Martian meteorites Research Papers - Academia.edu (original) (raw)

2025, Earth and Planetary Science Letters

Magnetic anomalies observed by the Mars Global Surveyor mission are attributed to crustal remanence. SNC (Shergotty-Nakhla-Chassigny) meteorites are likely samples of the Martian crust and are amenable to mineralogical and magnetic measurements essential to the understanding of the origin of magnetic anomalies. The recently discovered chassignite NWA 2737 and lherzolitic shergottite NWA 1950 display unusual magnetic characteristics that argue for a different magnetic carrier than the oxides and sulfides previously invoked in SNC meteorites. NWA 2737, the second member of the chassignite group, is a dunite with unusually dark-brown olivines and large magnetic susceptibility while Chassigny contains green olivines and is nearly a pure paramagnet. Dark olivines are also found in NWA 1950, a lherzolitic shergottite, which has singular magnetic properties when compared with other shergottites. The dark olivine color is due to the presence of Fe and FeNi metal nanoparticles, identified both by TEM and by magnetic measurements. Their size distribution encompasses the superparamagnetic to single domain transition at 30 K (10 nm range) and explains the magnetic properties of the bulk rocks. The formation of these nanoparticles is attributed to heating during the shock events that affected NWA 2737 and NWA 1950. The production of metal particles by shock-induced reduction of olivine has been invoked on surfaces deprived of atmosphere but never observed on Earth or Mars. Therefore, metal formed by shock in the heavily cratered Noachian crust is a possible carrier for crustal magnetic remanence. Widespread surface formation of metal nanoparticles could provide the precursor for the oxidized particles (goethite, hematite) observed in the Martian soils.

2025, Meteoritics & Planetary Science

We report a comprehensive imaging study including confocal microRaman spectroscopy, scanning electron microscopy (SEM), and 3-D extended focal imaging light microscopy of carbonate globules throughout a depth profile of the Martian meteorite Allan Hills (ALH) 84001 and similar objects in mantle peridotite xenoliths from the Bockfjorden volcanic complex (BVC), Svalbard. Carbonate and iron oxide zoning in ALH 84001 is similar to that seen in BVC globules. Hematite appears to be present in all ALH 84001 carbonate-bearing assemblages except within a magnesite outer rim found in some globules. Macromolecular carbon (MMC) was found in intimate association with magnetite in both ALH 84001 and BVC carbonates. The MMC synthesis mechanism appears similar to established reactions within the Fe-C-O system. By inference to a terrestrial analogue of mantle origin (BVC), these results appear to represent the first measurements of the products of an abiotic MMC synthesis mechanism in Martian samples. Furthermore, the ubiquitous but heterogeneous distribution of hematite throughout carbonate globules in ALH 84001 may be partly responsible for some of the wide range in measured oxygen isotopes reported in previous studies. Using BVC carbonates as a suitable analogue, we postulate that a low temperature hydrothermal model of ALH 84001 globule formation is most likely, although alteration (decarbonation) of a subset of globules possibly occurred during a later impact event.

2024, Chemical Geology

Volatile species (H 2 O, CO 2 , F, Cl, etc) have important effects on the formation 14 and crystallization history of basaltic magmas. Here, we have experimentally investigated 15 the effects of F on phase equilibria of Fe-Mg-rich basalt. Our results show that fluorine has large effects on the liquidus temperature and the chemistry of crystallizing minerals. Compared to the F-free system, addition of ~2 wt.% F moves the olivine-pigeonite 18 liquidus point down ~2 kbar and 95 °C (from 12 kbar, 1375 °C to 10 kbar, 1280 °C). 19 With increasing fluorine concentrations, Fe Mg Mineral Melt Kd − − dramatically increases for both pyroxene and olivine, suggesting that fluorine in basaltic magmas complexes primarily with MgO. Complexing with MgO in the melt decreases its MgO activity, and forces the crystallizing minerals to greater Fe/Mg, and so increases Fe Mg Mineral Melt Kd − −. Models of basalt generation, where the magma is fluorine-rich, need to include the effect of not only water but fluorine on liquidus depression and minerals crystallizing/melting. Our results suggest that fluorine may significantly aid in the petrogenesis of silica-poor, alkali-rich magmas in the Earth and Mars.

2024, Innovations in Biological Science Vol. 3

The present study describes Martian ooids formed by Martian microbes. NASA's Mars Rover Curiosity discovered plentiful indigenous spherical ooids at High Dune and Namib Dune in Bagnold dune field, Gale Crater, Mars. The spherical Martian ooids contain nuclei and range from 0.1 mm to 0.5 mm in diameter. Colors of the spherical Martian ooids are various, including white, yellow translucent, green, gray, and yellow. The spherical Martian ooids should have been formed by microbes, because 1) ooids of Earth have recently been found to be formed by microbes and 2) microbial borings are found in ooids of Earth and of Mars. There is no evidence that proves ooids are formed by agitated water.

2024, Science Advances

Organic synthesis on Mars occurs by the electrochemical reduction of CO 2 , a reaction that is highly relevant for abiotic organic synthesis on early Earth.

