¹Cisem Altunayar-Unsalan,²Ozan Unsalan,³Marian A. Szurgot,⁴Radosław A. Wach
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13754]
¹Central Research Testing and Analysis Laboratory Research and Application Center, Ege University, 35100 Bornova, Izmir, Turkey
²Department of Physics, Faculty of Science, Ege University, 35100 Bornova, Izmir, Turkey
³Center of Mathematics and Physics, Łódź University of Technology, Al. Politechniki 11, Łódź, 90924 Poland
⁴Institute of Applied Radiation Chemistry, Łódź University of Technology, Wróblewskiego 15, Łódź, 93-590 Poland
Published by arrangement with John Wiley & Sons

Meteorites are excavated fragments from asteroid surfaces and planets, and determining their thermophysical properties is important since they contain valuable information about internal structures of their parent bodies. We investigated thermophysical properties of the Sariçiçek meteorite by differential scanning calorimetry (DSC), measuring phase transition temperatures, enthalpy changes and specific heat capacities of samples and thermogravimetric analysis (TGA), investigating weight change in a sample as a function of temperature or time. DSC results indicate that troilite α/β and β/γ phase transition temperatures of the interior part of the meteorite were at 421.98 ± 0.02 and 581.74 ± 1.71 K, and troilite content of interior and crust parts of the meteorite were 0.28 and 0.02 wt%, respectively. Relict temperatures were calculated as 453 ± 10, 465 ± 17, and 588 ± 55 K; specific heat capacities were measured as 779, 745, and 663 J kg–1 K–1 at 300 K; and predicted as 568, 537, and 480 J kg–1 K–1 at 200 K, for interior, edge, and crust, respectively. TGA results revealed that Sariçiçek’s weight loss was 0.98% at 1170 °C, and water content and hydrogen abundance at 200–800 °C were 0.34% and 0.04%, respectively. Obtained results shed light on a thermal history of Sariçiçek’s parent body and provide further knowledge on thermal alteration of 4 Vesta.

¹J.-M.Dudley,¹A.H.Peslier,²R.L.Hervig
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2021.10.020]
¹Jacobs, NASA-Johnson Space Center, Mail Code X13, Houston, TX 77058, USA
²School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287, USA
Copyright Elsevier

Assessing the water abundance and hydrogen isotopic signature (δD) of the Martian interior dictates our understanding of the formation of inner solar-system planets, the origin of their volatiles, Martian volcanic history, and the potential for life-bearing environments on the surface of the red planet. Although several Martian meteorites, representing the planet’s crust, have been analyzed before for this assessment, little is known about the effect of shock on recorded hydrogen (H) in their mineral phases. Here, hydrogen contents and isotopes are measured by secondary ion mass spectrometry (SIMS) in an enriched olivine-phyric shergottite, Larkman Nunatak (LAR) 06319, containing impact-melted zones. Systematic 100 μm-long traverses in pyroxene and maskelynite grains reveal decreases of hundreds of µg/g H2O and increases in δD of thousands of ‰ towards the contact with impact-melted zones, which is interpreted as H diffusive loss during shock-melting. Diffusion modeling reveals that temperatures high enough to permit H diffusion following shock were maintained near the impact-melted zone for a few minutes. By comparison, the interior of pyroxenes > 200 μm away from impact-melted zones have some of the highest H content with 170-480 µg/g H2O and the lowest δD with ∼300 ‰. The latter values, obtained on the most Mg-rich, i.e. earliest crystallized pyroxenes, are used to estimate that the enriched shergottite mantle source contains 300-1000 µg/g H2O and has a δD of ∼300 ‰. This δD is similar to that of depleted shergottite and nakhlite mantle sources, but higher than Earth’s upper mantle, suggesting slightly different water source materials for the two planets. The enriched shergottite mantle source has ∼10 times more water than that inferred for the depleted shergottite source and for Earth’s upper mantle. The high water content and wide range of δD in olivine (from 90 µg/g H2O and 2700‰ to 1350 µg/g H2O and -14‰) is interpreted as overprinting by a combination of Martian and terrestrial surface alteration. Finally, the high δD recorded in the impact-melt produced glass (3350-4700 ‰), its moderate water content (100-230 µg/g H2O), and the presence of vesicles, are likely the result of incorporation of Martian surficial material (ice and atmospheric gases) and degassing during shock melting. This study shows that shock can induce H loss from minerals, accompanied by > 1000 ‰ δD increases. Additionally, although it confirms that the Martian mantle may be heterogeneous in its water content, it implies that the Martian mantle is homogeneous within uncertainties for δD.

