today, proposition explained traditionally by an early dense CO2, atmosphere. However, there are a number of problems with this notion: for instance, CO2 alone is not an efficient greenhouse gas because of its tendency to form clouds. Moreover, if there was an early dense CO2 atmosphere, it is necessary to explain where the elemental constituents now reside. There are two possibilities for the latter, namely loss to outer space of atmospheric CO2 or the formation of vast carbonate deposits. While some models of atmospheric loss predict that up to 0.4 bar of CO2 could be removed from the <span class="hlt">Martian</span> surface, this is still not enough to account for the original atmospheric inventory, usually considered to have been in the range of 1-5 bar. Thus, most models of the evolution of the <span class="hlt">Martian</span> surface require removal of CO2 from the atmosphere and into carbonate deposits. However, as yet, the evidence for the existence of carbonates on Mars is fairly scant. This is an issue that would have been resolved by results obtained from Mars Observer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20010045010&hterms=Evaporites&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DEvaporites','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20010045010&hterms=Evaporites&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DEvaporites"><span>Weathering of <span class="hlt">Martian</span> Evaporites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wentworth, S. J.; Velbel, M. A.; Thomas-Keprta, K. L.; Longazo, T. G.; McKay, D. S.</p> <p>2001-01-01</p> <p>Evaporites in <span class="hlt">martian</span> <span class="hlt">meteorites</span> contain weathering or alteration features that may provide clues about the <span class="hlt">martian</span> near-surface environment over time. Additional information is contained in the original extended abstract.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080026155','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080026155"><span>Formation of "Chemically Pure" Magnetite from Mg-Fe-Carbonates Implications for the Exclusively Inorganic Origin of Magnetite and Sulfides in <span class="hlt">Martian</span> <span class="hlt">Meteorite</span> ALH84001</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Golden, D. C.; Ming, Douglas W.; Lauer, H. V., Jr.; Morris, R. V.; Trieman, A. H.; McKay, G. A.</p> <p>2006-01-01</p> <p>Magnetite and sulfides in the black rims of carbonate globules in <span class="hlt">Martian</span> <span class="hlt">meteorite</span> ALH84001 have been <span class="hlt">studied</span> extensively because of the claim by McKay et al. that they are biogenic in origin. However, exclusively inorganic (abiotic) processes are able to account for the occurrence of carbonate-sulfide-magnetite assemblages in the <span class="hlt">meteorite</span>. We have previously precipitated chemically zoned and sulfide-bearing carbonate globules analogous to those in ALH84001 (at less than or equal to 150 C) from multiple fluxes of variable-composition Ca-Mg-Fe-CO2-S-H2O solutions. Brief heating of precipitated globules to approx. 470 C produced magnetite and pyrrhotite within the globules by thermal decomposition of siderite and pyrite, respectively. We have also shown that morphology of magnetite formed by inorganic thermal decomposition of Fe-rich carbonate is similar to the morphology of so-called biogenic magnetite in the carbonate globules of ALH84001. Magnetite crystals in the rims of carbonate globules in ALH84001 are chemically pure [Note: "Chemically pure" is defined here as magnetite with Mg at levels comparable or lower than Mg detected by [8] in ALH84001 magnetite]. A debate continues on whether or not chemically pure magnetite can form by the thermal decomposition of mixed Mg-Fe-carbonates that have formed under abiotic conditions. Thomas-Keprta et al. argue that it is not possible to form Mg-free magnetite from Mg-Fe-carbonate based on thermodynamic data. We previously suggested that chemically pure magnetite could form by the thermal decomposition of relatively pure siderite in the outer rims of the globules. Mg-Fe-carbonates may also thermally decompose under conditions conducive for formation of chemically pure magnetite. In this paper we show through laboratory experiments that chemically pure magnetite can form by an inorganic process from mixed Mg-Fe-carbonates.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140011731','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140011731"><span>Sm-Nd and Rb-Sr Isotopic Systematics of a Heavily Shocked <span class="hlt">Martian</span> <span class="hlt">Meteorite</span> Tissint and Petrogenesis of Depleted Shergottites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shih, C.-Y.; Nyquist, L. E.; Park, J.; Agee, Carl B.</p> <p>2014-01-01</p> <p>Tissint is a very fresh <span class="hlt">Martian</span> <span class="hlt">meteorite</span> that fell near the town of Tissint in Morocco on July 18, 2011. It contains abundant olivine megacrysts (23%) in a fine-grained matrix of pyroxene (55%), maskelynitized plagioclase (15%), opaques (4%) and melt pockets (3%) and is petrographically similar to lithologies A and C of picritic shergottite EETA 79001 [1,2]. The presence of 2 types of shock-induced glasses and all 7 high-pressure mineral phases that were ever found in melt pockets of <span class="hlt">Martian</span> <span class="hlt">meteorites</span> suggests it underwent an intensive shock metamorphism of 25 GPa and 2000 C localized in melt pockets [2]. Mineral textures suggest that olivines, pyroxenes and plagioclases probably did not experience such hightemperature. Earlier determinations of its age yielded 596+/-23 Ma [3] and 616+/-67 Ma [4], respectively, for the Sm-Nd system and 583+/-86 Ma for the Lu-Hf system [4], in agreement with the 575+/-18 Ma age of the oldest olivine-phyric depleted shergottite Dho 019 [5]. However, the exposure ages of Tissint (1 Ma [1, 6, 7]) and Dho 019 (20 Ma [8]) are very different requiring two separate ejection events. These previously determined Sm-Nd and Lu-Hf ages are older than the Ar-Ar maskelynite plateau age of 524+/-15 Ma [9], reversing the pattern usually observed for <span class="hlt">Martian</span> <span class="hlt">meteorites</span>. In order to clarify these age issues and place models for Tissint's petrogenesis on a firm basis, we present new Rb-Sr and Sm- Nd isotopic results for Tissint, and discuss (a) the shock effects on them and the Ar-Ar chronometer, (b) correlation of the determined ages with those of other depleted shergottites, and (c) the petrogenesis of depleted shergottites. Since the <span class="hlt">meteorite</span> is a recent fall, terrestrial contamination is expected to be minimal, but, the strong shock metamorphism might be expected to compromise the equilibrium of the isotopic systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100036629','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100036629"><span>Evidence for Differential Comminution/Aeolian Sorting and Chemical Weathering of <span class="hlt">Martian</span> Soils Preserved in Mars <span class="hlt">Meteorite</span> EET79001</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rao, M. N.; McKay, David S.</p> <p>2004-01-01</p> <p>Impact-melt glasses containing <span class="hlt">Martian</span> atmospheric gases in Mars <span class="hlt">meteorite</span> EET79001 are formed from <span class="hlt">Martian</span> soil fines that had undergone meteoroid-comminution and aeolian sorting accompanied by chemical weathering near Mars surface. Using SiO2 and SO3 as proxy for silicates and salts respectively in Mars soils, we find that SiO2 and SO3 correlate negatively with FeO and MgO and positively with Al2O3 and CaO in these glasses, indicating that the mafic and felsic components are depleted and enriched relative to the bulk host (Lith A/B) respectively as in the case of Moon soils. Though the overall pattern of mineral fractionation is similar between the soil fines on Mars and Moon, the magnitudes of the enrichments/depletions differ between these sample-suites because of pervasive aeolian activity on Mars. In addition to this mechanical processing, the <span class="hlt">Martian</span> soil fines, prior to impact-melting, have undergone acid-sulfate dissolution under oxidizing/reducing conditions. The S03 content in EET79001,507 (Lith B) glass is approx.18% compared to < 2% in EET79001, 506 (Lith A). SiO2 and SO3 negatively correlate with each other in ,507 glasses similar to Pathfinder soils. The positive correlation found between FeO and SO3 in ,507 glasses as well as Pathfinder rocks and soils is consistent with the deposition of ferric-hydroxysulfate on regolith grains in an oxidizing environment. As in the case of Pathfinder soils, the Al 2O3 vs SiO2 positive correlation and FeO VS S102 negative correlation observed in ,507 glasses indicate that SiO2 from the regolith is mobilized as soluble silicic acid at low pH. The large off-set in the end-member FeO abundance ( SO3=0) between Pathfinder soil-free rock and sulfur-free rock in ,507 glass precursors suggests that the soils comprising the ,507 glasses contain much larger proportion of fine-grained <span class="hlt">Martian</span> soil fraction that registers strong mafic depletion relative to Lith B. This inference is strongly supported by the Al2O3 - SO3</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110007846','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110007846"><span>Stable Chlorine Isotopes and Elemental Chlorine by Thermal Ionization Mass Spectrometry and Ion Chromatography; <span class="hlt">Martian</span> <span class="hlt">Meteorites</span>, Carbonaceous Chondrites and Standard Rocks</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nakamura, N.; Nyquist, L. E.; Reese, Y.; Shih, C.-Y.; Fujitani, T.; Okano, O.</p> <p>2011-01-01</p> <p>Recently significantly large mass fractionation of stable chlorine isotopes has been reported for terrestrial and lunar samples [1,2]. In addition, in view of possible early solar system processes [3] and also potential perchlorate-related fluid/microbial activities on the <span class="hlt">Martian</span> surface [4,5], a large chlorine isotopic fractionation might be expected for some types of planetary materials. Due to analytical difficulties of isotopic and elemental analyses, however, current chlorine analyses for planetary materials are controversial among different laboratories, particularly between IRMS (gas source mass spectrometry) and TIMS (Thermal Ionization Mass Spectrometry) groups [i.e. 1,6,7] for isotopic analyses, as well as between those doing pyrohydrolysis and other groups [i.e. 6,8]. Additional careful investigations of Cl isotope and elemental abundances are required to confirm real chlorine isotope and elemental variations for planetary materials. We have developed a TIMS technique combined with HF-leaching/ion chromatography at NASA JSC that is applicable to analysis of small amounts of <span class="hlt">meteoritic</span> and planetary materials. We present here results for several standard rocks and <span class="hlt">meteorites</span>, including <span class="hlt">Martian</span> <span class="hlt">meteorites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GeCoA.154...49L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeCoA.154...49L"><span>Formation of iddingsite veins in the <span class="hlt">martian</span> crust by centripetal replacement of olivine: Evidence from the nakhlite <span class="hlt">meteorite</span> Lafayette</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lee, M. R.; Tomkinson, T.; Hallis, L. J.; Mark, D. F.</p> <p>2015-04-01</p> <p>The Lafayette <span class="hlt">meteorite</span> is an olivine clinopyroxenite that crystallized on Mars ∼1300 million years ago within a lava flow or shallow sill. Liquid water entered this igneous rock ∼700 million years later to produce a suite of secondary minerals, collectively called 'iddingsite', that occur as veins within grains of augite and olivine. The deuterium/hydrogen ratio of water within these secondary minerals shows that the aqueous solutions were sourced from one or more near-surface reservoirs. Several petrographically distinct types of veins can be recognised by differences in their width, shape, and crystallographic orientation. Augite and olivine both contain veins of a very fine grained hydrous Fe- and Mg-rich silicate that are ∼1-2 μm in width and lack any preferred crystallographic orientation. These narrow veins formed by cementation of pore spaces that had been opened by fracturing and probably in response to shock. The subset of olivine-hosted veins whose axes lie parallel to (0 0 1) have serrated walls, and formed by widening of the narrow veins by interface coupled dissolution-precipitation. Widening started by replacement of the walls of the narrow precursor veins by Fe-Mg silicate, and a crystallographic control on the trajectory of the dissolution-precipitation front created micrometre-scale {1 1 1} serrations. The walls of many of the finely serrated veins were subsequently replaced by siderite, and the solutions responsible for carbonation of olivine also partially recrystallized the Fe-Mg silicate. Smectite was the last mineral to form and grew by replacement of siderite. This mineralization sequence shows that Lafayette was exposed to two discrete pulses of aqueous solutions, the first of which formed the Fe-Mg silicate, and the second mediated replacement of vein walls by siderite and smectite. The similarity in size, shape and crystallographic orientation of iddingsite veins in the Lafayette <span class="hlt">meteorite</span> and in terrestrial basalts demonstrates a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015M%26PS...50..326W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015M%26PS...50..326W"><span>Petrography and composition of <span class="hlt">Martian</span> regolith breccia <span class="hlt">meteorite</span> Northwest Africa 7475</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wittmann, Axel; Korotev, Randy L.; Jolliff, Bradley L.; Irving, Anthony J.; Moser, Desmond E.; Barker, Ivan; Rumble, Douglas</p> <p>2015-02-01</p> <p>The Northwest Africa (NWA) 7475 <span class="hlt">meteorite</span> is one of the several stones of paired regolith breccias from Mars based on petrography, oxygen isotope, mineral compositions, and bulk rock compositions. Its inventory of lithic clasts is dominated by vitrophyre impact melts that were emplaced while they were still molten. Other clast types include crystallized impact melt rocks, evolved plutonic rocks, possible basalts, contact metamorphosed rocks, and siltstones. Impact spherules and vitrophyre shards record airborne transport, and accreted dust rims were sintered on most clasts, presumably during residence in an ejecta plume. The clast assemblage records at least three impact events, one that formed an impact melt sheet on Mars ≤4.4 Ga ago, a second that assembled NWA 7475 from impactites associated with the impact melt sheet at 1.7-1.4 Ga, and a third that launched NWA 7475 from Mars ~5 Ma ago. Mildly shocked pyroxene and plagioclase constrain shock metamorphic conditions during launch to >5 and <15 GPa. The mild postshock-heating that resulted from these shock pressures would have been insufficient to sterilize this water-bearing lithology during launch. Magnetite, maghemite, and pyrite are likely products of secondary alteration on Mars. Textural relationships suggest that calcium-carbonate and goethite are probably of terrestrial origin, yet trace element chemistry indicates relatively low terrestrial alteration. Comparison of Mars Odyssey gamma-ray spectrometer data with the Fe and Th abundances of NWA 7475 points to a provenance in the ancient southern highlands of Mars. Gratteri crater, with an age of ~5 Ma and an apparent diameter of 6.9 km, marks one possible launch site of NWA 7475.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19910041576&hterms=thermoluminescence&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dthermoluminescence','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19910041576&hterms=thermoluminescence&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dthermoluminescence"><span>Metamorphism of eucrite <span class="hlt">meteorites</span> <span class="hlt">studied</span> quantitatively using induced thermoluminescence</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Batchelor, J. David; Sears, Derek W. G.</p> <p>1991-01-01</p> <p>Induced thermoluminescence <span class="hlt">studies</span> provide a new and quantitative means of determining relative metamorphic intensities for eucrite <span class="hlt">meteorites</span>, the simplest and most ancient products of basaltic volcanism. Using this technique, it is shown that the eucrites constitute a continuous metamorphic series and not, as commonly assumed, two groups of metamorphosed and nonmetamorphosed <span class="hlt">meteorites</span>. It is suggested that the method may have applications to other basalts.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19910041576&hterms=metamorphism&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dmetamorphism','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19910041576&hterms=metamorphism&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dmetamorphism"><span>Metamorphism of eucrite <span class="hlt">meteorites</span> <span class="hlt">studied</span> quantitatively using induced thermoluminescence</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Batchelor, J. David; Sears, Derek W. G.</p> <p>1991-01-01</p> <p>Induced thermoluminescence <span class="hlt">studies</span> provide a new and quantitative means of determining relative metamorphic intensities for eucrite <span class="hlt">meteorites</span>, the simplest and most ancient products of basaltic volcanism. Using this technique, it is shown that the eucrites constitute a continuous metamorphic series and not, as commonly assumed, two groups of metamorphosed and nonmetamorphosed <span class="hlt">meteorites</span>. It is suggested that the method may have applications to other basalts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20010035473&hterms=Allan&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DAllan','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20010035473&hterms=Allan&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DAllan"><span>Olivine in <span class="hlt">Martian</span> <span class="hlt">Meteorite</span> Allan Hills 84001: Evidence for a High-Temperature Origin and Implications for Signs of Life</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shearer, C. K.; Leshin, L. A.; Adcock, C. T.</p> <p>1999-01-01</p> <p>Olivine from <span class="hlt">Martian</span> <span class="hlt">meteorite</span> Allan Hills (ALH) 84001 occurs as clusters within orthopyroxene adjacent to fractures containing disrupted carbonate globules and feldspathic shock glass. The inclusions are irregular in shape and range in size from approx. 40 microns to submicrometer. Some of the inclusions are elongate and boudinage-like. The olivine grains are in sharp contact with the enclosing orthopyroxene and often contain small inclusions of chromite The olivine exhibits a very limited range of composition from Fo(sub 65) to Fo(sub 66) (n = 25). The delta(sup 18)O values of the olivine and orthopyroxene analyzed by ion microprobe range from +4.3 to +5.3% and are indistinguishable from each other within analytical uncertainty. The mineral chemistries, O-isotopic data, and textural relationships indicate that the olivine inclusions were produced at a temperature greater than 800 C. It is unlikely that the olivines formed during the same event that gave rise to the carbonates in ALH 84001, which have more elevated and variable delta(sup 18)O values, and were probably formed from fluids that were not in isotopic equilibrium with the orthopyroxene or olivine The reactions most likely instrumental in the formation of olivine could be either the dehydration of hydrous silicates that formed during carbonate precipitation or the reduction of orthopyroxene and spinel If the olivine was formed by either reaction during a postcarbonate beating event, the implications are profound with regards to the interpretations of McKay et al. Due to the low diffusion rates in carbonates, this rapid, high-temperature event would have resulted in the preservation of the fine-scale carbonate zoning' while partially devolatilizing select carbonate compositions on a submicrometer scale. This may have resulted in the formation of the minute magnetite grains that McKay et al attributed to biogenic activity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/14577885','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/14577885"><span>Submicron magnetite grains and carbon compounds in <span class="hlt">Martian</span> <span class="hlt">meteorite</span> ALH84001: inorganic, abiotic formation by shock and thermal metamorphism.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Treiman, Allan H</p> <p>2003-01-01</p> <p>Purported biogenic features of the ALH84001 <span class="hlt">Martian</span> <span class="hlt">meteorite</span> (the carbonate globules, their submicron magnetite grains, and organic matter) have reasonable inorganic origins, and a comprehensive hypothesis is offered here. The carbonate globules were deposited from hydrothermal water, without biological mediation. Thereafter, ALH84001 was affected by an impact shock event, which raised its temperature nearly instantaneously to 500-700K, and induced iron-rich carbonate in the globules to decompose to magnetite and other minerals. The rapidity of the temperature increase caused magnetite grains to nucleate in abundance; hence individual crystals were very small. Nucleation and growth of magnetite crystals were fastest along edges and faces of the precursor carbonate grains, forcing the magnetite grains to be platy or elongated, including the "truncated hexa-octahedra" shape. ALH84001 had formed at some depth within Mars where the lithostatic pressure was significantly above that of Mars' surface. Also, because the rock was at depth, the impact heat dissipated slowly. During this interval, magnetite crystals approached chemical equilibria with surrounding minerals and gas. Their composition, nearly pure Fe(3)O(4), reflects those of equilibria; elements that substitute into magnetite are either absent from iron-rich carbonate (e.g., Ti, Al, Cr), or partitioned into other minerals during magnetite formation (Mg, Mn). Many microstructural imperfections in the magnetite grains would have annealed out as the rock cooled. In this post-shock thermal regime, carbon-bearing gas from the decomposition of iron carbonates reacted with water in the rock (or from its surroundings) to produce organic matter via Fischer-Tropschlike reactions. Formation of such organic compounds like polycyclic aromatic hydrocarbons would have been catalyzed by the magnetite (formation of graphite, the thermochemically stable phase, would be kinetically hindered).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20010035473&hterms=sign&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dsign','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20010035473&hterms=sign&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dsign"><span>Olivine in <span class="hlt">Martian</span> <span class="hlt">Meteorite</span> Allan Hills 84001: Evidence for a High-Temperature Origin and Implications for Signs of Life</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shearer, C. K.; Leshin, L. A.; Adcock, C. T.</p> <p>1999-01-01</p> <p>Olivine from <span class="hlt">Martian</span> <span class="hlt">meteorite</span> Allan Hills (ALH) 84001 occurs as clusters within orthopyroxene adjacent to fractures containing disrupted carbonate globules and feldspathic shock glass. The inclusions are irregular in shape and range in size from approx. 40 microns to submicrometer. Some of the inclusions are elongate and boudinage-like. The olivine grains are in sharp contact with the enclosing orthopyroxene and often contain small inclusions of chromite The olivine exhibits a very limited range of composition from Fo(sub 65) to Fo(sub 66) (n = 25). The delta(sup 18)O values of the olivine and orthopyroxene analyzed by ion microprobe range from +4.3 to +5.3% and are indistinguishable from each other within analytical uncertainty. The mineral chemistries, O-isotopic data, and textural relationships indicate that the olivine inclusions were produced at a temperature greater than 800 C. It is unlikely that the olivines formed during the same event that gave rise to the carbonates in ALH 84001, which have more elevated and variable delta(sup 18)O values, and were probably formed from fluids that were not in isotopic equilibrium with the orthopyroxene or olivine The reactions most likely instrumental in the formation of olivine could be either the dehydration of hydrous silicates that formed during carbonate precipitation or the reduction of orthopyroxene and spinel If the olivine was formed by either reaction during a postcarbonate beating event, the implications are profound with regards to the interpretations of McKay et al. Due to the low diffusion rates in carbonates, this rapid, high-temperature event would have resulted in the preservation of the fine-scale carbonate zoning' while partially devolatilizing select carbonate compositions on a submicrometer scale. This may have resulted in the formation of the minute magnetite grains that McKay et al attributed to biogenic activity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002M%26PS...37..835G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002M%26PS...37..835G"><span>Sayh al Uhaymir 094: A new <span class="hlt">martian</span> <span class="hlt">meteorite</span> from the Oman desert</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gnos, E.; Hofmann, B.; Franchi, I. A.; Al-Kathiri, A.; Hauser, M.; Moser, L.</p> <p>2002-06-01</p> <p>Sayh al Uhaymir (SaU) 094 is a 223.3 g, partially crusted, strongly to very strongly shocked melanocratic olivine-porphyric rock of the shergottite group showing a microgabbroic texture. The rock consists of pyroxene (52.0-58.2 vol%)-dominantly prismatic pigeonite (En60-68Fs20-27Wo7-9) associated with minor augite (En46-49Fs15-16Wo28-31)-brown (shock-oxidized) olivine (Fo65-69; 22.1-31%), completely isotropic interstitial plagioclase glass (maskelynite; An50-64Or0.3-0.9; 8.6-13.0%), chromite and titanian magnesian chromite (0.9-1.0%), traces of ilmenite (Ilm80-86), pyrrhotite (Fe92-100; 0.1-0.2%), merrillite (<<0.1%), and pockets (4.8-6.7%) consisting of green basaltic to basaltic andesitic shock glass that is partially devitrified into a brown to black product along boundaries with the primary minerals. The average maximum dimensions of minerals are: olivine (1.5 mm), pyroxene (0.3 mm) and maskelynite (0.3 mm). Primary melt inclusions in olivine and chromite are common and account for 0.1-0.6% of the rock. X-ray tomography revealed that the specimen contains ~0.4 vol% of shock-melt associated vesicles, up to 3 mm in size, which show a preferred orientation. Fluidization of the maskelynite, melting and recrystallization of pyroxene, olivine and pyrrhotite indicate shock stage S6. Minor terrestrial weathering resulted in calcite-veining and minor oxidation of sulfides. The <span class="hlt">meteorite</span> is interpreted as paired with SaU 005/008/051. The modal composition is similar to Dar al Gani 476/489/670/735/876, with the exception that neither mesostasis nor titanomagnetite nor apatite are present and that all phases show little zonation. The restricted mineral composition, predominance of chromite among the oxides, and abundance of olivine indicate affinities to the lherzolitic shergottites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19920001575','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19920001575"><span>New <span class="hlt">studies</span> of <span class="hlt">Martian</span> volcanoes</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mouginis-Mark, P. J.; Robinson, M. S.; Zisk, S. H.</p> <p>1991-01-01</p> <p>To investigate the morphology, topography, and evolution of volcanic constructs on Mars, researchers have been <span class="hlt">studying</span> the volcanoes Olympus Mons, Tyrrhena Patera, and Apollinaris Patera. These <span class="hlt">studies</span> relied upon the analysis of digital Viking orbiter images to measure the depth and slopes of the summit area of Olympus Mons, upon new Earth-based radar measurements for the analysis of the slopes of Tyrrhena Patera, and upon the color characteristics of the flanks of Apollinaris Patera for information regarding surface properties.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013M%26PS...48..493L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013M%26PS...48..493L"><span>The Ksar Ghilane 002 shergottite—The 100th registered <span class="hlt">Martian</span> <span class="hlt">meteorite</span> fragment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Llorca, Jordi; Roszjar, Julia; Cartwright, Julia A.; Bischoff, Addi; Ott, Ulrich; Pack, Andreas; Merchel, Silke; Rugel, Georg; Fimiani, Leticia; Ludwig, Peter; Casado, José V.; Allepuz, David</p> <p>2013-03-01</p> <p>We report on the discovery of a new shergottite from Tunisia, Ksar Ghilane (KG) 002. This single stone, weighing 538 g, is a coarse-grained basaltic shergottite, mainly composed of maskelynitized plagioclase (approximately 52 vol%) and pyroxene (approximately 37 vol%). It also contains Fe-rich olivine (approximately 4.5 vol%), large Ca-phosphates, including both merrillites and Cl-apatites (approximately 3.4 vol%), minor amounts of silica or SiO2-normative K-rich glass, pyrrhotite, Ti-magnetite, ilmenite, and accessory baddeleyite. The largest crystals of pyroxene and plagioclase reach sizes of approximately 4 to 5 mm. Pyroxenes (Fs26-96En5-50Wo2-41). They typically range from cores of about Fs29En41Wo30 to rims of about Fs68En14Wo17. Maskelynite is Ab41-49An39-58Or1-7 in composition, but some can be as anorthitic as An93. Olivine (Fa91-96) occurs mainly within symplectitic intergrowths, in paragenesis with ilmenite, or at neighboring areas of symplectites. KG 002 is heavily shocked (S5) as indicated by mosaic extinction of pyroxenes, maskelynitized plagioclase, the occurrence of localized shock melt glass pockets, and low radiogenic He concentration. Oxygen isotopes confirm that it is a normal member of the SNC suite. KG 002 is slightly depleted in LREE and shows a positive Eu anomaly, providing evidence for complex magma genesis and mantle processes on Mars. Noble gases with a composition thought to be characteristic for <span class="hlt">Martian</span> interior is a dominant component. Measurements of 10Be, 26Al, and 53Mn and comparison with Monte Carlo calculations of production rates indicate that KG 002 has been exposed to cosmic rays most likely as a single meteoroid body of 35-65 cm radius. KG 002 strongly resembles Los Angeles and NWA 2800 basaltic shergottites in element composition, petrography, and mineral chemistry, suggesting a possible launch-pairing. The similar CRE ages of KG 002 and Los Angeles may suggest an ejection event at approximately 3.0 Ma.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..14.9373G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.9373G"><span>Paleomagnetic <span class="hlt">study</span> of the Kaba <span class="hlt">meteorite</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gattacceca, J.; Gounelle, M.; Lima, E. A.; Weiss, B. P.</p> <p>2012-04-01</p> <p>Kaba is the least thermally metamorphosed of all carbonaceous chondrites of the CV group [1], and shows no petrologic evidence for shock, making it a good candidate as a recorder of magnetic fields in the early solar system. Kaba belongs to the oxidized CVB sub-group, and contains abundant magnetite [2]. This magnetite was formed by aqueous alteration on the parent body [3] about 8 Myr after the formation of the solar system [4,5]. This age is at the boundary when external magnetic field sources of nebular or solar origin are supposed to decay. Previous paleomagnetic <span class="hlt">study</span> is limited to a two-step alternating field (AF) demagnetization up to 20 mT of a single fragment of unknown mass, for which no interpretation is proposed [6]. We conducted an exhaustive magnetic <span class="hlt">study</span> of the Kaba <span class="hlt">meteorite</span> including magnetic microscopy, AF demagnetization of the natural remanent magnetization 20 mutually oriented sub-samples (including separated chondrules), hysteresis properties, anisotropy of magnetic susceptibility. Our results showed that Kaba contains about 10 wt.% of pseudo-single domain magnetite. Preliminary paleomagnetic results indicate that the matrix possess an homogeneous natural remanent magnetization (NRM) that is stable upon AF demagnetization up to 120 mT, separated chondrules have rather unstable NRM and their ill-defined directions (when they can be defined) are scattered. The preliminary interpretation is that the fine-grained magnetite in the matrix carries a chemical remanent magnetization that was acquired in a paleofield of at least 10 µT on the parent body, 8 Myr after the formation of the solar system. We will discuss the possible origin of this paleofield, but we note that these preliminary results are in agreement with the recent suggestion, based on the paleomagnetism of Allende <span class="hlt">meteorite</span>, that the CV parent body had a dynamo-generated field at about the same time [7].</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20000004369&hterms=dinosaur&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Ddinosaur','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20000004369&hterms=dinosaur&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Ddinosaur"><span><span class="hlt">Meteorites</span> and the Evolution of Our Solar System</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nava, David F.</p> <p>1999-01-01</p> <p>The <span class="hlt">study</span> of <span class="hlt">meteorites</span> has long been of intense interest ever since these objects were discovered to be of extraterrestrial origin. <span class="hlt">Meteorite</span> research contributes to unraveling the mysteries in understanding the formation and evolution processes of our solar system. <span class="hlt">Meteorites</span>, of which there are a variety of widely diverse types of chemical and mineralogical compositions, are the most ancient of solar system objects that can be <span class="hlt">studied</span> in the laboratory. They preserve a unique historical record of the astronomical and astrophysical events of our solar system. This record is being discerned by a host of ever evolving analytical laboratory methods. Recent discoveries of what are believed to be <span class="hlt">Martian</span> <span class="hlt">meteorites</span>, lunar <span class="hlt">meteorites</span>, a <span class="hlt">meteorite</span> containing indigenous water, and the recovery from the Cretaceous layer of a small <span class="hlt">meteorite</span> fragment thought to be from the dinosaur-killing asteroid have fueled additional excitement for <span class="hlt">studying</span> <span class="hlt">meteorites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140000688','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140000688"><span>Consortium <span class="hlt">Study</span> of the Chelyabinsk <span class="hlt">Meteorite</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Righter, K.; Fries, M. D.; Gibson, E. K.; Harrington, R.; Keller, L. P.; McCoy, T. J.; Morris, R. V.; Nagao, K.; Nakamura-Messenger, K.; Niles, P.; Nyquist, L.; Park, J.; Peng, Z. X.; Shih, C.-Y.; Simon, J. I.; Zeigler, R. A.</p> <p>2013-01-01</p> <p>On February 15, 2013 approximately 17 m asteroid hit Earth, causing shock waves and air blasts over a portion of Russia. A significant amount of material has been recovered from this <span class="hlt">meteorite</span> fall, officially named Chelyabinsk.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730023014','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730023014"><span>Wind tunnel <span class="hlt">studies</span> of <span class="hlt">Martian</span> aeolian processes</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Greeley, R.; Iversen, J. D.; Pollack, J. B.; Udovich, N.; White, B.</p> <p>1973-01-01</p> <p>Preliminary results are reported of an investigation which involves wind tunnel simulations, geologic field <span class="hlt">studies</span>, theoretical model <span class="hlt">studies</span>, and analyses of Mariner 9 imagery. Threshold speed experiments were conducted for particles ranging in specific gravity from 1.3 to 11.35 and diameter from 10.2 micron to 1290 micron to verify and better define Bagnold's (1941) expressions for grain movement, particularly for low particle Reynolds numbers and to <span class="hlt">study</span> the effects of aerodynamic lift and surface roughness. Wind tunnel simulations were conducted to determine the flow field over raised rim craters and associated zones of deposition and erosion. A horseshoe vortex forms around the crater, resulting in two axial velocity maxima in the lee of the crater which cause a zone of preferential erosion in the wake of the crater. Reverse flow direction occurs on the floor of the crater. The result is a distinct pattern of erosion and deposition which is similar to some <span class="hlt">martian</span> craters and which indicates that some dark zones around <span class="hlt">Martian</span> craters are erosional and some light zones are depositional.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850035523&hterms=amoeba&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Damoeba','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850035523&hterms=amoeba&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Damoeba"><span>Petrographic <span class="hlt">studies</span> of refractory inclusions from the Murchison <span class="hlt">meteorite</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Macpherson, G. J.; Grossman, L.; Hashimoto, A.; Bar-Matthews, M.; Tanaka, T.