2024, Science

Mars' Atmosphere from Curiosity The Sample Analysis at Mars (SAM) instrument on the Curiosity rover that landed on Mars in August last year is designed to study the chemical and isotopic composition of the martian atmosphere. Mahaffy et al. (p. 263 ) present volume-mixing ratios of Mars' five major atmospheric constituents (CO 2 , Ar, N 2 , O 2 , and CO) and isotope measurements of 40 Ar/ 36 Ar and C and O in CO 2 , based on data from one of SAM's instruments, obtained between 31 August and 21 November 2012. Webster et al. (p. 260 ) used data from another of SAM's instruments obtained around the same period to determine isotope ratios of H, C, and O in atmospheric CO 2 and H 2 O. Agreement between the isotopic ratios measured by SAM with those of martian meteorites, measured in laboratories on Earth, confirms the origin of these meteorites and implies that the current atmospheric reservoirs of CO 2 and H 2 O were largely established after the period of early atmosphe...

2024, Science

2024

Compared to terrestrial basalts and eucrite meteorites, Apollo 11 and 12 basalts are consistently depleted in siderophile elements (Ir, Pd, Ag, Au) and volatile elements (Zn, Cd, In, Tl, Bi, Br), by factors of 10~1 to 10~2. The depletion of siderophiles suggests that the Earth and Moon segregated their metal and silicate in two discrete events, contrary to the fission hypothesis. Moreover, if the Eartheucrite pattern is typical of independently-formed planetary bodies, the greater depletion of the Moon speaks against an independent origin, as required by the capture hypothesis. The depletion of volatiles implies that the Moon either formed at higher temperatures (510°K vs. 470°K for the Earth and eucrites), or had a 100-fold lower growth rate in the terminal stages of accretion. This might be expected if it formed in the Earth's neighborhood. The coarse-grained, 13-cm layer of core 12028 shows extreme enrichment in Bi and Cd (38 and 22 ppm), some 10 3 to 10 5 times the content of Apollo 11 and 12 crystalline rocks and soil. Such material must be rare on the Moon, judging from the low Bi content of all soil and breccia samples examined to date. Sample 12013, on the other hand, seems to represent a more abundant rock type. Relative to Apollo 12 basalts, it is enriched in Rb, Cs, Tl, Zn, and Cd by factors of up to 10 2. About 10-20% of such material is required to account for the high Rb, Cs, and Cd content of nine Apollo 12 soils. Rock 12013 fits various trace element correlations for Apollo 11,12 rocks, which suggests a close genetic relationship to mare basalts, and a local rather than highland origin. All soil and breccia samples are enriched in elements thought to be largely of meteoritic origin: Ag, Au, Bi, Br, Cd, Ir, Te, Tl, and Zn. The enrichment pattern in most samples is dominated by material of C 1 chondrite composition, probably micrometeorites of cometary origin. The average abundance is 1.9% C 1 material or equivalent, and the average meteorite influx rate is 4x10"^ g cm-2 yr~l. Soil samples collected on crater rims, and some Apollo 12 breccias, show a smaller amount of meteoritic material, of less primitive composition. Apparently Bench, Head, and Surveyor Craters at the Apollo 12 site were made by ordinary chondrites or irons. An anorthosite sample from Apollo 11 soil shows a similar pattern. The meteoritic elements in Apollo 11 soil dissolve preferentially upon HNO3 treatment. Apparently they are located for the most part in small grains or on surfaces. The glassy exterior of rock 12017 is enriched in "meteoritic" elements (Au, Br, Cd, Ir, etc.) relative to the interior. Apparently the glass represents molten material splashed onto the rock from a crater, not a glazing made in place by a solar outburst, as proposed by Gold.

2024, 79th Annual Meeting of the Meteoritical Society

2023, Astrobiology

The Panoramic Camera (PanCam) instrument will provide visible-near IR multispectral imaging of the ExoMars rover's surroundings to identify regions of interest within the nearby terrain. This multispectral capability is dependant upon the 12 preselected ''geological'' filters that are integrated into two wide-angle cameras. First devised by the Imager for Mars Pathfinder team to detect iron oxides, this baseline filter set has remained largely unchanged for subsequent missions (Mars Exploration Rovers, Beagle 2, Phoenix) despite the advancing knowledge of the mineralogical diversity on Mars. Therefore, the geological filters for the ExoMars PanCam will be redesigned to accommodate the astrobiology focus of ExoMars, where hydrated mineral terrains (evidence of past liquid water) will be priority targets. Here, we conduct an initial investigation into new filter wavelengths for the ExoMars PanCam and present results from tests performed on Mars analog rocks. Two new filter sets were devised: one with filters spaced every 50 nm (''F1-12'') and another that utilizes a novel filter selection method based upon hydrated mineral reflectance spectra (''F2-12''). These new filter sets, along with the Beagle 2 filter set (currently the baseline for the ExoMars PanCam), were tested on their ability to identify hydrated minerals and biosignatures present in Mars analog rocks. The filter sets, with varying degrees of ability, detected the spectral features of minerals jarosite, opaline silica, alunite, nontronite, and siderite present in these rock samples. None of the filter sets, however, were able to detect fossilized biomat structures and small (<2 mm) mineralogical heterogeneities present in silica sinters. Both new filter sets outperformed the Beagle 2 filters, with F2-12 detecting the most spectral features produced by hydrated minerals and providing the best discrimination between samples. Future work involving more extensive testing on Mars analog samples that exhibit a wider range of mineralogies would be the next step in carefully evaluating the new filter sets.