¹Philip T.Metzger,²W.M.Grundy,³Mark V.Sykes,⁴Alan Stern,⁵James F.Bell III,⁶Charlene E.Detelich,⁷Kirby Runyon,⁸Michael Summers
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2021.114768]
¹Florida Space Institute, University of Central Florida, 12354 Research Parkway, Partnership 1 Building, Suite 214, Orlando, FL 32826-0650, USA
²Lowell Observatory, 1400 W. Mars Hill Rd., Flagtsaff, AZ 86001, USA
³Planetary Science Institute, 1700 E. Fort Lowell, Suite 106, Tucson, AZ 85719, USA
⁴Southwest Research Institute, 1050 Walnut St, Suite 300, Boulder, CO 80302, USA
⁵Arizona State University, School of Earth and Space Exploration, Box 876004, Tempe, AZ 85287-6004, USA
⁶Department of Geological Sciences, University of Alaska Anchorage, 311 Providence Drive, CPSB 101, Anchorage, AK 99508, USA
⁷Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA
⁸George Mason University, 4400 University Drive, Fairfax, VA 22030, USA
Copyright Elsevier

We argue that taxonomical concept development is vital for planetary science as in all branches of science, but its importance has been obscured by unique historical developments. The literature shows that the concept of planet developed by scientists during the Copernican Revolution was theory-laden and pragmatic for science. It included both primaries and satellites as planets due to their common intrinsic, geological characteristics. About two centuries later the non-scientific public had just adopted heliocentrism and was motivated to preserve elements of geocentrism including teleology and the assumptions of astrology. This motivated development of a folk concept of planet that contradicted the scientific view. The folk taxonomy was based on what an object orbits, making satellites out to be non-planets and ignoring most asteroids. Astronomers continued to keep primaries and moons classed together as planets and continued teaching that taxonomy until the 1920s. The astronomical community lost interest in planets ca. 1910 to 1955 and during that period complacently accepted the folk concept. Enough time has now elapsed so that modern astronomers forgot this history and rewrote it to claim that the folk taxonomy is the one that was created by the Copernican scientists. Starting ca. 1960 when spacecraft missions were developed to send back detailed new data, there was an explosion of publishing about planets including the satellites, leading to revival of the Copernican planet concept. We present evidence that taxonomical alignment with geological complexity is the most useful scientific taxonomy for planets. It is this complexity of both primary and secondary planets that is a key part of the chain of origins for life in the cosmos.

¹Andrew D. Langendam,¹Andrew G. Tomkins,²Katy A. Evans,³Nicholas C. Wilson,³Colin M. MacRae,⁴Natasha R. Stephen,³Aaron Torpy
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13755]
¹School of Earth, Atmosphere and Environment, Monash University, Melbourne, Victoria, 3800 Australia
²Department of Applied Geology, Curtin University, Perth, Western Australia, 6845 Australia
³Microbeam Laboratory, CSIRO Mineral Resources, Clayton, Victoria, 3169 Australia
⁴Plymouth Electron Microscopy Centre, University of Plymouth, Drake Circus, Plymouth, Devon, PL4 8AA UK
Published by arrangement with John Wiley & Sons