</p> <p>1984-01-01</p> <p>Textural and mineral-chemical data on freeze-thaw disaggregated refractory inclusions from the Murchison <span class="hlt">meteorite</span> are reported. The data were obtained with neutron activation analysis, SEM, and spectroscopy, the <span class="hlt">study</span> revealed corundum-bearing inclusions, spinel-hibonite aggregates and spherules, and spinel-pyroxene and elivine-pyroxene inclusions. One of the three spinel-, pyroxene-, forsterite-rich inclusions had an amoeba-shaped spinel-pyroxene core, implying vapor-to-solid condensation and therefore crystallization from a melt. It is concluded that the <span class="hlt">meteorite</span> formation encompassed diverse nebular materials, and that further <span class="hlt">studies</span> of the <span class="hlt">meteorite</span> will enhance the data base on the planetary nebular processes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850035523&hterms=kawasaki&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dkawasaki','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850035523&hterms=kawasaki&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dkawasaki"><span>Petrographic <span class="hlt">studies</span> of refractory inclusions from the Murchison <span class="hlt">meteorite</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Macpherson, G. J.; Grossman, L.; Hashimoto, A.; Bar-Matthews, M.; Tanaka, T.</p> <p>1984-01-01</p> <p>Textural and mineral-chemical data on freeze-thaw disaggregated refractory inclusions from the Murchison <span class="hlt">meteorite</span> are reported. The data were obtained with neutron activation analysis, SEM, and spectroscopy, the <span class="hlt">study</span> revealed corundum-bearing inclusions, spinel-hibonite aggregates and spherules, and spinel-pyroxene and elivine-pyroxene inclusions. One of the three spinel-, pyroxene-, forsterite-rich inclusions had an amoeba-shaped spinel-pyroxene core, implying vapor-to-solid condensation and therefore crystallization from a melt. It is concluded that the <span class="hlt">meteorite</span> formation encompassed diverse nebular materials, and that further <span class="hlt">studies</span> of the <span class="hlt">meteorite</span> will enhance the data base on the planetary nebular processes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850007298&hterms=nuclear+fusion&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dnuclear%2Bfusion','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850007298&hterms=nuclear+fusion&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dnuclear%2Bfusion"><span>Atmospheric heating of <span class="hlt">meteorites</span>: Results from nuclear track <span class="hlt">studies</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jha, R.</p> <p>1984-01-01</p> <p>A quantitative model to estimate the degree of annealing of nuclear tracks in mineral grains subjected to a variable temperature history was proposed. This model is applied to <span class="hlt">study</span> the track annealing records in different <span class="hlt">meteorites</span> resulting from their atmospheric heating. Scale lengths were measured of complete and partial track annealing, delta X sub 1 and delta X sub 2, respectively. In mineral grain close to fusion crust in about a dozen <span class="hlt">meteorites</span>. Values of delta X sub 1 and delta X sub 2 depend on extent and duration of heating during atmospheric transit and hence on <span class="hlt">meteorite</span> entry parameters. To estimate track annealing, the temperature history during atmospheric heating at different distances from the crusted surface of the <span class="hlt">meteorite</span> is obtained by solving heat conduction equation in conjunction with <span class="hlt">meteorite</span> entry model, and use of the annealing model to evaluate the degree of annealing of tracks. It is shown that the measured values of delta X sub 1 and delta X sub 2 in three of the <span class="hlt">meteorites</span> <span class="hlt">studied</span> are consistent with values using preatmospheric mass, entry velocity and entry angle of these <span class="hlt">meteorites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850007298&hterms=Nuclear+fusion&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DNuclear%2Bfusion','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850007298&hterms=Nuclear+fusion&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DNuclear%2Bfusion"><span>Atmospheric heating of <span class="hlt">meteorites</span>: Results from nuclear track <span class="hlt">studies</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jha, R.</p> <p>1984-01-01</p> <p>A quantitative model to estimate the degree of annealing of nuclear tracks in mineral grains subjected to a variable temperature history was proposed. This model is applied to <span class="hlt">study</span> the track annealing records in different <span class="hlt">meteorites</span> resulting from their atmospheric heating. Scale lengths were measured of complete and partial track annealing, delta X sub 1 and delta X sub 2, respectively. In mineral grain close to fusion crust in about a dozen <span class="hlt">meteorites</span>. Values of delta X sub 1 and delta X sub 2 depend on extent and duration of heating during atmospheric transit and hence on <span class="hlt">meteorite</span> entry parameters. To estimate track annealing, the temperature history during atmospheric heating at different distances from the crusted surface of the <span class="hlt">meteorite</span> is obtained by solving heat conduction equation in conjunction with <span class="hlt">meteorite</span> entry model, and use of the annealing model to evaluate the degree of annealing of tracks. It is shown that the measured values of delta X sub 1 and delta X sub 2 in three of the <span class="hlt">meteorites</span> <span class="hlt">studied</span> are consistent with values using preatmospheric mass, entry velocity and entry angle of these <span class="hlt">meteorites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20030110601&hterms=clean&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dclean','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20030110601&hterms=clean&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dclean"><span>Comparison of Synchrotron MicroXANES Determination of Fe(3+)/Sigma Fe with Moessbauer Values for Clean Mineral Separates of Pyroxene from <span class="hlt">Martian</span> <span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Delaney, J. S.; Dyar, M. D.</p> <p>2003-01-01</p> <p>The oxidation state of Fe in <span class="hlt">Martian</span> <span class="hlt">meteorites</span> is a parameter of great interest and the ability to determine this value in micrometer scale samples is important. Intense, tunable x-ray sources at large synchrotron storage rings are being exploited to examine the Fe K-absorption edge with energy resolution of approx. 1-1.5eV in spots of 10x15 microns on thin sections of a wide variety of materials including several <span class="hlt">Martian</span> <span class="hlt">meteorites</span>. Synchrotron microXANES (SmX) spectroscopy is the technique that provides the most flexible capability for investigating Fe(3+)/Sigma Fe. Variation of Fe(3+)/Sigma Fe is manifested as a function of the energy of the pre-edge to the Fe absorption edge produced by the sample. SmX is at present the only technique that can be used with conventional polished thin sections. Data for a broad spectrum of minerals have been produced and indicate that SmX can be used with a large variety of samples types.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20030110601&hterms=values&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dvalues','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20030110601&hterms=values&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dvalues"><span>Comparison of Synchrotron MicroXANES Determination of Fe(3+)/Sigma Fe with Moessbauer Values for Clean Mineral Separates of Pyroxene from <span class="hlt">Martian</span> <span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Delaney, J. S.; Dyar, M. D.</p> <p>2003-01-01</p> <p>The oxidation state of Fe in <span class="hlt">Martian</span> <span class="hlt">meteorites</span> is a parameter of great interest and the ability to determine this value in micrometer scale samples is important. Intense, tunable x-ray sources at large synchrotron storage rings are being exploited to examine the Fe K-absorption edge with energy resolution of approx. 1-1.5eV in spots of 10x15 microns on thin sections of a wide variety of materials including several <span class="hlt">Martian</span> <span class="hlt">meteorites</span>. Synchrotron microXANES (SmX) spectroscopy is the technique that provides the most flexible capability for investigating Fe(3+)/Sigma Fe. Variation of Fe(3+)/Sigma Fe is manifested as a function of the energy of the pre-edge to the Fe absorption edge produced by the sample. SmX is at present the only technique that can be used with conventional polished thin sections. Data for a broad spectrum of minerals have been produced and indicate that SmX can be used with a large variety of samples types.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014GeCoA.140..334W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014GeCoA.140..334W"><span>Heterogeneous mineral assemblages in <span class="hlt">martian</span> <span class="hlt">meteorite</span> Tissint as a result of a recent small impact event on Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Walton, E. L.; Sharp, T. G.; Hu, J.; Filiberto, J.</p> <p>2014-09-01</p> <p>The microtexture and mineralogy of shock melts in the Tissint <span class="hlt">martian</span> <span class="hlt">meteorite</span> were investigated using scanning electron microscopy, Raman spectroscopy, transmission electron microscopy and synchrotron micro X-ray diffraction to understand shock conditions and duration. Distinct mineral assemblages occur within and adjacent to the shock melts as a function of the thickness and hence cooling history. The matrix of thin veins and pockets of shock melt consists of clinopyroxene + ringwoodite ± stishovite embedded in glass with minor Fe-sulfide. The margins of host rock olivine in contact with the melt, as well as entrained olivine fragments, are now amorphosed silicate perovskite + magnesiowüstite or clinopyroxene + magnesiowüstite. The pressure stabilities of these mineral assemblages are ∼15 GPa and >19 GPa, respectively. The ∼200-μm-wide margin of a thicker, mm-size (up to 1.4 mm) shock melt vein contains clinopyroxene + olivine, with central regions comprising glass + vesicles + Fe-sulfide spheres. Fragments of host rock within the melt are polycrystalline olivine (after olivine) and tissintite + glass (after plagioclase). From these mineral assemblages the crystallization pressure at the vein edge was as high as 14 GPa. The interior crystallized at ambient pressure. The shock melts in Tissint quench-crystallized during and after release from the peak shock pressure; crystallization pressures and those determined from olivine dissociation therefore represent the minimum shock loading. Shock deformation in host rock minerals and complete transformation of plagioclase to maskelynite suggest the peak shock pressure experienced by Tissint ⩾ 29-30 GPa. These pressure estimates support our assessment that the peak shock pressure in Tissint was significantly higher than the minimum 19 GPa required to transform olivine to silicate perovskite plus magnesiowüstite. Small volumes of shock melt (<100 μm) quench rapidly (0.01 s), whereas thermal equilibration will</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/7242171','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/7242171"><span><span class="hlt">Meteoritic</span> basalts. Final report, 1986-1989</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Treiman, A.H.</p> <p>1989-10-01</p> <p>The objectives were to: explain the abundances of siderophile elements in the SNC <span class="hlt">meteorite</span> suite, of putative <span class="hlt">Martian</span> origin; discover the magmatic origins and possibly magma compositions behind the Nakhla <span class="hlt">meteorite</span>, one of the SNC <span class="hlt">meteorites</span>; and a re-evaluation of the petrology of Angra dos Reis, a unique <span class="hlt">meteorite</span> linked to the earliest planetary bodies of the solar nebula. A re-evaluation of its petrography showed that the accepted scenario for its origin, as a cumulate igneous rock, was not consistent with the <span class="hlt">meteorite</span>'s textures (Treiman). More likely is that the <span class="hlt">meteorite</span> represents a prophyritic igneous rock, originally with magma dominant. <span class="hlt">Studies</span> of the Nakhla <span class="hlt">meteorite</span>, of possible <span class="hlt">Martian</span> origin, although difficult, were successful. It became necessary to reject the basic categorization of Nakhla: that is was a cumulate igneous rock. Detailed <span class="hlt">studies</span> of the chemical zoning of Nakhlas' minerals, coupled with the failure of experimental <span class="hlt">studies</span> to yield expected results, forced the conclusion that Nakhla is not a cumulate rock in the usual sense: a rock composed of igneous crystals and intercrystal magma. <span class="hlt">Study</span> of the siderophile element abundances in the SNC <span class="hlt">meteorite</span> groups involved trying to find reasonable core formation processes and parameters that would reproduce the observed abundances. Modelling was successful, and delimited a range of models which overlap with those reasonable from geophysical constraints.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=mars+AND+investigation&pg=2&id=ED248165','ERIC'); return false;" href="http://eric.ed.gov/?q=mars+AND+investigation&pg=2&id=ED248165"><span>The <span class="hlt">Martian</span> Chronicles. A Sound Filmstrip Program. <span class="hlt">Study</span> Guide.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Christesen, Barbara</p> <p></p> <p>This filmstrip <span class="hlt">study</span> guide dramatizes several stories from Ray Bradbury's "The <span class="hlt">Martian</span> Chronicles" concerning basic issues of human nature: the need to respect cultural differences and the importance of preserving the environment. A collection of 26 short stories, "The <span class="hlt">Martian</span> Chronicles" describes the colonization of Mars. The…</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=ray+AND+bradbury&pg=3&id=ED248165','ERIC'); return false;" href="https://eric.ed.gov/?q=ray+AND+bradbury&pg=3&id=ED248165"><span>The <span class="hlt">Martian</span> Chronicles. A Sound Filmstrip Program. <span class="hlt">Study</span> Guide.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Christesen, Barbara</p> <p></p> <p>This filmstrip <span class="hlt">study</span> guide dramatizes several stories from Ray Bradbury's "The <span class="hlt">Martian</span> Chronicles" concerning basic issues of human nature: the need to respect cultural differences and the importance of preserving the environment. A collection of 26 short stories, "The <span class="hlt">Martian</span> Chronicles" describes the colonization of Mars. The…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19780060590&hterms=martensitic+transformation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dmartensitic%2Btransformation','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19780060590&hterms=martensitic+transformation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dmartensitic%2Btransformation"><span>A microstructural <span class="hlt">study</span> of the Tishomingo <span class="hlt">meteorite</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ives, L. K.; Kasen, M. B.; Schramm, R. E.; Ruff, A. W.; Reed, R. P.</p> <p>1978-01-01</p> <p>Metallography, electron microscopy, and X-ray diffraction techniques were employed to <span class="hlt">study</span> a fragment of the Tishomingo iron <span class="hlt">meteorite</span>. The results suggest the following thermal-mechanical history: The fragment was originally a large crystal of taenite (gamma). Cooling through the alpha + gamma phase boundary did not result in accompanying precipitation of kamacite (alpha). Transformation to a martensitic structure initiated between -25 and -65 C. Transformation continued as the temperature fell to -75 to -115 C, resulting in approx 80% martensite (alpha-prime). Subsequent shock deformation and thermal aging processes substantially modified the taenite and martensite microstructures. Twins in the retained taenite phase are attributed to shock deformation at a pressure estimated for a single event at about 170 kbar. The existing complex altered martensite structure containing both taenite and kamacite (3-15% Ni) particles was apparently the product of both shock deformation and thermal aging processes. The maximum temperature reached during thermal aging is estimated to be less than 400 C and perhaps below 310 C.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.P13A1917A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.P13A1917A"><span>Lunar and <span class="hlt">Meteorite</span> Thin Sections for Undergraduate and Graduate <span class="hlt">Studies</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Allen, J.; Allen, C.</p> <p>2012-12-01</p> <p>The Johnson Space Center (JSC) has the unique responsibility to curate NASA's extraterrestrial samples from past and future missions. Curation includes documentation, preservation, preparation, and distribution of samples for research, education, and public outreach. <span class="hlt">Studies</span> of rock and soil samples from the Moon and <span class="hlt">meteorites</span> continue to yield useful information about the early history of the Moon, the Earth, and the inner solar system. Petrographic Thin Section Packages containing polished thin sections of samples from either the Lunar or <span class="hlt">Meteorite</span> collections have been prepared. Each set of twelve sections of Apollo lunar samples or twelve sections of <span class="hlt">meteorites</span> is available for loan from JSC. The thin sections sets are designed for use in domestic college and university courses in petrology. The loan period is very strict and limited to two weeks. Contact Ms. Mary Luckey, Education Sample Curator. Email address: mary.k.luckey@nasa.gov Each set of slides is accompanied by teaching materials and a sample disk of representative lunar or <span class="hlt">meteorite</span> samples. It is important to note that the samples in these sets are not exactly the same as the ones listed here. This list represents one set of samples. A key education resource available on the Curation website is Antarctic <span class="hlt">Meteorite</span> Teaching Collection: Educational <span class="hlt">Meteorite</span> Thin Sections, originally compiled by Bevan French, Glenn McPherson, and Roy Clarke and revised by Kevin Righter in 2010. Curation Websites College and university staff and students are encouraged to access the Lunar Petrographic Thin Section Set Publication and the <span class="hlt">Meteorite</span> Petrographic Thin Section Package Resource which feature many thin section images and detailed descriptions of the samples, research results. http://curator.jsc.nasa.gov/Education/index.cfm Request research samples: http://curator.jsc.nasa.gov/ JSC-CURATION-EDUCATION-DISKS@mail.nasa.govLunar Thin Sections; <span class="hlt">Meteorite</span> Thin Sections;</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JAfES.134..644K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JAfES.134..644K"><span><span class="hlt">Meteorite</span> falls in Africa</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Khiri, Fouad; Ibhi, Abderrahmane; Saint-Gerant, Thierry; Medjkane, Mohand; Ouknine, Lahcen</p> <p>2017-10-01</p> <p>The <span class="hlt">study</span> of <span class="hlt">meteorites</span> provides insight into the earliest history of our solar system. From 1800, about the year <span class="hlt">meteorites</span> were first recognized as objects falling from the sky, until December 2014, 158 observed <span class="hlt">meteorite</span> falls were recorded in Africa. Their collected mass ranges from 1.4 g to 175 kg with the 1-10 kg cases predominant. The average rate of African falls is low with only one fall recovery per 1.35-year time interval (or 0.023 per year per million km2). This African collection is dominated by ordinary chondrites (78%) just like in the worldwide falls. The seventeen achondrites include three <span class="hlt">Martian</span> <span class="hlt">meteorite</span> falls (Nakhla of Egypt, Tissint of Morocco and Zagami of Nigeria). Observed Iron <span class="hlt">meteorite</span> falls are relatively rare and represent only 5%. The falls' rate in Africa is variable in time and in space. The number of falls continues to grow since 1860, 80% of which were recovered during the period between 1910 and 2014. Most of these documented <span class="hlt">meteorite</span> falls have been recovered from North-Western Africa, Eastern Africa and Southern Africa. They are concentrated in countries which have a large surface area and a large population with a uniform distribution. Other factors are also favorable for observing and collecting <span class="hlt">meteorite</span> falls across the African territory, such as: a genuine <span class="hlt">meteorite</span> education, a semi-arid to arid climate (clear sky throughout the year most of the time), croplands or sparse grasslands and possible access to the fall location with a low percentage of forest cover and dense road network.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012E%26PSL.341..195N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012E%26PSL.341..195N"><span>U-Pb isotopic systematics of shock-loaded and annealed baddeleyite: Implications for crystallization ages of <span class="hlt">Martian</span> <span class="hlt">meteorite</span> shergottites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Niihara, Takafumi; Kaiden, Hiroshi; Misawa, Keiji; Sekine, Toshimori; Mikouchi, Takashi</p> <p>2012-08-01</p> <p>Shock-recovery and annealing experiments on basalt-baddeleyite mixtures were undertaken to evaluate shock effects on U-Pb isotopic systematics of baddeleyite. Shock pressures up to 57 GPa caused fracturing of constituent phases, mosaicism of olivine, maskelynitization of plagioclase, and melting, but the phase transition from monoclinic baddeleyite structure to high-pressure/temperature polymorphs of ZrO2 was not confirmed. The U-Pb isotopic systems of the shock-loaded baddeleyite did not show a large-scale isotopic disturbance. The samples shock-recovered from 47 GPa were then employed for annealing experiments at 1000 or 1300 °C, indicating that the basalt-baddeleyite mixture was almost totally melted except olivine and baddeleyite. Fine-grained euhedral zircon crystallized from the melt was observed around the relict baddeleyite in the sample annealed at 1300 °C for 1 h. The U-Pb isotopic systems of baddeleyite showed isotopic disturbances: many data points for the samples annealed at 1000 °C plotted above the concordia. Both radiogenic lead loss/uranium gain and radiogenic lead gain/uranium loss were observed in the baddeleyite annealed at 1300 °C. Complete radiogenic lead loss due to shock metamorphism and subsequent annealing was not observed in the shock-loaded/annealed baddeleyites <span class="hlt">studied</span> here. These results confirm that the U-Pb isotopic systematics of baddeleyite are durable for shock metamorphism. Since shergottites still preserve Fe-Mg and/or Ca zonings in major constituent phases (i.e. pyroxene and olivine), the shock effects observed in <span class="hlt">Martian</span> baddeleyites seem to be less intense compared to that under the present experimental conditions. An implication is that the U-Pb systems of baddeleyite in shergottites will provide crystallization ages of <span class="hlt">Martian</span> magmatic rocks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.P54B..06G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.P54B..06G"><span>Comparison of Laser Induced Breakdown Spectroscopy (LIBS) on <span class="hlt">Martian</span> <span class="hlt">Meteorite</span> NWA 7034 to ChemCam Observations at Gale Crater, Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gordon, S.; Newsom, H. E.; Agee, C. B.; Santos, A. R.; Clegg, S. M.; Wiens, R. C.; Lasue, J.; Sautter, V.</p> <p>2014-12-01</p> <p>The ChemCam instrument on board the Mars Science Laboratory (MSL) Curiosity rover uses laser-induced breakdown spectroscopy (LIBS) to analyze rock and soil targets on Mars from up to 7 m away. The Nd:KGW laser can shoot up to 1000 shots at one location and profile up to 1 mm depth into a rock. Identical LIBS instrumentation is located at Los Alamos National Laboratory and was used to analyze <span class="hlt">martian</span> <span class="hlt">meteorite</span> NWA 7034, a non-SNC basaltic breccia whose bulk composition matches the <span class="hlt">martian</span> surface. Initial LIBS analysis of NWA 7034 included observations on two basaltic clasts in the <span class="hlt">meteorite</span>. Electron microprobe analysis (EPMA) was performed on the two clasts for comparison with elemental compositions measured using LIBS. The two instruments give similar compositions of major oxides within the error of both techniques. EPMA analysis was also completed on three light-toned clasts and a dark-toned clast in the <span class="hlt">meteorite</span>. The light-toned clasts have Al/Si vs. (Fe+Mg)/Si compositions ranging from felsic to mafic, and the dark-toned clast shows a mafic composition. A Sammon's map was created to compare LIBS data for NWA 7034 and ChemCam targets Stark, Crestaurum, Link, Portage, Jake_M, Mara, Thor_Lake, Coronation, Pearson, and Prebble. This nonlinear statistical mapping technique is used for clustering assessment of LIBS data in two dimensions. The map shows NWA 7034 clustering in its own location, and the closest similar ChemCam rock targets are La_Reine and Ashuamipi, which are both coarse grained targets that have a mafic component consistent with augite. The most similar ChemCam soil targets are the Crestaurum and Portage. Creation of maps with a greater number of targets will show more of the similarities between NWA 7034 and ChemCam target rocks and soils. Further analysis will compare NWA 7034 LIBS data, data from the paired <span class="hlt">meteorite</span> NWA 7533, and a variety of ChemCam targets that are similar in morphology and texture.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120001834','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120001834"><span>Evidence from Olivine-Hosted Melt Inclusions that the <span class="hlt">Martian</span> Mantle has a Chondritic D/H Ratio and that Some Young Basalts have Assimilated Old Crust</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Usui, Tomohiro; Alexander, O'D.; Wang, J.; Simon, J. I.; Jones, J. H.</p> <p>2012-01-01</p> <p>Magmatic degassing of volatile elements affects the climate and near-surface environment of Mars. Telescopic and <span class="hlt">meteorite</span> <span class="hlt">studies</span> have revealed that the <span class="hlt">Martian</span> atmosphere and near-surface materials have D/H ratios 5-6 times terrestrial values [e.g., 1, 2]. Such high D/H ratios are interpreted to result from the preferential loss of H relative to heavier D from the <span class="hlt">Martian</span> atmosphere, assuming that the original <span class="hlt">Martian</span> water inventory had a D/H ratio similar to terrestrial values and to H in primitive <span class="hlt">meteorites</span> [e.g., 1, 3]. However, the primordial <span class="hlt">Martian</span> D/H ratio has, until now, not been well constrained. The uncertainty over the <span class="hlt">Martian</span> primordial D/H ratio has arisen both from the scarcity of primitive <span class="hlt">Martian</span> <span class="hlt">meteorites</span> and as a result of contamination by terrestrial and, perhaps, <span class="hlt">Martian</span> surface waters that obscure the signature of the <span class="hlt">Martian</span> mantle. This <span class="hlt">study</span> reports a comprehensive dataset of magmatic volatiles and D/H ratios in <span class="hlt">Martian</span> primary magmas based on low-contamination, in situ ion microprobe analyses of olivine-hosted melt inclusions from both depleted [Yamato 980459 (Y98)] and enriched [Larkman Nunatak 06319 (LAR06)] <span class="hlt">Martian</span> basaltic <span class="hlt">meteorites</span>. Analyses of these primitive melts provide definitive evidence that the <span class="hlt">Martian</span> mantle has retained a primordial D/H ratio and that young <span class="hlt">Martian</span> basalts have assimilated old <span class="hlt">Martian</span> crust.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5343502','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5343502"><span>Shock-transformation of whitlockite to merrillite and the implications for <span class="hlt">meteoritic</span> phosphate</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Adcock, C. T.; Tschauner, O.; Hausrath, E. M.; Udry, A.; Luo, S. N.; Cai, Y.; Ren, M.; Lanzirotti, A.; Newville, M.; Kunz, M.; Lin, C.</p> <p>2017-01-01</p> <p><span class="hlt">Meteorites</span> represent the only samples available for <span class="hlt">study</span> on Earth of a number of planetary bodies. The minerals within <span class="hlt">meteorites</span> therefore hold the key to addressing numerous questions about our solar system. Of particular interest is the Ca-phosphate mineral merrillite, the anhydrous end-member of the merrillite–whitlockite solid solution series. For example, the anhydrous nature of merrillite in <span class="hlt">Martian</span> <span class="hlt">meteorites</span> has been interpreted as evidence of water-limited late-stage <span class="hlt">Martian</span> melts. However, recent research on apatite in the same <span class="hlt">meteorites</span> suggests higher water content in melts. One complication of using <span class="hlt">meteorites</span> rather than direct samples is the shock compression all <span class="hlt">meteorites</span> have experienced, which can alter <span class="hlt">meteorite</span> mineralogy. Here we show whitlockite transformation into merrillite by shock-compression levels relevant to <span class="hlt">meteorites</span>, including <span class="hlt">Martian</span> <span class="hlt">meteorites</span>. The results open the possibility that at least part of <span class="hlt">meteoritic</span> merrillite may have originally been H+-bearing whitlockite with implications for interpreting <span class="hlt">meteorites</span> and the need for future sample return. PMID:28262701</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1379764-shock-transformation-whitlockite-merrillite-implications-meteoritic-phosphate','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1379764-shock-transformation-whitlockite-merrillite-implications-meteoritic-phosphate"><span>Shock-transformation of whitlockite to merrillite and the implications for <span class="hlt">meteoritic</span> phosphate</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Adcock, C. T.; Tschauner, O.; Hausrath, E. M.; ...</p> <p>2017-03-06</p> <p><span class="hlt">Meteorites</span> represent the only samples available for <span class="hlt">study</span> on Earth of a number of planetary bodies. The minerals within <span class="hlt">meteorites</span> therefore hold the key to addressing numerous questions about our solar system. Of particular interest is the Ca-phosphate mineral merrillite, the anhydrous end-member of the merrillite-whitlockite solid solution series. For example, the anhydrous nature of merrillite in <span class="hlt">Martian</span> <span class="hlt">meteorites</span> has been interpreted as evidence of water-limited late-stage <span class="hlt">Martian</span> melts. However, recent research on apatite in the same <span class="hlt">meteorites</span> suggests higher water content in melts. One complication of using <span class="hlt">meteorites</span> rather than direct samples is the shock compression all <span class="hlt">meteorites</span> havemore » experienced, which can alter <span class="hlt">meteorite</span> mineralogy. Here we show whitlockite transformation into merrillite by shock-compression levels relevant to <span class="hlt">meteorites</span>, including <span class="hlt">Martian</span> <span class="hlt">meteorites</span>. The results open the possibility that at least part of <span class="hlt">meteoritic</span> merrillite may have originally been H + -bearing whitlockite with implications for interpreting <span class="hlt">meteorites</span> and the need for future sample return.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017NatCo...814667A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017NatCo...814667A"><span>Shock-transformation of whitlockite to merrillite and the implications for <span class="hlt">meteoritic</span> phosphate</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Adcock, C. T.; Tschauner, O.; Hausrath, E. M.; Udry, A.; Luo, S. N.; Cai, Y.; Ren, M.; Lanzirotti, A.; Newville, M.; Kunz, M.; Lin, C.</p> <p>2017-03-01</p> <p><span class="hlt">Meteorites</span> represent the only samples available for <span class="hlt">study</span> on Earth of a number of planetary bodies. The minerals within <span class="hlt">meteorites</span> therefore hold the key to addressing numerous questions about our solar system. Of particular interest is the Ca-phosphate mineral merrillite, the anhydrous end-member of the merrillite-whitlockite solid solution series. For example, the anhydrous nature of merrillite in <span class="hlt">Martian</span> <span class="hlt">meteorites</span> has been interpreted as evidence of water-limited late-stage <span class="hlt">Martian</span> melts. However, recent research on apatite in the same <span class="hlt">meteorites</span> suggests higher water content in melts. One complication of using <span class="hlt">meteorites</span> rather than direct samples is the shock compression all <span class="hlt">meteorites</span> have experienced, which can alter <span class="hlt">meteorite</span> mineralogy. Here we show whitlockite transformation into merrillite by shock-compression levels relevant to <span class="hlt">meteorites</span>, including <span class="hlt">Martian</span> <span class="hlt">meteorites</span>. The results open the possibility that at least part of <span class="hlt">meteoritic</span> merrillite may have originally been H+-bearing whitlockite with implications for interpreting <span class="hlt">meteorites</span> and the need for future sample return.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19990027237','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19990027237"><span><span class="hlt">Studies</span> of the <span class="hlt">Martian</span> Magnetic Field</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Russell, C. T.</p> <p>1998-01-01</p> <p>This report covers two awards: the first NAGW-2573 was awarded to enable participation in the Mars 94 mission that slipped to become the Mars 96 mission. Upon the unfortunate failure of Mars 96 to achieve its intended trajectory, the second grant was awarded to closeout the Mars 96 activities. Our initial efforts concentrated on assisting our colleagues: W. Riedler, K. Schwingenschuh, K. Gringanz, M. Verigin and Ye. Yeroshenko with advice on the development of the magnetic field portion of the investigation and to help them with test activities. We also worked with them to properly analyze the Phobos magnetic field and plasma data in order to optimize the return from the Mars 94/96 mission. This activity resulted in 18 papers on Mars scientific topics, and two on the instrumentation. One of these latter two papers was the last of the papers written, and speaks to the value of the closeout award. These 20 papers are listed in the attached bibliography. Because we had previously <span class="hlt">studied</span> Venus and Titan and since it was becoming evident that the magnetic field was very weak, we compared the various properties of the <span class="hlt">Martian</span> interaction with those of the analogous interactions at Venus and Titan while other papers simply analyzed the properties of the interaction as Phobos 2 observed them. One very interesting observation was the identification of ions picked up in the solar wind, originating in Mars neutral atmosphere. These had been predicted by our earlier observation of cyclotron waves at the proton gyrofrequency in the region upstream from Mars in the solar wind. Of course, the key question we addressed was that of the intrinsic or induced nature of the <span class="hlt">Martian</span> magnetic field. We found little evidence for the former and much for the latter point of view. We also discussed the instrumentation planned for the Mars balloon and the instrumentation on the orbiter. In all these <span class="hlt">studies</span> were very rewarding despite the short span of the Phobos data. Although they did not</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940017205','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940017205"><span>Wet inside and out? Constraints on water in the <span class="hlt">Martian</span> mantle and on outgassed water, based on melt inclusions in SNC <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mcsween, H. Y., Jr.; Harvey, R. P.</p> <p>1993-01-01</p> <p>Constraints on the volatile inventory and outgassing history of Mars are critical to understanding the origin of ancient valley systems and paleoclimates. Planetary accretion models for Mars allow either a volatile-rich or volatile-poor mantle, depending on whether the accreted materials were fully oxidized or whether accretion was homogeneous so that water was lost through reaction with metallic iron. The amount of water that has been outgassed from the interior is likewise a contentious subject, and estimates of globally distributed water based on various geochemical and geological measurements vary from a few meters to more than a thousand meters. New data on SNC <span class="hlt">meteorites</span>, which are thought to be <span class="hlt">Martian</span> igneous rocks, provide constraints on both mantle and outgassed water.