¹Kenan Han,¹Duojun Wang,¹Ruixin Zhang,¹Peng Chen,¹Nao Cai,¹Rui Zhang,¹Yang Cao
Journal Geophysical Research (Planets) (in Press) Link to Article [https://doi.org/10.1029/2022JE007692]
¹High Pressure Science Center, College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, China
Published ba arrangement with John Wiley & Sons

Thermal conductivity (κ) and thermal diffusivity (D) of tremolite were measured at up to 2.5 GPa and 1373 K using the transient plane-source method in a multi-anvil apparatus. Thermal conductivity and thermal diffusivity of tremolite decrease monotonically before dehydration (<1173) and increase significantly after dehydration. Tremolite exhibits a positive pressure dependence before dehydration. Heat capacity (C) of tremolite calculated from κ and D shows a positive pressure dependence, and is controlled by an almost constant thermal expansion coefficient (α) with temperature. Conductive heat transfer and radiative heat transport dominate the heat transport process before dehydration, and the significant increase in thermal conductivity after dehydration is attributed to convective heat transfer. A compositional model of the Venusian lithosphere composed of a basaltic crust and peridotite mantle with or without tremolite was established. The thickness of the Venusian lithosphere with or without tremolite for Venus was calculated by combining the heat flow (from 20 to 80 mW/m2) at a certain depth (from 5 to 25 km) of crust, ranging from 24.4 to 184.6 km.

¹Parastoo Ghaznavi,¹Yogita Kadlag,²David Haberthür,²Ruslan Hlushchuk,¹Ingo Leya
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.13996]
¹Space Sciences and Planetology, University of Bern, Bern, Switzerland
²Institute of Anatomy, University of Bern, Bern, Switzerland
Published by arrangement with John Wiley & Sons

Micro-computed tomography (μCT) is a fast and powerful technology for studying textural, physical, and chemical properties of solid objects in three dimensions. While regularly used for sample documentation and curation, it is often assumed that μCT techniques are essentially nondestructive or at least very little destructive. However, there are very few studies proving or rejecting the assumption of nondestructiveness. Here we study whether X-ray tomographic imaging affects the noble gas budget of matrix samples from the CV3 carbonaceous chondrite Allende. We irradiated powdered and homogenized matrix samples in the Bruker SkyScan 1272 μCT instrument at three different X-ray tube acceleration voltages of 30, 70, and 100 keV. By comparing the noble gas concentrations and especially the elemental and isotopic ratios of the irradiated samples with data for two non-irradiated aliquots, we found no significant differences. Our study therefore demonstrates that X-ray tomographic imaging has no measurable effect on the noble gas budget and can therefore safely be used for sample characterization prior to noble gas studies.

¹Cristian Carli et al. (>10)
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.13998]
¹IAPS-INAF, Rome, Italy
Published by arrangement with John Wiley & Sons

Al Huwaysah 010 is an ungrouped achondrite meteorite, recently referred to as a brachinite-like meteorite. This meteorite, showing a fine-grained assemblage of low-Ca pyroxene and opaque phases, is strongly reduced in comparison to other reduced brachinites. The occurrence of some tiny plates of graphite and oldhamite in this meteorite suggests that a partial melt residue has experienced a further reduction process. Olivine, the most abundant phase, is compositionally homogeneous (Fo83.3) as well as the clinopyroxene (En45.5Fs10.8Wo43.7) and the plagioclase (Ab69.5). Orthopyroxene (En85.4Fs13.9Wo0.7) also occurs but only in a fine intergrowth. Other accessory phases are Fe metal grains (Ni-free or Cr-bearing Fe-Ni alloy), troilite, chlorapatite, pentlandite (as inclusions in chromite). The sample shows two different closure temperatures: the highest (≈900°C) is determined via the olivine–chromite intercrystalline geothermometer and the lowest temperature (≈520°C) is determined via the pyroxene-based intracrystalline geothermometer. These temperatures may represent, respectively, the closure temperature associated with the formation and a subsequent impact event excavating the sample from the parental body. The visible to near-infrared (VNIR) reflectance spectra of Al Huwaysah 010 exhibit low reflectance, consistent with the presence of darkening components, and weak absorptions indicative of olivine and pyroxene. Comparing the spectral parameters of Al Huwaysah 010 to potential parent bodies characterized by olivine–pyroxene mineralogy, we find that it falls within the field previously attributed to the SIII type asteroids. These results lead us to classify the Al Huwaysah 010 meteorite as the most reduced brachinite, whose VNIR spectral features show strong affinities with those of SIII asteroids.