2023

2023, Earth and Planetary Science Letters

Laser-driven shock experiments were carried out on Mn and Mg-bearing natural crystalline siderite under vacuum. Raman spectroscopy and transmission electron microscopy were performed on samples recovered from shock pressures between 8.4 GPa and 25.9 GPa. Two different iron oxides were observed in the laser impact crater: hematitealready present in the starting sample and a spinel-structured phase, both associated with iron carbonates. This nanometer-sized Mn-bearing magnetite-like phase results from shock-induced decarbonation of siderite. High-pressure shocks, such as meteorite impacts, are a plausible mechanism for generating nanocrystals of magnetite from Fe-carbonate-bearing terrestrial and extraterrestrial materials.

2023

2023, Geochimica et Cosmochimica Acta

This paper provides important insights into the generation, extraction and crystallization of clast-laden impact melt rocks from the Araguainha impact structure, central Brazil. Despite the mixed nature of the Araguainha target rocks (comprising a 2 km thick sequence of sedimentary rocks and underlying granitic basement), the exposed melt bodies are characterised by an alkali-rich granitic matrix embedding mineral and rock fragments derived only from the target granite. The melt rocks occur in the form of a massive impact melt sheet overlying the eroded central uplift structure, and as melt veins in the granite of the core of the central uplift. Bulk-rock major and trace element data (including platinum group elements) indicate that the precursor melts were generated locally, principally by partial melting of the target granite, without any contribution from the sedimentary sequence or the projectile. The dense network of melt veins was formed in isolation, by selective melting of plagioclase and alkali feldspar within the granite target. Plagioclase and alkali feldspar melted discretely and congruently, producing domains in the matrix of the melt veins, which closely match the stoichiometry of these minerals. The compositionally discrete initial melt phases migrated through a dense network of microfractures before being assembled into larger melt veins. Freezing of the melt veins was substantially fast, and the melt components were quenched in the form of alkali-feldspar and plagioclase schlieren in the matrix of the melt veins. The overlying impact melt rock is, in contrast, characterised by a granophyric matrix consisting of albite, sanidine, quartz, biotite and chlorite. In this case, melt components appear to have been more mobile and to have mixed completely to form a granitic parental melt. We relate the melting of the minerals to post-shock temperatures that exceeded the melting point of feldspars.

2023, Science

2023, Meteoritics & Planetary Science

We report a comprehensive imaging study including confocal microRaman spectroscopy, scanning electron microscopy (SEM), and 3-D extended focal imaging light microscopy of carbonate globules throughout a depth profile of the Martian meteorite Allan Hills (ALH) 84001 and similar objects in mantle peridotite xenoliths from the Bockfjorden volcanic complex (BVC), Svalbard. Carbonate and iron oxide zoning in ALH 84001 is similar to that seen in BVC globules. Hematite appears to be present in all ALH 84001 carbonate-bearing assemblages except within a magnesite outer rim found in some globules. Macromolecular carbon (MMC) was found in intimate association with magnetite in both ALH 84001 and BVC carbonates. The MMC synthesis mechanism appears similar to established reactions within the Fe-CO system. By inference to a terrestrial analogue of mantle origin (BVC), these results appear to represent the first measurements of the products of an abiotic MMC synthesis mechanism in Martian samples. Furthermore, the ubiquitous but heterogeneous distribution of hematite throughout carbonate globules in ALH 84001 may be partly responsible for some of the wide range in measured oxygen isotopes reported in previous studies. Using BVC carbonates as a suitable analogue, we postulate that a low temperature hydrothermal model of ALH 84001 globule formation is most likely, although alteration (decarbonation) of a subset of globules possibly occurred during a later impact event.

2023, Research Article

As space exploration advances, the importance of tapping resources from other planets, known as
In-Situ Resource Utilization (ISRU), becomes increasingly vital to reduce the cost of resupply
missions. On Mars, resources such as water, regolith, light, and CO2 can be used to grow food, and
previous studies have demonstrated the possibility of growing plants such as Arabidopsis thaliana
in Martian regolith simulants such as JSC-1 and MMS-1. This study focuses on the development,
impact on stress related genes, and the survivability of OsSnRK1a and OsTOR mutants of rice
plants grown in MMS1. Results showed that plants grown in pure MMS1 had stunted growth, poor
root morphology, and lower photosynthetic activity, but the addition of any proportion of PM in
MMS1 improved growth and root characteristics compared to 100% MMS1. While the rice plants
showed signs of stress in MMS1, the study suggests that the physical and chemical characteristics
of MMS1 can support their growth, provided the levels of (Mg(ClO4)2) are kept in check.
Additionally, the study provides evidence that rice plant with OsSnRK1a mutation has the
potential to germinate and grow in MMS1 with (Mg(ClO4)2). Overall, the results demonstrate that
it is possible to grow rice plants in Martian regolith and is improved by amending the soil with
potting mix and editing specific rice genes to promote survivability.