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1816619C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1816619C"><span><span class="hlt">Meteorite</span> crater impact <span class="hlt">study</span>: a new way to <span class="hlt">study</span> seismology at school with exciting experiments, and an example of <span class="hlt">meteorite</span> astroblema in France (Rochechouart)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Carrer, Diane; Berenguer, Jean-Luc; MacMurray, Andrew</p> <p>2016-04-01</p> <p>The InSIGHT mission to Mars (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) supported by NASA, IPGP and CNES, is a great opportunity for teachers and pupils to <span class="hlt">study</span> the Red planet, but also to <span class="hlt">study</span> other fields of geology at school, such as seismology. With our pupils, we are following the InSight mission and we look forward to analyze seismic data registered by the SEIS seismometer , once it will be available (the InSight mission will launch in 2018 from California, and will land to Mars in 2018 or 2019). As this mission needs <span class="hlt">meteorite</span> impacts to generate seismic waves ( to discover the <span class="hlt">Martian</span> interior structure) , we've decided to model those <span class="hlt">meteorite</span> strikes in the classroom. With our pupils, we've modeled <span class="hlt">meteorite</span> impact craters with different impactors , such as tennis balls, baseballs, or pingpong balls, and used an analogue substratum made by flour and cocoa. Then, we kept on going our geophysical investigation , <span class="hlt">studying</span> several parameters. For instance, we've <span class="hlt">studied</span> the link between size of impactor and size of crater , the link between mass of impactor and Crater Formation, and the link between velocity of impactor and crater formation. In this geophysical approach , potential energy and kinetic energy can be introduced in terms of energy transfer as the impactor falls ( calculation of the velocity of impact and plotting that against crater diameter using v = (2gh)1/2). For each crater formation made in class by students, we have registered seismological data thanks to Audacity software, and <span class="hlt">study</span> the seismic signal propagation. This exemple of hands-on activity with pupils, and its wide range of geophysical calculation shows how we can do simple experiment modeling <span class="hlt">meteorite</span> crater impact and exploit registered seismological data at school. We've finaly focused our work with the very famous example of the astroblema of Rochechouart in the South-west of France ( crater formation : - 214 My) , in which it's easy to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21969535','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21969535"><span>Combining <span class="hlt">meteorites</span> and missions to explore Mars.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>McCoy, Timothy J; Corrigan, Catherine M; Herd, Christopher D K</p> <p>2011-11-29</p> <p>Laboratory <span class="hlt">studies</span> of <span class="hlt">meteorites</span> and robotic exploration of Mars reveal scant atmosphere, no evidence of plate tectonics, past evidence for abundant water, and a protracted igneous evolution. Despite indirect hints, direct evidence of a <span class="hlt">martian</span> origin came with the discovery of trapped atmospheric gases in one <span class="hlt">meteorite</span>. Since then, the <span class="hlt">study</span> of <span class="hlt">martian</span> <span class="hlt">meteorites</span> and findings from missions have been linked. Although the <span class="hlt">meteorite</span> source locations are unknown, impact ejection modeling and spectral mapping of Mars suggest derivation from small craters in terrains of Amazonian to Hesperian age. Whereas most <span class="hlt">martian</span> <span class="hlt">meteorites</span> are young (< 1.3 Ga), the spread of whole rock isotopic compositions results from crystallization of a magma ocean > 4.5 Ga and formation of enriched and depleted reservoirs. However, the history inferred from <span class="hlt">martian</span> <span class="hlt">meteorites</span> conflicts with results from recent Mars missions, calling into doubt whether the igneous histor y inferred from the <span class="hlt">meteorites</span> is applicable to Mars as a whole. Allan Hills 84001 dates to 4.09 Ga and contains fluid-deposited carbonates. Accompanying debate about the mechanism and temperature of origin of the carbonates came several features suggestive of past microbial life in the carbonates. Although highly disputed, the suggestion spurred interest in habitable extreme environments on Earth and throughout the Solar System. A flotilla of subsequent spacecraft has redefined Mars from a volcanic planet to a hydrologically active planet that may have harbored life. Understanding the history and habitability of Mars depends on understanding the coupling of the atmosphere, surface, and subsurface. Sample return that brings back direct evidence from these diverse reservoirs is essential.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3228422','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3228422"><span>Combining <span class="hlt">meteorites</span> and missions to explore Mars</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>McCoy, Timothy J.; Corrigan, Catherine M.; Herd, Christopher D. K.</p> <p>2011-01-01</p> <p>Laboratory <span class="hlt">studies</span> of <span class="hlt">meteorites</span> and robotic exploration of Mars reveal scant atmosphere, no evidence of plate tectonics, past evidence for abundant water, and a protracted igneous evolution. Despite indirect hints, direct evidence of a <span class="hlt">martian</span> origin came with the discovery of trapped atmospheric gases in one <span class="hlt">meteorite</span>. Since then, the <span class="hlt">study</span> of <span class="hlt">martian</span> <span class="hlt">meteorites</span> and findings from missions have been linked. Although the <span class="hlt">meteorite</span> source locations are unknown, impact ejection modeling and spectral mapping of Mars suggest derivation from small craters in terrains of Amazonian to Hesperian age. Whereas most <span class="hlt">martian</span> <span class="hlt">meteorites</span> are young (< 1.3 Ga), the spread of whole rock isotopic compositions results from crystallization of a magma ocean > 4.5 Ga and formation of enriched and depleted reservoirs. However, the history inferred from <span class="hlt">martian</span> <span class="hlt">meteorites</span> conflicts with results from recent Mars missions, calling into doubt whether the igneous histor y inferred from the <span class="hlt">meteorites</span> is applicable to Mars as a whole. Allan Hills 84001 dates to 4.09 Ga and contains fluid-deposited carbonates. Accompanying debate about the mechanism and temperature of origin of the carbonates came several features suggestive of past microbial life in the carbonates. Although highly disputed, the suggestion spurred interest in habitable extreme environments on Earth and throughout the Solar System. A flotilla of subsequent spacecraft has redefined Mars from a volcanic planet to a hydrologically active planet that may have harbored life. Understanding the history and habitability of Mars depends on understanding the coupling of the atmosphere, surface, and subsurface. Sample return that brings back direct evidence from these diverse reservoirs is essential. PMID:21969535</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940028720','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940028720"><span>The mineralogic evolution of the <span class="hlt">Martian</span> surface through time: Implications from chemical reaction path modeling <span class="hlt">studies</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Plumlee, G. S.; Ridley, W. I.; Debraal, J. D.; Reed, M. H.</p> <p>1993-01-01</p> <p>Chemical reaction path calculations were used to model the minerals that might have formed at or near the <span class="hlt">Martian</span> surface as a result of volcano or <span class="hlt">meteorite</span> impact driven hydrothermal systems; weathering at the <span class="hlt">Martian</span> surface during an early warm, wet climate; and near-zero or sub-zero C brine-regolith reactions in the current cold climate. Although the chemical reaction path calculations carried out do not define the exact mineralogical evolution of the <span class="hlt">Martian</span> surface over time, they do place valuable geochemical constraints on the types of minerals that formed from an aqueous phase under various surficial and geochemically complex conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940020876','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940020876"><span>A geochemical <span class="hlt">study</span> of acapulcoite and lodranite <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Field, Stephen W.</p> <p>1993-01-01</p> <p>Lodranites and acapulcoites (primitive achondrites) are two classes of <span class="hlt">meteorites</span> with geochemical signatures similar to chondrite <span class="hlt">meteorites</span>. Lodranites and acapulcoites, however, have few or none of the chondrules characteristic of the chondrites. Texturally the primitive achondrites appear to have been recystallized though planetary igneous or metamorphic processes. A <span class="hlt">study</span> of five primitive achondrites, two lodranites, two acapulcoites, and one supposedly intermediate acapulcoite/lodranite, were analyzed petrographically and geochemically to determine the igneous and metamorphic processes which have affected them. Acapulcoites show little evidence of melt extraction. The geochemistry of lodranite samples indicates silicate and metal/sulfide melts were removed from the rocks. The mineralogy and geochemistry of the intermediate <span class="hlt">meteorite</span> suggest the rock is a metal rich acapulcoite and not a lodranite.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120003248','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120003248"><span>Lunar and <span class="hlt">Meteorite</span> Thin Sections for Undergraduate and Graduate <span class="hlt">Studies</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Allen, J.; Galindo, C.; Luckey, M.; Reustle, J.; Todd, N.; Allen, C.</p> <p>2012-01-01</p> <p>The Johnson Space Center (JSC) has the unique responsibility to curate NASA's extraterrestrial samples from past and future missions. Curation includes documentation, preservation, preparation, and distribution of samples for research, education, and public outreach. Between 1969 and 1972 six Apollo missions brought back 382 kilograms of lunar rocks, core samples, pebbles, sand and dust from the lunar surface. JSC also curates <span class="hlt">meteorites</span> collected on US expeditions to Antarctica including rocks from Moon, Mars, and many asteroids including Vesta. <span class="hlt">Studies</span> of rock and soil samples from the Moon and <span class="hlt">meteorites</span> continue to yield useful information about the early history of the Moon, the Earth, and the inner solar system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016LPICo1921.6557O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016LPICo1921.6557O"><span><span class="hlt">Study</span> of the Circumstance of <span class="hlt">Meteorites</span> "Northwest Africa" Finds Contribution to an Appropriate Renomenclature</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ouknine, L.; Kliri, F.; Ibhi, A.</p> <p>2016-08-01</p> <p>This work tries to respond to solicitations from researchers of the region to highlight the <span class="hlt">meteorites</span> recovered in Morocco and neighboring countries. The objectives assigned to this <span class="hlt">study</span> are the contextualization of the finds of <span class="hlt">meteorites</span> NWA.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20130009928','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20130009928"><span>Shock Experiments on Basalt - Ferric Sulfate Mixes at 21 GPa & 49 GPa and their Relevance to <span class="hlt">Martian</span> <span class="hlt">Meteorite</span> Impact Glasses</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rao, M. N.; Ross, D. K.; See, T. H.; Nyquist, L. E.; Sutton, S.; Asimow, P.</p> <p>2013-01-01</p> <p>Large abundance of <span class="hlt">Martian</span> atmospheric gases and neutron-induced isotopic excesses as well as Rb-Sr isotopic variations determined in some impact glasses in basaltic shergottites (e.g., Shergotty #DBS, Zagami #H1 and EET79001 #27, #8 and #104) provide definitive evidence for the occurrence of a <span class="hlt">Martian</span> regolith component in their constituent mineral assemblages. Some of these glass-es, known as gas-rich impact-melts (GRIM), contain numerous micron-sized iron sulfide blebs along with minor amounts of iron sulfate particulates. As these GRIM glasses contain a <span class="hlt">Martian</span> regolith component and as iron sulfates (but not sulfides) are found to occur abundantly on the Mars surface, we suggested that the sulfide blebs in GRIMs were likely generated by shock-reduction of the parental iron sulfate bearing regolith material that had been incorporated into the cavities/crevices of basaltic host rock prior to the impact event on Mars. To test whether the sulfates could be reduced to sulfides by impact shock, we carried out laboratory shock experiments on a basalt plus ferric sulfate mixture at 49 GPa at the Caltech Shock Wave Laboratory and at 21 GPa at Johnson Space Center (JSC) Experimental Impact Laboratory. The experimental details and the preliminary results for the Caltech 49 GPa experiment were presented at LPSC last year. Here, we report the results for the 21 GPa experiment at JSC and compare these results to obtain further insight into the mechanism of the bleb formation in the GRIM glasses.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012LPI....43.1010P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012LPI....43.1010P"><span>Experimental <span class="hlt">Martian</span> Eclogite with a QUE 94201 Composition</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Papike, J. J.; Burger, P. V.; Shearer, C. K.; McCubbin, F. M.; Elardo, S. M.</p> <p>2012-03-01</p> <p>High-pressure techniques were used to synthesize a <span class="hlt">martian</span> eclogite based on the composition of <span class="hlt">martian</span> <span class="hlt">meteorite</span> QUE 94201. The resultant eclogite may be representative of <span class="hlt">martian</span> melts whose ascent has been arrested in the upper mantle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040056036&hterms=Samarium&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DSamarium','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040056036&hterms=Samarium&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DSamarium"><span>Oxygen Fugacity of the <span class="hlt">Martian</span> Mantle from Pigeonite/Melt Partitioning of Samarium, Europium and Gadolinium</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Musselwhite, D. S.; Jnes, J. H.; Shearer, C.</p> <p>2004-01-01</p> <p>This <span class="hlt">study</span> is part of an ongoing effort to calibrate the pyroxene/melt REE oxybarometer for conditions relevant to the <span class="hlt">martian</span> <span class="hlt">meteorites</span>. These efforts have been motivated by reports of redox variations among the shergottites . We have conducted experiments on <span class="hlt">martian</span> composition pigeonite/melt rare earth element partitioning as a function of fO2.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040056036&hterms=Gadolinium&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DGadolinium','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040056036&hterms=Gadolinium&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DGadolinium"><span>Oxygen Fugacity of the <span class="hlt">Martian</span> Mantle from Pigeonite/Melt Partitioning of Samarium, Europium and Gadolinium</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Musselwhite, D. S.; Jnes, J. H.; Shearer, C.</p> <p>2004-01-01</p> <p>This <span class="hlt">study</span> is part of an ongoing effort to calibrate the pyroxene/melt REE oxybarometer for conditions relevant to the <span class="hlt">martian</span> <span class="hlt">meteorites</span>. These efforts have been motivated by reports of redox variations among the shergottites . We have conducted experiments on <span class="hlt">martian</span> composition pigeonite/melt rare earth element partitioning as a function of fO2.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4297357','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4297357"><span>Dating the <span class="hlt">Martian</span> <span class="hlt">meteorite</span> Zagami by the 87Rb-87Sr isochron method with a prototype in situ resonance ionization mass spectrometer</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Scott Anderson, F; Levine, Jonathan; Whitaker, Tom J</p> <p>2015-01-01</p> <p>RATIONALE The geologic history of the Solar System builds on an extensive record of impact flux models, crater counts, and ∼270 kg of lunar samples analyzed in terrestrial laboratories. However, estimates of impactor flux may be biased by the fact that most of the dated Apollo samples were only tenuously connected to an assumed geologic context. Moreover, uncertainties in the modeled cratering rates are significant enough to lead to estimated errors for dates on Mars and the Moon of ∼1 Ga. Given the great cost of sample return missions, combined with the need to sample multiple terrains on multiple planets, we have developed a prototype instrument that can be used for in situ dating to better constrain the age of planetary samples. METHODS We demonstrate the first use of laser ablation resonance ionization mass spectrometry for 87Rb-87Sr isochron dating of geological specimens. The demands of accuracy and precision have required us to meet challenges including regulation of the ambient temperature, measurement of appropriate backgrounds, sufficient ablation laser intensity, avoidance of the defocusing effect of the plasma created by ablation pulses, and shielding of our detector from atoms and ions of other elements. RESULTS To test whether we could meaningfully date planetary materials, we have analyzed a piece of the <span class="hlt">Martian</span> <span class="hlt">meteorite</span> Zagami. In each of four separate measurements we obtained 87Rb-87Sr isochron ages for Zagami consistent with its published age, and, in both of two measurements that reached completion, we obtained better than 200 Ma precision. Combining all our data into a single isochron with 581 spot analyses gives an 87Rb-87Sr age for this specimen of 360 ±90 Ma. CONCLUSIONS Our analyses of the Zagami <span class="hlt">meteorite</span> represent the first successful application of resonance ionization mass spectrometry to isochron geochronology. Furthermore, the technique is miniaturizable for spaceflight and in situ dating on other planetary bodies. © 2014 The</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25641494','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25641494"><span>Dating the <span class="hlt">Martian</span> <span class="hlt">meteorite</span> Zagami by the ⁸⁷Rb-⁸⁷Sr isochron method with a prototype in situ resonance ionization mass spectrometer.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Anderson, F Scott; Levine, Jonathan; Whitaker, Tom J</p> <p>2015-01-30</p> <p>The geologic history of the Solar System builds on an extensive record of impact flux models, crater counts, and ~270 kg of lunar samples analyzed in terrestrial laboratories. However, estimates of impactor flux may be biased by the fact that most of the dated Apollo samples were only tenuously connected to an assumed geologic context. Moreover, uncertainties in the modeled cratering rates are significant enough to lead to estimated errors for dates on Mars and the Moon of ~1 Ga. Given the great cost of sample return missions, combined with the need to sample multiple terrains on multiple planets, we have developed a prototype instrument that can be used for in situ dating to better constrain the age of planetary samples. We demonstrate the first use of laser ablation resonance ionization mass spectrometry for (87)Rb-(87)Sr isochron dating of geological specimens. The demands of accuracy and precision have required us to meet challenges including regulation of the ambient temperature, measurement of appropriate backgrounds, sufficient ablation laser intensity, avoidance of the defocusing effect of the plasma created by ablation pulses, and shielding of our detector from atoms and ions of other elements. To test whether we could meaningfully date planetary materials, we have analyzed a piece of the <span class="hlt">Martian</span> <span class="hlt">meteorite</span> Zagami. In each of four separate measurements we obtained (87)Rb-(87)Sr isochron ages for Zagami consistent with its published age, and, in both of two measurements that reached completion, we obtained better than 200 Ma precision. Combining all our data into a single isochron with 581 spot analyses gives an (87)Rb-(87)Sr age for this specimen of 360 ±90 Ma. Our analyses of the Zagami <span class="hlt">meteorite</span> represent the first successful application of resonance ionization mass spectrometry to isochron geochronology. Furthermore, the technique is miniaturizable for spaceflight and in situ dating on other planetary bodies. © 2014 The Authors. Rapid Communications in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040056047&hterms=crystallization&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dcrystallization','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040056047&hterms=crystallization&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dcrystallization"><span>Yamato 980459: Crystallization of <span class="hlt">Martian</span> Magnesian Magma</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Koizumi, E.; Mikouchi, T.; McKay, G.; Monkawa, A.; Chokai, J.; Miyamoto, M.</p> <p>2004-01-01</p> <p>Recently, several basaltic shergottites have been found that include magnesian olivines as a major minerals. These have been called olivinephyric shergottites. Yamato 980459, which is a new <span class="hlt">martian</span> <span class="hlt">meteorite</span> recovered from the Antarctica by the Japanese Antarctic expedition, is one of them. This <span class="hlt">meteorite</span> is different from other olivine-phyric shergottites in several key features and will give us important clues to understand crystallization of <span class="hlt">martian</span> <span class="hlt">meteorites</span> and the evolution of <span class="hlt">Martian</span> magma.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1982AmSci..70..156C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1982AmSci..70..156C"><span>Antarctic <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cassidy, W. A.; Rancitelli, L. A.</p> <p>1982-04-01</p> <p>An abundance of <span class="hlt">meteorites</span> has been discovered on two sites in the Antarctic which may assist in the <span class="hlt">study</span> of the origins of <span class="hlt">meteorites</span> and the history of the solar system. Characteristics particular to those <span class="hlt">meteorites</span> discovered in this region are explained. These specimens, being well preserved due to the climate, have implications in the <span class="hlt">study</span> of the cosmic ray flux through time, the meteoroid complex in space, and cosmic ray exposure ages. Implications for the <span class="hlt">study</span> of the Antarctic, particularly the ice flow, are also discussed. Further discoveries of <span class="hlt">meteorites</span> in this region are anticipated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000psrd.reptE..39T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000psrd.reptE..39T"><span>Liquid Water on Mars: The Story from <span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Taylor, G. J.</p> <p>2000-05-01</p> <p>Two <span class="hlt">studies</span> shed light on the nature and timing of alteration by water of rocks from Mars. One is an experimental <span class="hlt">study</span> of the alteration of a rock similar to <span class="hlt">Martian</span> <span class="hlt">meteorites</span>, conducted by Leslie Baker, Deborah Agenbroad, and Scott Wood (University of Idaho). They exposed crushed pieces of terrestrial lava flows to water at 23 C and 75 C and normal atmospheric pressure, and to hot water at 200 C to 400 C and a pressure 1000 times normal atmospheric to see what minerals would form. On the basis of a detailed comparison between the experimental products and the <span class="hlt">Martian</span> <span class="hlt">meteorites</span> Baker and colleagues conclude that the rocks from which <span class="hlt">Martian</span> <span class="hlt">meteorites</span> derived were intermittently exposed to water or water vapor; they were not exposed for a long time to large volumes of water. In an independent <span class="hlt">study</span>, a team led by Tim Swindle (University of Arizona) tried to determine the time of formation of a reddish-brown alteration product in the <span class="hlt">Martian</span> <span class="hlt">meteorite</span> Lafayette. This <span class="hlt">meteorite</span> appears to have formed from magma 1.3 billion years ago, but the rusty-looking weathering product, a mixture of clay minerals, iron oxide, and iron hydride, formed long after the original rock had crystallized. Although the precise time is not pinned down, their measurements indicate formation during the past 650 million years. Taken together, these <span class="hlt">studies</span> suggest that water flowed intermittently on the surface of Mars during the past 650 million years.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001DPS....33.1910K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001DPS....33.1910K"><span>Principal Components Analysis <span class="hlt">Studies</span> of <span class="hlt">Martian</span> Clouds</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Klassen, D. R.; Bell, J. F., III</p> <p>2001-11-01</p> <p>We present the principal components analysis (PCA) of absolutely calibrated multi-spectral images of Mars as a function of <span class="hlt">Martian</span> season. The PCA technique is a mathematical rotation and translation of the data from a brightness/wavelength space to a vector space of principal ``traits'' that lie along the directions of maximal variance. The first of these traits, accounting for over 90% of the data variance, is overall brightness and represented by an average Mars spectrum. Interpretation of the remaining traits, which account for the remaining ~10% of the variance, is not always the same and depends upon what other components are in the scene and thus, varies with <span class="hlt">Martian</span> season. For example, during seasons with large amounts of water ice in the scene, the second trait correlates with the ice and anti-corrlates with temperature. We will investigate the interpretation of the second, and successive important PCA traits. Although these PCA traits are orthogonal in their own vector space, it is unlikely that any one trait represents a singular, mineralogic, spectral end-member. It is more likely that there are many spectral endmembers that vary identically to within the noise level, that the PCA technique will not be able to distinguish them. Another possibility is that similar absorption features among spectral endmembers may be tied to one PCA trait, for example ''amount of 2 \\micron\\ absorption''. We thus attempt to extract spectral endmembers by matching linear combinations of the PCA traits to USGS, JHU, and JPL spectral libraries as aquired through the JPL Aster project. The recovered spectral endmembers are then linearly combined to model the multi-spectral image set. We present here the spectral abundance maps of the water ice/frost endmember which allow us to track <span class="hlt">Martian</span> clouds and ground frosts. This work supported in part through NASA Planetary Astronomy Grant NAG5-6776. All data gathered at the NASA Infrared Telescope Facility in collaboration with</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3193235','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3193235"><span>Carbonates in the <span class="hlt">Martian</span> <span class="hlt">meteorite</span> Allan Hills 84001 formed at 18 ± 4 °C in a near-surface aqueous environment</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Halevy, Itay; Fischer, Woodward W.; Eiler, John M.</p> <p>2011-01-01</p> <p>Despite evidence for liquid water at the surface of Mars during the Noachian epoch, the temperature of early aqueous environments has been impossible to establish, raising questions of whether the surface of Mars was ever warmer than today. We address this problem by determining the precipitation temperature of secondary carbonate minerals preserved in the oldest known sample of Mars’ crust—the approximately 4.1 billion-year-old <span class="hlt">meteorite</span> Allan Hills 84001 (ALH84001). The formation environment of these carbonates, which are constrained to be slightly younger than the crystallization age of the rock (i.e., 3.9 to 4.0 billion years), has been poorly understood, hindering insight into the hydrologic and carbon cycles of earliest Mars. Using “clumped” isotope thermometry we find that the carbonates in ALH84001 precipitated at a temperature of approximately 18 °C, with water and carbon dioxide derived from the ancient <span class="hlt">Martian</span> atmosphere. Furthermore, covarying carbonate carbon and oxygen isotope ratios are constrained to have formed at constant, low temperatures, pointing to deposition from a gradually evaporating, subsurface water body—likely a shallow aquifer (meters to tens of meters below the surface). Despite the mild temperatures, the apparently ephemeral nature of water in this environment leaves open the question of its habitability. PMID:21969543</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3076842','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3076842"><span>Natural dissociation of olivine to (Mg,Fe)SiO3 perovskite and magnesiowüstite in a shocked <span class="hlt">Martian</span> <span class="hlt">meteorite</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Miyahara, Masaaki; Ohtani, Eiji; Ozawa, Shin; Kimura, Makoto; El Goresy, Ahmed; Sakai, Takeshi; Nagase, Toshiro; Hiraga, Kenji; Hirao, Naohisa; Ohishi, Yasuo</p> <p>2011-01-01</p> <p>We report evidence for the natural dissociation of olivine in a shergottite at high-pressure and high-temperature conditions induced by a dynamic event on Mars. Olivine (Fa34-41) adjacent to or entrained in the shock melt vein and melt pockets of <span class="hlt">Martian</span> <span class="hlt">meteorite</span> olivine-phyric shergottite Dar al Gani 735 dissociated into (Mg,Fe)SiO3 perovskite (Pv)+magnesiowüstite (Mw), whereby perovskite partially vitrified during decompression. Transmission electron microscopy observations reveal that microtexture of olivine dissociation products evolves from lamellar to equigranular with increasing temperature at the same pressure condition. This is in accord with the observations of synthetic samples recovered from high-pressure and high-temperature experiments. Equigranular (Mg,Fe)SiO3 Pv and Mw have 50–100 nm in diameter, and lamellar (Mg,Fe)SiO3 Pv and Mw have approximately 20 and approximately 10 nm in thickness, respectively. Partitioning coefficient, KPv/Mw = [FeO/MgO]/[FeO/MgO]Mw, between (Mg,Fe)SiO3 Pv and Mw in equigranular and lamellar textures are approximately 0.15 and approximately 0.78, respectively. The dissociation of olivine implies that the pressure and temperature conditions recorded in the shock melt vein and melt pockets during the dynamic event were approximately 25 GPa but 700 °C at least. PMID:21444781</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016M%26PS...51..407W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016M%26PS...51..407W"><span>Noble gases in 18 <span class="hlt">Martian</span> <span class="hlt">meteorites</span> and angrite Northwest Africa 7812—Exposure ages, trapped gases, and a re-evaluation of the evidence for solar cosmic ray-produced neon in shergottites and other achondrites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wieler, R.; Huber, L.; Busemann, H.; Seiler, S.; Leya, I.; Maden, C.; Masarik, J.; Meier, M. M. M.; Nagao, K.; Trappitsch, R.; Irving, A. J.</p> <p>2016-02-01</p> <p>We present noble gas data for 16 shergottites, 2 nakhlites (NWA 5790, NWA 10153), and 1 angrite (NWA 7812). Noble gas exposure ages of the shergottites fall in the 1-6 Ma range found in previous <span class="hlt">studies</span>. Three depleted olivine-phyric shergottites (Tissint, NWA 6162, NWA 7635) have exposure ages of ~1 Ma, in agreement with published data for similar specimens. The exposure age of NWA 10153 (~12.2 Ma) falls in the range of 9-13 Ma reported for other nakhlites. Our preferred age of ~7.3 Ma for NWA 5790 is lower than this range, and it is possible that NWA 5790 represents a distinct ejection event. A Tissint glass sample contains Xe from the <span class="hlt">Martian</span> atmosphere. Several samples show a remarkably low (21Ne/22Ne)cos ratio < 0.80, as previously observed in a many shergottites and in various other rare achondrites. This was explained by solar cosmic ray-produced Ne (SCR Ne) in addition to the commonly found galactic cosmic ray-produced Ne, implying very low preatmospheric shielding and ablation loss. We revisit this by comparing measured (21Ne/22Ne)cos ratios with predictions by cosmogenic nuclide production models. Indeed, several shergottites, acalpulcoites/lodranites, angrites (including NWA 7812), and the Brachina-like <span class="hlt">meteorite</span> LEW 88763 likely contain SCR Ne, as previously postulated for many of them. The SCR contribution may influence the calculation of exposure ages. One likely reason that SCR nuclides are predominantly detected in <span class="hlt">meteorites</span> from rare classes is because they usually are analyzed for cosmogenic nuclides even if they had a very small (preatmospheric) mass and hence low ablation loss.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012SPIE.8521E..05P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012SPIE.8521E..05P"><span>Microbiological <span class="hlt">study</span> of the Murchison CM2 <span class="hlt">meteorite</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pikuta, Elena V.; Hoover, Richard B.</p> <p>2012-10-01</p> <p>In 1864, Louis Pasteur attempted to cultivate living microorganisms from pristine samples of the Orgueil CI1 carbonaceous <span class="hlt">meteorite</span>. His results were negative and never published, but recorded it in his laboratory notebooks. At that time, only aerobic liquid or agar-based organic reach media were used, as his research on anaerobes had just started. In our laboratory the Murchison CM2 carbonaceous <span class="hlt">meteorite</span> was selected to expand on these <span class="hlt">studies</span> for microbiological <span class="hlt">study</span> by cultivation on anaerobic mineral media. Since the surface could have been more easily contaminated, interior fragments of a sample of the Murchison <span class="hlt">meteorite</span> were extracted and crushed under sterile conditions. The resulting powder was then mixed in anoxic medium and injected into Hungate tubes containing anaerobic media with various growth substrates at different pH and salinity and incubated at different temperatures. The goal of the experiments was to determine if living cells would grow from the material of freshly fractured interior fragments of the stone. If any growth occurred, work could then be carried out to assess the nature of the environmental contamination by observations of the culture growth (rates of speed and biodiversity); live/dead fluorescent staining to determine contamination level and DNA analysis to establish the microbial species present. In this paper we report the results of that <span class="hlt">study</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1996LPI....27..705K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996LPI....27..705K"><span>QUE94201, a New <span class="hlt">Martian</span> <span class="hlt">Meteorite</span> that May Represent a Bulk Melt Rather than a Cumulate Fraction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kring, D. A.; Gleason, J. D.; Hill, D. H.; Jull, A. J. T.; Boynton, W. V.</p> <p>1996-03-01</p> <p>QUE94201 is a new mafic achondrite dominated by pyroxene and plagioclase. Petrologic and geochemical analyses of a bulk chip (,16) and thin-section (,7) indicate the sample is a basaltic gabbro that is related to previously described basaltic and lherzolitic shergottites of suspected <span class="hlt">martian</span> origin. However, unlike the cumulate fractions represented by other shergottites, QUE94201 is a plutonic rock that fractionally crystallized in what appears (petrographically) to be a closed system. QUE94201 contains more Fe-rich pyroxene and more bulk Al, Ti, and P than other shergottites, including lithology B of EETA79001, and thus appears to be more evolved. However, QUE94201 is also more LREE-depleted than other shergottites which suggests it has not assimilated as much of the LREE-enriched mantle component thought to have affected the compositions of other shergottites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19800023802','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19800023802"><span>Mineralogic and petrologic <span class="hlt">studies</span> of lunar samples and <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wood, J. A.</p> <p>1980-01-01</p> <p>Experimental and thermodynamic research on the pressure temperature limits of the stability of the mineral assemblages found in pristine, spinel bearing lunar highland lithologies demonstrated the likelihood that the minerals originated in the lower stratigraphic levels of the primordial crust. The phase equilibrium in silicate solid/liquid systems of planetary importance were thermochemically interpreted in order to model the early formation of the crusts and maneles of Earth and Moon sized planets. The petrography and chemical composition of coarse grained gabbro, the chemical analysis and age dating of clasts from Apollo 16 breccia, the analysis of glass particles from Apollo 16 soil samples, the <span class="hlt">study</span> of Allende and Mokoia <span class="hlt">meteorites</span> as a source of information about events in the solar nebula, and the hydrothermal alteration of amorphous materials were also investigated. The capabilities of a model for addressing the problem of the origin of the Earth's moon by the disruptive capture mechanism are examined as well as models of the thermal evolution of hypothetical <span class="hlt">meteorite</span> bodies. Progress in determining the composition of stony <span class="hlt">meteorite</span> specimens collected at the Allan Hills site during the Antarctic field exploration is reported.