^1,2Zachary F.M. Burton,^2,3Janice L. Bishop,⁴Peter A.J. Englert,⁵Anna Szynkiewicz,⁶Christian Koeberl,⁴Przemyslaw Dera,⁴Warren McKenzie,⁷Everett K. Gibson
American Mineralogist 108, 1017-1031 Link to Article [http://www.minsocam.org/msa/ammin/toc/2023/Abstracts/AM108P1017.pdf]
¹Department of Earth and Planetary Sciences, Stanford University, Stanford, California 94305, U.S.A.
²Carl Sagan Center, The SETI Institute, Mountain View, California 94043, U.S.A.
³NASA Ames Research Center, Moffett Field, California 94035, U.S.A.
⁴Hawai‘i Institute of Geophysics and Planetology, University of Hawai‘i at Mānoa, Honolulu, Hawaii 96822, U.S.A.
⁵Department of Earth and Planetary Sciences, University of Tennessee, Knoxville, Tennessee 37996, U.S.A.
⁶Department of Lithospheric Research, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria 7
NASA Johnson Space Center, Houston, Texas 77058, U.S.A
Copyright: The Mineralogical Society of America

Understanding past and present aqueous activity on Mars is critical to constraining martian aqueous
geochemistry and habitability, and to searching for life on Mars. Assemblages of minerals observed
at or near the martian surface include phyllosilicates, sulfates, iron oxides/hydroxides, and chlorides,
all of which are indicative of a complex history of aqueous activity and alteration in the martian past.
Furthermore, features observed on parts of the martian surface suggest present-day activity of subsurface
brines and at least transient liquid water. Terrestrial analogs for younger and colder (Hesperian–Amazonian) martian geologic and climatic conditions are available in the McMurdo Dry Valleys (MDV)
of Antarctica and provide opportunities for improved understanding of more recent aqueous activity
on Mars. Here, we study the VXE-6 intermittent brine pond site from Wright Valley in the MDV
region and use coordinated spectroscopy, X-ray diffraction, and elemental analyses to characterize
the mineralogy and chemistry of surface sediments that have evolved in response to aqueous activity
at this site. We find that brine pond activity results in mineral assemblages akin to aqueous alteration
products associated with younger sites on Mars. In particular, surficial chlorides, a transition layer
of poorly crystalline aluminosilicates and iron oxides/hydroxides, and a deeper gypsum-rich interval
within the upper 10 cm of sediment are closely related at this Antarctic brine pond site. Activity of the
Antarctic brine pond and associated mineral formation presents a process analog for chemical alteration on the martian surface during episodes of transient liquid water activity during the late Hesperian
and/or more recently. Our results provide a relevant example of how aqueous activity in a cold and
dry Mars-like climate may explain the co-occurrence of chlorides, clays, iron oxides/hydroxides, and
sulfates observed on Mars.

^1,2Proteek Chowdhury,²Maryjo Brounce,³Jeremy W. Boyce,³Francis M. McCubbin
Journal of Geophysicaöl Research (Planets) (in Press) Link to Article [https://doi.org/10.1029/2022JE007634]
¹Department of Earth, Environmental, and Planetary Sciences, Rice University, Houston, TX
²Department of Earth and Planetary Sciences, University of California, Riverside,CA
³Astromaterials Research and Exploration Science Division, NASA Johnson Space Center, Houston, TX
Published by arrangement with John Wiley & Sons

Apatite can incorporate sulfur in its reduced form (S2-) when apatite equilibrates with a silicate melt at reducing conditions. Incorporation of sulfate (S6+) has been observed in terrestrial apatite under oxidizing conditions. Thus, it has been suggested that the proportions of S6+/S2- in apatite may record the oxygen fugacity (fO2) during the formation and/or equilibration of apatite grains with a silicate melt in a wide variety of igneous and metamorphic rocks, including from Earth, Mars, the Moon, and in materials from the asteroid belt. Martian rocks, which record fO2 values intermediate between those recorded by rocks from the Moon and Earth, may have apatite that contains only S2- or mixtures of S6+ and S2-. Here, we present new measurements of the oxidation state of sulfur in apatite grains in the basaltic shergottite, Shergotty, which exhibits spectral features consistent with the presence of sulfide (S2-) structurally bound in apatite, and no evidence for the presence of sulfite (S4+) or sulfate (S6+). The presence of sulfide-only apatite in Shergotty is consistent with other mineralogical records of fO2 in this meteorite, which are calculated from other late-stage crystallizing phases like Fe-Ti oxides as well as from early crystallizing phases like clinopyroxene (DEuCpx/melt) of ΔIW+1.9 to ΔIW+3.5. At these fO2 values, S is present in silicate melts as only S2-, and this suggests that the oxidation state of sulfur records and preserves the fO2 during the igneous crystallization of apatite reinforcing the idea that sulfur in apatite can be used as an igneous oxybarometer.