Ureilite meteorites contain regions of localized olivine reduction to Fe metal widely accepted to have formed by redox reactions involving oxidation of graphite, a process known as secondary smelting. However, the possibility that other reductants might be responsible for this process has largely been ignored. Here, 17 ureilite samples are investigated to assess whether, instead of smelting involving only solid reactants, a CHOS gas/fluid could have caused much of the smelting. Features consistent with gas- or supercritical fluid-driven reduction were found to be abundant in all ureilites, such as fracture-focused smelting, plume-like reaction fronts, and addition of sulfur. Many of these are developed away from graphite. In some ureilites, it is clear that the redox process coincided with annealing, and we suggest that this was caused by enhanced diffusion facilitated by a higher density gas or fluid, rather than slow cooling, which requires elevated pressure. The C-CO and CH4-C-H2O buffers were modeled to examine their relative potential to drive reduction. This modeling showed that a CH4-rich fluid is able to produce the observed mineral compositions at elevated pressures. This result, coupled with the observed textures, is used to develop a likely series of reactions. We suggest that at higher pressures, a H2-CH4-H2S-S2-bearing fluid-like phase, and at lower pressures, an equivalent gas, were able to infiltrate grain boundaries and fine fractures. Sulfidation to form troilite may have acted to maintain highly reduced gas/fluid conditions. The presence of hydrocarbons in ureilites supports a role for reduction driven by CHOS gas/fluid.

^1,2Jon M. Friedrich,^2,3,4Michael K. Weisberg,¹Lucille C. Malecek,²C. E. Nehru
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13751]
¹Department of Chemistry, Fordham University, Bronx, New York, 10458 USA
²Department of Earth and Planetary Sciences, American Museum of Natural History, New York, New York, 10024 USA
³Department of Physical Sciences, Kingsborough Community College, Brooklyn, New York, 11235 USA
⁴Graduate Center of the City University of New York, New York, New York, 10016 USA
Publsihed by arrangement with John Wiley & Sons

We use X-ray microtomography (µCT) and digital data extraction techniques for the three-dimensional (3-D) petrographic investigation of the Tucson meteorite. Our results show that the silicate-free metal regions in Tucson exist as discrete objects surrounded by a continuous silicate-containing metal “matrix.” Volumetric measurements of the silicate-free metal regions in Tucson demonstrate that they are akin to the sizes of metallic nodules found in CBa chondrites. Silicate-free metal regions have bladed or prolate shapes. Nonmetallic minerals in Tucson are predominately equant or prolate in shape. Nonmetallic mineral grains and silicate-free metal regions in Tucson share a common orientation and are part of a petrofabric composed of a lineation. Any foliation in Tucson is weakly developed. We interpret the petrofabric as being the result of a single event on the Tucson parent body, during which Tucson experienced shearing forces. Our 3-D petrographic investigation supports the idea that Tucson is an unusual member of the CR chondrite clan.

¹David A. Kring,²Martin J. Whitehouse,^1,3Martin Schmieder
Astrobiology (in Press) Link to Article [https://doi.org/10.1089/ast.2020.2286]
¹Lunar and Planetary Institute, Universities Space Research Association, Houston, Texas, USA
²Department of Geosciences, Swedish Museum of Natural History, Stockholm, Sweden
³HNU–Neu-Ulm University of Applied Sciences, Neu-Ulm, Germany

We currently do not have a copyright agreement with this publisher and cannot display the abstract here

^1,2,3Danielle N. Simkus,^2,3José C. Aponte,²Jamie E. Elsila,^2,3Hannah L. McLain,²Eric T. Parker,²Jason P. Dworkin,²Daniel P. Glavin
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13757]
¹NASA Postdoctoral Program at NASA Goddard Space Flight Center, Greenbelt, Maryland, 20771 USA
²Solar System Exploration Division, Code 690, NASA Goddard Space Flight Center, Greenbelt, Maryland, 20771 USA
³Department of Physics, Catholic University of America, Washington, D.C., 20064 USA
Published by arrangement with John Wiley & Sons