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100017340','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100017340"><span>A High Resolution Microprobe <span class="hlt">Study</span> of EETA79001 Lithology C</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Schrader, Christian M.; Cohen, B. A.; Donovan, J. J.; Vicenzi, E. P.</p> <p>2010-01-01</p> <p>Antarctic <span class="hlt">meteorite</span> EETA79001 has received substantial attention for possibly containing a component of <span class="hlt">Martian</span> soil in its impact glass (Lithology C) [1]. The composition of <span class="hlt">Martian</span> soil can illuminate near-surface processes such as impact gardening [2] and hydrothermal and volcanic activity [3,4]. Impact melts in <span class="hlt">meteorites</span> represent our most direct samples of <span class="hlt">Martian</span> regolith. We present the initial findings from a high-resolution electron microprobe <span class="hlt">study</span> of Lithology C from <span class="hlt">Martian</span> <span class="hlt">meteorite</span> EETA79001. As this <span class="hlt">study</span> develops we aim to extract details of a potential soil composition and to examine <span class="hlt">Martian</span> surface processes using elemental ratios and correlations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011psrd.reptE.155M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011psrd.reptE.155M"><span>Timeline of <span class="hlt">Martian</span> Volcanism</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Martel, L. M. V.</p> <p>2011-05-01</p> <p>A recent <span class="hlt">study</span> of <span class="hlt">Martian</span> volcanism presents a timeline of the last major eruptions from 20 large volcanoes, based on the relative ages of caldera surfaces determined by crater counting. Stuart Robbins, Gaetano Di Achille, and Brian Hynek (University of Colorado) counted craters on high-resolution images from the the Context Camera (CTX) on Mars Reconnaissance Orbiter to date individual calderas, or terraces within calderas, on the 20 major <span class="hlt">Martian</span> volcanoes. Based on their timeline and mapping, rates and durations of eruptions and transitions from explosive to effusive activity varied from volcano to volcano. The work confirms previous findings by others that volcanism was continuous throughout <span class="hlt">Martian</span> geologic history until about one to two hundred million years ago, the final volcanic events were not synchronous across the planet, and the latest large-scale caldera activity ended about 150 million years ago in the Tharsis province. This timing correlates well with the crystallization ages (~165-170 million years) determined for the youngest basaltic <span class="hlt">Martian</span> <span class="hlt">meteorites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017M%26PS...52.1014R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017M%26PS...52.1014R"><span>The <span class="hlt">Meteoritical</span> Bulletin, No. 103</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ruzicka, Alex; Grossman, Jeffrey; Bouvier, Audrey; Agee, Carl B.</p> <p>2017-05-01</p> <p><span class="hlt">Meteoritical</span> Bulletin 103 contains 2582 <span class="hlt">meteorites</span> including 10 falls (Ardón, Demsa, Jinju, Križevci, Kuresoi, Novato, Tinajdad, Tirhert, Vicência, Wolcott), with 2174 ordinary chondrites, 130 HED achondrites, 113 carbonaceous chondrites, 41 ureilites, 27 lunar <span class="hlt">meteorites</span>, 24 enstatite chondrites, 21 iron <span class="hlt">meteorites</span>, 15 primitive achondrites, 11 mesosiderites, 10 <span class="hlt">Martian</span> <span class="hlt">meteorites</span>, 6 Rumuruti chondrites, 5 ungrouped achondrites, 2 enstatite achondrites, 1 relict <span class="hlt">meteorite</span>, 1 pallasite, and 1 angrite, and with 1511 from Antarctica, 588 from Africa, 361 from Asia, 86 from South America, 28 from North America, and 6 from Europe. Note: 1 <span class="hlt">meteorite</span> from Russia was counted as European. The complete contents of this bulletin (244 pages) are available on line. Information about approved <span class="hlt">meteorites</span> can be obtained from the <span class="hlt">Meteoritical</span> Bulletin Database (MBD) available on line at <url href="http://www.lpi.usra.edu/meteor/">http://www.lpi.usra.edu/meteor/.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160002653','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160002653"><span>Indigenous Carbonaceous Matter in the Nakhla Mars <span class="hlt">Meteorite</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Clemett, S. J.; Thomas-Keprta, K. L.; Rahman, Z.; Le, L.; Wentworth, S. J.; Gibson, E. K.; McKay, D. S.</p> <p>2016-01-01</p> <p>Detailed microanalysis of the <span class="hlt">Martian</span> <span class="hlt">meteorite</span> Nakhla has shown there are morphologically distinct carbonaceous features spatially associated with low-T aqueous alteration phases including salts and id-dingsite. A comprehensive suite of analytical instrumentation including optical microscopy, field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) spectroscopy, focused ion beam (FIB) microscopy, transmission electron microscopy (TEM), two-step laser mass spectrometry (mu-L(sup 2)MS), laser mu-Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), and nanoscale secondary ion mass spectrometry (NanoSIMS) are being used to characterize the carbonaceous matter and host mineralogy. The search for carbonaceous matter on Mars has proved challenging. Viking Landers failed to unambiguously detect simple organics at either of the two landing sites although the <span class="hlt">Martian</span> surface is estimated to have acquired at least 10(exp15) kg of C as a consequence of <span class="hlt">meteoritic</span> accretion over the last several Ga. The dearth of organics at the <span class="hlt">Martian</span> surface has been attributed to various oxidative processes including UV photolysis and peroxide activity. Consequently, investigations of <span class="hlt">Martian</span> organics need to be focused on the sub-surface regolith where such surface processes are either severely attenuated or absent. Fortuitously since <span class="hlt">Martian</span> <span class="hlt">meteorites</span> are derived from buried regolith materials they provide a unique opportunity to <span class="hlt">study</span> <span class="hlt">Martian</span> organic geochemistry.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20030111247&hterms=visible+spectroscopy&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dvisible%2Bspectroscopy','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20030111247&hterms=visible+spectroscopy&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dvisible%2Bspectroscopy"><span>Lunar Mare Basalts as Analogues for <span class="hlt">Martian</span> Volcanic Compositions: Evidence from Visible, Near-IR, and Thermal Emission Spectroscopy</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Graff, T. G.; Morris, R. V.; Christensen, P. R.</p> <p>2003-01-01</p> <p>The lunar mare basalts potentially provide a unique sample suite for understanding the nature of basalts on the <span class="hlt">martian</span> surface. Our current knowledge of the mineralogical and chemical composition of the basaltic material on Mars comes from <span class="hlt">studies</span> of the basaltic <span class="hlt">martian</span> <span class="hlt">meteorites</span> and from orbital and surface remote sensing observations. Petrographic observations of basaltic <span class="hlt">martian</span> <span class="hlt">meteorites</span> (e.g., Shergotty, Zagami, and EETA79001) show that the dominant phases are pyroxene (primarily pigeonite and augite), maskelynite (a diaplectic glass formed from plagioclase by shock), and olivine [1,2]. Pigeonite, a low calcium pyroxene, is generally not found in abundance in terrestrial basalts, but does often occur on the Moon [3]. Lunar samples thus provide a means to examine a variety of pigeonite-rich basalts that also have bulk elemental compositions (particularly low-Ti Apollo 15 mare basalts) that are comparable to basaltic SNC <span class="hlt">meteorites</span> [4,5]. Furthermore, lunar basalts may be mineralogically better suited as analogues of the <span class="hlt">martian</span> surface basalts than the basaltic <span class="hlt">martian</span> <span class="hlt">meteorites</span> because the plagioclase feldspar in the basaltic <span class="hlt">Martian</span> <span class="hlt">meteorites</span>, but not in the lunar surface basalts, is largely present as maskelynite [1,2]. Analysis of lunar mare basalts my also lead to additional endmember spectra for spectral libraries. This is particularly important analysis of <span class="hlt">martian</span> thermal emission spectra, because the spectral library apparently contains a single pigeonite spectrum derived from a synthetic sample [6].</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20030111247&hterms=Basalt&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DBasalt','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20030111247&hterms=Basalt&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DBasalt"><span>Lunar Mare Basalts as Analogues for <span class="hlt">Martian</span> Volcanic Compositions: Evidence from Visible, Near-IR, and Thermal Emission Spectroscopy</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Graff, T. G.; Morris, R. V.; Christensen, P. R.</p> <p>2003-01-01</p> <p>The lunar mare basalts potentially provide a unique sample suite for understanding the nature of basalts on the <span class="hlt">martian</span> surface. Our current knowledge of the mineralogical and chemical composition of the basaltic material on Mars comes from <span class="hlt">studies</span> of the basaltic <span class="hlt">martian</span> <span class="hlt">meteorites</span> and from orbital and surface remote sensing observations. Petrographic observations of basaltic <span class="hlt">martian</span> <span class="hlt">meteorites</span> (e.g., Shergotty, Zagami, and EETA79001) show that the dominant phases are pyroxene (primarily pigeonite and augite), maskelynite (a diaplectic glass formed from plagioclase by shock), and olivine [1,2]. Pigeonite, a low calcium pyroxene, is generally not found in abundance in terrestrial basalts, but does often occur on the Moon [3]. Lunar samples thus provide a means to examine a variety of pigeonite-rich basalts that also have bulk elemental compositions (particularly low-Ti Apollo 15 mare basalts) that are comparable to basaltic SNC <span class="hlt">meteorites</span> [4,5]. Furthermore, lunar basalts may be mineralogically better suited as analogues of the <span class="hlt">martian</span> surface basalts than the basaltic <span class="hlt">martian</span> <span class="hlt">meteorites</span> because the plagioclase feldspar in the basaltic <span class="hlt">Martian</span> <span class="hlt">meteorites</span>, but not in the lunar surface basalts, is largely present as maskelynite [1,2]. Analysis of lunar mare basalts my also lead to additional endmember spectra for spectral libraries. This is particularly important analysis of <span class="hlt">martian</span> thermal emission spectra, because the spectral library apparently contains a single pigeonite spectrum derived from a synthetic sample [6].</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012M%26PSA..75.5133O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012M%26PSA..75.5133O"><span>UV-Radiation Induced Methane Emission from Murchison - Possible Implications for Methane in the <span class="hlt">Martian</span> Atmosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ott, U.; Keppler, F.; Vigano, I.; McLeod, A.; Früchtl, M.; Röckmann, T.</p> <p>2012-09-01</p> <p>Exposure of the Murchison <span class="hlt">meteorite</span> to UV radiation releases large quantities of methane. Acting on <span class="hlt">meteoritic</span> debris on the <span class="hlt">Martian</span> surface, the process may be of importance for the <span class="hlt">Martian</span> atmosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040088818&hterms=Ferrous&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DFerrous','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040088818&hterms=Ferrous&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DFerrous"><span>An abiotic origin for hydrocarbons in the Allan Hills 84001 <span class="hlt">martian</span> <span class="hlt">meteorite</span> through cooling of magmatic and impact-generated gases</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shock, E. L.</p> <p>2000-01-01</p> <p>Thermodynamic calculations of metastable equilibria were used to evaluate the potential for abiotic synthesis of aliphatic and polycyclic aromatic hydrocarbons (PAHs) in the <span class="hlt">martian</span> <span class="hlt">meteorite</span> Allan Hills (ALH) 84001. The calculations show that PAHs and normal alkanes could form metastably from CO, CO2, and H2 below approximately 250-300 degrees C during rapid cooling of trapped magmatic or impact-generated gases. Depending on temperature, bulk composition, and oxidation-reduction conditions, PAHs and normal alkanes can form simultaneously or separately. Moreover, PAHs can form at lower H/C ratios, higher CO/CO2 ratios, and higher temperatures than normal alkanes. Dry conditions with H/C ratios less than approximately 0.01-0.001 together with high CO/CO2 ratios also favor the formation of unalkylated PAHs. The observed abundance of PAHs, their low alkylation, and a variable but high aromatic to aliphatic ratio in ALH 84001 all correspond to low H/C and high CO/CO2 ratios in magmatic and impact gases and can be used to deduce spatial variations of these ratios. Some hydrocarbons could have been formed from trapped magmatic gases, especially if the cooling was fast enough to prevent reequilibration. We propose that subsequent impact heating(s) in ALH 84001 could have led to dissociation of ferrous carbonates to yield fine-grain magnetite, formation of a CO-rich local gas phase, reduction of water vapor to H2, reequilibration of the trapped magmatic gases, aromatization of hydrocarbons formed previously, and overprinting of the synthesis from magmatic gases, if any. Rapid cooling and high-temperature quenching of CO-, H2-rich impact gases could have led to magnetite-catalyzed hydrocarbon synthesis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11543519','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11543519"><span>An abiotic origin for hydrocarbons in the Allan Hills 84001 <span class="hlt">martian</span> <span class="hlt">meteorite</span> through cooling of magmatic and impact-generated gases.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zolotov MYu; Shock, E L</p> <p>2000-05-01</p> <p>Thermodynamic calculations of metastable equilibria were used to evaluate the potential for abiotic synthesis of aliphatic and polycyclic aromatic hydrocarbons (PAHs) in the <span class="hlt">martian</span> <span class="hlt">meteorite</span> Allan Hills (ALH) 84001. The calculations show that PAHs and normal alkanes could form metastably from CO, CO2, and H2 below approximately 250-300 degrees C during rapid cooling of trapped magmatic or impact-generated gases. Depending on temperature, bulk composition, and oxidation-reduction conditions, PAHs and normal alkanes can form simultaneously or separately. Moreover, PAHs can form at lower H/C ratios, higher CO/CO2 ratios, and higher temperatures than normal alkanes. Dry conditions with H/C ratios less than approximately 0.01-0.001 together with high CO/CO2 ratios also favor the formation of unalkylated PAHs. The observed abundance of PAHs, their low alkylation, and a variable but high aromatic to aliphatic ratio in ALH 84001 all correspond to low H/C and high CO/CO2 ratios in magmatic and impact gases and can be used to deduce spatial variations of these ratios. Some hydrocarbons could have been formed from trapped magmatic gases, especially if the cooling was fast enough to prevent reequilibration. We propose that subsequent impact heating(s) in ALH 84001 could have led to dissociation of ferrous carbonates to yield fine-grain magnetite, formation of a CO-rich local gas phase, reduction of water vapor to H2, reequilibration of the trapped magmatic gases, aromatization of hydrocarbons formed previously, and overprinting of the synthesis from magmatic gases, if any. Rapid cooling and high-temperature quenching of CO-, H2-rich impact gases could have led to magnetite-catalyzed hydrocarbon synthesis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040088818&hterms=prevent+volcanic+eruption&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dprevent%2Bvolcanic%2Beruption','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040088818&hterms=prevent+volcanic+eruption&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dprevent%2Bvolcanic%2Beruption"><span>An abiotic origin for hydrocarbons in the Allan Hills 84001 <span class="hlt">martian</span> <span class="hlt">meteorite</span> through cooling of magmatic and impact-generated gases</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shock, E. L.</p> <p>2000-01-01</p> <p>Thermodynamic calculations of metastable equilibria were used to evaluate the potential for abiotic synthesis of aliphatic and polycyclic aromatic hydrocarbons (PAHs) in the <span class="hlt">martian</span> <span class="hlt">meteorite</span> Allan Hills (ALH) 84001. The calculations show that PAHs and normal alkanes could form metastably from CO, CO2, and H2 below approximately 250-300 degrees C during rapid cooling of trapped magmatic or impact-generated gases. Depending on temperature, bulk composition, and oxidation-reduction conditions, PAHs and normal alkanes can form simultaneously or separately. Moreover, PAHs can form at lower H/C ratios, higher CO/CO2 ratios, and higher temperatures than normal alkanes. Dry conditions with H/C ratios less than approximately 0.01-0.001 together with high CO/CO2 ratios also favor the formation of unalkylated PAHs. The observed abundance of PAHs, their low alkylation, and a variable but high aromatic to aliphatic ratio in ALH 84001 all correspond to low H/C and high CO/CO2 ratios in magmatic and impact gases and can be used to deduce spatial variations of these ratios. Some hydrocarbons could have been formed from trapped magmatic gases, especially if the cooling was fast enough to prevent reequilibration. We propose that subsequent impact heating(s) in ALH 84001 could have led to dissociation of ferrous carbonates to yield fine-grain magnetite, formation of a CO-rich local gas phase, reduction of water vapor to H2, reequilibration of the trapped magmatic gases, aromatization of hydrocarbons formed previously, and overprinting of the synthesis from magmatic gases, if any. Rapid cooling and high-temperature quenching of CO-, H2-rich impact gases could have led to magnetite-catalyzed hydrocarbon synthesis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010Icar..207..616F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010Icar..207..616F"><span>Testing the survival of microfossils in artificial <span class="hlt">martian</span> sedimentary <span class="hlt">meteorites</span> during entry into Earth’s atmosphere: The STONE 6 experiment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Foucher, Frédéric; Westall, Frances; Brandstätter, Franz; Demets, René; Parnell, John; Cockell, Charles S.; Edwards, Howell G. M.; Bény, Jean-Michel; Brack, André</p> <p>2010-06-01</p> <p>If life ever appeared on Mars, could we find traces of primitive life embedded in sedimentary <span class="hlt">meteorites</span>? To answer this question, a 3.5-byr-old volcanic sediment containing microfossils was embedded in the heat shield of a space capsule in order to test survival of the rock and the microfossils during entry into the Earth's atmosphere (the STONE 6 experiment). The silicified volcanic sediment from the Kitty's Gap Chert (Pilbara, Australia) is considered to be an excellent analogue for Noachian-age volcanic sediments. The microfossils in the chert are also analogues for potential <span class="hlt">martian</span> life. An additional goal was to investigate the survival of living microorganisms ( Chroococcidiopsis) protected by a 2-cm thick layer of rock in order to test whether living endolithic organisms could survive atmospheric entry when protected by a rocky coating. Mineralogical alteration of the sediment due to shock heating was manifested by the formation of a fusion crust, cracks in the chert due to prograde and retrograde changes of α quartz to β quartz, increase in the size of the fluid inclusions, and dewatering of the hydromuscovite-replaced volcanic protoliths. The carbonaceous microfossils embedded in the chert matrix survived in the rock away from the fusion crust but there was an increase in the maturity index of the kerogen towards the crust. We conclude that this kind of sediment can survive atmospheric entry and, if it contains microfossils, they could also survive. The living microorganisms were, however, completely carbonised by flame leakage to the back of the sample and therefore non-viable. However, using an analytical model to estimate the temperature reached within the sample thickness, we conclude that, even without flame leakage, the living organisms probably need to be protected by at least 5 cm of rock in order to be shielded from the intense heat of entry.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1376028-new-approach-cosmogenic-corrections-chronometry-implications-ages-martian-meteorites','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1376028-new-approach-cosmogenic-corrections-chronometry-implications-ages-martian-meteorites"><span>A new approach to cosmogenic corrections in 40Ar/39Ar chronometry: Implications for the ages of <span class="hlt">Martian</span> <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Cassata, W. S.; Borg, L. E.</p> <p>2016-05-04</p> <p>Anomalously old 40Ar/39Ar ages are commonly obtained from Shergottites and are generally attributed to uncertainties regarding the isotopic composition of the trapped component and/or the presence of excess 40Ar. Old ages can also be obtained if inaccurate corrections for cosmogenic 36Ar are applied. Current methods for making the cosmogenic correction require simplifying assumptions regarding the spatial homogeneity of target elements for cosmogenic production and the distribution of cosmogenic nuclides relative to trapped and reactor-derived Ar isotopes. To mitigate uncertainties arising from these assumptions, a new cosmogenic correction approach utilizing the exposure age determined on an un-irradiated aliquot and step-wise productionmore » rate estimates that account for spatial variations in Ca and K is described. Data obtained from NWA 4468 and an unofficial pairing of NWA 2975, which yield anomalously old ages when corrected for cosmogenic 36Ar using conventional techniques, are used to illustrate the efficacy of this new approach. For these samples, anomalous age determinations are rectified solely by the improved cosmogenic correction technique described herein. Ages of 188 ± 17 and 184 ± 17 Ma are obtained for NWA 4468 and NWA 2975, respectively, both of which are indistinguishable from ages obtained by other radioisotopic systems. For other Shergottites that have multiple trapped components, have experienced diffusive loss of Ar, or contain excess Ar, more accurate cosmogenic corrections may aid in the interpretation of anomalous ages. In conclusion, the trapped 40Ar/36Ar ratios inferred from inverse isochron diagrams obtained from NWA 4468 and NWA 2975 are significantly lower than the <span class="hlt">Martian</span> atmospheric value, and may represent upper mantle or crustal components.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeCoA.187..279C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeCoA.187..279C"><span>A new approach to cosmogenic corrections in 40Ar/39Ar chronometry: Implications for the ages of <span class="hlt">Martian</span> <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cassata, W. S.; Borg, L. E.</p> <p>2016-08-01</p> <p>Anomalously old 40Ar/39Ar ages are commonly obtained from Shergottites and are generally attributed to uncertainties regarding the isotopic composition of the trapped component and/or the presence of excess 40Ar. Old ages can also be obtained if inaccurate corrections for cosmogenic 36Ar are applied. Current methods for making the cosmogenic correction require simplifying assumptions regarding the spatial homogeneity of target elements for cosmogenic production and the distribution of cosmogenic nuclides relative to trapped and reactor-derived Ar isotopes. To mitigate uncertainties arising from these assumptions, a new cosmogenic correction approach utilizing the exposure age determined on an un-irradiated aliquot and step-wise production rate estimates that account for spatial variations in Ca and K is described. Data obtained from NWA 4468 and an unofficial pairing of NWA 2975, which yield anomalously old ages when corrected for cosmogenic 36Ar using conventional techniques, are used to illustrate the efficacy of this new approach. For these samples, anomalous age determinations are rectified solely by the improved cosmogenic correction technique described herein. Ages of 188 ± 17 and 184 ± 17 Ma are obtained for NWA 4468 and NWA 2975, respectively, both of which are indistinguishable from ages obtained by other radioisotopic systems. For other Shergottites that have multiple trapped components, have experienced diffusive loss of Ar, or contain excess Ar, more accurate cosmogenic corrections may aid in the interpretation of anomalous ages. The trapped 40Ar/36Ar ratios inferred from inverse isochron diagrams obtained from NWA 4468 and NWA 2975 are significantly lower than the <span class="hlt">Martian</span> atmospheric value, and may represent upper mantle or crustal components.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.P31A2028A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.P31A2028A"><span>Craters of the Moon National Monument as a Terrestrial Mars Analog: Examination of Mars Analog Phosphate Minerals, Phosphate Mineral Shock-Recovery Experiments, and Phosphate Minerals in <span class="hlt">Martian</span> <span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Adcock, C. T.; Hausrath, E.; Tschauner, O. D.; Udry, A.</p> <p>2015-12-01</p> <p><span class="hlt">Martian</span> analogs, <span class="hlt">meteorites</span>, and data from unmanned missions have greatly advanced our understanding of <span class="hlt">martian</span> surface and near-surface processes. In particular, terrestrial analogs allow us to investigate Mars-relevant geomorphic, geochemical, petrogenetic, and hydrologic processes, as well as potential habitability. Craters of the Moon National Monument (COTM), located on the Snake River Plain of Idaho in the United States, represents a valuable phosphate-rich Mars analog, allowing us to examine phosphate minerals, important as volatile indicators and potential nutrient providers, under Mars-relevant conditions. COTM is in an arid to semi-arid environment with sub-freezing lows much of the year. Though wetter than present day Mars (24 - 38 cm MAP) [1], COTM may be analogous to a warmer and wetter past Mars. The area is also the locale of numerous lava flows, a number of which have been dated (2,000 to >18,000 y.b.p.) [2]. The flows have experienced weathering over time and thus represent a chronosequence with application to weathering on Mars. The flows have unusual chemistries, including high average phosphate contents (P2O5 1.75 wt% n=23 flows) [2], close to those in rocks analyzed at Gusev Crater, Mars (P2O5 1.79 wt% n=18 rocks) [3]. The Mars-like high phosphorus contents indicate a potential petrogenetic link and are also of astrobiological interest. Further, current samples of Mars phosphate minerals are limited to <span class="hlt">meteorites</span> which have been heavily shocked - COTM represents a potential pre-shock and geochemical analog to Mars. We investigated weathering on COTM basalts and shock effects on Mars-relevant phosphate minerals. We used scanning electron microscopy, backscattered electron imagery, and X-Ray analysis/mapping to investigate COTM thin sections. Synchrotron diffraction was used to investigate <span class="hlt">martian</span> <span class="hlt">meteorites</span> and laboratory shocked Mars/COTM-relevant minerals for comparison. Results of our investigations indicate porosity development correlates</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA10640&hterms=First+year+students&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DFirst%2Byear%2Bstudents','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA10640&hterms=First+year+students&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DFirst%2Byear%2Bstudents"><span>Durham, North Carolina, Students <span class="hlt">Study</span> <span class="hlt">Martian</span> Volcanism</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2008-01-01</p> <p><p/> This image of the wall of a graben a depressed block of land between two parellel faults in Tyrrhena Terra, in Mars' ancient southern highlands, was taken by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) at 0914 UTC (4:14 a.m. EST) on February 6, 2008, near 17.3 degrees south latitude, 95.5 degrees east longitude. CRISM's image was taken in 544 colors covering 0.36-3.92 micrometers, and shows features as small as 35 meters (115 feet) across. The region covered is just over 10 kilometers (6.2 miles) wide at its narrowest point. <p/> This image was part of an investigation planned by students in four high schools in Durham, North Carolina. The students are working with the CRISM science team in a project called the Mars Exploration Student Data Teams (MESDT), which is part of NASA's Mars Public Engagement Program and Arizona State University's Mars Education Program. Starting with a medium-resolution map of the area, taken as part of CRISM's 'multispectral survey' campaign to map Mars in 72 colors at 200 meters (660 feet) per pixel, the students identified a key rock outcrop to test their hypothesis that the irregular depression was formed by <span class="hlt">Martian</span> volcanism. They provided the coordinates of the target to CRISM's operations team, who took a high-resolution image of the site. The Context Imager (CTX) accompanied CRISM with a 6 meter (20 feet) per pixel, high-resolution image to sharpen the relationship of spectral variations to the underlying surface structures. The Durham students worked with a mentor on the CRISM team to analyze the data, and presented their results at the 39th Lunar and Planetary Science Conference, held in League City, Texas, on March 10-14, 2008. <p/> The upper panel of the image shows the location of the CRISM data and the surrounding, larger CTX image, overlain on an image mosaic taken by the Thermal Emission Imaging System (THEMIS) on Mars Odyssey. The mosaic has been color-coded for elevation using data from the Mars</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA10640&hterms=exercise+depression&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dexercise%2Bdepression','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA10640&hterms=exercise+depression&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dexercise%2Bdepression"><span>Durham, North Carolina, Students <span class="hlt">Study</span> <span class="hlt">Martian</span> Volcanism</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2008-01-01</p> <p><p/> This image of the wall of a graben a depressed block of land between two parellel faults in Tyrrhena Terra, in Mars' ancient southern highlands, was taken by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) at 0914 UTC (4:14 a.m. EST) on February 6, 2008, near 17.3 degrees south latitude, 95.5 degrees east longitude. CRISM's image was taken in 544 colors covering 0.36-3.92 micrometers, and shows features as small as 35 meters (115 feet) across. The region covered is just over 10 kilometers (6.2 miles) wide at its narrowest point. <p/> This image was part of an investigation planned by students in four high schools in Durham, North Carolina. The students are working with the CRISM science team in a project called the Mars Exploration Student Data Teams (MESDT), which is part of NASA's Mars Public Engagement Program and Arizona State University's Mars Education Program. Starting with a medium-resolution map of the area, taken as part of CRISM's 'multispectral survey' campaign to map Mars in 72 colors at 200 meters (660 feet) per pixel, the students identified a key rock outcrop to test their hypothesis that the irregular depression was formed by <span class="hlt">Martian</span> volcanism. They provided the coordinates of the target to CRISM's operations team, who took a high-resolution image of the site. The Context Imager (CTX) accompanied CRISM with a 6 meter (20 feet) per pixel, high-resolution image to sharpen the relationship of spectral variations to the underlying surface structures. The Durham students worked with a mentor on the CRISM team to analyze the data, and presented their results at the 39th Lunar and Planetary Science Conference, held in League City, Texas, on March 10-14, 2008. <p/> The upper panel of the image shows the location of the CRISM data and the surrounding, larger CTX image, overlain on an image mosaic taken by the Thermal Emission Imaging System (THEMIS) on Mars Odyssey. The mosaic has been color-coded for elevation using data from the Mars</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19790055301&hterms=Wedekind&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DWedekind','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19790055301&hterms=Wedekind&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DWedekind"><span>Experimental <span class="hlt">studies</span> of oblique impact. [of <span class="hlt">meteorites</span> on planetary surfaces</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gault, D. E.; Wedekind, J. A.</p> <p>1978-01-01</p> <p><span class="hlt">Meteoritic</span> materials most probably impact planetary bodies along oblique trajectories inclined less than 45 deg above their surfaces. Laboratory <span class="hlt">studies</span> of hypervelocity impacts against rock and particulate media are presented that indicate important effects of obliquity on crater size, shape, and ejecta distribution. The effects are particularly important to crater size-frequency analyses and geologic interpretations of crater formations. Impacts at shallow incidence, which are not uncommon, lead to ricochet of the impacting object accompanied with some entrained excavated materials at velocities only slightly reduced from the pre-impact value.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050060790','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050060790"><span>Experimental <span class="hlt">Studies</span> of Phase Equilibria of <span class="hlt">Meteorites</span> and Planetary Bodies</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Stolper, Edward M.</p> <p>2005-01-01</p> <p>The primary theme of this project was the application of experimental petrology and geochemistry to a variety of problems in <span class="hlt">meteoritics</span> and planetary geology. The <span class="hlt">studies</span> were designed to help develop constraints on the histories of primitive <span class="hlt">meteorites</span> and their components, the environments in which they formed and evolved, and to understand quantitatively the processes involved in the evolution of igneous rocks on the earth and other planetary bodies. We undertook several projects relating to the origin of CAIs and chondrules. Systematics in the thermodynamic properties of CAI-like liquids were investigated and used to elucidate speciation of multi-valent cations and sulfide capacity of silicate melts and to constrain redox conditions and the vapor pressures of volatile species over molten chondrules. We experimentally determined vanadium speciation in <span class="hlt">meteoritic</span> pyroxenes and in pyroxenes crystallized from CAI-like melts under very reducing conditions. We also found that bulk oxygen isotope compositions of chondrules in the moderately unequilibrated LL chondrites are related to the relative timing of plagioclase crystallization. We completed an experimental <span class="hlt">study</span> on the vaporization of beta-SiC and SiO2 (glass or cristobalite) in reducing gases and established the conditions under which these presolar grains could have survived in the solar nebula. We expanded our technique for determining the thermodynamic properties of minerals and liquids to iron-bearing systems. We determined activity-composition relationships in Pt-Fe, Pt-Cr and Pt-Fe-Cr alloys. Results were used to determine the thermodynamic properties of chromite-picrochromite spinels including the free energy of formation of end-member FeCr2O4. We also established a new approach for evaluating Pt-Fe saturation experiments. We calculated the T-fO2 relationships in equilibrated ordinary chondrites and thereby constrained the conditions of metamorphism in their parent bodies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/947812','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/947812"><span>New electron microscopy techniques of the <span class="hlt">study</span> of <span class="hlt">meteoritic</span> metal.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Michael, Joseph Richard; Goldstein, Joseph I.; Kotula, Paul Gabriel; Jones, R. H.