¹O.Beyssac et al. (>10)
Journal of Geophysical Research (Planets) (in Press) Link to Article [https://doi.org/10.1029/2022JE007638]
¹Institut de Minéralogie, CNRS, Sorbonne Université, Muséum National d’Histoire Naturelle, de Physique des Matériaux et de Cosmochimie, 75005 Paris, France
Published by arrangement with John Wiley & Sons

Séítah is the stratigraphically lowest formation visited by Perseverance in the Jezero crater floor. We present the data obtained by SuperCam: texture by imagery, chemistry by LIBS, and mineralogy by VISIR and Raman spectroscopy. The Séítah formation consists of igneous, weakly altered, rocks dominated by millimeter-size grains of olivine with the presence of low-Ca and high-Ca pyroxenes, and other primary minerals (e.g., plagioclase, Cr-Fe-Ti oxides, phosphates). Along a ∼140 m long section in Séítah, SuperCam analyses showed evidence of geochemical and mineralogical variations, from the contact with the overlying Máaz formation, going deeper in the formation. Bulk rock and olivine Mg#, grain size, olivine content increase gradually further from the contact. Along the section, olivine Mg# are not in equilibrium with the bulk rock Mg#, indicating local olivine accumulation. These observations are consistent with Séítah being the deep ultramafic member of a cumulate series derived from the fractional crystallization and slow cooling of the parent magma at depth. Possible magmatic processes and exhumation mechanisms of Séítah are discussed. Séítah rocks show some affinity with some rocks at Gusev crater, and with some martian meteorites suggesting that such rocks are not rare on the surface of Mars. Séítah is part of the Nili Fossae regional olivine-carbonate unit observed from orbit. Future exploration of Perseverance on the rim and outside of the crater will help determine if the observations from the crater floor can be extrapolated to the whole unit, or if this unit is composed of distinct sub-units with various origins.

¹Vivian Z. Sun et al. (>10)
Journal of Geophysical Research (Planets) (in Press) Open Access Link to Article [https://doi.org/10.1029/2022JE007613]
¹Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
Published by arrangement with John Wiley & Sons

The Mars 2020 Perseverance rover landed in Jezero crater on February 18, 2021. After a 100-sol period of commissioning and the Ingenuity Helicopter technology demonstration, Perseverance began its first science campaign to explore the enigmatic Jezero crater floor, whose igneous or sedimentary origins have been much debated in the scientific community. This paper describes the campaign plan developed to explore the crater floor’s Máaz and Séítah formations and summarizes the results of the campaign between sols 100-379. By the end of the campaign, Perseverance had traversed more than 5 km, created seven abrasion patches, and sealed nine samples and a witness tube. Analysis of remote and proximity science observations show that the Máaz and Séítah formations are igneous in origin and composed of five and two geologic members, respectively. The Séítah formation represents the olivine-rich cumulate formed from differentiation of a slowly cooling melt or magma body, and the Máaz formation likely represents a separate series of lava flows emplaced after Séítah. The Máaz and Séítah rocks also preserve evidence of multiple episodes of aqueous alteration in secondary minerals like carbonate, Fe/Mg phyllosilicates, sulfates, and perchlorate, and surficial coatings. Post-emplacement processes tilted the rocks near the Máaz-Séítah contact and substantial erosion modified the crater floor rocks to their present-day expressions. Results from this crater floor campaign, including those obtained upon return of the collected samples, will help to build the geologic history of events that occurred in Jezero crater and provide time constraints on the formation of the Jezero delta.

MSR Campaign Science Group (MCSG) et al. (>10)
Meteoritics & Planetary Science (in Press) Open Access link to Article [doi: 10.1111/maps.139811]
Published by arrangement with John Wiley & Sons

The Mars 2020/Mars Sample Return (MSR) Sample Depot Science CommunityWorkshop was held on September 28 and 30, 2022, to assess the Scientifically-ReturnWorthy (SRW) value of the full collection of samples acquired by the rover Perseverance atJezero Crater, and of a proposed subset of samples to be left as a First Depot at a location within Jezero Crater called Three Forks. The primary outcome of the workshop was thatthe community is in consensus on the following statement: The proposed set of ten sampletubes that includes seven rock samples, one regolith sample, one atmospheric sample, andone witness tube constitutes a SRW collection that: (1) represents the diversity of theexplored region around the landing site, (2) covers partially or fully, in a balanced way, allof the International MSR Objectives and Samples Team scientific objectives that areapplicable to Jezero Crater, and (3) the analyses of samples in this First Depot on Earthwould be of fundamental importance, providing a substantial improvement in ourunderstanding of Mars. At the conclusion of the meeting, there was overall communitysupport for forming the First Depot as described at the workshop and placing it at theThree Forks site. The community also recognized that the diversity of the Rover Cache (thesample collection that remains on the rover after placing the First Depot) will significantlyimprove with the samples that are planned to be obtained in the future by the Perseverancerover and that the Rover Cache is the primary target for MSR to return to Earth.