2023, Geochimica et Cosmochimica Acta

Northwest Africa 5790, the latest nakhlite find, is composed of 58 vol. % augite, 6 % olivine and % vitrophyric intercumulus material. Its petrology is comparable to previously discovered nakhlites but with key differences: (1) Augite cores display an unusual zoning between Mg 54 and 60; (2) Olivine macrocrysts have a primary Fe-rich core composition (Mg= 35); (3) the modal proportion of mesostasis is the highest ever described in a nakhlite; (4) It is the most magnetite-rich nakhlite, together with MIL 03346, and exhibits the least anisotropic fabric. Complex primary zoning in cumulus augite indicates resorption due to complex processes such as remobilization of former cumulates in a new magma batch. Textural relationships indicate unambiguously that olivine was growing around resorbed augite, and that olivine growth was continuous while pyroxene growth resumed at a final stage. Olivine core compositions (Mg= 35) are out of equilibrium with the augite core compositions (Mg 60-63) and with the previously inferred nakhlite parental magma (Mg= 29). The presence of oscillatory zoning in olivine and augite precludes subsolidus diffusion that could have modified olivine compositions. NWA 5790 evidences at least two magma batches before eruption, with the implication that melt in equilibrium with augite cores was never in contact with olivine. Iddingsite is absent. Accordingly, the previous scenarios for nakhlite petrogenesis must be revised. The first primary parent magmas of nakhlites generated varied augite cumulates at depth (Mg# 66 to 60) as they differentiated to different extents. A subsequent more evolved magma batch entrained accumulated augite crystals to the surface where they were partly resorbed while olivine crystallized. Trace element variations indicate unambiguously that they represent consanguineous but different magma batches. The compositional differences among the various nakhlites suggest a number of successive lava flows. To account for all observations we propose a petrogenetic model for nakhlites based on several (at least three) thick flows. Although NWA5790 belongs to the very top of one flow, it should come from the lowest flow sampled, based on the lack of iddingsite.

2023

The mineralogical and isotopic properties of enveloping compound chondrules, which consist of a core chondrule within a host one, constrain the physicochemical conditions of multiple heating events during chondrule formation [1, 2]. We present in-situ O, Mg isotopic measurements on an enveloping compound chondrule from Allende meteorite. Sample Description: The enveloping compound chondrule studied is composed of two Al-rich chondrules. The core chondrule mainly consists of low-Ca pyroxene (En95), plagioclase (An85-95) and spinel. The subhedral spinel grains are distributed within the low-Ca pyroxene and plagioclase. The minor oxide element concentrations of spinel are follows; FeO; 2.0-5.6wt%, Cr 2 O 3 ; 1.5-3.2wt%, TiO 2 ; 0.1-0.4wt%, V 2 O 3 ; up to 0.2wt%. Al/Mg ratios in the spinel are about 2. On the other hand, the host chondrule mainly consists of porphyritic olivine grains (Fo85-100), low-Ca pyroxene (En95) and plagioclase (An85-95). Al/Mg ratios in the anorthite ranged from 100 to 140 in both chondrules. Based on the mineralogy and bulk chemical composition, the core and the host may be classified into group 2 and group 3 plagioclase-olivine inclusions (POI), respectively [3]. Results: The data of each oxygen isotopic measurement are plotted along the CCAM line. The spinel grains in the core have oxygen isotopic compositions of-15‰ in δ 18 O SMOW , which are greatly different from those of the spinel in typical Type B CAIs (about-40‰ in δ 18 O SMOW), but are close to that of spinel in a spinel-bearing BO chondrule (-14.2±1.2‰) from Allende [4]. Also, V 2 O 3 contents of spinel grains (up to 0.2wt%) are lower than the typical spinel compositions in CAIs (0.1~1.0wt%) from Allende [5]. Therefore, they are probably not relict CAI spinel but crystallized from a melt during the core chondrule-forming event. In both the core and host chondrules, low-Ca pyroxenes range from-5 to 0‰ and plagioclases from 10 to 15‰ in δ 18 O SMOW. The degree of 16 O enrichment correlates with the textually inferred crystallization sequence, that is, spinel (-15‰), pyroxene (~0‰) and then the plagioclase (~15‰). This correlation may result from incomplete O isotopic exchange with 16 Opoor nebular gas under a rate-limiting process such as diffusion in melt and/or surface reaction. Furthermore, the similarity of O isotope composition of constituent minerals between the core and host suggests that the oxygen isotope composition of the nebular gas reservoirs has not changed significantly during the multiple heating events that formed enveloping compounds. More discussion from 26 Al-26 Mg measurement will be presented at the meeting.