</p> <p>2005-02-01</p> <p>Metallic Phases in extraterrestrial materials are composed of Fe-Ni with minor amounts of Co, P, Si, Cr, etc. Electron microscopy techniques (SEM, TEM, EPMA, AEM) have been used for almost 50 years to <span class="hlt">study</span> micron and submicron microscopic features in the metal phases (Fig. 1) such as clear taenite, cloudy zone, plessite, etc [1,2]. However lack of instrumentation to prepare TEM thin foils in specific sample locations and to obtain micro-scale crystallographic data have limited these investigations. New techniques such as the focused ion beam (FIB) and the electron backscatter electron diffraction (EBSD) techniques have overcome these limitations. The application of the FIB instrument has allowed us to prepare {approx}10 um long by {approx} 5um deep TEM thin sections of metal phases from specific regions of metal particles, in chondrites, irons and stony iron <span class="hlt">meteorites</span>, identified by optical and SEM observation. Using a FEI dual beam FIB we were able to <span class="hlt">study</span> very small metal particles in samples of CH chondrites [3] and zoneless plessite (ZP) in ordinary chondrites. Fig. 2 shows a SEM photomicrograph of a {approx}40 um ZP particle in Kernouve, a H6 chondrite. Fig. 3a,b shows a TEM photograph of a section of the FIB prepared TEM foil of the ZP particle and a Ni trace through a tetrataenite/kamacite region of the particle. It has been proposed that the Widmanstatten pattern in low P iron <span class="hlt">meteorites</span> forms by martensite decomposition, via the reaction {gamma} {yields} {alpha}{sub 2} + {gamma} {yields} {alpha} + {gamma} in which {alpha}{sub 2}, martensite, decomposes to the equilibrium {alpha} and {gamma} phases during the cooling process [4]. In order to show if this mechanism for Widmanstatten pattern formation is correct, crystallographic information is needed from the {gamma} or taenite phases throughout a given <span class="hlt">meteorite</span>. The EBSD technique was employed in this <span class="hlt">study</span> to obtain the orientation of the taenite surrounding the initial martensite phase and the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19960017269','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19960017269"><span>Numerical Model <span class="hlt">Studies</span> of the <span class="hlt">Martian</span> Mesoscale Circulations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Segal, M.; Arritt, R. W.</p> <p>1996-01-01</p> <p><span class="hlt">Studies</span> concerning mesoscale topographical effects on <span class="hlt">Martian</span> flows examined low-level jets in the near equatorial latitudes and the dynamical intensification of flow by steep terrain. Continuation of work from previous years included evaluating the dissipation of cold air mass outbreaks due to enhanced sensible heat flux, further sensitivity and scaling evaluations for generalization of the characteristics of <span class="hlt">Martian</span> mesoscale circulation caused by horizontal sensible heat-flux gradients, and evaluations of the significance that non-uniform surface would have on enhancing the polar CO2 ice sublimation during the spring. The sensitivity of maximum and minimum atmospheric temperatures to changes in wind speed, surface albedo, and deep soil temperature was investigated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015M%26PS...50.1661R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015M%26PS...50.1661R"><span>The <span class="hlt">Meteoritical</span> Bulletin, No. 101</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ruzicka, Alex; Grossman, Jeffrey; Bouvier, Audrey; Herd, Christopher D. K.; Agee, Carl B.</p> <p>2015-09-01</p> <p><span class="hlt">Meteoritical</span> Bulletin 101 contains 2639 <span class="hlt">meteorites</span> accepted by the Nomenclature Committee in 2012, including 1 fall (Battle Mountain), with 2308 ordinary chondrites, 156 carbonaceous chondrites, 63 HED achondrites, 17 relict <span class="hlt">meteorites</span>, 16 Rumuruti chondrites, 15 enstatite chondrites, 15 ureilites, 10 iron <span class="hlt">meteorites</span>, 9 lunar <span class="hlt">meteorites</span>, 9 primitive achondrites, 8 ungrouped achondrites, 7 mesosiderites, 4 <span class="hlt">Martian</span> <span class="hlt">meteorites</span>, and 2 Pallasites, and with 1812 from Antarctica, 437 from Asia, 301 from Africa, 43 from South America, 21 from Europe (including Russia), 21 from North America, 3 from Oceania, and 1 from unknown. Information about approved <span class="hlt">meteorites</span> can be obtained from the <span class="hlt">Meteoritical</span> Bulletin Database (MBD) available on line at <url href="http://www.lpi.usra.edu/meteor/">http://www.lpi.usra.edu/meteor/.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005PhDT........24M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005PhDT........24M"><span>Laboratory <span class="hlt">studies</span> in planetary science and quantitative analysis of evaporation rates under current <span class="hlt">Martian</span> conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Moore, Shauntae</p> <p>2005-12-01</p> <p>Laboratory measurements have been performed that are intended to shed light on several problems in planetary science. Thermoluminescence measurements of ordinary chondrites have been performed as part of an effort to identify the most primitive materials in the solar system. Experiments to <span class="hlt">study</span> the fractionation of metal and silicate grains on asteroid surfaces have been performed on NASA's microgravity facility because of its relevance to <span class="hlt">meteorite</span> origins and the exploration of asteroids by robotic spacecraft. The results of these <span class="hlt">studies</span> are presented in this thesis as a conference presentation whose summary appeared in the journal <span class="hlt">Meteoritics</span> and Planetary Science and a paper that appeared in the journal Geophysical Research Letters. The rest of the thesis describes measurements on the stability of water on the surface of Mars and is submitted in normal thesis format, although at the time of submission some of this work has appeared in Geophysical Research Letters and some has been submitted to the journal Astrobiology. The thermoluminescence <span class="hlt">studies</span> were used to derive petrologic classifications for several type 3 ordinary chondrites from North Africa, some of which are very low and have the potential to provide new insights to the early solar system and its formation. The metal-silicate fractionation work suggests that the differences in composition observed among the major chondrite groups, the H, L and LL chondrites, could be the result of processes occurring on the surface of the <span class="hlt">meteorite</span> parent body, probably an asteroid. They also suggest that minor disturbances of the surface will cause separation of components in the asteroid regolith and this should be borne in mind in robotics exploration of asteroids. The stability of water on Mars was investigated by measuring the evaporation rate of liquid water in a Mars-like environment produced in a large chamber on Earth. The evaporation rates measured are in good agreement with model-dependent theoretical</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992Metic..27R.226G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992Metic..27R.226G"><span>U-Pb <span class="hlt">Study</span> of the Acapulco <span class="hlt">Meteorite</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gopel, Ch.; Manhes, G.; Allegre, C. J.</p> <p>1992-07-01</p> <p>The Acapulco <span class="hlt">meteorite</span> is currently <span class="hlt">studied</span> by a consortium in order to elucidate the origin and history of its parent body. This <span class="hlt">meteorite</span> is characterized by an approximately chondritic bulk chemistry, its major element composition is close to that of average H chondrites. Volatile elements and noble gases are, however, enriched nearly to the level of C1 chondrites and U and Th show an even higher enrichment (Palme et al., 1981). The texture of Acapulco is equigranular; chondrules are absent. Previous work with long-lived isotopes indicated some unexpected results considering the recrystallized texture and the estimated high equilibration temperature (1350 degrees K): a K/Ar age of 4.7 +- 0.3 aeon, an internal Sm-Nd isochrone indicating a recrystallization age of 4.60 + 0.03 aeon and recently an Ar/Ar age of 4.51 aeon (Palme et al., 1982; Prinzhofer et al., 1991). We present U and Pb concentrations and Pb isotopic compositions measured in bulk samples and mineral separates from Acapulco. Small bulk samples show slightly radiogenic Pb isotopic compositions (^206Pb/^204Pb= 22-36); similar to the majority of <span class="hlt">meteorites</span> they appear to have more radiogenic Pb than could have been derived from U decay. The U concentrations range from 64 to 96 ppb. Compared to C1, Acapulco is enriched in U by a factor of 5-10. ^204Pb concentrations of the fragments (~6 ppb) are lower than C1 level (47 ppb); they lie in the range of H 4-6 chondrites (0.2 up to 7 ppb) (Tatsumoto et al., 1976). Three different mineral phases were separated and analyzed: plagioclase, troilite, and phosphate. The phosphate separate shows a high U concentration. Using the modal abundance of the minerals, phosphates account for half of the U in the bulk rock. The Acapulco phosphate contains more ^204Pb (17,1 ppb) than phosphates from L-, H-, and LL- chondrites, and its resulting Pb isotopic composition is less radiogenic. The Pb/Pb model age of the phosphate relative to primordial lead is 4.557 +- 0.002 aeon</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013GeCoA.107..299W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013GeCoA.107..299W"><span>Shock metamorphism of Elephant Moraine A79001: Implications for olivine-ringwoodite transformation and the complex thermal history of heavily shocked <span class="hlt">Martian</span> <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Walton, Erin L.</p> <p>2013-04-01</p> <p>Lithology A of <span class="hlt">Martian</span> <span class="hlt">meteorite</span> Elephant Moraine (EET) A79001 contains fragments entrained within a 100 μm-thick shear-induced shock vein. These fragments, the shock vein matrix and walls of olivine along the vein, as well as shock deformation and transformation in rock-forming minerals in the bulk rock, were investigated using scanning electron microscopy, the electron microprobe and Raman spectroscopy. The presence of ringwoodite, the spinel-structured high-pressure (Mg,Fe)2SiO4 polymorph, has been confirmed in EETA79001 for the first time. Ringwoodite occurs within and around the shock vein, exhibiting granular and lamellar textures. In both textures ringwoodite consists of ˜500 nm size distinct grains. Ringwoodite lamellae are 115 nm to 1.3 μm wide. Planar fractures in olivine provided sites for heterogeneous nucleation of ringwoodite. Analyses performed on the largest grains (⩾1 μm) show that ringwoodite is consistently higher in iron (Fa27.4-32.4) relative to surrounding olivine (Fa25.1-267.7), implying that there was Fe-Mg exchange during their transformation, and therefore their growth was diffusion-controlled. In the shock environment, diffusion takes place dynamically, i.e., with concurrent deformation and grain size reduction. This results in enhanced diffusion rates (⩾10-8 m2/s) over nm - μm distances. Shock deformation in host rock minerals including strong mosaicism, pervasive fracturing, polysynthetic twinning (pyroxene only), extensive shock melting, local transformation of olivine to ringwoodite, and complete transformation of plagioclase to maskelynite in the bulk rock, indicate that EETA79001 was strongly shocked. The short shock duration (0.01 s) combined with a complex thermal history, resulted in crystallization of the 100 μm thick shock vein in EETA79001 during the pressure release, and partial back-transformation of ringwoodite to olivine. Based on the pressure stabilities of clinopyroxene + ringwoodite, crystallization at the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013M%26PS...48..270B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013M%26PS...48..270B"><span><span class="hlt">Meteorites</span> from meteor showers: A case <span class="hlt">study</span> of the Taurids</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brown, Peter; Marchenko, Valerie; Moser, Danielle E.; Weryk, Robert; Cooke, William</p> <p>2013-02-01</p> <p>We propose that the Taurid meteor shower may contain bodies able to survive and be recovered as <span class="hlt">meteorites</span>. We review the expected properties of <span class="hlt">meteorite</span>-producing fireballs, and suggest that end heights below 35 km and terminal speeds below 10 km s-1 are necessary conditions for fireballs expected to produce <span class="hlt">meteorites</span>. Applying the meteoroid strength index (PE criteria) of Ceplecha and McCrosky (1976) to a suite of 33 photographically recorded Taurid fireballs, we find a large spread in the apparent meteoroid strengths within the stream, including some very strong meteoroids. We also examine in detail the flight behavior of a Taurid fireball (SOMN 101031) and show that it has the potential to be a (small) <span class="hlt">meteorite</span>-producing event. Similarly, photographic observations of a bright, potential Taurid fireball recorded in November of 1995 in Spain show that it also had <span class="hlt">meteorite</span>-producing characteristics, despite a very high entry velocity (33 km s-1). Finally, we note that the recent Maribo <span class="hlt">meteorite</span> fall may have had a very high entry velocity (28 km s-1), further suggesting that survival of <span class="hlt">meteorites</span> at Taurid-like velocities is possible. Application of a numerical entry model also shows plausible survival of <span class="hlt">meteorites</span> at Taurid-like velocities, provided the initial meteoroids are fairly strong and large, both of which are characteristics found in the Taurid stream.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014LPICo1800.5084O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014LPICo1800.5084O"><span>A <span class="hlt">Study</span> on the Fall Year of the Sasagase <span class="hlt">Meteorite</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Owada, M.; Murai, Y.; Yoneda, S.</p> <p>2014-09-01</p> <p>Three independent historical documents on the Sasagase <span class="hlt">meteorite</span> fall have been found and the fall date of the Sasagase is Feb. 16th 1704, unlike the conventional date of Feb. 13, 1688. Also the fall date of the Numakai <span class="hlt">meteorite</span> is Sept. 4, 1925.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017hsa9.conf..543C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017hsa9.conf..543C"><span><span class="hlt">Study</span> of clouds and dust aerosols in the <span class="hlt">Martian</span> atmosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen-Chen, H.; Pérez-Hoyos, S.; Sánchez-Lavega, A.</p> <p>2017-03-01</p> <p>Observation of Mars’ atmosphere has evolved to a state of permanent monitoring of its main components. In this work, we focus on the <span class="hlt">study</span> of clouds and dust aerosols in the <span class="hlt">Martian</span> atmosphere by means of spacecraft observations, particularly VMC on-board Mars Express, and surface vehicles, mainly cameras on the MSL rover. Orbiting instrument observations provide a general view of the planet, which allows covering a huge area in a short time. This is very interesting, for example, to <span class="hlt">study</span> global dust events in Mars. On the other hand, ground-based instruments are better suited to analyse local properties of dust particles from in-situ acquired first hand data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992jpnt.confQT...P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992jpnt.confQT...P"><span>Engine system assessment <span class="hlt">study</span> using <span class="hlt">Martian</span> propellants</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pelaccio, D.; Jacobs, M.; Collins, J.; Scheil, C.; Meyer, M.</p> <p>1992-07-01</p> <p>A feasibility <span class="hlt">study</span> was performed that identified and characterized promising chemical propulsion system designs that utilize two or more of the propellant combinations: LOX/H2, LOX/CH4 and LOX/CO. The engine systems examined focused on the usage of common subsystem/component hardware where feasible. From the evaluation baseline employed, tripropellant MTV LOX cooled and bipropellant LEV and MEV engine systems are identified.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19950008255','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950008255"><span>Engine system assessment <span class="hlt">study</span> using <span class="hlt">Martian</span> propellants</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Pelaccio, Dennis; Jacobs, Mark; Scheil, Christine; Collins, John</p> <p>1992-01-01</p> <p>A top-level feasibility <span class="hlt">study</span> was conducted that identified and characterized promising chemical propulsion system designs which use two or more of the following propellant combinations: LOX/H2, LOX/CH4, and LOX/CO. The engine systems examined emphasized the usage of common subsystem/component hardware where possible. In support of this <span class="hlt">study</span>, numerous mission scenarios were characterized that used various combinations of Earth, lunar, and Mars propellants to establish engine system requirements to assess the promising engine system design concept examined, and to determine overall exploration leverage of such systems compared to state-of-the-art cryogenic (LOX/H2) propulsion systems. Initially in the <span class="hlt">study</span>, critical propulsion system technologies were assessed. Candidate expander and gas generator cycle LOX/H2/CO, LOX/H2/CH4, and LOX/CO/CH4 engine system designs were parametrically evaluated. From this evaluation baseline, tripropellant Mars Transfer Vehicle (MTV) LOX cooled and bipropellant Lunar Excursion Vehicle (LEV) and Mars Excursion Vehicle (MEV) engine systems were identified. Representative tankage designs for a MTV were also investigated. Re-evaluation of the missions using the baseline engine design showed that in general the slightly lower performance, smaller, lower weight gas generator cycle-based engines required less overall mission Mars and in situ propellant production (ISPP) infrastructure support compared to the larger, heavier, higher performing expander cycle engine systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992saic.rept.....P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992saic.rept.....P"><span>Engine system assessment <span class="hlt">study</span> using <span class="hlt">Martian</span> propellants</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pelaccio, Dennis; Jacobs, Mark; Scheil, Christine; Collins, John</p> <p>1992-06-01</p> <p>A top-level feasibility <span class="hlt">study</span> was conducted that identified and characterized promising chemical propulsion system designs which use two or more of the following propellant combinations: LOX/H2, LOX/CH4, and LOX/CO. The engine systems examined emphasized the usage of common subsystem/component hardware where possible. In support of this <span class="hlt">study</span>, numerous mission scenarios were characterized that used various combinations of Earth, lunar, and Mars propellants to establish engine system requirements to assess the promising engine system design concept examined, and to determine overall exploration leverage of such systems compared to state-of-the-art cryogenic (LOX/H2) propulsion systems. Initially in the <span class="hlt">study</span>, critical propulsion system technologies were assessed. Candidate expander and gas generator cycle LOX/H2/CO, LOX/H2/CH4, and LOX/CO/CH4 engine system designs were parametrically evaluated. From this evaluation baseline, tripropellant Mars Transfer Vehicle (MTV) LOX cooled and bipropellant Lunar Excursion Vehicle (LEV) and Mars Excursion Vehicle (MEV) engine systems were identified. Representative tankage designs for a MTV were also investigated. Re-evaluation of the missions using the baseline engine design showed that in general the slightly lower performance, smaller, lower weight gas generator cycle-based engines required less overall mission Mars and in situ propellant production (ISPP) infrastructure support compared to the larger, heavier, higher performing expander cycle engine systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014RMxAC..44..133V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014RMxAC..44..133V"><span>The SNC <span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Varela, M. E.</p> <p>2014-10-01</p> <p>The SNC (Shergotty-Nakhla-Chassigny) group, are achondritic <span class="hlt">meteorites</span>. Of all SNC <span class="hlt">meteorites</span> recognized up to date, shergottites are the most abundant group. The petrographic <span class="hlt">study</span> of Shergotty began several years ago when Tschermak, (1872) identified this rock as an extraterrestrial basalt. Oxygen isotopes in SNC <span class="hlt">meteorites</span> indicate that these rocks are from a single planetary body (Clayton and Mayeda, 1983). Because the abundance patterns of rare gases trapped in glasses from shock melts (e.g., Pepin, 1985) turned out to be very similar to the <span class="hlt">Martian</span> atmosphere (as analyzed by the Viking landers, Owen, 1976), the SNC <span class="hlt">meteorites</span> are believed to originate from Mars (e.g. McSween, 1994). Possibly, they were ejected from the <span class="hlt">Martian</span> surface either in a giant impact or in several impact events (Meyer 2006). Although there is a broad consensus for nakhlites and chassignites being -1.3Ga old, the age of the shergottites is a matter of ongoing debates. Different lines of evidences indicate that these rocks are young (180Ma and 330-475Ma), or very old (> 4Ga). However, the young age in shergottites could be the result of a resetting of these chronometers by either strong impacts or fluid percolation on these rocks (Bouvier et al., 2005-2009). Thus, it is important to check the presence of secondary processes, such as re-equilibration or pressure-induce metamorphism (El Goresy et al., 2013) that can produce major changes in compositions and obscure the primary information. A useful tool, that is used to reconstruct the condition prevailing during the formation of early phases or the secondary processes to which the rock was exposed, is the <span class="hlt">study</span> of glass-bearing inclusions hosted by different mineral phases. I will discuss the identification of extreme compositional variations in many of these inclusions (Varela et al. 2007-2013) that constrain the assumption that these objects are the result of closed-system crystallization. The question then arises whether these</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1985JMatS..20..590H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1985JMatS..20..590H"><span>A transmission electron microscopic <span class="hlt">study</span> of the Bethany iron <span class="hlt">meteorite</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hasan, F.; Axon, H. J.</p> <p>1985-02-01</p> <p>The Bethany iron <span class="hlt">meteorite</span>, which is a part of the Gibeon shower, is a fine octahedrite with zoned plessite fields of various sizes. The optically irresolvable microstructural details inside the plessitic fields have been <span class="hlt">studied</span> by transmission electron microscopy, and the crystallographic relationships between the primary kamacite (alpha) and the parent taenite (gamma), and between the alpha and gamma particles in the coarse plessite, have been examined using electron diffraction. In the case of primary kamacite, the orientation-relationship with gamma was close to the Nishiyama-Wasserman relationship, whereas, for the plessitic alpha, the orientation-relationship with gamma was close to Kurdjumov-Sachs. It was also found that the (111)-gamma and (110)-alpha planes were not strictly parallel. Additionally, measurements of the composition profile through the zoned plessite have been made using STEM microanalysis technique, and related to microstructure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080010782','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080010782"><span>Moessbauer and Electron Microprobe <span class="hlt">Studies</span> of Density Separates of <span class="hlt">Martian</span> Nakhlite Mil03346: Implications for Interpretation of Moessbauer Spectra Acquired by the Mars Exploration Rovers</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Morris, R. V.; McKay, G. A.; Agresti, D. G.; Li, Loan</p> <p>2008-01-01</p> <p><span class="hlt">Martian</span> <span class="hlt">meteorite</span> MIL03346 is described as an augite-rich cumulate rock with approx.80%, approx.3%, and approx.21% modal phase proportions of augite (CPX), olivine and glassy mesostasis, respectively, and is classified as a nakhlite [1]. The Mossbauer spectrum for whole rock (WR) MIL 03346 is unusual for <span class="hlt">Martian</span> <span class="hlt">meteorites</span> in that it has a distinct magnetite subspectrum (7% subspectral area) [2]. The <span class="hlt">meteorite</span> also has products of pre-terrestrial aqueous alteration ("iddingsite") that is associated primarily with the basaltic glass and olivine. The Mossbauer spectrometers on the Mars Exploration Rovers have measured the Fe oxidation state and the Fe mineralogical composition of rocks and soils on the planet s surface since their landing in Gusev Crater and Meridiani Planum in January, 2004 [3,4]. The MIL 03346 <span class="hlt">meteorite</span> provides an opportunity to "ground truth" or refine Fe phase identifications. This is particularly the case for the so-called "nanophase ferric oxide" (npOx) component. NpOx is a generic name for a ferric rich product of oxidative alteration. On Earth, where we can take samples apart and <span class="hlt">study</span> individual phases, examples of npOx include ferrihydrite, schwertmannite, akagaaneite, and superparamagnetic (small particle) goethite and hematite. It is also possible for ferric iron to be associated to some unknown extent with igneous phases like pyroxene. We report here an electron microprobe (EMPA) and Moessbauer (MB) <span class="hlt">study</span> of density separates of MIL 03346. The same separates were used for isotopic <span class="hlt">studies</span> by [5]. Experimental techniques are described by [6,7].</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015M%26PS...50.1662R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015M%26PS...50.1662R"><span>The <span class="hlt">Meteoritical</span> Bulletin, No. 102</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ruzicka, Alex; Grossman, Jeffrey; Bouvier, Audrey; Herd, Christopher D. K.; Agee, Carl B.</p> <p>2015-09-01</p> <p><span class="hlt">Meteoritical</span> Bulletin 102 contains 3141 <span class="hlt">meteorites</span> including 12 falls (Boumdeid (2003), Boumdeid (2011), Braunschweig, Chelyabinsk, Dongyang, Draveil, Heyetang, Indian Butte, Katol, Ladkee, Ouadangou, Xining), with 2611 ordinary chondrites, 264 HED achondrites, 124 carbonaceous chondrites, 30 ureilites, 20 <span class="hlt">Martian</span> <span class="hlt">meteorites</span>, 16 primitive achondrites, 16 Rumuruti chondrites, 15 mesosiderites, 12 iron <span class="hlt">meteorites</span>, 10 lunar <span class="hlt">meteorites</span>, 9 enstatite chondrites, 4 enstatite achondrites, 4 Pallasites, 4 ungrouped achondrites, and 2 angrites, and with 1708 from Antarctica, 956 from Africa, 294 from South America, 126 from Asia, 47 from North America, 6 from Europe (including Russia), and 4 from Oceania. Information about approved <span class="hlt">meteorites</span> can be obtained from the <span class="hlt">Meteoritical</span> Bulletin Database (MBD) available on line at <url href="http://www.lpi.usra.edu/meteor/">http://www.lpi.usra.edu/meteor/.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014me13.conf...57J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014me13.conf...57J"><span>Recent documented <span class="hlt">meteorite</span> falls, a review of <span class="hlt">meteorite</span> - asteroid links</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jenniskens, P.</p> <p>2014-07-01</p> <p>Since the previous Meteoroids 2010 meeting, 25 confirmed <span class="hlt">meteorite</span> falls have been reported, and one additional <span class="hlt">meteorite</span> was linked tentatively to an observed fireball. All but two of those are classified as ordinary chondrites. Sutter's Mill is a rare carbonaceous chondrite, while <span class="hlt">Martian</span> <span class="hlt">meteorite</span> Tissint is a Shergotite. For 18 of these falls the associated fireball was observed, but only four provided a pre-atmospheric orbit derived from video and photographic records. Results were published for Sutter's Mill, Novato, and Chelyabinsk, providing insight into the asteroid belt source regions for CM2, L and LL type chondrites, respectively. Proposed <span class="hlt">meteorite</span>-asteroid links are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160003506','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160003506"><span>Two Distinct Secondary Carbonate Species in OC <span class="hlt">Meteorites</span> from Antarctica are Possible Analogs for Mars Carbonates</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Evans, M. E.; Niles, P. B.; Locke, D. R.; Chapman, P.</p> <p>2016-01-01</p> <p><span class="hlt">Meteorites</span> falling in Antarctica are captured in ice and stored until the glacial flow transports them to the surface where they can be collected. Prior to collection, they are altered during interactions between the rock, the cryosphere, and the hydrosphere. The purpose of this <span class="hlt">study</span> is to characterize the stable isotope values of terrestrial, secondary carbonate minerals from Ordinary Chondrite (OC) <span class="hlt">meteorites</span> collected in Antarctica. This facilitates better understanding of terrestrial weathering in <span class="hlt">martian</span> <span class="hlt">meteorites</span> as well as mechanisms for weathering in cold, arid environments as an analog to Mars. OC samples were selected for analysis based upon size and collection proximity to known <span class="hlt">martian</span> <span class="hlt">meteorites</span>. They were also selected based on petrologic type (3+) such that they were likely to be carbonate-free before falling to Earth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20010044901&hterms=origin+life&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dorigin%2Blife','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20010044901&hterms=origin+life&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dorigin%2Blife"><span>A Hypothesis for the Abiotic and Non-<span class="hlt">Martian</span> Origins of Putative Signs of Ancient <span class="hlt">Martian</span> Life in ALH84001</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Treiman, Allan H.</p> <p>2001-01-01</p> <p>Putative evidence of <span class="hlt">martian</span> life in ALH84001 can be explained by abiotic and non-<span class="hlt">martian</span> processes consistent with the <span class="hlt">meteorite</span>'s geological history. Additional information is contained in the original extended abstract.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20010044901&hterms=sign&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dsign','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20010044901&hterms=sign&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dsign"><span>A Hypothesis for the Abiotic and Non-<span class="hlt">Martian</span> Origins of Putative Signs of Ancient <span class="hlt">Martian</span> Life in ALH84001</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Treiman, Allan H.</p> <p>2001-01-01</p> <p>Putative evidence of <span class="hlt">martian</span> life in ALH84001 can be explained by abiotic and non-<span class="hlt">martian</span> processes consistent with the <span class="hlt">meteorite</span>'s geological history. Additional information is contained in the original extended abstract.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22407548','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22407548"><span>Pyrolysis and mass spectrometry <span class="hlt">studies</span> of <span class="hlt">meteoritic</span> organic matter.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sephton, M A</p> <p>2012-01-01</p> <p><span class="hlt">Meteorites</span> are fragments of extraterrestrial materials that fall to the Earth's surface. The carbon-rich <span class="hlt">meteorites</span> are derived from ancient asteroids that have remained relatively unprocessed since the formation of the Solar System 4.56 billion years ago. They contain a variety of extraterrestrial organic molecules that are a record of chemical evolution in the early Solar System and subsequent aqueous and thermal processes on their parent bodies. The major organic component (>70%) is a macromolecular material that resists straightforward solvent extraction. In response to its intractable nature, the most common means of investigating this exotic material involves a combination of thermal decomposition (pyrolysis) and mass spectrometry. Recently the approach has also been used to explore controversial claims of organic matter in <span class="hlt">meteorites</span> from Mars. This review summarizes the pyrolysis data obtained from <span class="hlt">meteorites</span> and outlines key interpretations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012LPI....43.2805A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012LPI....43.2805A"><span>Lunar and <span class="hlt">Meteorite</span> Thin Sections for Undergraduate and Graduate <span class="hlt">Studies</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Allen, J.; Galindo, C.; Luckey, M.; Reustle, J.; Todd, N.; Allen, C.</p> <p>2012-03-01</p> <p>Lunar and <span class="hlt">meteorite</span> thin sections sets are available from JSC Curation for loans to domestic university petrology classes. See the new website for information http://curator.jsc.nasa.gov/Education/index.cfm.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11536554','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11536554"><span>Graphitic carbon in the Allende <span class="hlt">meteorite</span>: a microstructural <span class="hlt">study</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Smith, P P; Buseck, P R</p> <p>1981-04-17</p> <p>High-resolution transmission electron microscopy, shows that carbon in the Allende carbonaceous chondrite <span class="hlt">meteorite</span> is predominantly a poorly crystalline graphite. Such material is of interest as an important carrier of the isotopically anomalous noble gases found in carbonaceous chondrites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19810045995&hterms=322&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dp%25EF%25BF%25BD%2526%2523322','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19810045995&hterms=322&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dp%25EF%25BF%25BD%2526%2523322"><span>Graphitic carbon in the Allende <span class="hlt">meteorite</span> - A microstructural <span class="hlt">study</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Smith, P. P. K.; Buseck, P. R.</p> <p>1981-01-01</p> <p>High-resolution transmission electron microscopy shows that carbon in the Allende carbonaceous chondrite <span class="hlt">meteorite</span> is predominantly a poorly crystalline graphite. Such material is of interest as an important carrier of the isotopically anomalous noble gases found in carbonaceous chondrites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850037919&hterms=united+kingdom+history&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dunited%2Bkingdom%2Bhistory','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850037919&hterms=united+kingdom+history&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dunited%2Bkingdom%2Bhistory"><span>Thermoluminescence and the shock and reheating history of <span class="hlt">meteorites</span>. II - Annealing <span class="hlt">studies</span> of the Kernouve <span class="hlt">meteorite</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sears, D. W. G.; Bakhtiar, N.; Keck, B. D.; Weeks, K. S.</p> <p>1984-01-01</p> <p>Samples of the unshocked, equilibrated chondrite, Kernouve (H6), have been annealed for 1-100 hours at 500-1200 C, their thermoluminescence sensitivity measured and Na, K, Mn, Ca, and Sc determined by instrumental neutron activation analysis. The TL sensitivity decreased with temperature until by 1000 C it had fallen by 40 percent. The process responsible has an activation energy of 8 kcal/mole and probably involves diffusion. Samples annealed 1000-1200 C had TL sensitivities 0.01 times the unannealed values, most of the decrease occurring at 1100 C. This process has an activation energy of 100 kcal/mole and is probably related to the melting of the TL phosphor, feldspar, with some decomposition and loss of Cs, Na and K. <span class="hlt">Meteorites</span> whose petrography indicates heating above 1100 C by natural shock heating events (shock facies d-f), have TL sensitivities similar to samples annealed above 1100 C.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850037919&hterms=thermoluminescence&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dthermoluminescence','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850037919&hterms=thermoluminescence&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dthermoluminescence"><span>Thermoluminescence and the shock and reheating history of <span class="hlt">meteorites</span>. II - Annealing <span class="hlt">studies</span> of the Kernouve <span class="hlt">meteorite</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sears, D. W. G.; Bakhtiar, N.; Keck, B. D.; Weeks, K. S.</p> <p>1984-01-01</p> <p>Samples of the unshocked, equilibrated chondrite, Kernouve (H6), have been annealed for 1-100 hours at 500-1200 C, their thermoluminescence sensitivity measured and Na, K, Mn, Ca, and Sc determined by instrumental neutron activation analysis. The TL sensitivity decreased with temperature until by 1000 C it had fallen by 40 percent. The process responsible has an activation energy of 8 kcal/mole and probably involves diffusion. Samples annealed 1000-1200 C had TL sensitivities 0.01 times the unannealed values, most of the decrease occurring at 1100 C. This process has an activation energy of 100 kcal/mole and is probably related to the melting of the TL phosphor, feldspar, with some decomposition and loss of Cs, Na and K. <span class="hlt">Meteorites</span> whose petrography indicates heating above 1100 C by natural shock heating events (shock facies d-f), have TL sensitivities similar to samples annealed above 1100 C.