Investigating the organic contents of enstatite chondrite meteorites may offer insights into both early inner solar system and early Earth chemistry. Enstatite chondrite meteorites have highly reduced and anhydrous compositions, and their bulk isotopic compositions closely resemble terrestrial values, suggesting that their parent body asteroids accreted within the inner protoplanetary disk and were a primary contributor during Earth’s late accretion (Javoy, 1995; Piani et al., 2020). Here, we present the first report of amino acids in enstatite chondrite meteorite samples. Three EH3 meteorites were analyzed (Dominion Range [DOM] 14021, Larkman Nunatak [LAR] 12001, and Larkman Nunatak 06252). The acid-hydrolyzed water extracts of the meteorites contained low abundances (1.5–215.9 pmol g−1) of n-ω-amino acids (glycine, β-alanine, γ-amino-n-butyric acid [γ-ABA], δ-amino-n-valeric acid [δ-AVA], and ϵ-amino-n-caproic acid [ϵ-ACA]), but amino acids were not present above detection limits in the nonhydrolyzed samples. The low amino acid abundances and the predominance of n-ω-amino acids resemble amino acid distributions previously observed for thermally altered chondrites. These results suggest that the parent body asteroid was not conducive to the synthesis and/or preservation of α-amino acids, or free amino acids in general, and that EH3 chondrite-like material may not have been a primary contributor of diverse or abundant free amino acids to the early Earth.

¹Daniel P.Mason,¹Megan E.Elwood Madden
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2021.114759]
¹School of Geosciences, University of Oklahoma, 100 E Boyd St., Norman, OK, USA
Copyright Elsevier

Raman spectroscopy is an ideal tool to analyze the geochemistry and mineralogy of heterogenous mixtures of solids, liquid, and gases in situ, while maintaining planetary protection protocols. Here we characterize saturated CaCl2, MgCl2, MgSO4, Na2SO4, NaCl, and NaClO4 brines, as well as ultrapure water, and mixed MgSO4-NaCl, MgSO4-NaClO4, Na2SO4-NaCl, Na2SO4-NaClO4, and NaCl-NaClO4 brines from 200 K to 295 K to determine how changes in temperature affect spectral signatures of planetary analogue brines. The resulting reference dataset can be used to interpret spectra from future samples analyzed in situ on planetary bodies. Sulfate and perchlorate brines produced clear, distinct peaks associated with each polyatomic anion. While chloride brines did not produce anion peaks, subtle changes were observed in the OH-stretching region, suggesting changes to the molecular water vibration states due to complexation. Solid-liquid phase transitions were clearly observed in each of the solutions using both 785 nm (red) and 532 nm (green) excitation lasers, particularly in the OH-stretching region between 3000 and 4000 cm−1 with the 532 nm laser. Differences observed in the spectra of frozen sulfate brines suggest that cooling rates may influence the hydration state and/or crystallinity of the solid magnesium and sodium- sulfate salts. These experiments and the resulting spectral library will allow future researchers to use Raman spectroscopy to look for in situ melting, freezing, evaporation, and deliquescence as well as identify the composition of high salinity brines and their frozen products in a range of planetary environments, including permafrost and recurring slope lineae on Mars, potential ice and salt-rich regolith on asteroids such as Ceres, and ice shells and possible seeps or geysers on icy moons and other bodies.

¹Josefine A.M.Nanne,²Francis Nimmo,³Jeffrey N.Cuzzi,¹Thorsten Kleine
Earth and Planetary Science Letters 511, 44-54 Link to Article [https://doi.org/10.1016/j.epsl.2019.01.027]
¹Institut für Planetologie, University of Münster, Wilhelm-Klemm-Straße 10, 48149 Münster, Germany
²Department of Earth and Planetary Sciences, University of California Santa Cruz, Santa Cruz, CA 95064, USA
³Space Science Division, Ames Research Center, Moffett Field, CA 94035, USA
Copyright Elsevier