2023

Introduction: Martian meteorites are the only tangible material available for laboratory-based study of our planetary neighbor, Mars. Thus, it is important to thoroughly analyze martian meteorite samples to robustly constrain the geological processes operating during Mars' history. Shergottites, the most prevalent type of martian meteorite, are mafic to ultramafic igneous rocks. Three distinct petrographic groups make up the shergottites: olivine-phyric, basaltic, and poikilitic [1]. The shergottite groups have also been categorized on the basis of their light rare earth element (LREE) concentrations into enriched, intermediate, and depleted [1-3]. Here we investigate the petrogenetic relationships amongst the enriched and intermediate poikilitic shergottites. Poikilitic shergottites are gabbroic intrusive rocks that likely represent an important lithology of the martian crust, as the surface of Mars is largely basaltic in composition [4]. It has previously been suggested that the poikilitic shergottites may have originated from a common igneous body on Mars [5]. However, although the enriched and intermediate poikilitic shergottites share textural and mineralogical similarities, the enriched poikilitic shergottites exhibit comparable ejection and crystallization ages to some basaltic and olivine-phyric enriched shergottites [2-6]. In addition, early models suggesting a common igneous body for these meteorites were based on intermediate shergottites only, as enriched end-members for this group were only identified in 2010 [7]. In this study, we investigate quantitative textural analyses of various enriched and intermediate poikilitic shergottites to constrain their emplacement within the martian crust and understand their links and relationships with other enriched shergottite groups. Methods: Crystal size distribution (CSD) and spatial distribution pattern (SDP) textural analyses are wellestablished and useful tools to assess the crystallization histories and spatial associations of the analyzed crystal populations [8-10]. These analyses allow for constraints to be placed on the emplacement processes of igneous rocks, such as magma residence time, crystal accumulation, and textural coarsening. CSD analyses have been applied to the earliest crystallizing phase, olivine, in four enriched poikilitic shergottites (Northwest Africa-NWA 4468, NWA 10169, NWA 7397, NWA 10618). In addition, we will also present CSD and SDP analyses of two intermediate poikilitic shergottites, Allan Hills (ALHA) 77005 and Lewis Cliff (LEW) 88516. To produce CSDs and SDPs for the olivine populations within the analyzed enriched and intermediate poikilitic shergottites, olivine grain boundaries were traced by hand using reflected and transmitted light mosaic images. The grain dimensions were measured using ImageJ software, which were then put into CSDslice software [9]. CSDslice software is a database that is used to obtain the best-fit 3D shape ratio (long-, intermediate-, and short-axis ratio) of the 2D measured grain population. The best-fit 3D shape was then entered into CSDcorrections software to generate the CSD plots. The R-value, used for SDP analyses, was obtained using Big-R software available in CSDcorrections software [10]. Results and Discussion: If the enriched poikilitic shergottites all crystallized from a similar igneous intrusion on Mars, then our preliminary results of the CSD analyses imply that NWA 10618 crystallized at a lower cooling rate than NWA 10619, NWA 7397, and NWA 4468. Additionally, NWA 7397 and NWA 4468 crystallized at similar conditions, and likely are the shallowest of the four enriched poikilitic shergottites if all the enriched poikilitic shergottites crystallized in a single magmatic intrusion. These interpretations are based on the slopes of the CSD profiles, which are related to growth rates and magma residence times. In a single igneous body, we would expect the samples at the base of the body to exhibit the longest residence time, and therefore the shallowest slope. The textural analyses results for the intermediate poikilitic shergottites will be presented at the conference. Future Work: The work here are preliminary results of a more expansive study to fully characterize the petrogenetic relationships amongst the entire suite of poikilitic shergottites. Future work will include CSD and SDP on additional enriched and intermediate poikilitic shergottites, as well as analysis of more thin sections from each sample.

2022, Meteoritics & Planetary Science

The Sayh al Uhaymir (SaU) 150 meteorite was found on a gravel plateau, 43.3 km south of Ghaba, Oman, on October 8, 2002. Oxygen isotope (δ 17 O 2.78; δ 18 O 4.74), CRE age (∼1.3 Ma), and noble gas studies confirm its Martian origin. SaU 150 is classified as an olivine-phyric basalt, having a porphyritic texture with olivine macrocrysts set in a finer-grained matrix of pigeonite and interstitial maskelynite, with minor augite, spinel, ilmenite, merrillite, pyrrhotite, pentlandite, and secondary (terrestrial) calcite and iron oxides. The bulk rock composition, in particular mg (68) [molar Mg/(Mg + Fe) × 100], Fe/Mn (37.9), and Na/Al (0.22), are characteristic of Martian meteorites. Based on mineral compositions, cooling rates determined from crystal morphology, and crystal size distribution, it is deduced that the parent magma formed in a steady-state growth regime (magma chamber) that cooled at <2 °C/hr. Subsequent eruption as a thick lava flow or hypabyssal intrusion entrained a small fraction of xenocrystic olivine and gave rise to a magmatic foliation, with slow cooling allowing for near homogenization of igneous minerals. SaU 150 experienced an equilibration shock pressure of 33-45 GPa in a single impact event. Post-shock heat gave rise to localized melting (∼11 vol%). Larger volume melts remained fluid after pressure release and crystallized dendritic olivine and pyroxene with fractal dimensions of 1.80-1.89 and 1.89-1.95, respectively, at −ΔT >70-365 °C. SaU 150 is essentially identical to SaU 005/094, all representing samples of the same fall that are similar to, but distinct from, the DaG shergottites.