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008epsc.conf..700C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008epsc.conf..700C"><span>A multi-instrument Exomars <span class="hlt">study</span> of meteoroid effects on the <span class="hlt">Martian</span> environment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Christou, A. A.; Griffiths, A. D.; McAuliffe, J. P.; Koschny, D.; Paetzold, M.; Oberst, J.; Trigo-Rodriguez, J. M.; Vaubaillon, J.; Withers, P.; Chappelow, J. E.; Patel, M. R.</p> <p>2008-09-01</p> <p>Mars, like the Earth, encounters meteoroids of various sizes, composition and origin during its orbital trek around the Sun. Those meteoroids' mass and kinetic energy are incorporated into the <span class="hlt">Martian</span> environment through: atmospheric ablation and deposition of meteoroid constituents in the upper atmosphere; efficient atmospheric braking leading to a <span class="hlt">meteorite</span> on the surface; and hard impact, resulting in luminous flares (and/or plumes), seismic shaking and crater excavation [1]. These effects have been modelled theoretically but in situ measurements needed to test these models have hitherto been lacking. The Exomars instrument suite presents an excellent opportunity to carry out such observations and compare with similar processes detected at the Earth and Moon. The following investigations that we advocate promote synergism between the different instruments, require no hardware modification or space qualification of "soft" mission resources such as inflight software and provide maximum science for the effort. Meteor activity at Mars would be punctuated by annually recurring showers and occasional outbursts with pronounced effects on the <span class="hlt">Martian</span> atmosphere and surface [2, 3, 4, 5]. These, mostly cometary, meteoroids, have been delivering prebiotic material to Mars for the past 4.5 Gyr. As the present <span class="hlt">Martian</span> atmosphere has similarities with that of the early Earth, the astrobiological relevance of meteor showers as exogenous sources of organics and water for both Earth and Mars is obvious. These events can now be predicted with sufficient reliability both at Mars [4] and the Earth (eg [6, 7]) to justify targeted observational campaigns. Relevant measurements include: dual-eye panoramic camera detection of visible meteors in the <span class="hlt">Martian</span> sky using existing flight-qualified change-detection software to minimise data volume [8]; radio occultation height profiles of ionospheric electron density during the orbital phase of the mission [9] and of the total electron</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017M%26PS...52..493H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017M%26PS...52..493H"><span><span class="hlt">Martian</span> cratering 11. Utilizing decameter scale crater populations to <span class="hlt">study</span> <span class="hlt">Martian</span> history</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hartmann, W. K.; Daubar, I. J.</p> <p>2017-03-01</p> <p>New information has been obtained in recent years regarding formation rates and the production size-frequency distribution (PSFD) of decameter-scale primary <span class="hlt">Martian</span> craters formed during recent orbiter missions. Here we compare the PSFD of the currently forming small primaries (P) with new data on the PSFD of the total small crater population that includes primaries and field secondaries (P + fS), which represents an average over longer time periods. The two data sets, if used in a combined manner, have extraordinary potential for clarifying not only the evolutionary history and resurfacing episodes of small <span class="hlt">Martian</span> geological formations (as small as one or few km2) but also possible episodes of recent climatic change. In response to recent discussions of statistical methodologies, we point out that crater counts do not produce idealized statistics, and that inherent uncertainties limit improvements that can be made by more sophisticated statistical analyses. We propose three mutually supportive procedures for interpreting crater counts of small craters in this context. Applications of these procedures support suggestions that topographic features in upper meters of mid-latitude ice-rich areas date only from the last few periods of extreme <span class="hlt">Martian</span> obliquity, and associated predicted climate excursions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20130009093','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20130009093"><span>Anhydrous Liquid Line of Descent of Yamato 980459 and Evolution of <span class="hlt">Martian</span> Parental Magmas</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rapp, J. F.; Draper, David S.; Mercer, C. M.</p> <p>2013-01-01</p> <p><span class="hlt">Martian</span> basalts represented by the shergottite <span class="hlt">meteorites</span> reflect derivation from highly depleted mantle sources (high Nd, strong LREE depletions, low fO2)[1-3], with evidence of mixing with a much more enriched and oxidized reservoir, most likely a late-stage product of crystallization of an initial <span class="hlt">martian</span> magma ocean [3-6]. The <span class="hlt">martian</span> basaltic <span class="hlt">meteorites</span> Yamato 980459 (Y98) and QUE 94201 (QUE) have bulk compositions that appear to represent bonafide liquids, rather than products of protracted crystallization. These two <span class="hlt">meteorites</span> also represent the most primitive and evolved examples of the depleted basaltic shergottite suite. Magmatic liquids serve as effective probes of their source regions, and thus <span class="hlt">studying</span> the potential relationship between magmas represented by Y98 and QUE can yield important information on the formation and evolution of <span class="hlt">martian</span> basalts. Although the ages of these <span class="hlt">meteorites</span> preclude that they are petrogenetically related to each other, they represent the best existing candidates for genuine liquids (other <span class="hlt">meteorites</span> are suggested to represent liquid compositions, including LAR 06319 [7] and NWA 5789 [8], but only Y98 and QUE have been verified experimentally). They span much of the bulk-compositional range of <span class="hlt">martian</span> basaltic <span class="hlt">meteorites</span>, and represent end-member liquid compositions likely to arise from partial melting of the <span class="hlt">martian</span> mantle. Recent efforts to model Y98-like parent liquid evolution by fractional crystallization using MELTS [6] produced a derivative liquid composition that closely matches QUE bulk composition, although it required a some-what unusual crystallization sequence. Experimental endeavours to verify this result at 1 bar have, however, been inconclusive [9].</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19970040877','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19970040877"><span>Numerical Model <span class="hlt">Studies</span> of the <span class="hlt">Martian</span> Mesoscale Circulations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Segal, Moti; Arritt, Raymond W.</p> <p>1997-01-01</p> <p>The <span class="hlt">study</span> objectives were to evaluate by numerical modeling various possible mesoscale circulation on Mars and related atmospheric boundary layer processes. The <span class="hlt">study</span> was in collaboration with J. Tillman of the University of Washington (who supported the <span class="hlt">study</span> observationally). Interaction has been made with J. Prusa of Iowa State University in numerical modeling investigation of dynamical effects of topographically-influenced flow. Modeling simulations included evaluations of surface physical characteristics on: (i) the <span class="hlt">Martian</span> atmospheric boundary layer and (ii) their impact on thermally and dynamically forced mesoscale flows. Special model evaluations were made in support of selection of the Pathfinder landing sites. J. Tillman's finding of VL-2 inter-annual temperature difference was followed by model simulations attempting to point out the forcing for this feature. Publication of the results in the reviewed literature in pending upon completion of the manuscripts in preparation as indicated later.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19990064166&hterms=Reference+point&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DReference%2Bpoint','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19990064166&hterms=Reference+point&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DReference%2Bpoint"><span><span class="hlt">Martian</span> Aerocapture Terminal Point Guidance: A Reference Path Optimization <span class="hlt">Study</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ro, Theodore U.; Queen, Eric M.; Striepe, Scott A.</p> <p>1999-01-01</p> <p>An effective method of terminal point guidance is to employ influence coefficients, which are solved from a set of differential equations adjoint to the linearized perturbations of the equations of motion about a reference trajectory. Hence, to optimize this type of guidance, one must first optimize the reference trajectory that the guidance is based upon. This <span class="hlt">study</span> concentrates on various methods to optimize a reference trajectory for a <span class="hlt">Martian</span> aerocapture maneuver, including a parametric analysis and first order gradient method. Resulting reference trajectories were tested in separate 2000 6-DOF Monte Carlo runs, using the Atmospheric Guidance Algorithm Testbed for the Mars Surveyor Program 2001 (MSP '01) Orbiter. These results were compared to an August 1998 <span class="hlt">study</span> using the same terminal point control guidance algorithm and simulation testbed. Satisfactory improvements over the 1998 <span class="hlt">study</span> are amply demonstrated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980211455','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980211455"><span>Mineralogic and Petrologic <span class="hlt">Studies</span> of <span class="hlt">Meteorites</span> and Lunar Samples</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wood, John A.</p> <p>1998-01-01</p> <p>In the period named, P.I. Wood and his Research Associate M.I. Petaev published or submitted for publication the following papers and abstracts, which address the subjects: Simulation of melting-crystallization relationships in chondritic and achondritic igneous systems. METEOMOD: A numerical model for the calculation of melting-crystalyization relationships in <span class="hlt">meteoritic</span> igneous systems. Secondary Ca-Fe-rich minerals in the Bali-like and Allende-like oxidized CV3 chondrites and Allende dark inclusions. Silica minerals in the Gibeon IVA iron <span class="hlt">meteorite</span>. Drusy vugs in the Albion iron <span class="hlt">meteorite</span>: Mineralogy and textures. Search for exsolved ferromagnesian olivines: A <span class="hlt">meteoritic</span> survey. Cr-bearing minerals in the Gibeon IVA iron: Indicators of sulfur and oxygen fugacities in the parent body. Lunar Planet. Computer modelling of ordinary chondrite melting. Drusy vugs in the Albion iron <span class="hlt">meteorite</span>: Early speculation on the origin. Also Processing of chondritic and planetary material in spiral density waves in the nebula. Chondrite formation by turbulence and shock in the solar nebula.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhDT........58C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhDT........58C"><span><span class="hlt">Martian</span> Chlorine Chemistry: A <span class="hlt">Study</span> of Perchlorate on the <span class="hlt">Martian</span> Surface, Evidence of an Ongoing Formation Mechanism and Implications of a Complex Chlorine Cycle</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Carrier, Brandi L.</p> <p>2015-10-01</p> <p>The research presented herein addresses the detection of perchlorate on Mars, evidence of perchlorate in Mars <span class="hlt">meteorite</span> EETA 79001, determination of the perchlorate parent salts at the Phoenix landing site, and the ongoing formation of perchlorate from chloride minerals as well as from other oxychlorine species. The detection of perchlorate in three samples by the Phoenix Wet Chemistry Laboratory and the implication of these results are discussed. The further detection of perchlorate in Mars <span class="hlt">meteorite</span> EETA 79001 by ion chromatography and the determination of the parent salts of the perchlorate detected at the Phoenix landing site by electrochemical analyses and ion chromatography are detailed and the implications of the identity of the parent salts are discussed. The possible formation pathways for <span class="hlt">martian</span> perchlorate are then explored and a possible mechanism for ongoing perchlorate formation on the <span class="hlt">martian</span> surface is detailed. Perchlorate is shown to be formed upon exposure of chloride minerals, as well as of chlorite and chlorate salts, to current Mars relevant conditions including temperature, pressure, ultraviolet radiation and atmospheric composition. The implications of this ongoing perchlorate formation for the survival and detection of organics, the oxidizing nature of the soil, formation of liquid brines and recurring slope lineae are discussed. Further preliminary experiments have been conducted to investigate the effects of perchlorate formation on the survival and degradation of organic compounds.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920019748&hterms=qualitative+study&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dqualitative%2Bstudy','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920019748&hterms=qualitative+study&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dqualitative%2Bstudy"><span><span class="hlt">Martian</span> impact crater degradation <span class="hlt">studies</span>: Implications for localized obliteration episodes</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Barlow, N. G.</p> <p>1992-01-01</p> <p>Early spacecraft missions to Mars revealed that impact craters display a range of degradational states, but full appreciation of the range of preservational characteristics was not revealed until the Mariner 9 and Viking missions in the 1970's. Many <span class="hlt">studies</span> have described the spatial and temporal distribution of obliteration episodes based on qualitative descriptions of crater degradation. Recent advances in photoclinometric techniques have led to improved estimates of crater morphometric characteristics. The present <span class="hlt">study</span> is using photoclinometry to determine crater profiles and is comparing these results with the crater geometry expected for pristine craters of identical size. The result is an estimate of the degree of degradation suffered by <span class="hlt">Martian</span> impact craters in selected regions of the planet. Size-frequency distribution analyses of craters displaying similar degrees of degradation within localized regions of the planet may provide information about the timing of obliteration episodes in these regions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20170005735','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20170005735"><span>Pulmonary Inflammatory Responses to Acute <span class="hlt">Meteorite</span> Dust Exposures - to Acute <span class="hlt">Meteorite</span> Dust Exposures - Exploration</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Harrington, A. D.; McCubbin, F. M.; Kaur, J.; Smirnov, A.; Galdanes, K.; Schoonen, M. A. A.; Chen, L. C.; Tsirka, S. E.; Gordon, T.</p> <p>2017-01-01</p> <p>New initiatives to begin lunar and <span class="hlt">martian</span> colonization within the next few decades are illustrative of the resurgence of interest in space travel. One of NASA's major concerns with extended human space exploration is the inadvertent and repeated exposure to unknown dust. This highly interdisciplinary <span class="hlt">study</span> evaluates both the geochemical reactivity (e.g. iron solubility and acellular reactive oxygen species (ROS) generation) and the relative toxicity (e.g. in vitro and in vivo pulmonary inflammation) of six <span class="hlt">meteorite</span> samples representing either basalt or regolith breccia on the surface of the Moon, Mars, and Asteroid 4Vesta. Terrestrial mid-ocean ridge basalt (MORB) is also used for comparison. The MORB demonstrated higher geochemical reactivity than most of the <span class="hlt">meteorite</span> samples but caused the lowest acute pulmonary inflammation (API). Notably, the two <span class="hlt">martian</span> <span class="hlt">meteorites</span> generated some of the highest API but only the basaltic sample is significantly reactive geochemically. Furthermore, while there is a correlation between a <span class="hlt">meteorite</span>'s soluble iron content and its ability to generate acellular ROS, there is no direct correlation between a particle's ability to generate ROS acellularly and its ability to generate API. However, assorted in vivo API markers did demonstrate strong positive correlations with increasing bulk Fenton metal content. In summary, this comprehensive dataset allows for not only the toxicological evaluation of astromaterials but also clarifies important correlations between geochemistry and health.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AIPC.1781b0015C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AIPC.1781b0015C"><span>Iron <span class="hlt">meteorite</span> fragment <span class="hlt">studied</span> by atomic and nuclear analytical methods</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cesnek, Martin; Štefánik, Milan; Kmječ, Tomáš; Miglierini, Marcel</p> <p>2016-10-01</p> <p>Chemical and structural compositions of a fragment of Sikhote-Alin iron <span class="hlt">meteorite</span> were investigated by X-ray fluorescence analysis (XRF), neutron activation analysis (NAA) and Mössbauer spectroscopy (MS). XRF and NAA revealed the presence of chemical elements which are characteristic for iron <span class="hlt">meteorites</span>. XRF also showed a significant amount of Si and Al on the surface of the fragment. MS spectra revealed possible presence of α-Fe(Ni, Co) phase with different local Ni concentration. Furthermore, paramagnetic singlet was detected in Mössbauer spectra recorded at room temperature and at 4.2 K.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMMR31A2280M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMMR31A2280M"><span>Discovery of Ahrensite γ-Fe2SiO4 and Tissintite (Ca,Na,[])AlSi2O6, Two New Shock-induced Minerals from the Tissint <span class="hlt">Martian</span> <span class="hlt">Meteorite</span>: a Nanomineralogy Investigation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ma, C.; Tschauner, O. D.; Liu, Y.; Sinogeikin, S. V.; Zhuravlev, K. K.; Prakapenka, V.; Dera, P. K.; Taylor, L. A.</p> <p>2013-12-01</p> <p>The recent <span class="hlt">Martian</span> <span class="hlt">meteorite</span> fall, Tissint, is a fresh olivine-phyric shergottite, with strong shock features. During our nano-mineralogy investigation of the Tissint <span class="hlt">meteorite</span> with a combined analytical scanning electron microscope and synchrotron diffraction approach, two new shock-induced minerals have been discovered; these provide new insights into understanding shock conditions and impact processes on Mars. Ahrensite (IMA 2013-028), the Fe-analogue (γ-Fe2SiO4) of ringwoodite, is a new high-pressure mineral identified in Tissint. Both ahrensite and ringwoodite occur in Tissint as fine-grained polycrystalline aggregates in the rims of olivines around some shock-melt pockets. The morphology and texture of these silicate-spinels suggest formation by a solid-state transformation from Fe-rich olivine. Associated with the ahrensite and ringwoodite, inside melt pockets, often resides a thin layer of vitrified silicate-perovskite and magnesio-wüstite or wüstite. Such transitions represent a unique pressure and temperature gradient. Tissintite (IMA 2013-027), (Ca,Na,[])AlSi2O6 with the C2/c clinopyroxene structure, is a new jadeite-like mineral in Tissint. It appears as fine-grained aggregates within plagioclase glass, inside many shock-melt pockets. Both ahrensite and tissintite are high-pressure minerals formed by shock during the impact event(s) on Mars that excavated and ejected the rock off Mars. We will discuss the path of structure analysis for both new-mineral cases. Such novel methodology be utilized for many cases of mineralogical phase identification or structure analysis; this demonstrates how nano-mineralogy can be addressed and how it may play a unique role in <span class="hlt">meteorite</span> and Mars rock research, in general.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA07269&hterms=Basketball&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DBasketball','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA07269&hterms=Basketball&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DBasketball"><span>Iron <span class="hlt">Meteorite</span> on Mars</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2005-01-01</p> <p><p/> NASA's Mars Exploration Rover Opportunity has found an iron <span class="hlt">meteorite</span> on Mars, the first <span class="hlt">meteorite</span> of any type ever identified on another planet. The pitted, basketball-size object is mostly made of iron and nickel. Readings from spectrometers on the rover determined that composition. Opportunity used its panoramic camera to take the images used in this approximately true-color composite on the rover's 339th <span class="hlt">martian</span> day, or sol (Jan. 6, 2005). This composite combines images taken through the panoramic camera's 600-nanometer (red), 530-nanometer (green), and 480-nanometer (blue) filters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1006637','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1006637"><span>The nature of <span class="hlt">Martian</span> fluids based on mobile element <span class="hlt">studies</span> in salt-assemblages from <span class="hlt">Martian</span> <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Rao, M.N.; Nyquist, L.E.; Wentworth, S.J.; Sutton, S.R.; Garrison, D.H.</p> <p>2008-08-04</p> <p>The S, Cl, and Br abundances determined in salt assemblages in Nakhla and Lafayette olivine fracture fillings and in gas-rich impact-melt (GRIM) glasses from Shergotty and EET79001 Lithologies A & B using EMPA/EDS/APS X-ray Microprobe techniques are compared with the S and Cl abundances determined by Gooding and coworkers in similar samples using quadrupole mass-spectrometric techniques. All the analytical methods yield relatively high Cl and low SO{sub 3} abundances in Nakhla indicating a SO{sub 3}/Cl ratio of {approx}0.2. The same ratio in Lafayette secondary salts seems to be {approx}2. In the case of GRIM glasses from Shergotty and EET79001 Lith A & Lith B, the SO{sub 3} abundance is found to be high whereas the Cl abundance is low yielding a SO{sub 3}/Cl ratio of {approx}5--300 (large errors are associated with these ratios because of low Cl signals). The salts found in Nakhla fracturefillings are inferred to have formed from Cl-rich fluids (high pH) near nakhlite source region on Mars, whereas the secondary minerals found in shergottite GRIM glasses seem to be associated with SO{sub 3}-rich fluids (low pH) near shergottite source region on Mars. The Cl-rich fluids seem to have infiltrated into the nakhlite source region {approx}600 Ma ago, whereas the SO{sub 3}-rich fluids likely percolated into the shergottite source region at {approx}180 Ma (or less) suggesting the possible existence of two types of fluid sources on Mars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008JGRE..113.6002R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008JGRE..113.6002R"><span>The nature of <span class="hlt">Martian</span> fluids based on mobile element <span class="hlt">studies</span> in salt-assemblages from <span class="hlt">Martian</span> <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rao, M. N.; Nyquist, L. E.; Wentworth, S. J.; Sutton, S. R.; Garrison, D. H.</p> <p>2008-06-01</p> <p>The S, Cl, and Br abundances determined in salt assemblages in Nakhla and Lafayette olivine fracturefillings and in gas-rich impact-melt (GRIM) glasses from Shergotty and EET79001 Lithologies A & B using EMPA/EDS/APS X-ray Microprobe techniques are compared with the S and Cl abundances determined by Gooding and coworkers in similar samples using quadrupole mass-spectrometric techniques. All the analytical methods yield relatively high Cl and low SO3 abundances in Nakhla indicating a SO3/Cl ratio of ~0.2. The same ratio in Lafayette secondary salts seems to be ~2. In the case of GRIM glasses from Shergotty and EET79001 Lith A & Lith B, the SO3 abundance is found to be high whereas the Cl abundance is low yielding a SO3/Cl ratio of ~5-300 (large errors are associated with these ratios because of low Cl signals). The salts found in Nakhla fracturefillings are inferred to have formed from Cl-rich fluids (high pH) near nakhlite source region on Mars, whereas the secondary minerals found in shergottite GRIM glasses seem to be associated with SO3-rich fluids (low pH) near shergottite source region on Mars. The Cl-rich fluids seem to have infiltrated into the nakhlite source region ~600 Ma ago, whereas the SO3-rich fluids likely percolated into the shergottite source region at ~180 Ma (or less) suggesting the possible existence of two types of fluid sources on Mars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920019834&hterms=Percent+Composition&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DPercent%2BComposition','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920019834&hterms=Percent+Composition&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DPercent%2BComposition"><span>On the isotopic composition of magmatic carbon in SNC <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wright, I. P.; Grady, M. M.; Pillinger, C. T.</p> <p>1992-01-01</p> <p>SNC <span class="hlt">meteorites</span> are thought, from many lines of evidence, to come from Mars. A line of investigation which has been pursued in our laboratory over the years involves measurement of the stable isotopic composition of carbon, in its various forms, in SNC <span class="hlt">meteorites</span>. In order to establish a firm basis for <span class="hlt">studying</span> the isotopic systematics of carbon in the <span class="hlt">martian</span> surface environment, it is first necessary to try and constrain the delta C-13 of bulk Mars. Taking all of the available information, it would seem that the delta C-13 of the Earth's mantle lies somewhere in the range of -5 to -7 percent. Preliminary assessment of magnetic carbon in SNC <span class="hlt">meteorites</span>, would tend to suggest a delta C-13 of 20 to 30 percent, which is conspicuously different from that of the terrestrial mantle. It is not obvious why there should be such a difference between the two planets, although many explanations are possible. One of these possibilities, that previous delta C-13 measurements for magnetic carbon in SNC <span class="hlt">meteorites</span> are in error to some degree, is being actively investigated. The most recent results seem to constrain the theta C-13 of the magnetic carbon in SNC <span class="hlt">meteorites</span> to about -20 percent, which is not at odds with previous estimates. As such, it is considered that a detailed investigation of the carbon isotopic systematics of <span class="hlt">martian</span> surface materials does have the necessary information with which to proceed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013M%26PSA..76.5366I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013M%26PSA..76.5366I"><span>Fall, Searching and First <span class="hlt">Study</span> of the Chelyabinsk <span class="hlt">Meteorite</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ivanova, M. A.; Badyukov, D. D.; Ryazantsev, K. M.; Lorenz, C. A.; Demidova, S. I.; Sadilenko, D. A.; Artemieva, N.; Korochantsev, A. V.; Skripnik, A. Ya.; Ivanov, A. V.; Nazarov, M. A.</p> <p>2013-09-01</p> <p>On the territory of Russian Federation the Chelyabinsk event was the biggest and the most dramatic observed LL5 chondrite <span class="hlt">meteorite</span> fall since the Tunguska event. For a moment 99% of the main mass was not found and probably presents atmospheric loss.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012LPICo1679.4355E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012LPICo1679.4355E"><span>Explore and <span class="hlt">Study</span> a <span class="hlt">Martian</span> Lava Tube or Cave</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Edberg, S. J.</p> <p>2012-06-01</p> <p>A rover exploring <span class="hlt">Martian</span> lava tubes would provide crucial data for geology, exobiology, and human exploration disciplines. It would engage the public and provide valuable data on the history of Mars and on potential sites for human habitats.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013GeCoA.104..358P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013GeCoA.104..358P"><span>Experimental and crystal chemical <span class="hlt">study</span> of the basalt-eclogite transition in Mars and implications for <span class="hlt">martian</span> magmatism</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Papike, J. J.; Burger, P. V.; Shearer, C. K.; McCubbin, F. M.</p> <p>2013-03-01</p> <p>This paper represents the start of a campaign to identify possible source regions for pyroxene-phyric "enriched" and "depleted" <span class="hlt">martian</span> basalts using high pressure <span class="hlt">studies</span> on <span class="hlt">martian</span> <span class="hlt">meteorite</span> compositions that represent liquids or near liquids. Our first experiments focus upon mineralogical and crystal chemical aspects of the basalt-eclogite transformation on Mars. It is anticipated that like Earth, eclogites are not the dominant upper mantle assemblage. However, like Earth they may be important hosts for P, Cl, F, OH, Ti, REE, Sr, Y, high-field-strength elements, Hf, and Zr in the upper mantle. This initial experimental <span class="hlt">study</span> evaluates the major and trace element crystal chemistry of potential <span class="hlt">martian</span> eclogite assemblages using a <span class="hlt">martian</span> melt composition (QUE 94201). This composition is appropriate for this <span class="hlt">study</span> because it is evolved, so it is pyroxene-phyric, contains abundant phosphate, which is important for storage of REE, and is very well <span class="hlt">studied</span>. In the high pressure experiments, garnet and omphacitic pyroxene are the dominant phases. The garnet has a compositional range from Al56.9Gr + An24.6Py18.5 to Al41.5Gr + An28.1Py30.4 to Al40.3Gr + An22.6Py37.1 (where Al = almandine, Gr+An = grossular + andradite, and Py = Pyrope) and the pyroxene has jadeite and acmite components of up to 26.0 and 9.9%, respectively. The garnet is enriched in REE over omphacite; this is especially true for the HREE which likely remain sequestered in residual garnet during melting. This observation suggests that garnet may play a key role in producing the relatively flat REE patterns of enriched <span class="hlt">martian</span> basalts. The prime substitution couple that incorporates REE into garnet is: REE3+X Site + Mg2+Y Site ↔ R2+X Site + Al3+Y Site, where R2+ = Ca, Mn2+, Fe2+, and Mg. This is a very effective couple that accounts for both charge balance and ionic size restrictions in individual sites. The prime substitution couple that incorporates REE into omphacite is: REE3+M2 Site + Na1+M2 Site</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120013688','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120013688"><span><span class="hlt">Martian</span> Igneous Geochemistry: The Nature of the <span class="hlt">Martian</span> Mantle</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mittlefehldt, D. W.; Elkins-Tanton, L. T.; Peng, Z. X.; Herrin, J. S.</p> <p>2012-01-01</p> <p>Mafic igneous rocks probe the interiors of their parent objects, reflecting the compositions and mineralogies of their source regions, and the magmatic processes that engendered them. Incompatible trace element contents of mafic igneous rocks are widely used to constrain the petrologic evolution of planets. We focus on incompatible element ratios of <span class="hlt">martian</span> <span class="hlt">meteorites</span> to constrain the petrologic evolution of Mars in the context of magma ocean/cumulate overturn models [1]. Most <span class="hlt">martian</span> <span class="hlt">meteorites</span> contain some cumulus grains, but regardless, their incompatible element ratios are close to those of their parent magmas. <span class="hlt">Martian</span> <span class="hlt">meteorites</span> form two main petrologic/ age groupings; a 1.3 Ga group composed of clinopyroxenites (nakhlites) and dunites (chassignites), and a <1 Ga group composed of basalts and lherzolites (shergottites).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70026875','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70026875"><span>The <span class="hlt">Meteoritical</span> Bulletin, No. 88, 2004 July</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Russell, S.S.; Folco, L.; Grady, M.M.; Zolensky, M.E.; Jones, R.; Righter, K.; Zipfel, J.; Grossman, J.N.</p> <p>2004-01-01</p> <p>The <span class="hlt">Meteoritical</span> Bulletin No. 88 lists information for 1610 newly classified <span class="hlt">meteorites</span>, comprising 753 from Antarctica, 302 from Africa, 505 from Asia (495 of which are from Oman), 40 from North America, 5 from South America, 4 from Europe, and 1 of unknown origin. Information is provided for 9 falls (Alby sur Che??ran, Al Zarnkh, Devgaon, Kamioka, Kendrapara, Maromandia, New Orleans, Sivas, and Villalbeto de la Pen??a). Noteworthy specimens include a eucrite fall (Alby sur Che??ran), 6 <span class="hlt">martian</span> <span class="hlt">meteorites</span>, 13 lunar <span class="hlt">meteorites</span>, and 12 irons including one weighing 3 metric ions (Dronino). ?? <span class="hlt">Meteoritical</span> Society, 2004.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012PEPI..200..113U','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012PEPI..200..113U"><span>Magnetic <span class="hlt">study</span> of <span class="hlt">meteorites</span> recovered in the Atacama desert (Chile): Implications for <span class="hlt">meteorite</span> paleomagnetism and the stability of hot desert surfaces</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Uehara, Minoru; Gattacceca, Jérôme; Rochette, Pierre; Demory, François; Valenzuela, Edith Millarca</p> <p>2012-06-01</p> <p>We conducted a detailed paleomagnetic <span class="hlt">study</span> of 18 ordinary chondrites recovered in a hot desert (the Atacama desert, Chile) to clarify the significance of the natural remanent magnetizations of weathered <span class="hlt">meteorites</span>. We show that the more weathered <span class="hlt">meteorites</span> (weathering grade W3) possess a stable magnetization unblocked over two temperature intervals (140-320 °C, and 500-550 °C). This magnetization was acquired on Earth as indicated by the paleomagnetic directions of large <span class="hlt">meteorites</span> (>150 g) that are in the direction of the terrestrial field. Rock magnetic data suggest that this stable magnetization is a chemical remanent magnetization acquired by maghemite and magnetite upon their formation as weathering products. On the other hand, the natural remanent magnetization of ordinary chondrites showing little or no weathering (weathering grades W0 and W1) are much weaker, and very unstable upon demagnetization, a similar behavior to the magnetization of <span class="hlt">meteorite</span> falls. Therefore, up to the weathering grade W1, weathering does not largely overprint the original extraterrestrial magnetization of these <span class="hlt">meteorites</span>. This is confirmed at microscopic scale by magnetic imaging: tetrataenite and kamacite have randomly oriented magnetization at mineral scale that is canceled out at larger scale (>1 mm3), whereas a small fraction of the weathering products has a weak but unidirectional magnetization that masks the weak extraterrestrial magnetization. This suggests that extraterrestrial magnetization can survive mild weathering (below weathering grade W2), and that such <span class="hlt">meteorites</span> remain worthwhile targets for <span class="hlt">study</span> of extraterrestrial paleomagnetism. For <span class="hlt">meteorites</span> with weathering grade W3 or more, the extraterrestrial signal can only be <span class="hlt">studied</span> at microscopic scale. These data also show that over a time scale of several kyr to several tens of kyr, large stones (>150 g) have remained still at the surface of the Atacama desert whereas smaller ones have moved only by rotation</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70023756','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70023756"><span>The <span class="hlt">Meteoritical</span> Bulletin, no. 85, 2001 September</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Grossman, J.N.; Zipfel, J.