¹Y. O. CHETVERIKOV,^1,2V. F. EZHOV,^3,4M. S. GLUKHOV,^5,6E. M. IVANKOVA,²A. S. LOSHACHENKO,²V. D. KALGANOV,^2,7O. V. YAKUBOVICH
Meteoritics & Planetary Science (in Press) Link to Article [doi: 10.1111/maps.13991]
¹Petersburg Nuclear Physics Institute named by B. P. Konstantinov of National Research Center “Kurchatov Institute”,Gatchina, Russia
²Saint Petersburg State University, St. Petersburg, Russia
³Kazan Federal University, Kazan, Russia
⁴Zavaritsky Institute of Geology and Geochemistry, Ural Branch of the Russian Academy of Sciences, Yekaterinburg, Russia
⁵Institute of Macromolecular Compounds, Russian Academy of Sciences, St. Petersburg, Russia
⁶Kirov Military Medical Academy, St. Petersburg, Russia7Institute of Precambrian Geology and Geochronology, Russian Academy of Sciences, St. Petersburg, Russia
Published by arrangement with John Wiley & Sons

Dust particles obtained by filtering fresh snow collected from May to September2017 in the vicinity of Vostok station in Antarctica were examined using a scanning electronmicroscope. The collection of dust particles contains 197 spherules ranging from 0.5 to 117μmin diameter, the most abundant ones (n=188) by far being iron oxide spherules. Analyses ofmeteorological and human activity data suggest an extraterrestrial origin of most of thespherical particles. The particle size distribution histogram showed a smooth increase in theirnumber with decreasing size and a dramatic drop at sizes smaller than 3μm. The number ofspherical particles has an uneven distribution over time, with an intense peak in July 27–28,2017 which correlates by dates with the peak of the Southern Delta Aquariids meteor shower.The size distribution of the particles collected during the same period indicates the presenceof a mechanism that accelerates their fall to the Earth. We propose that they are effectivecenters of condensation of ice crystals in stratospheric clouds. Our data indicate thatcollection of micrometeorites with sizes of several microns from the fresh snow is possible,opening a new way for sampling micrometeorites, including separate meteor showers.

^1,2,3,4Marie J.B. Henderson,⁴Briony H.N. Horgan,⁵Samuel J. Lawrence,⁶Julie D. Stopar,⁶Lisa R. Gaddis
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2023.115628]
¹Solar System Exploration Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
²Center for Space Sciences and Technology, University of Maryland, Baltimore County, Baltimore, MD 21250, USA
³Center for Research and Exploration in Space Science and Technology, NASA/GSFC, Greenbelt, MD 20771, USA
⁴Purdue University, West Lafayette, IN 47907, USA
⁵NASA Johnson Space Center, Houston, TX 77058, USA
⁶Lunar and Planetary Institute, Houston, TX 77058, USA
Copyright Elsevier

The Marius Hills Volcanic Complex exhibits the highest concentration of extrusive volcanic landforms on the Moon, in the form of both domes and cones. The interpretive advancements made in this investigation result from improved spectral resolution and analysis techniques. Moon Mineralogy Mapper (M3) spectral analysis shows that the rounded landforms in MHVC exhibit spectra consistent with glass, confirming a cinder cone with an explosive volcanic origin. The presence of scoria-like glass-rich pyroclasts that should be distinct from the glass beads collected during Apollo. This research provides evidence that spectroscopy can identify volcanic landforms when visible images of the morphology are inconclusive, which is essential for future exploration of volcanic terrains. The likely concurrent eruption of the domes and cones with the differences in the mineralogy of the resulting edifices (e.g., presence of glass) add supporting evidence to the hypothesis that extrinsic properties (e.g., ascent rate), not changes in magma composition (e.g., amount of volatiles), led to the different volcanic morphologies. Combining the morphology and the spectral data, we hypothesize that the magma evolution of the region was long-lived and with distinct early edifice-forming and later mare-forming episodes. The long-lived volcanism recorded in multiple volcanic units within close proximity in MHVC would be ideal for future exploration and eventual sample return.