2022

SIMS carbonate oxygen isotope analysis has been performed on a set of paired CM2 Antarctic chondrites. Results are compared to carbonate type and bulk values and show that different carbonate populations possess distinct isotopic values.

2022, 36th Annual Lunar and Planetary Science …

Title: Thin Wafer Transmission Mössbauer Spectra of Four Shergottites: Implications for Mineralogy of Rocks at Mars Exploration Rover Sites. Authors: Seda, T.; Irving, AJ. Publication: 36th Annual Lunar and Planetary Science ...

2022, Journal of Geophysical Research: Planets

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2022, Science Advances

Organic synthesis on Mars occurs by the electrochemical reduction of CO 2 , a reaction that is highly relevant for abiotic organic synthesis on early Earth.

2022

Introduction: The δO, δO, δC, and δC compositions of bulk carbonate have been measured from paired Antarctic CM2 chondrites (EET96006, EET96016, EET96017, and EET96019) [1,2]. Further oxygen isotopic compositional constraints are placed here by Secondary Ionization Mass Spectrometry (SIMS) of in-situ carbonates. Here we report oxygen isotopic analyses of CM calcite populations for 27 calcium carbonate grains. Some comparisons with the data of Benedix et al 2003 [3] of CM falls are included. Techniques: Four polished thick-sections were gold-coated with a Hummer 6.2 Anatech sputtercoating unit. Oxygen isotopic analysis of carbonates (δO, δO) was performed with the ASU CAMECA IMS 6F SIMS with a Cs primary ion beam (10 keV, 25μm spot size). Instrumental Mass Fractionation (IMF) was determined to be 24.88‰ for δO and 12.44‰ for δO by analyzing a terrestrial calcite standard (Joplin calcite, with a δO value of 5.8‰). Uncertainties on individual analyses, taking into account the variation...

2022

Studies of Olivine-Phyric Shergottites RBT 04262 and LAR 06319: Isotopic Evidence for Relationship to Enriched Basaltic Shergottites [#1360] Rb-Sr and Sm-Nd data for olivine-phyric shergottites RBT 04262 and LAR 06319 show that they are... more

2022, Meteoritics & Planetary Science

This is the author manuscript accepted for publication and has undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and... more

2022

SEPARATE LAUNCH SITES ON MARS. A. J. Irving, S. M. Kuehner, T. J. Lapen, M. Righter, H. Busemann, R. Wieler and K. Nishiizumi Dept. of Earth & Space Sciences, University of Washington, Seattle, WA (irvingaj@uw.edu), Dept. of Earth & Atmospheric Sciences, University of Houston, TX, Inst. für Geochemie & Petrologie, ETH Zürich, Switzerland, Space Sciences Laboratory, University of California, Berkeley, CA.

2022, Geochimica et Cosmochimica Acta

The martian meteorite Northwest Africa (NWA) 10169 is classified as a member of the geochemically enriched poikilitic shergottites, based on mineral composition, Lu-Hf and Sm-Nd isotope systematics, and rare earth element (REE) concentrations. Similar to other enriched and intermediate poikilitic shergottites, NWA 10169 is a cumulate rock that exhibits a bimodal texture characterized by large pyroxene oikocrysts (poikilitic texture) surrounded by olivine-rich interstitial material (non-poikilitic texture). Olivine chadacrysts and pyroxene oikocrysts have higher Mg#s (molar Mg/Mg + Fe) than those in the interstitial areas, suggesting that the poikilitic texture represents early-stage crystallization and accumulation, as opposed to late-stage non-poikilitic (i.e., interstitial material) crystallization. Calculated oxygen fugacity values are more reduced (FMQ À2.3 ± 0.2) within the poikilitic regions, and more oxidized (FMQ À1.1 ± 0.1) within the interstitial areas, likely representing auto-oxidation and degassing during magma crystallization. Calculated parental melt compositions using olivinehosted melt inclusions display a dichotomy between K-poor and K-rich melts, thus possibly indicating mixing of parental melt with K-rich melt. The 176 Lu-176 Hf crystallization age for NWA 10169 is 167 ± 31 Ma, consistent with the ages reported for other enriched shergottites. Based on the isochron initial 176 Hf/ 177 Hf value, the modeled source 176 Lu/ 177 Hf composition for NWA 10169 is 0.02748 ± 0.00037, identical within uncertainty to the source compositions of the enriched shergottites Shergotty, Zagami, LAR 06319, NWA 4468, and Roberts Massif (RBT) 04262, suggesting a shared, long-lived geochemical source, and distinct from the source of other enriched shergottites Los Angeles, NWA 856, and NWA 7320. This study reveals that at least two sources are responsible for the enriched shergottites, and that the martian mantle is more heterogeneous than previously thought. Additionally, the enriched shergottites, which share a source with NWA 10169, have consistent crystallization ages and magmatic histories, indicating that a common magmatic system on Mars is likely responsible for the formation of this group.