</p> <p>2001-01-01</p> <p><span class="hlt">Meteoritical</span> Bulletin No. 85 lists information for 1376 newly classified <span class="hlt">meteorites</span>, comprising 658 from Antarctica, 409 from Africa, 265 from Asia (262 of which are from Oman), 31 from North America, 7 from South America, 3 from Australia, and 3 from Europe. Information is provided for 11 falls (Dergaon, Dunbogan, Gujba, Independence, Itqiy, Mora??vka, Oued el Hadjar, Sayama, Sologne, Valera, and Worden). Noteworthy non-Antarctic specimens include 5 <span class="hlt">martian</span> <span class="hlt">meteorites</span> (Dar al Gani 876, Northwest Africa 480 and 817, and Sayh al Uhaymir 051 and 094); 6 lunar <span class="hlt">meteorites</span> (Dhofar 081, 280, and 287, and Northwest Africa 479, 482, and 773); an ungrouped enstatite-rich <span class="hlt">meteorite</span> (Itqiy); a Bencubbin-like <span class="hlt">meteorite</span> (Gujba); 9 iron <span class="hlt">meteorites</span>; and a wide variety of other interesting stony <span class="hlt">meteorites</span>, including CH, CK, CM, CO, CR, CV, R, enstatite, and unequilibrated ordinary chondrites, primitive achondrites, HED achondrites, and ureilites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GeCoA.208..198G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeCoA.208..198G"><span>Effective radium-226 concentration in <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Girault, Frédéric; Perrier, Frédéric; Moreira, Manuel; Zanda, Brigitte; Rochette, Pierre; Teitler, Yoram</p> <p>2017-07-01</p> <p>The analysis of noble gases in <span class="hlt">meteorites</span> provides constraints on the early solar system and the pre-solar nebula. This requires a better characterization and understanding of the capture, production, and release of noble gases in <span class="hlt">meteorites</span>. The knowledge of transfer properties of noble gases for each individual <span class="hlt">meteorite</span> could benefit from using radon-222, radioactive daughter of radium-226. The radon-222 emanating power is commonly quantified by the effective radium-226 concentration (ECRa), the product of the bulk radium-226 concentration and of the emanation coefficient E, which represents the probability of one decaying radium-226 to inject one radon-222 into the free porous network. Owing to a non-destructive, high-sensitivity accumulation method based on long photomultiplier counting sessions, we are now able to measure ECRa of <span class="hlt">meteorite</span> samples, which usually have mass smaller than 15 g and ECRa < 0.5 Bq kg-1. We report here the results obtained from 41 different <span class="hlt">meteorites</span>, based on 129 measurements on 70 samples using two variants of our method, showing satisfactory repeatability and a detection limit below 10-2 Bq kg-1 for a sample mass of 1 g. While two <span class="hlt">meteorites</span> remain below detection level, we obtain for 39 <span class="hlt">meteorites</span> heterogeneous ECRa values with mean (min-max range) of ca. 0.1 (0.018-1.30) Bq kg-1. Carbonaceous chondrites exhibit the largest ECRa values and eucrites the smallest. Such values are smaller than typical values from most terrestrial rocks, but comparable with those from Archean rocks (mean of ca. 0.18 Bq kg-1), an end-member of terrestrial rocks. Using uranium concentration from the literature, E is inferred from ECRa for all the <span class="hlt">meteorite</span> samples. Values of E for <span class="hlt">meteorites</span> (mean 40 ± 4%) are higher than E values for Archean rocks and reported values for lunar and <span class="hlt">Martian</span> soils. Exceptionally large E values likely suggest that the 238U-226Ra pair would not be at equilibrium in most <span class="hlt">meteorites</span> and that uranium and/or radium are most</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20030062176&hterms=schwarz&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dschwarz','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20030062176&hterms=schwarz&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dschwarz"><span>JSC Mars-1 <span class="hlt">Martian</span> Soil Simulant: Melting Experiments and Electron Microprobe <span class="hlt">Studies</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Carpenter, P.; Sebille, L.; Boles, W.; Chadwell, M.; Schwarz, L.</p> <p>2003-01-01</p> <p>JSC Mars-1 has been developed as a <span class="hlt">Martian</span> regolith simulant, and is the <1 mm size fraction of a palagonitic tephra (a glassy volcanic ash altered at low temperatures) from Pu'u Nene cinder cone on the Island of Hawaii. The Mars-1 simulant forms the basis for numerous terrestrial <span class="hlt">studies</span> which aim to evaluate the suitability of <span class="hlt">Martian</span> soil for materials processing. <span class="hlt">Martian</span> soil may be sintered to form building materials for construction, and also melted or reacted to extract metals for various uses, as well as oxygen for life support.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20030062176&hterms=Palagonitic&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DPalagonitic','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20030062176&hterms=Palagonitic&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DPalagonitic"><span>JSC Mars-1 <span class="hlt">Martian</span> Soil Simulant: Melting Experiments and Electron Microprobe <span class="hlt">Studies</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Carpenter, P.; Sebille, L.; Boles, W.; Chadwell, M.; Schwarz, L.</p> <p>2003-01-01</p> <p>JSC Mars-1 has been developed as a <span class="hlt">Martian</span> regolith simulant, and is the <1 mm size fraction of a palagonitic tephra (a glassy volcanic ash altered at low temperatures) from Pu'u Nene cinder cone on the Island of Hawaii. The Mars-1 simulant forms the basis for numerous terrestrial <span class="hlt">studies</span> which aim to evaluate the suitability of <span class="hlt">Martian</span> soil for materials processing. <span class="hlt">Martian</span> soil may be sintered to form building materials for construction, and also melted or reacted to extract metals for various uses, as well as oxygen for life support.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013M%26PS...48.2371G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013M%26PS...48.2371G"><span>K2O-rich trapped melt in olivine in the Nakhla <span class="hlt">meteorite</span>: Implications for petrogenesis of nakhlites and evolution of the <span class="hlt">Martian</span> mantle</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Goodrich, Cyrena Anne; Treiman, Allan H.; Filiberto, Justin; Gross, Juliane; Jercinovic, Michael</p> <p>2013-12-01</p> <p>We used new analytical and theoretical methods to determine the major and minor element compositions of the primary trapped liquid (PTLs) represented by melt inclusions in olivine and augite in the <span class="hlt">Martian</span> clinopyroxenite, Nakhla, for comparison with previously proposed compositions for the Nakhla (or nakhlite) parent magma. We particularly focused on obtaining accurate K2O contents, and on testing whether high K2O contents and K2O/Na2O ratios obtained in previous <span class="hlt">studies</span> of melt inclusions in olivine in Nakhla could have been due to unrepresentative sampling, systematic errors arising from electron microprobe techniques, late alteration of the inclusions, and/or boundary layer effects. Based on analyses of 35 melt inclusions in olivine cores, the PTL in olivine, PTLoliv, contained (by wt) approximately 47% SiO2, 6.3% Al2O3, 9.6% CaO, 1.8% K2O, and 0.9% Na2O, with K2O/Na2O = 2.0. We infer that the high K2O content of PTLoliv is not due to boundary layer effects and represents a real property of the melt from which the host olivine crystallized. This melt was cosaturated with olivine and augite. Its mg# is model-dependent and is constrained only to be ≥19 (equilibrium Fo = 40). Based on analyses of 91 melt inclusions in augite cores, the PTL in augite, PTLaug, contained (by wt) 53-54% SiO2, 7-8% Al2O3, 0.8-1.1% K2O, and 1.1-1.4% Na2O, with K2O/Na2O = 0.7-0.8. This K2O content and K2O/Na2O ratio are significantly higher than inferred in <span class="hlt">studies</span> of melt inclusions in augite in Nakhla by experimental rehomogenization. PTLaug was saturated only with augite, and in equilibrium with augite cores of mg# 62. PTLaug represents the Nakhla parent magma, and does not evolve to PTLoliv by fractional crystallization. We therefore conclude that olivine cores in Nakhla (and, by extension, other nakhlites) are xenocrystic. We propose that PTLoliv and PTLaug were generated from the same source region. PTLoliv was generated first and emplaced to form olivine-rich cumulate rocks</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19940007592&hterms=Thermal+floors&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DThermal%2Bfloors','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19940007592&hterms=Thermal+floors&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DThermal%2Bfloors"><span>Thermal <span class="hlt">studies</span> of <span class="hlt">Martian</span> channels and valleys using Termoskan data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Betts, B. H.; Murray, B. C.</p> <p>1993-01-01</p> <p>The Termoskan instrument on board the Phobos '88 spacecraft acquired the highest spatial resolution thermal data ever obtained for Mars. Included in the thermal images are 2 km per pixel observations of 4 major channel and valley systems: Shalbatana Vallis; Simud Vallis, Hydraotes Chaos, and the associated outflow channel connecting it with the eastern end of Vallis Marineris; Al-Qahira Vallis; and Ma'adim Vallis. Simultaneous broad band visible channel data were obtained for all but Ma'adim Vallis. We find that all 4 valley systems have higher inertias than their surroundings, consistent with previous thermal <span class="hlt">studies</span> of <span class="hlt">Martian</span> channels. We conclude that the higher inertia is likely due to some intrinsic difference associated with the channel floors, rather than due only to dark aeolian deposits as suggested by some previous <span class="hlt">studies</span>. Our conclusion is based largely upon the localized nature of the dark deposits in contrast with the thermal homogeneity of the channel floors. Thus, these channels and valleys show an uncommon (for Mars) connection between morphology and inertia.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980021283','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980021283"><span><span class="hlt">Meteorites</span>, Microfossils and Exobiology</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hoover, Richard B.</p> <p>1997-01-01</p> <p>The discovery of evidence for biogenic activity and possible microfossils in a <span class="hlt">Martian</span> <span class="hlt">meteorite</span> may have initiated a paradigm shift regarding the existence of extraterrestrial microbial life. Terrestrial extremophiles that live in deep granite and hydrothermal vents and nanofossils in volcanic tuffs have altered the premise that microbial life and microfossils are inconsistent with volcanic activity and igneous rocks. Evidence for biogenic activity and microfossils in <span class="hlt">meteorites</span> can no longer be dismissed solely because the <span class="hlt">meteoritic</span> rock matrix is not sedimentary. <span class="hlt">Meteorite</span> impact-ejection and comets provide mechanisms for planetary cross-contamination of biogenic chemicals, microfossils, and living microorganisms. Hence, previously dismissed evidence for complex indigenous biochemicals and possible microfossils in carbonaceous chondrites must be re-examined. Many similar, unidentifiable, biological-like microstructures have been found in different carbonaceous chondrites and the prevailing terrestrial contaminant model is considered suspect. This paper reports the discovery of microfossils indigenous to the Murchison <span class="hlt">meteorite</span>. These forms were found in-situ in freshly broken, interior surfaces of the <span class="hlt">meteorite</span>. Environmental Scanning Electron Microscope (ESEM) and optical microscopy images indicate that a population of different biological-like forms are represented. Energy Dispersive Spectroscopy reveals these forms have high carbon content overlaying an elemental distribution similar to the matrix. Efforts at identification with terrestrial microfossils and microorganisms were negative. Some forms strongly resemble bodies previously isolated in the Orgueil <span class="hlt">meteorite</span> and considered microfossils by prior researchers. The Murchison forms are interpreted to represent an indigenous population of the preserved and altered carbonized remains (microfossils) of microorganisms that lived in the parent body of this <span class="hlt">meteorite</span> at diverse times during the past 4.5 billion</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GeCoA.157...56S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeCoA.157...56S"><span>Petrology of igneous clasts in Northwest Africa 7034: Implications for the petrologic diversity of the <span class="hlt">martian</span> crust</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Santos, Alison R.; Agee, Carl B.; McCubbin, Francis M.; Shearer, Charles K.; Burger, Paul V.; Tartèse, Romain; Anand, Mahesh</p> <p>2015-05-01</p> <p>The <span class="hlt">martian</span> <span class="hlt">meteorite</span> Northwest Africa (NWA) 7034 was examined both petrographically and geochemically using several micro-beam techniques including electron probe microanalysis and secondary ion mass spectrometry. We have identified various clast types of igneous, sedimentary, and impact origin that occur within the breccia, and we define a classification scheme for these materials based on our observations, although our primary focus here is on the petrology of the igneous clasts. A number of different igneous clasts are present in this <span class="hlt">meteorite</span>, and our <span class="hlt">study</span> revealed the presence of at least four different igneous lithologies (basalt, basaltic andesite, trachyandesite, and an Fe, Ti, and P (FTP) rich lithology). These lithologies do not appear to be related by simple igneous processes such as fractional crystallization, indicating NWA 7034 is a polymict breccia that contains samples from several different igneous sources. The basalt lithologies are a good match for measured rock compositions from the <span class="hlt">martian</span> surface, however more exotic lithologies (e.g., trachyandesite and FTP lithologies) show this <span class="hlt">meteorite</span> contains previously unsampled rock types from Mars. These new rock types provide evidence for a much greater variety of igneous rocks within the <span class="hlt">martian</span> crust than previously revealed by <span class="hlt">martian</span> <span class="hlt">meteorites</span>, and supports recent rover observations of lithologic diversity across the <span class="hlt">martian</span> surface. Furthermore, the ancient ages for the lithologic components in NWA 7034 indicate Mars developed this lithologic diversity in the early stages of crust formation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19890023540&hterms=John+holloway&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DJohn%2Bholloway','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19890023540&hterms=John+holloway&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DJohn%2Bholloway"><span><span class="hlt">Martian</span> mantle primary melts - An experimental <span class="hlt">study</span> of iron-rich garnet lherzolite minimum melt composition</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bertka, Constance M.; Holloway, John R.</p> <p>1988-01-01</p> <p>The minimum melt composition in equilibrium with an iron-rich garnet lherzolite assemblage is ascertained from a <span class="hlt">study</span> of the liquidus relations of iron-rich basaltic compositions at 23 kb. The experimentally determined primary melt composition and its calculated sodium content reveal that <span class="hlt">Martian</span> garnet lherzolite minimum melts are picritic alkali olivine basalts. <span class="hlt">Martian</span> primary melts are found to be more picritic than terrestrial garnet lherzolite primary melts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050174593','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050174593"><span>Synchrotron-based Infrared Microspectroscopy as a Useful Tool to <span class="hlt">Study</span> Hydration States of <span class="hlt">Meteorite</span> Constituents</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Moroz, L. V.; Schmidt, M.; Schade, U.; Hiroi, T.; Ivanova, M. A.</p> <p>2005-01-01</p> <p>The <span class="hlt">meteorites</span> Dho 225 and Dho 735 were recently found in Oman. <span class="hlt">Studies</span> of their mineralogical and chemical composition suggest that these unusual <span class="hlt">meteorites</span> are thermally metamorphosed CM2 chondrites [1,2,3]. Similar to Antarctic metamorphosed carbonaceous chondrites, the Dho 225 and Dho 735 are enriched in heavy oxygen compared to normal CMs [1,2]. However, IR <span class="hlt">studies</span> indicating dehydration of matrix phyllosilicates are needed to confirm that the two new <span class="hlt">meteorites</span> from Oman are thermally metamorphosed [4]. Synchrotron-based IR microspectroscopy is a new promising technique which allows the acquisition of IR spectra from extremely small samples. Here we demonstrate that this non-destructive technique is a useful tool to <span class="hlt">study</span> hydration states of carbonaceous chondrites in situ. In addition, we acquired reflectance spectra of bulk powders of the Dho 225 and Dho 735 in the range of 0.3-50 microns.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005LPI....36.1198C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005LPI....36.1198C"><span>Albedo <span class="hlt">Study</span> of the Depositional Fans Associated with <span class="hlt">Martian</span> Gullies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Craig, J.; Sears, D. W. G.</p> <p>2005-03-01</p> <p>This work is a two-part investigation of the albedo of the depositional aprons or fans associated with <span class="hlt">Martian</span> gully features. Using Adobe Systems Photoshop 5.0 software we analyzed numerous Mars Global Surveyor MOC and Mars Odyssey THEMIS images.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840013410','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840013410"><span>Mineralogic and petrologic <span class="hlt">studies</span> of <span class="hlt">meteorites</span> and lunar samples</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wood, J. A.</p> <p>1984-01-01</p> <p>During a 13 year period beginning in 1971, the Extraterrestrial Petrology Group examined lunar soils from all 6 Apollo missions and those returned by the Soviet Luna 16, Luna 20, and Luna 24 missions. In addition, the properties and apparent origin of the carbonaceous chondrites were examined. Chondrules, calcium-aluminum-rich inclusions (CAI) and the fine grained matrix materials that accompany chondrules and CAI's in primitive <span class="hlt">meteorites</span> were investigated. The effects of planetary hydrothermal alteration of matrix materials in the C1 chondrite was also investigated. Full length papers and extended abstracts published during the grant are listed chronologically.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017M%26PS...52.1660W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017M%26PS...52.1660W"><span><span class="hlt">Meteorite</span> transport—Revisited</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wisdom, Jack</p> <p>2017-08-01</p> <p><span class="hlt">Meteorites</span> are delivered from the asteroid belt by way of chaotic zones (Wisdom 1985a). The dominant sources are believed to be the chaotic zones associated with the ν6 secular resonance, the 3:1 mean motion resonance, and the 5:2 mean motion resonance. Though the <span class="hlt">meteorite</span> transport process has been previously <span class="hlt">studied</span>, those <span class="hlt">studies</span> have limitations. Here I reassess the <span class="hlt">meteorite</span> transport process with fewer limitations. Prior <span class="hlt">studies</span> have not been able to reproduce the afternoon excess (the fact that approximately twice as many <span class="hlt">meteorites</span> fall in the afternoon as in the morning) and suggested that the afternoon excess is an observational artifact; here it is shown that the afternoon excess is in fact consistent with the transport of <span class="hlt">meteorites</span> by way of chaotic zones in the asteroid belt. By <span class="hlt">studying</span> models with and without the inner planets it is found that the inner planets significantly speed up the transport of <span class="hlt">meteorites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930068552&hterms=Koeberl&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D10%26Ntt%3DKoeberl','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930068552&hterms=Koeberl&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D10%26Ntt%3DKoeberl"><span>Lunar <span class="hlt">meteorite</span> Yamato-86032 - Mineralogical, petrological, and geochemical <span class="hlt">studies</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Koeberl, Christian; Kurat, Gero; Brandstaetter, Franz</p> <p>1990-01-01</p> <p>Yamato-86032 is a shock-lithified anorthositic fragmental breccia. It consists mainly of highly feldspathic meta-breccias and meta-meltrocks and possibly contains a small contribution from mare lithologies, but there is no indication of a KREEP component. In many respects Y-86032 is similar to the previously described lunar <span class="hlt">meteorites</span> Y-82192/3, but there are some notable differences. We have analyzed about 40 major and trace elements in bulk matrix, impact melt, and clast samples from two chips of Y-86032. The abundances of most lithophile and incompatible elements are lower in Y-86032 than in Y-82192 (which contains very low abundances compared to normal lunar highland rocks). The REE abundances are comparable to those of Y-82192. The elements Sc, Cr, Mn, Fe and Co have significantly lower abundances than in Y-82192, and the siderophile element pattern is also different. Since cosmic ray exposure data indicate pairing of Y-86032 with Y-82192/3, the source region for these <span class="hlt">meteorites</span> on the moon must have been fairly heterogeneous.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19910025730&hterms=electron+microscopy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Delectron%2Bmicroscopy','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19910025730&hterms=electron+microscopy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Delectron%2Bmicroscopy"><span>Electron microscopy <span class="hlt">study</span> of the iron <span class="hlt">meteorite</span> Santa Catharina</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zhang, J.; Williams, D. B.; Goldstein, J. I.; Clarke, R. S., Jr.</p> <p>1990-01-01</p> <p>A characterization of the microstructural features of Santa Catharina (SC) from the millimeter to submicron scale is presented. The same specimen was examined using an optical microscope, a scanning electron microscope, an electron probe microanalyzer, and an analytical electron microscope. Findings include the fact that SC metal nodules may have different bulk Ni values, leading to different microstructures upon cooling; that SC USNM 6293 is the less corroded sample, as tetrataenite exists as less than 10 nm ordered domains throughout the entire fcc matrix (it is noted that this structure is the same as that of the Twin City <span class="hlt">meteorite</span> and identical to clear taenite II in the retained taenite regions of the octahedrites); that SC USNM 3043 has a more complicated microstructure due to corrosion; and that the low Ni phase of the cloudy zone was selectively corroded in some areas and formed the dark regions, indicating that the SC <span class="hlt">meteorite</span> corrosion process was electrochemical in nature and may involve Cl-containing akaganeite.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016HyInt.237..107E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016HyInt.237..107E"><span>57Fe Mössbauer <span class="hlt">study</span> of the chainpur <span class="hlt">meteorite</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Elewa, Nancy N.; Cobas, R.; Cadogan, J. M.</p> <p>2016-12-01</p> <p>The Chainpur <span class="hlt">meteorite</span> is one of 23 ordinary chondrites classified as LL3-type (low-Fe & low-metal). It was observed as a shower of stones falling on May 9, 1907 in Uttar Pradesh, India. We report here the characterization of the Fe-bearing phases in this chondrite using 57Fe Mössbauer spectroscopy carried out at 298 K, 120 K, 50 K and 13 K. The paramagnetic doublets of olivine and pyroxene dominate the room temperature spectrum, accounting for around 70 % of the spectral area. Moreover, a doublet present with a spectral area of 5 % and assigned to a superparamagnetic Fe 3+ phase is a consequence of terrestrial weathering. On the basis of the measured 57Fe electric quadrupole splitting of the olivine component at room temperature we estimate the mean Fe:Mg ratio in this <span class="hlt">meteoritic</span> olivine to be around 35:65 % although there is clearly a wide range of composition. The effects of magnetic ordering of the major components olivine and pyroxene are observed at 13 K.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017APS..APR.T1021D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017APS..APR.T1021D"><span>Comparative <span class="hlt">study</span> of carbonaceous <span class="hlt">meteoritic</span> fragments by micro-Raman spectroscopy and SEM/EDS.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dall'Asén, AnalíA.; Mittelstaedt, Jacob; Kim, Jin-Sun; Baer, Brandon; Paul, Raka; Gerton, Jordan; Bromley, Benjamin; Kenyon, Scott</p> <p>2017-01-01</p> <p><span class="hlt">Meteorites</span> provide precious clues about the formation of planets in the solar system. In particular, carbonaceous chondritic <span class="hlt">meteorites</span>, considered the most primitive surviving materials from the early Solar System, can contribute to understand how planetisimals (the precursors to planets, of 1-100 km in radius) formed from dust (micron-size grains). These relics are mainly composed of chondrules (micro/millimeter-sized inclusions) surrounded by a matrix of microparticles. Here we present a comparative <span class="hlt">study</span> of the structure and composition of the chondrules and surrounding matrix of different carbonaceous chondritic <span class="hlt">meteorites</span> using low- and high-resolution micro-Raman spectroscopy and SEM/EDS (Scanning Electron Microscopy/Energy Dispersive X-ray Spectroscopy). We examine how these properties vary in different regions of the chondrules and matrix, capturing details from micrometer to millimeter scales. We compare the structure and composition between different samples, looking for signatures of the physical processes that drove their formation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19890057036&hterms=neon&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dneon','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19890057036&hterms=neon&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dneon"><span>Neon isotope <span class="hlt">studies</span> of Fayetteville and Kapoeta <span class="hlt">meteorites</span> and clues to ancient solar activity</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Padia, J. T.; Rao, M. N.</p> <p>1989-01-01</p> <p>Under the assumption that the solar-flare bombardment of the irradiated grains of gas-rich <span class="hlt">meteorites</span> occurred about 4.5 b.y. ago on the parent body regoliths at 3 A.U., an estimate of the solar cosmic ray-produced Ne-21 is made by <span class="hlt">studying</span> etched pyroxene minera separates from both light and dark portions of the gas-rich <span class="hlt">meteorites</span> Fayetteville and Kapoeta. Excesses of solar cosmic ray Ne-21 were observed in dark portions of these <span class="hlt">meteorites</span>, after accounting for their galactic cosmic ray Ne-21 production and solar flare Ne-21. In order to produce the estimated solar cosmic ray Ne-21 in the present samples, highly enhanced solar cosmic ray proton fluxes from the ancient sun are required.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19890057036&hterms=Neon&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DNeon','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19890057036&hterms=Neon&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DNeon"><span>Neon isotope <span class="hlt">studies</span> of Fayetteville and Kapoeta <span class="hlt">meteorites</span> and clues to ancient solar activity</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Padia, J. T.; Rao, M. N.</p> <p>1989-01-01</p> <p>Under the assumption that the solar-flare bombardment of the irradiated grains of gas-rich <span class="hlt">meteorites</span> occurred about 4.5 b.y. ago on the parent body regoliths at 3 A.U., an estimate of the solar cosmic ray-produced Ne-21 is made by <span class="hlt">studying</span> etched pyroxene minera separates from both light and dark portions of the gas-rich <span class="hlt">meteorites</span> Fayetteville and Kapoeta. Excesses of solar cosmic ray Ne-21 were observed in dark portions of these <span class="hlt">meteorites</span>, after accounting for their galactic cosmic ray Ne-21 production and solar flare Ne-21. In order to produce the estimated solar cosmic ray Ne-21 in the present samples, highly enhanced solar cosmic ray proton fluxes from the ancient sun are required.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20020046467&hterms=Rutherford&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DRutherford','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20020046467&hterms=Rutherford&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DRutherford"><span>An Experimental <span class="hlt">Study</span> of Eu/Gd Partitioning Between a Shergottite Melt and Pigeonite: Implications for the Oxygen Fugacity of the <span class="hlt">Martian</span> Interior</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>McCanta, M. C.; Rutherford, M. J.; Jones, J. H.</p> <p>2002-01-01</p> <p>We experimentally investigated the partitioning behavior of Eu/Gd between a synthetic shergottite melt and pigeonite as a function of oxygen fugacity. This has implications for the oxidation state of the source region of the <span class="hlt">martian</span> <span class="hlt">meteorites</span>. Additional information is contained in the original extended abstract.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014M%26PS...49E...1R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014M%26PS...49E...1R"><span>The <span class="hlt">Meteoritical</span> Bulletin, No. 100, 2014 June</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ruzicka, Alex; Grossman, Jeffrey N.; Garvie, Laurence</p> <p>2014-08-01</p> <p><span class="hlt">Meteoritical</span> Bulletin 100 contains 1943 <span class="hlt">meteorites</span> including 8 falls (Boumdeid [2011], Huaxi, Košice, Silistra, Sołtmany, Sutter's Mill, Thika, Tissint), with 1575 ordinary chondrites, 139 carbonaceous chondrites, 96 HED achondrites, 25 ureilites, 18 primitive achondrites, 17 iron <span class="hlt">meteorites</span>, 15 enstatite chondrites, 11 lunar <span class="hlt">meteorites</span>, 10 mesosiderites, 10 ungrouped achondrites, 8 pallasites, 8 <span class="hlt">Martian</span> <span class="hlt">meteorites</span>, 6 Rumuruti chondrites, 3 enstatite achondrites, and 2 angrites, and with 937 from Antarctica, 592 from Africa, 230 from Asia, 95 from South America, 44 from North America, 36 from Oceania, 6 from Europe, and 1 from an unknown location. This will be the last Bulletin published in the current format. Information about approved <span class="hlt">meteorites</span> can be obtained from the <span class="hlt">Meteoritical</span> Bulletin Database (MBD) available online at http://www.lpi.usra.edu/meteor/</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040085427&hterms=barometer&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dbarometer','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040085427&hterms=barometer&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dbarometer"><span>Oxygen Fugacity of the <span class="hlt">Martian</span> Mantle from Pigeonite/Melt Partitioning of Samarium, Europium and Gadolinium</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Musselwhite, S.; Jones, J. H.; Shearer, C.</p> <p>2004-01-01</p> <p>This <span class="hlt">study</span> is part of an ongoing effort to calibrate the pyroxene/melt Eu oxybarometer for conditions relevant to the <span class="hlt">martian</span> <span class="hlt">meteorites</span>. There is fairly good agreement between a determinations using equilibria between Fe-Ti oxides and the estimates from Eu anomalies in shergottite augites in tenns of which <span class="hlt">meteorites</span> are more or less oxidized. The Eu calibration was for angrite composition pyroxenes which are rather extreme. However, application of a calibration for <span class="hlt">martian</span> composition augites 113 does not significantly reduce the discrepancy between the two methods. One possible reason for this discrepancy is that augites are non-liquidus. The use of pigeonite rather than augite as the oxy-barometer phase is considered. We have conducted experiments on <span class="hlt">martian</span> composition pigeonite/melt REE partitioning as a function of fO2.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040085427&hterms=Gadolinium&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DGadolinium','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040085427&hterms=Gadolinium&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DGadolinium"><span>Oxygen Fugacity of the <span class="hlt">Martian</span> Mantle from Pigeonite/Melt Partitioning of Samarium, Europium and Gadolinium</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Musselwhite, S.; Jones, J. H.; Shearer, C.</p> <p>2004-01-01</p> <p>This <span class="hlt">study</span> is part of an ongoing effort to calibrate the pyroxene/melt Eu oxybarometer for conditions relevant to the <span class="hlt">martian</span> <span class="hlt">meteorites</span>. There is fairly good agreement between a determinations using equilibria between Fe-Ti oxides and the estimates from Eu anomalies in shergottite augites in tenns of which <span class="hlt">meteorites</span> are more or less oxidized. The Eu calibration was for angrite composition pyroxenes which are rather extreme. However, application of a calibration for <span class="hlt">martian</span> composition augites 113 does not significantly reduce the discrepancy between the two methods. One possible reason for this discrepancy is that augites are non-liquidus. The use of pigeonite rather than augite as the oxy-barometer phase is considered. We have conducted experiments on <span class="hlt">martian</span> composition pigeonite/melt REE partitioning as a function of fO2.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140012903','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140012903"><span>A TEM Investigation of the Fine-Grained Matrix of the <span class="hlt">Martian</span> Basaltic Breccia NWA 7034</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Muttik, N.; Keller, L. P.; Agee, C. B.; McCubbin, F. M.; Santos, A. R.; Rahman, Z.</p> <p>2014-01-01</p> <p>The <span class="hlt">martian</span> basaltic breccia NWA 7034 is characterized by fine-grained groundmass containing several different types of mineral grains and lithologic clasts. The matrix composition closely resembles <span class="hlt">Martian</span> crustal rock and soil composition measured by recent rover and orbiter missions. The first results of NWA 7034 suggest that the brecciation of this <span class="hlt">martian</span> <span class="hlt">meteorite</span> may have formed due to eruptive volcanic processes; however, impact related brecciation processes have been proposed for paired <span class="hlt">meteorites</span> NWA 7533 and NWA 7475]. Due to the very fine grain size of matrix, its textural details are difficult to resolve by optical and microprobe observations. In order to examine the potential nature of brecciation, transmission electron microscopy (TEM) <span class="hlt">studies</span> combined with focused ion-beam technique (FIB) has been undertaken. Here we present the preliminary observations of fine-grained groundmass of NWA 7034 from different matrix areas by describing its textural and mineralogical variations and micro-structural characteristics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000came.work..286S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000came.work..286S"><span>The <span class="hlt">Martian</span> Oasis Detector</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smith, P. H.; tomasko, M. G.; McEwen, A.; Rice, J.</p> <p>2000-07-01</p> <p>The next phase of unmanned Mars missions paves the way for astronauts to land on the surface of Mars. There are lessons to be learned from the unmanned precursor missions to the Moon and the Apollo lunar surface expeditions. These unmanned missions (Ranger, Lunar Orbiter, and Surveyor) provided the following valuable information, useful from both a scientific and engineering perspective, which was required to prepare the way for the manned exploration of the lunar surface: (1) high resolution imagery instrumental to Apollo landing site selection also tremendously advanced the state of Nearside and Farside regional geology; (2) demonstrated precision landing (less than two kilometers from target) and soft landing capability; (3) established that the surface had sufficient bearing strength to support a spacecraft; and (4) examination of the chemical composition and mechanical properties of the surface. The search for extinct or extant life on Mars will follow the water. However, geomorphic <span class="hlt">studies</span> have shown that Mars has had liquid water on its surface throughout its geologic history. A cornucopia of potential landing sites with water histories (lakes, floodplains, oceans, deltas, hydrothermal regions) presently exist. How will we narrow down site selection and increase the likelihood of finding the signs of life? One way to do this is to identify '<span class="hlt">Martian</span> oases.' It is known that the <span class="hlt">Martian</span> surface is often highly fractured and some areas have karst structures that support underground caves. Much of the water that formed the channels and valley networks is thought to be frozen underground. All that is needed to create the potential for liquid water is a near surface source of heat; recent lava flows and <span class="hlt">Martian</span> <span class="hlt">meteorites</span> attest to the potential for volcanic activity. If we can locate even one spot where fracturing, ice, and underground heat are co-located then we have the potential for an oasis. Such a discovery could truly excite the imaginations of both the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EPSC...10..604C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EPSC...10..604C"><span>Vigie Ciel a collaborative project to <span class="hlt">study</span> fireballs and organise <span class="hlt">meteorite</span> recoveries</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Colas, F.; Zanda, B.; Bouley, S.; Lewin, E.; Vaubaillon, J.; Marmo, C.; Rotaru, M.; Labenne, L.; Julien, J. F.; Linares, M.; Steinhausser, A.; Rault, J. L.; Vernazza, P.