The isotopic composition of meteorites reveals a fundamental dichotomy between non-carbonaceous (NC) and carbonaceous (CC) meteorites. However, the origin of this dichotomy—whether it results from processes within the solar protoplanetary disk or is an inherited heterogeneity from the solar system’s parental molecular cloud—is not known. To evaluate the origin of the NC–CC dichotomy, we report Ni isotopic data for a comprehensive set of iron meteorites, with a special focus on groups that have not been analyzed before and belong to the CC group. The new Ni isotopic data demonstrate that the NC–CC dichotomy extends to Ni isotopes, and that CC meteorites are characterized by a ubiquitous 58Ni excess over NC meteorites. These data combined with prior observations reveal that, in general, the CC reservoir is characterized by an excess in nuclides produced in neutron-rich stellar environments, such as 50Ti, 54Cr, 58Ni, and r-process Mo isotopes. Because the NC–CC dichotomy exists for refractory (Ti, Mo) and non-refractory (Ni, Cr) elements, and is only evident for nuclides produced in specific, neutron-rich stellar environments, it neither reflects thermal processing of presolar carriers in the disk, nor the heterogeneous distribution of isotopically anomalous Ca–Al-rich inclusions (CAI). Instead, the NC–CC dichotomy reflects the distinct isotopic composition of later infalling material from the solar system’s parental molecular cloud, which affected the inner and outer regions of the disk differently. Simple models of the infall process by themselves can support either infall of increasingly NC-like material onto an initially CC-like disk, or infall of increasingly CC-like material in the absence of disk evolution by spreading. However, provided that CAIs formed close to the Sun, followed by rapid outward transport, their isotopic composition likely reflects that of the earliest infalling material, implying that the composition of the inner disk (i.e., the NC reservoir) is dominated by later infalling material, whereas the outer disk (i.e., the CC reservoir) preserved a compositional signature of the earliest disk. The isotopic difference between the inner and outer disk was likely maintained through the rapid formation of Jupiter, which prevented complete homogenization between material from inside (NC reservoir) and outside (CC reservoir) its orbit.

¹C.M.O’D.Alexander,²M.J.Nilges,¹G.D.Cody,³C.D.K.Herd
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2021.10.007]
¹Earth and Planets Laboratory, Carnegie Institution for Science, 5241 Broad Branch Road NW, Washington, DC 20015, USA
²EPR Laboratory, School of Chemical Sciences, Univ. Illinois at Urbana-Champaign, 505 S. Mathews Avenue, Urbana, IL 61801, USA
³Dept. Earth and Atmospheric Sciences, Univ. Alberta, Edmonton, Alberta T6G 2E3, Canada
Copyright Elsevier

The insoluble organic material (IOM) in primitive chondritic meteorites is very enriched in D (up to δD≈3500 ‰ in bulk). Based largely on a series of electron paramagnetic resonance (EPR) studies of IOM from three meteorites (Orgueil, Murchison and Tagish Lake), it has been suggested that these enrichments are the result of exchange with H2D+ in the solar nebula and that exchange with radicals in the IOM was particularly facile so that they are enormously enriched in D (δD≥95000 ‰). To try to test whether radicals are largely responsible for the D enrichments in IOM, we have used EPR to measure the radical concentrations (spins/g) and g-factors of 18 IOM separates from C1-2 chondrites of varying petrologic type and chemical group that have a much wider range of H isotopic compositions (δD≈600-3500 ‰) than in previous studies. We confirm the previous studies findings that IOM exhibits non-Curie law behavior and that it does not completely saturate even at microwave excitation powers of 200 mW. We also have obtained similar g-factor values. However, our IOM samples typically exhibit a lower and more limited range of spin concentrations, and smaller deviations from Curie law behavior than in previous studies. Nor do we observe correlations between bulk δD and either spins/g or non-Curie law behavior that would be expected if exchange between H2D+ and radicals, as previously proposed, was the cause of the D-enrichments in IOM. Indeed, in general the radical concentrations and the degree of non-Curie law behavior do not seem to correlate with any of the measured IOM properties, with chondrite group or parent body history (e.g., degree of aqueous alteration). The only exceptions are the IOM in four Tagish Lake lithologies whose spin concentrations increase with increasing degree of thermal processing as indicated by decreasing H/C and δD, and increasing aromaticity.