2022, Space Sciences Series of ISSI

As Viking Landers did not measure rock compositions, Pathfinder (PF) data are the first in this respect. This review gives no proof yet whether the PF rocks are igneous or sedimentary, but for petrogenetic reasons they could be igneous. We suggest a model in which Mars is covered by about 50% basaltic and 50% andesitic igneous rocks. The soils are a mixture of the two with addition of Mg-sulfate and-chloride plus iron compounds possibly derived from the hematite deposits.

2022, Communications Earth & Environment

Multiple lines of evidence indicate an active hydrogeological history of Mars and chemolithoautotrophy-suited environments within its Noachian terrains. As a result, one of the primary aims of upcoming missions to Mars is to search for signs of ancient life. Here we report on laboratory-scaled microbially assisted chemolithoautotrophic biotransformation of the Noachian Martian breccia Northwest Africa (NWA) 7034 composed of ancient (~4.5 Gyr old) crustal materials from Mars. Nanoanalytical hyperspectral analysis provides clues for the trafficking and distribution of meteorite inorganic constituents in the microbial cell. We decipher biomineralization patterns associated with the biotransformation and reveal microbial nanometer-sized lithologies located inside the cell and on its outer surface layer. These investigations provide an opportunity to trace the putative bioalteration processes of the Martian crust and to assess the potential biogenicity of Martian materials.

2022, Astrobiology

Mars was habitable in its early history, but the consensus is that it is quite inhospitable today, in particular because its modern climate cannot support stable liquid water at the surface. Here, we report the presence of magmatic Fe/Mg clay minerals within the mesostasis of the martian meteorite NWA 5790, an unaltered 1.3 Ga nakhlite archetypal of the martian crust. These magmatic clay minerals exhibit a vesicular texture that forms a network of microcavities or pockets, which could serve as microreactors and allow molecular crowding, a necessary step for the emergence of life. Because their formation does not depend on climate, such niches for emerging life may have been generated on Mars at many periods throughout its history, regardless of the stability or availability of liquid water at the surface.

2022, Comptes Rendus. Géoscience

Despite an apparent north/south topographic dichotomy that formed >4.0 Ga, the young Martian meteorites (<2.4 Ga) and first-order remote sensing observations revealed a surface of Mars that is uniformly basaltic. This simplistic vision has been challenged by the discovery of a brecciated meteorite and additional spacecraft data that all point to the presence of alkaline igneous rocks, thereby demonstrating an unexpected igneous diversity on Mars. In the present paper, we review a variety of effusive alkaline rocks (basalts to trachytes) recognized so far in the southern hemisphere of Mars as observed from a unique 4.47 Ga Martian meteorite, as well as ground, and orbital data. The complementary of effusive alkaline rocks and plutonic orthopyroxene-rich rocks in early Mars is discussed. We propose that mantle-derived magmas at high extent of melting at rather low pressure either erupted forming orthopyroxene-rich lavas, or crystallized at shallow crustal depths, fractionating orthopyroxene which sank to the bottom of the chamber and residual alkaline magmas which erupted at the surface of Mars. Widespread low pressure fractionation processes could also be related to heavy bombardment on the early Martian crust generating melt sheets that ultimately differentiated. The Noachian crust is more diverse than being merely basaltic.

2022, Meteoritics & Planetary Science

The nakhlites, a subgroup of eight clinopyroxenites thought to come from a single geological unit at the Martian surface, show melt inclusions in augite and olivine. In contrast to olivine-hosted melt inclusions, augite-hosted melt inclusions are not surrounded by fractures, and are thus considered preferential candidates for reconstructing parent liquid compositions. Furthermore, two types of augite-hosted melt inclusion have been defined and characterized in four different nakhlites (Northwest Africa [NWA] 817, Nakhla, Governador Valadares, and NWA 998): Type-I isolated inclusions in augite cores that contain euhedral to subhedral augite, Ti-magnetite, and pigeonite plus silica-rich glass and a gas bubble; Type-II microinclusions that form trails crosscutting host augite crystals. Fast-heating experiments were performed on selected pristine primary augite-hosted melt inclusions from these four samples. Of these, only data from Nakhla were considered robust for reconstruction of a nakhlite parental magma composition (NPM). Based upon careful petrographic selection and consideration of iron-magnesium ratios, our data are used to propose an NPM, which is basaltic (49.1 wt% SiO 2), of high Ca ⁄ Al (1.95), and K 2 O-poor (0.32 wt%). Thermodynamic modeling at an oxygen fugacity one log unit below the QFM buffer using the MELTS and PETROLOG programs implies that Mg-rich olivine was not a liquidus phase for this composition. Our analysis is used to suggest that olivine megacrysts found in the nakhlites are unlikely to have coprecipitated with augite, and thus may have been introduced during or subsequent to accumulation in the magma chamber, possibly from more evolved portions of the same chamber.