</p> <p>2015-10-01</p> <p>Research on fireballs and <span class="hlt">meteorites</span> has always been of interest to the public, due to the beauty of shooting stars in the night sky and to the extraterrestrial origin of <span class="hlt">meteorites</span>. A fireball observation network called FRIPON [1] (Colas et al, 2015) is currently being setup, funded by ANR (Agence Nationale pour la Recherche). It will cover France with 100 cameras and is expected to be operational for the end of 2015. FRIPON will detect fireballs and hence allow us to define <span class="hlt">meteorite</span> strewn fields within 24h, so that <span class="hlt">meteorite</span> searches can be launched very early on. Because of the need to search all over France, including in private land, it is important that the general public be aware of our project and be willing to help or participate. Indeed, as the main goal of FRIPON is to recover fresh <span class="hlt">meteorites</span> (within a few days), our aim is to be able to organize a search with at least 50 persons to scan an area of a few km2 within a week. Help from the public would hence be most helpful but it is also important to have an operational and trained research team. This project thus appears as a unique occasion to involve the public in a scientific project while promoting informal scientific education. This prompted us to set up Vigie-Ciel, a citizen science network centered on <span class="hlt">meteorite</span> recovery. FRIPON is an open network based on open-source software, it will accept citizenrun cameras. In addition to fireballs, it will allow scientists and Vigie-Ciel participants to <span class="hlt">study</span> anything that can be observed by all-sky cameras: bird migrations, bats, clouds, lightning, etc. The data will be freely available to all.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19750003808','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19750003808"><span><span class="hlt">Studies</span> of <span class="hlt">Martian</span> polar regions. [using CO2 flow</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Smith, C. I.; Clark, B. R.; Eschman, D. F.</p> <p>1974-01-01</p> <p>The flow law determined experimentally for solid CO2 establishes that an hypothesis of glacial flow of CO2 at the <span class="hlt">Martian</span> poles is not physically unrealistic. Compression experiments carried out under 1 atmosphere pressure and constant strain rate conditions demonstrate that the strength of CO2 near its sublimation point is considerably less than the strength of water ice near its melting point. A plausible glacial model for the <span class="hlt">Martian</span> polar caps was constructed. The CO2 deposited near the pole would have flowed outward laterally to relieve high internal shear stresses. The topography of the polar caps, and the uniform layering and general extent of the layered deposits were explained using this model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017LPICo1963.2019K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017LPICo1963.2019K"><span>Preliminary Results on <span class="hlt">Studying</span> of <span class="hlt">Meteorites</span> from Geological Museum of Kazan University by X-Ray Fluorescence and Computed X-Ray Tomography</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kuzina, D. M.; Nurgaliev, D. K.; Gareev, B. I.; Batalin, G. A.; Silantev, V. V.; Statsenko, E. O.</p> <p>2017-02-01</p> <p>Micro X-ray fluorescence and X-ray computed tomography used for <span class="hlt">studying</span> <span class="hlt">meteorites</span> (particularly chondrules and iron-nickel alloys) from Geological Museum (Kazan), their elemental composition, and distribution of these objects in the body of <span class="hlt">meteorite</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008JGRE..113.6004P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008JGRE..113.6004P"><span><span class="hlt">Martian</span> dunite NWA 2737: Integrated spectroscopic analyses of brown olivine</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pieters, Carle M.; Klima, Rachel L.; Hiroi, Takahiro; Dyar, M. Darby; Lane, Melissa D.; Treiman, Allan H.; Noble, Sarah K.; Sunshine, Jessica M.; Bishop, Janice L.</p> <p>2008-06-01</p> <p>A second <span class="hlt">Martian</span> <span class="hlt">meteorite</span> has been identified that is composed primarily of heavily shocked dunite, Northwest Africa (NWA) 2737. This <span class="hlt">meteorite</span> has several similarities to the Chassigny dunite cumulate, but the olivine is more Mg rich and, most notably, is very dark and visually brown. Carefully coordinated analyses of NWA 2737 whole-rock and olivine separates were undertaken using visible and near-infrared reflectance, midinfrared emission and reflectance, and Mössbauer spectroscopic <span class="hlt">studies</span> of the same samples along with detailed petrography, chemistry, scanning electron microscopy, and transmission electron microscopy analyses. Midinfrared spectra of this sample indicate that the olivine is fully crystalline and that its molecular structure remains intact. The unusual color and spectral properties that extend from the visible through the near-infrared part of the spectrum are shown to be due to nanophase metallic iron particles dispersed throughout the olivine during a major shock event on Mars. Although a minor amount of Fe3+ is present, it cannot account for the well-documented unusual optical properties of <span class="hlt">Martian</span> <span class="hlt">meteorite</span> NWA 2737. Perhaps unique to the <span class="hlt">Martian</span> environment, this ``brown'' olivine exhibits spectral properties that can potentially be used to remotely explore the pressure-temperature history of surface geology as well as assess surface composition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940011824','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940011824"><span>Complex radiation-thermal history of Kaidun <span class="hlt">meteorite</span> on data of track <span class="hlt">study</span> of silicate minerals</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kashkarov, L. L.; Korotkova, N. N.; Skripnik, A. YA.</p> <p>1993-01-01</p> <p>The results of track <span class="hlt">study</span> of approximately 80 individual silicate mineral crystals (ol, px, plag) picked out from Kaidun <span class="hlt">meteorite</span> are presented. A wide range of observed rho(sub VH) value distributions indicate the complex irradiation history of Kaidun minerals. In one anortite crystal having two track groups with different parameters the pre-accretion irradiation traces were observed in all probability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014LPICo1800.5102H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014LPICo1800.5102H"><span>Why <span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Heikal, M. Th. S.</p> <p>2014-09-01</p> <p>The present work is focused on the characteristic features of <span class="hlt">meteorites</span>, different types and their composition, world distribution, the global effects of large <span class="hlt">meteorite</span> impacts through the geologic eras, economic aspects and environmental assessments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040056056&hterms=whole+grains&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dwhole%2Bgrains','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040056056&hterms=whole+grains&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dwhole%2Bgrains"><span>Evidence for a Wet, Reduced <span class="hlt">Martian</span> Interior</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Dyar, M. D.; Mackwell, S. J.; Seaman, S. J.; Marchand, G. J.</p> <p>2004-01-01</p> <p>Knowledge of the oxygen fugacity and hydrogen content of the source regions of <span class="hlt">martian</span> <span class="hlt">meteorites</span> is of paramount importance in constraining phase equilibria, crystallization sequences, and geodynamic processes of the <span class="hlt">martian</span> interior, as well as models of the planet's evolution. To date, these interpretations have been hindered by the paucity in SNC <span class="hlt">meteorites</span> of Fe-Ti oxides used in conventional oxybarometry, and by the presence of secondary alteration products that make it impossible to quantify primary hydrogen abundances in SNC minerals and melts based on whole rock samples. We present here the first transmission FTIR spectra of individual mineral grains from SNC <span class="hlt">meteorites</span>, and interpret those results along with Mossbauer data on mineral separates from the same <span class="hlt">meteorites</span>. Our goal is to quantify the amount of water and the oxygen fugacity present in the source regions for the rocks comprising the <span class="hlt">meteorites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120007400','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120007400"><span>Iron Redox Systematics of Shergottites and <span class="hlt">Martian</span> Magmas</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Righter, Kevin; Danielson, L. R.; Martin, A. M.; Newville, M.; Choi, Y.</p> <p>2010-01-01</p> <p><span class="hlt">Martian</span> <span class="hlt">meteorites</span> record a range of oxygen fugacities from near the IW buffer to above FMQ buffer [1]. In terrestrial magmas, Fe(3+)/ SigmaFe for this fO2 range are between 0 and 0.25 [2]. Such variation will affect the stability of oxides, pyroxenes, and how the melt equilibrates with volatile species. An understanding of the variation of Fe(3+)/SigmaFe for <span class="hlt">martian</span> magmas is lacking, and previous work has been on FeO-poor and Al2O3-rich terrestrial basalts. We have initiated a <span class="hlt">study</span> of the iron redox systematics of <span class="hlt">martian</span> magmas to better understand FeO and Fe2O3 stability, the stability of magnetite, and the low Ca/high Ca pyroxene [3] ratios observed at the surface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19990079409&hterms=Magnesium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DMagnesium','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19990079409&hterms=Magnesium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DMagnesium"><span>Meteoric Magnesium Ions in the <span class="hlt">Martian</span> Atmosphere</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Pesnell, William Dean; Grebowsky, Joseph</p> <p>1999-01-01</p> <p>From a thorough modeling of the altitude profile of <span class="hlt">meteoritic</span> ionization in the <span class="hlt">Martian</span> atmosphere we deduce that a persistent layer of magnesium ions should exist around an altitude of 70 km. Based on current estimates of the meteoroid mass flux density, a peak ion density of about 10(exp 4) ions/cm is predicted. Allowing for the uncertainties in all of the model parameters, this value is probably within an order of magnitude of the correct density. Of these parameters, the peak density is most sensitive to the meteoroid mass flux density which directly determines the ablated line density into a source function for Mg. Unlike the terrestrial case, where the metallic ion production is dominated by charge-exchange of the deposited neutral Mg with the ambient ions, Mg+ in the <span class="hlt">Martian</span> atmosphere is produced predominantly by photoionization. The low ultraviolet absorption of the <span class="hlt">Martian</span> atmosphere makes Mars an excellent laboratory in which to <span class="hlt">study</span> meteoric ablation. Resonance lines not seen in the spectra of terrestrial meteors may be visible to a surface observatory in the <span class="hlt">Martian</span> highlands.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014M%26PS...49.2017N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014M%26PS...49.2017N"><span>Mid-infrared <span class="hlt">study</span> of stones from the Sutter's Mill <span class="hlt">meteorite</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nuevo, Michel; Sandford, Scott A.; Flynn, George J.; Wirick, Susan</p> <p>2014-11-01</p> <p>The Sutter's Mill <span class="hlt">meteorite</span> fell in northern California on April 22, 2012. Several fragments of the <span class="hlt">meteorite</span> were recovered, some of them shortly after the fall, others several days later after a heavy rainstorm. In this work, we analyzed several samples of four fragments―SM2, SM12, SM20, and SM30―from the Sutter's Mill <span class="hlt">meteorite</span> with two infrared (IR) microscopes operating in the 4000-650 cm-1 (2.5-15.4 μm) range. Spectra show absorption features associated with minerals such as olivines, phyllosilicates, carbonates, and possibly pyroxenes, as well as organics. Spectra of specific minerals vary from one particle to another within a given stone, and even within a single particle, indicating a nonuniform mineral composition. Infrared features associated with aliphatic CH2 and CH3 groups associated with organics are also seen in several spectra. However, the presence of organics in the samples <span class="hlt">studied</span> is not clear because these features overlap with carbonate overtone bands. Finally, other samples collected within days after the rainstorm show evidence for bacterial terrestrial contamination, which indicates how quickly <span class="hlt">meteorites</span> can be contaminated on such small scales.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009M%26PS...44..891W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009M%26PS...44..891W"><span>Labile trace elements in basaltic achondrites: Can they distinguish between <span class="hlt">meteorites</span> from the Moon, Mars, and V-type asteroids?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wolf, Stephen F.; Wang, Ming-Sheng; Lipschutz, Michael E.</p> <p>2009-06-01</p> <p>We report data for 14 mainly labile trace elements (Ag, Au, Bi, Cd, Cs, Ga, In, Rb, Sb, Se, Te, Tl, U, and Zn) in eight whole-rock lunar <span class="hlt">meteorites</span> (Asuka [A-] 881757, Dar al Gani [DaG] 262, Elephant Moraine [EET] 87521, Queen Alexandra Range [QUE] 93069, QUE 94269, QUE 94281, Yamato [Y-] 793169, and Y-981031), and <span class="hlt">Martian</span> <span class="hlt">meteorite</span> (DaG 476) and incorporate these into a comparative <span class="hlt">study</span> of basaltic <span class="hlt">meteorites</span> from the Moon, Mars, and V-type asteroids. Multivariate cluster analysis of data for these elements in 14 lunar, 13 <span class="hlt">Martian</span>, and 34 howardite, eucrite, and diogenite (HED) <span class="hlt">meteorites</span> demonstrate that materials from these three parents are distinguishable using these markers of late, low-temperature episodes. This distinguishability is essentially as complete as that based on markers of high-temperature igneous processes. Concentrations of these elements in 14 lunar <span class="hlt">meteorites</span> are essentially lognormally distributed and generally more homogeneous than in <span class="hlt">Martian</span> and HED <span class="hlt">meteorites</span>. Mean siderophile and labile element concentrations in the 14 lunar <span class="hlt">meteorites</span> indicate the presence of a CI-equivalent micrometeorite admixture of 2.6% When only feldspathic samples are considered, our data show a slightly higher value of 3.4% consistent with an increasing micrometeorite content in regolith samples of higher maturity. Concentrations of labile elements in the 8 feldspathic samples hint at the presence of a fractionated highly labile element component, possibly volcanic in origin, at a level comparable to the micrometeorite component. Apparently, the process(es) that contributed to establishing lunar <span class="hlt">meteorite</span> siderophile and labile trace element contents occurred in a system open to highly labile element transport.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19790055161&hterms=experimental+group&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dexperimental%2Bgroup','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19790055161&hterms=experimental+group&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dexperimental%2Bgroup"><span>Fractional crystallization of iron <span class="hlt">meteorites</span>, an experimental <span class="hlt">study</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Goldstein, J. I.; Friel, J. J.</p> <p>1978-01-01</p> <p>Measurements of the distribution coefficients of various elements (Ni, Co, P, Pt, Ir, Ge, Cr, and Au) between solid and liquid phases were made for FeNi alloys. A high thermal gradient crystal growing furnace was employed in order to promote plane front solidification, rapid mixing in the liquid and a minimum of diffusion in the solid. Eight measurements of the nickel distribution coefficient gave an average value of 0.91 plus or minus 0.03 and this value was independent of the Ni concentration in the range 5.5 to 8.75 wt. % Ni. Equilibrium distribution coefficients were also calculated by correcting for the diffusion boundary layer present in the liquid. These values are within 20% of the measured distribution coefficient values. Except for Co and Ni, all the measured distribution coefficient values are closer to 1.0 than those calculated by Scott (1972) for the IIIAB irons. Using the experimental values and the calculated equilibrium values for ternary additions to FeNi melts, it appears that fractional crystallization processes will not explain the observed chemical variations in the major iron <span class="hlt">meteorite</span> groups. Alternative explanations are suggested which also recognize the fact that cooling rates vary widely in several chemical groups.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009IJAsB...8...27B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009IJAsB...8...27B"><span>Electrochemical <span class="hlt">studies</span> of iron <span class="hlt">meteorites</span>: phosphorus redox chemistry on the early Earth</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bryant, David E.; Greenfield, David; Walshaw, Richard D.; Evans, Suzanne M.; Nimmo, Alexander E.; Smith, Caroline L.; Wang, Liming; Pasek, Matthew A.; Kee, Terence P.</p> <p>2009-01-01</p> <p>The mineral schreibersite, (Fe,Ni)3P, a ubiquitous component of iron <span class="hlt">meteorites</span>, is known to undergo anoxic hydrolytic modification to afford a range of phosphorus oxyacids. H-phosphonic acid (H3PO3) is the principal hydrolytic product under hydrothermal conditions, as confirmed here by 31P-NMR spectroscopic <span class="hlt">studies</span> on shavings of the Seymchan pallasite (Magadan, Russia, 1967), but in the presence of photochemical irradiation a more reduced derivative, H-phosphinic (H3PO2) acid, dominates. The significance of such lower oxidation state oxyacids of phosphorus to prebiotic chemistry upon the early Earth lies with the facts that such forms of phosphorus are considerably more soluble and chemically reactive than orthophosphate, the commonly found form of phosphorus on Earth, thus allowing nature a mechanism to circumvent the so-called Phosphate Problem. This paper describes the Galvanic corrosion of Fe3P, a hydrolytic modification pathway for schreibersite, leading again to H-phosphinic acid as the key P-containing product. We envisage this pathway to be highly significant within a <span class="hlt">meteoritic</span> context as iron <span class="hlt">meteorites</span> are polymetallic composites in which dissimilar metals, with different electrochemical potentials, are connected by an electrically conducting matrix. In the presence of a suitable electrolyte medium, i.e., salt water, galvanic corrosion can take place. In addition to model electrochemical <span class="hlt">studies</span>, we also report the first application of the Kelvin technique to map surface potentials of a <span class="hlt">meteorite</span> sample that allows the electrochemical differentiation of schreibersite inclusions within an Fe:Ni matrix. Such experiments, coupled with thermodynamic calculations, may allow us to better understand the chemical redox behaviour of <span class="hlt">meteoritic</span> components with early Earth environments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950042229&hterms=Cais&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DCais','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950042229&hterms=Cais&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DCais"><span>An ion microprobe <span class="hlt">study</span> of CAIs from CO3 <span class="hlt">meteorites</span>. [Abstract only</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Russell, S. S.; Greenwood, R. C.; Fahey, A. J.; Huss, G. R.; Wasserburg, G. J.</p> <p>1994-01-01</p> <p>When attempting to interpret the history of Ca, Al-rich inclusions (CAIs) it is often difficult to distinguish between primary features inherited from the nebula and those produced during secondary processing on the parent body. We have undertaken a systematic <span class="hlt">study</span> of CAIs from 10 CO chondrites, believed to represent a metamorphic sequence with the goal of distinguishing primary and secondary features. ALHA 77307 (3.0), Colony (3.0), Kainsaz (3.1), Felix (3.2), ALH 82101 (3.3), Ornans (3.3), Lance (3.4), ALHA 77003 (3.5), Warrenton (3.6), and Isna (3.7) were examined by Scanning Electron Microscopy (SEM) and optical microscopy. We have identified 141 CAIs within these samples, and <span class="hlt">studied</span> in detail the petrology of 34 inclusions. The primary phases in the lower petrologic types are spinel, melilite, and hibonite. Perovskite, FeS, ilmenite, anorthite, kirschsteinite, and metallic Fe are present as minor phases. Melilite becomes less abundant in higher petrologic types and was not detected in chondrites of type 3.5 and above, confirming previous reports that this mineral easily breaks down during heating. Iron, an element that would not be expected to condense at high temperatures, has a lower abundance in spinel from low-petrologic-type <span class="hlt">meteorites</span> than those of higher grade, and CaTiO3 is replaced by FeTiO3 in <span class="hlt">meteorites</span> of higher petrologic type. The abundance of CAIs is similar in each <span class="hlt">meteorite</span>. Eight inclusions have been analyzed by ion probe. The results are summarized. The results obtained to date show that CAIs in CO <span class="hlt">meteorites</span>, like those from other <span class="hlt">meteorite</span> classes, contain Mg* and that Mg in some inclusions has been redistributed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20020090131&hterms=Mechanical+soils&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DMechanical%2Bsoils','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20020090131&hterms=Mechanical+soils&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DMechanical%2Bsoils"><span>Shergottite Impact Melt Glasses Contain Soil from <span class="hlt">Martian</span> Uplands</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rao, M. N.; McKay, D. S.</p> <p>2002-01-01</p> <p><span class="hlt">Martian</span> <span class="hlt">meteorite</span> (shergottite) impact melt glasses that contain high concentrations of <span class="hlt">martian</span> atmospheric noble gases and show significant variations in Sr-87/Sr-86 isotopic ratios are likely to contain <span class="hlt">Martian</span> surface fines mixed with coarser regolith materials. The mixed soil constituents were molten due to shock at the time of meteoroid impact near the <span class="hlt">Martian</span> surface and the molten glass got incorporated into the voids and cracks in some shergottite <span class="hlt">meteorites</span>. Earlier, Rao et al. found large enrichments of sulfur (sulfate) during an electron-microprobe <span class="hlt">study</span> of several impact melt glass veins and pods in EET79001,LithC thin sections. As sulfur is very abundant in <span class="hlt">Martian</span> soil, these S excesses were attributed to the mixing of a soil component containing aqueously altered secondary minerals with the LithC precursor materials prior to impact melt generation. Recently, we <span class="hlt">studied</span> additional impact melt glasses in two basaltic shergottites, Zagami and Shergotty using procedures similar to those described by Rao et al. Significant S enrichments in Zagami and Shergotty impact melt glass veins similar to the EET79001, LithC glasses were found. In addition, we noticed the depletion of the mafic component accompanied by the enrichment of felsic component in these impact melt glass veins relative to the bulk host rock in the shergottites. To explain these observations, we present a model based on comminution of basaltic rocks due to meteroid bombardment on <span class="hlt">martian</span> regolith and mechanical fractionation leading to enrichment of felsics and depletion of mafics in the fine grained dust which is locally mobilized as a result of saltation and deflation due to the pervasive aeolian activity on Mars.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20030106383&hterms=Mechanical+soils&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DMechanical%2Bsoils','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20030106383&hterms=Mechanical+soils&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DMechanical%2Bsoils"><span>Shergottite Impact Melt Glasses Contain Soil from <span class="hlt">Martian</span> Uplands</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rao, M. N.; McKay, D. S.</p> <p>2002-01-01</p> <p><span class="hlt">Martian</span> <span class="hlt">meteorite</span> (shergottite) impact melt glasses that contain high concentrations of <span class="hlt">martian</span> atmospheric noble gases and show significant variations in Sr-87/Sr-86 isotopic ratios are likely to contain <span class="hlt">Martian</span> surface fines mixed with coarser regolith materials. The mixed soil constituents were molten due to shock at the time of meteoroid impact near the <span class="hlt">Martian</span> surface and the molten glass got incorporated into the voids and cracks in some shergottite <span class="hlt">meteorites</span>. Earlier, Rao et al. found large enrichments of sulfur (sulfate) during an electron-microprobe <span class="hlt">study</span> of several impact melt glass veins and pods in EET79001,LithC thin sections. As sulfur is very abundant in <span class="hlt">Martian</span> soil, these S excesses were attributed to the mixing of a soil component containing aqueously altered secondary minerals with the LithC precursor materials prior to impact melt generation. Recently, we <span class="hlt">studied</span> additional impact melt glasses in two basaltic shergottites, Zagami and Shergotty using procedures similar to those described. Significant S enrichments in Zagami and Shergotty impact melt glass veins similar to the EET79001, LithC glasses were found. In addition, we noticed the depletion of the mafic component accompanied by the enrichment of felsic component in these impact melt glass veins relative to the bulk host rock in the shergottites. To explain these observations, we present a model based on comminution of basaltic rocks due to meteoroid bombardment on <span class="hlt">martian</span> regolith and mechanical fractionation leading to enrichment of felsics and depletion of mafics in the fine grained dust which is locally mobilized as a result of saltation and deflation due to the pervasive aeolian activity on Mars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUFM.P51A0901S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFM.P51A0901S"><span>Isotopic and trace element composition of <span class="hlt">martian</span> enriched reservoir</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shimoda, G.; Ikeda, Y.</p> <p>2005-12-01</p> <p>The shergottite, nakhlite and chassignite (SNC) <span class="hlt">meteorites</span> are widely accepted as being of <span class="hlt">martian</span> origin, and have been <span class="hlt">studied</span> extensively in relation to chemical evolution of Mars. One of notable result of these <span class="hlt">studies</span> is finding of 142Nd and 182W isotopic anomalies in SNC <span class="hlt">meteorites</span>. As these isotopic anomalies should result from decay of the extinct radionuclides 146Sm and 182Hf, it is commonly interpreted that Mars accreted and differentiated rapidly (e.g., Lee and Halliday, 1997). Since this early differentiation process should accompany global magma ocean (Gaetani and Grove, 1997; Righter and Drake, 1996, 1997), it is plausible that the early differentiation process produced chemically stratified mantle (Borg et al. 2003; Shimoda et al., 2005). The magma source materials of the SNC <span class="hlt">meteorites</span> (magmas) are considered to be products of the early differentiation process of Mars that are characterized by time-integrated LREE depletions or enrichments. As the degree of depletion is significantly greater than terrestrial magmas, it is suggested that Mars has chemically distinct reservoirs. Similar result is obtained by <span class="hlt">studies</span> of Lu-W-Hf, Re-Os and 146Sm-142Nd systematics that indicate the presence of enriched and depleted reservoirs in Mar (Blichert-Toft et al., 1999; Brandon et al, 2000). These lines of isotopic evidence suggest that Mars preserves layered mantle structure that was produced during the early differentiation process. Although the <span class="hlt">martian</span> geochemical reservoirs is commonly accepted, little constraint has been given to the chemical composition of the <span class="hlt">martian</span> geochemical reservoirs. Recently, Shimoda et al (2005) have proposed a model to explain the origin of <span class="hlt">martian</span> magmatism; the <span class="hlt">martian</span> magmatism was induced by plume melting from the hydrated deepest mantle reservoir with depleted geochemical signature. Although the model successfully explains the chemical composition of SNC <span class="hlt">meteorites</span> that have depleted geochemical characters, additional</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080026260','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080026260"><span>Magnetite in <span class="hlt">Martian</span> <span class="hlt">Meteorite</span> Mil 03346 and Gusev Adirondack Class Basalt: Mossbauer Evidence for Variability in the Oxidation State of Adirondack Lavas</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Morris, R. V.; McKay, G. A.; Ming, D. W.; Klingelhoefer, G.; Schroeder, C.; Rodionov, D.; Yen, A.</p> <p>2006-01-01</p> <p>The Moessbauer spectrometers on the Mars Exploration Rovers Spirit (Gusev crater) and Opportunity (Meridiani Planum) have returned information on the oxidation state of iron, the mineralogical composition of Fe-bearing phases, and the distribution of Fe among oxidation states and phases [1,2,3]. To date, approx.100 and approx.85 surface targets have been analyzed by the Spirit and Opportunity spectrometers, respectively. Twelve component subspectra (8 doublets and 4 sextets) have been identified and most have been assigned to mineralogical compositions [4]. Two sextet subspectra result from the opaque and strongly magnetic mineral magnetite (Fe3O4 for the stoichiometric composition), one each for the crystallographic sites occupied by tetrahedrally-coordinated Fe3+ and by octahedrally-coordinated Fe3+ and Fe2+. At Gusev crater, the percentage of total Fe associated with magnetite for rocks ranges from 0 to approx. 35% (Fig. 1) [3]. The range for soils (approx.5 to approx.12% of total Fe from Mt, with one exception) is narrower. The ubiquitous presence of Mt in soil firmly establishes the phase as the strongly magnetic component in <span class="hlt">martian</span> soil [4,5].</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080026167','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080026167"><span>Magnetite in <span class="hlt">Martian</span> <span class="hlt">Meteorite</span> Mil 03346 and Gusev Adirondack Class Basalt: Moessbauer Evidence for Variability in the Oxidation State of Adirondack Lavas</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Morris, R. V.; McKay, G. A.; Ming, D. W.; Klingelhoefer, G.; Schroeder, C.; Rodionov, D.; Yen, A.</p> <p>2006-01-01</p> <p>The Moessbauer spectrometers on the Mars Exploration Rovers Spirit (Gusev crater) and Opportunity (Meridiani Planum) have returned information on the oxidation state of iron, the mineralogical composition of Fe-bearing phases, and the distribution of Fe among oxidation states and phases [1,2,3]. To date, 100 and 85 surface targets have been analyzed by the Spirit and Opportunity spectrometers, respectively. Twelve component subspectra (8 doublets and 4 sextets) have been identified and most have been assigned to mineralogical compositions [4]. Two sextet subspectra result from the opaque and strongly magnetic mineral magnetite (Fe3O4 for the stoichiometric composition), one each for the crystallographic sites occupied by tetrahedrally-coordinated Fe3+ and by octahedrally-coordinated Fe3+ and Fe2+. At Gusev crater, the percentage of total Fe associated with magnetite for rocks ranges from 0 to 35% (Fig. 1) [3]. The range for soils (5 to 12% of total Fe from Mt, with one exception) is narrower. The ubiquitous presence of Mt in soil firmly establishes the phase as the strongly magnetic component in <span class="hlt">martian</span> soil</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920064072&hterms=magnetism&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dmagnetism','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920064072&hterms=magnetism&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dmagnetism"><span>The relict magnetism of <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cisowski, S. M.; Hood, L. L.</p> <p>1991-01-01</p> <p><span class="hlt">Meteorite</span> paleomagnetic <span class="hlt">studies</span> are reviewed and evaluated. Possible mechanisms for producing early solar system magnetic fields that could have been responsible for the magnetization of some or all <span class="hlt">meteorite</span> classes are explored. A detailed review of paleointensity results derived from the various classes of <span class="hlt">meteorites</span> is given, and the likelihood that the results might related to solar or nebulawide magnetic fields is considered. The implications of <span class="hlt">meteorite</span> magnetism for early solar system evolution are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920064072&hterms=Magnetism&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DMagnetism','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920064072&hterms=Magnetism&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DMagnetism"><span>The relict magnetism of <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cisowski, S. M.; Hood, L. L.</p> <p>1991-01-01</p> <p><span class="hlt">Meteorite</span> paleomagnetic <span class="hlt">studies</span> are reviewed and evaluated. Possible mechanisms for producing early solar system magnetic fields that could have been responsible for the magnetization of some or all <span class="hlt">meteorite</span> classes are explored. A detailed review of paleointensity results derived from the various classes of <span class="hlt">meteorites</span> is given, and the likelihood that the results might related to solar or nebulawide magnetic fields is considered. The implications of <span class="hlt">meteorite</span> magnetism for early solar system evolution are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19740018174','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19740018174"><span>Magnetism in <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Herndon, J. M.; Rowe, M. W.</p> <p>1974-01-01</p> <p>An overview is presented of magnetism in <span class="hlt">meteorites</span>. A glossary of magnetism terminology followed by discussion of the various techniques used for magnetism <span class="hlt">studies</span> in <span class="hlt">meteorites</span> are included. The generalized results from use of these techniques by workers in the field are described. A brief critical analysis is offered.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20170005389','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20170005389"><span>Kinetic Damage from <span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cooke, William; Brown, Peter; Matney, Mark</p> <p>2017-01-01</p> <p>A Near Earth object impacting into Earth's atmosphere may produce damaging effects at the surface due to airblast, thermal pulse, or kinetic impact in the form of <span class="hlt">meteorites</span>. At large sizes (greater than many tens of meters), the damage is amplified by the hypersonic impact of these large projectiles moving with cosmic velocity, leaving explosively produced craters. However, much more common is simple "kinetic" damage caused by the impact of smaller <span class="hlt">meteorites</span> moving at terminal speeds. As of this date a handful of instances are definitively known of people or structures being directly hit and/or damaged by the kinetic impact of <span class="hlt">meteorites</span>. <span class="hlt">Meteorites</span> known to have struck humans include the Sylacauga, Alabama fall (1954) and the Mbale <span class="hlt">meteorite</span> fall (1992). Much more common is kinetic <span class="hlt">meteorite</span> damage to cars, buildings, and even a post box (Claxton, Georgia - 1984). Historical accounts indicate that direct kinetic damage by <span class="hlt">meteorites</span> may be more common than recent accounts suggest (Yau et al., 1994). In this talk we will examine the contemporary <span class="hlt">meteorite</span> flux and estimate the frequency of kinetic damage to various structures, as well as how the <span class="hlt">meteorite</span> flux might affect the rate of human casualties. This will update an earlier <span class="h