2021, Geochimica et Cosmochimica Acta

The martian meteorite breccia Northwest Africa (NWA) 7034 and its paired meteorites NWA 7533 and NWA 7475 are the first samples of martian regolith available for study on Earth. These are likely polymict breccias because separate clasts have chemical compositions [2-4] that are not consistent with a single source. NWA 7034 contains a variety of clasts, similar to clasts also described in NWA 7533: gabbroic clasts consisting of pyroxene, feldspar, phosphates, and oxides, phosphate-rich clasts containing the same phases as the gabbroic clasts, but with larger apatites and oxides, a mugearite clast, a trachyandesite clast, and two types of "melt" clasts [1-3]. [1] found small melt spherules, and a large vitrophyric clast containing skeletal pyroxene and olivine in a glassy matrix. We focused our study on this single large vitrophyric clast in NWA 7034 (Fig. 1). This melt clast has a texture not previously observed in martian meteorites and may represent a new martian composition. It is likely to be compositionally representative of the protolith rock based on its large size (5 x 4.5 mm) and relatively fine-grained texture. Fig. 1 X-Ray Mg map of the whole NWA 7034 vitrophyre clast.

2021

Introduction: The martian meteorite “Black Beauty” (NWA 7034) has been classified as a polymict breccia enriched in water (6000 ppm+ OH) in recent studies by Agee, McCubbin, and others [1-4]. However, 3-dimensional analysis of the interior mineral interrelationships has been limited by lack of suitable nondestructive evaluation (NDE) techniques at relevant “whole-rock” scales [2]. On the basis of recent work with x-ray computed tomography (xCT) of lunar samples [6-10] it is now possible to measure sub-micron 3D relationships associated with whole-rock interior mineral phases [11]. Here we report on preliminary 3D observations (volumetric) of internal phases within “Black Beauty” (BB) using xCT systems at NASA GSFC and the US Army Research Laboratory (ARL). In addition we report on first-ever xCT results for the shergottite NWA 10567 [13]. Volumetric data segmentation is used to quantify mineral-phase geometric distributions and relationships at different scales (< 5 m to 25 m)....

2020, Meteoritics & Planetary Science

The Tissint Martian meteorite is an unusual depleted olivine-phyric shergottite, reportedly sourced from a mantle-derived melt within a deep magma chamber. Here, we report major and trace element data for Tissint olivine and pyroxene, and use these data to provide new insights into the dynamics of the Tissint magma chamber. The presence of irregularly spaced oscillatory phosphorous (P)-rich bands in olivine, along with geochemical evidence indicative of a closed magmatic system, implies that the olivine grains were subject to solute trapping caused by vigorous crystal convection within the Tissint magma chamber. Calculated equilibration temperatures for the earliest crystallizing (antecrystic) olivine cores suggest a Tissint magma source temperature of 1680°C, and a local Martian mantle temperature of 1560°C during the late Amazonian-the latter being consistent with the ambient mantle temperature of Archean Earth.

2019, Geochimica et Cosmochimica Acta

Martian lava flows likely acquired S-rich material from the regolith during their emplacement on the planet’s surface. We investigated five of the twenty known nakhlites (Nakhla, Lafayette, Miller Range (MIL) 090032, Yamato 000593, and... more

2018

Northwest Africa 5790, the latest nakhlite find, is composed of 58 vol.% augite, 6% olivine and 36% vitrophyric intercu-mulus material. Its petrology is comparable to previously discovered nakhlites but with key differences: (1) Augite cores display an unusual zoning between Mg# 54 and 60; (2) Olivine macrocrysts have a primary Fe-rich core composition (Mg# = 35); (3) The modal proportion of mesostasis is the highest ever described in a nakhlite; (4) It is the most magnetite-rich nakhlite, together with MIL 03346, and exhibits the least anisotropic fabric. Complex primary zoning in cumu-lus augite indicates resorption due to complex processes such as remobilization of former cumulates in a new magma batch. Textural relationships indicate unambiguously that olivine was growing around resorbed augite, and that olivine growth was continuous while pyroxene growth resumed at a final stage. Olivine core compositions (Mg# = 35) are out of equilibrium with the augite core compositions (Mg# 60–63) and with the previously inferred nakhlite parental magma (Mg# = 29). The presence of oscillatory zoning in olivine and augite precludes subsolidus diffusion that could have modified olivine compositions. NWA 5790 evidences at least two magma batches before eruption, with the implication that melt in equilibrium with augite cores was never in contact with olivine. Iddingsite is absent. Accordingly, the previous scenarios for nakhlite petrogenesis must be revised. The first primary parent magmas of nakh-lites generated varied augite cumulates at depth (Mg# 66–60) as they differentiated to different extents. A subsequent more evolved magma batch entrained accumulated augite crystals to the surface where they were partly resorbed while olivine crystallized. Trace element variations indicate unambiguously that they represent consanguineous but different magma batches. The compositional differences among the various nakhlites suggest a number of successive lava flows. To account for all observations we propose a petrogenetic model for nakhlites based on several (at least three) thick flows. Although NWA 5790 belongs to the very top of one flow, it should come from the lowest flow sampled, based on the lack of iddingsite.

2017

A fresh, fusion-crusted 868 gram stone found in Morocco in 2009 is a highly unusual polymict breccia composed of several texturally-equilibrated chondritic lithologies. Two of the lithologies appear to be related to each other with affinities with CR chondrites, but the third lithology has very different mineralogical and oxygen isotopic characteristics.