¹Jérôme Gattacceca,¹Pierre Rochette,¹Yoann Quesnel,²Sounthone Singsoupho
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13703]
¹CNRS, Aix-Marseille Univ, IRD, INRAE, Aix-en-Provence, France
²Department of Physics, Faculty of Natural Sciences, National University of Laos, Vientiane, Laos
Published by arrangement with John Wiley & Sons

Among Australasian tektites, the so-called Muong Nong tektites stand out for their peculiar layering and blocky aspect. Although the source crater for the Australasian tektites is not known, Muong Nong tektites are generally considered as a relatively proximal ejecta. The mechanism responsible for the formation of the layering has been a matter of debate. In this work, we revisit the paleomagnetism of Muong Nong tektites. They retain a thermoremanent magnetization acquired during cooling below 585 °C in the presence of the ambient geomagnetic field, and carried magnetite in most samples, although at least one sample containing metallic iron was detected. The inclination of the paleomagnetic direction with respect to the layering plane clusters around 18 ± 12°, compatible with the inclination of the geomagnetic field for this latitude at the time of impact. This indicates that the layering of the Muong Nong tektites was subhorizontal while they were cooling below 585 °C. The preferred scenario for the formation of the layering of layered tektite is therefore by horizontal shear in pools or sheets of molten material.

¹O. Pravdivtseva,²M. E. Varela,¹A. Meshik,³A. J. Campbell,²M. Saavedra,⁴D. Topa
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13708]
¹Laboratory for Space Sciences and Physics Department, Washington University, CB1105, Saint Louis, Missouri, 63130 USA
²ICATE (CONICET-UNSJ), Avenida España 1512 sur, San Juan, J5402DSP Argentina
³Department of the Geophysical Sciences, University of Chicago, 5734 S. Ellis Ave., Chicago, Illinois, 60637 USA
⁴Central Research Laboratories, Natural History Museum, Burgring 7, Vienna, 1010 Austria
Published by arrangement with John Wiley & Sons

The petrographic study of the San Juan A2 polished section demonstrated textural and compositional similarities with the Campo del Cielo IAB iron meteorite, with trace element abundances in metal following the pattern of bulk Campo del Cielo. Xenon, neon, and helium isotopic compositions have been measured in radial graphite rims, massive graphite inclusions, fine-grained graphite aggregates, cliftonite, and platy graphite. Two silicate inclusions and two areas of metal were also analyzed. ³He/⁴He versus ⁴He/²¹Ne data for San Juan metal plot next to the values reported for the El Taco fragment of Campo del Cielo, supporting San Juan being a part of the Campo del Cielo meteorite shower. Based on the Ne isotopic composition of its components, and the observed correlation between ¹²⁸Xe and ¹²⁹Xe, the San Juan A fragment of Campo del Cielo was well shielded from the primary galactic cosmic ray high-energy irradiation. Its size allowed the secondary neutrons to be fairly well thermalized, receiving an equivalent (normalized to the research reactor with highly thermalized neutron spectrum) fluence of thermal and epithermal neutrons of 6.6 × 10¹⁷ n cm⁻². Considering 1.8 × 10⁸ years single-stage and constant exposure geometry irradiation history for Campo del Cielo, and assuming the identical neutron flux spectra for the research reactor and Campo del Cielo, the average thermal equivalent neutron flux for San Juan is about 1.2 × 10² n cm⁻² s⁻¹. Xe isotopic composition in the radial graphite rims and platy graphite shows evidence of live ¹²⁹I in San Juan and is consistent with a mixture of iodine-derived and tellurium-derived Xe.

¹Nisha K. Ramkissoon,¹Stuart M. R. Turner,¹Michael C. Macey,¹Susanne P. Schwenzer,²Mark H. Reed,¹Victoria K. Pearson,¹Karen Olsson-Francis
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13697]
¹AstrobiologyOU, STEM, The Open University, Walton Hall, Milton Keynes, MK7 6AA UK
²Earth Sciences Department, University of Oregon, Eugene, Oregon, 97403–1272 USA
Published by arrangement with John Wiley & Sons

Hydrothermal systems that formed as a result of impact events possess all the key requirements for life: liquid water, a supply of bio-essential elements, and potential energy sources. Therefore, they are prime locations in the search for life on other planets. Here, we apply thermochemical modeling to determine secondary mineral formation within an impact-generated hydrothermal system, using geochemical data returned for two soils on Mars found in regions that have previously experienced alteration. The computed mineral reaction pathways provide a basis for Gibbs energy calculations that enable both the identification of available geochemical energy, obtained from Fe-based redox reactions, that could be utilized by potential microbial life within these environments, and an estimate of potential cell numbers. Our results suggest that water–rock interactions occurring within impact-generated hydrothermal systems could support a range of Fe-based redox reactions. The geochemical energy produced from these reactions would be substantial and indicates that crater environments have the potential to support microbial cell numbers similar to what has been identified in terrestrial environments.

¹Peiyu Wu,¹Esteban Gazel,²Arya Udry,¹Jacob B. Setera,²Amanda Ostwald
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13700]
¹Department of Earth and Atmospheric Sciences, Cornell University, Ithaca, New York, 14850 USA
²Department of Geoscience, University of Nevada, Las Vegas, Nevada, 89154 USA
Published by arrangement with John Wiley & Sons

Northwest Africa (NWA) 2737, one of the only three discovered Martian chassignites, provides critical constraints on the evolution of the Martian mantle and crust. Because of chassignites’ cumulative nature, they contain abundant melt inclusions (MI). MI are small droplets of melts trapped by crystals during the cooling of magma. They are critical to the study of pre-eruptive parental magma compositions, and thus, provide snapshots of the composition and evolution of Martian magmatic systems. Here, we present fractional crystallization models using parental magma composition calculated from NWA 2737 melt inclusions as starting compositions. We used the thermodynamic modeling software MELTS to model fractional crystallization of NWA 2737 parental magma compositions with a wide range of parameters (pressure, water content, oxygen fugacity). Our models show that the felsic compositions recently analyzed at the Martian surface in Gale crater, especially Sparkle and Angmaat, the two rocks thought to be analogous to the earliest continental crust on Earth, can be obtained by fractional crystallization of chassignite-like parental melts. Our results suggest a link between the processes that resulted in chassignites and the rocks analyzed in situ at Gale crater. To assess the possible scenarios for Martian magma migration and storage processes, we compared chassignites to terrestrial analogs formed via various mechanisms and proposed two mechanisms that may explain the intrusive and effusive rocks found in situ at Gale crater: (1) emplacement and fractionation in a closed-system crustal reservoir and (2) eruption of mafic to intermediate lavas of a relatively open system subject to constant replenishment.

¹Lingzhi Sun,¹Paul G. Lucey,¹Abigail Flom,¹Chiara Ferrari-Wong,²Ryan A. Zeigler,^2,3Juliane Gross,⁴Noah E. Petro,⁵Charles K. Shearer,²Francis M. McCubbin,^VariousThe ANGSA Science Team
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13715]
¹Department of Earth Sciences, Hawai‘i Institute of Geophysics and Planetology, University of Hawai‘i at Manoa, 1680 East-West Rd, Honolulu, Hawai‘i, 96822 USA
²Astromaterials Acquisition and Curation Office, NASA Johnson Space Center, Houston, Texas, 77058 USA
³Department of Earth & Planetary Sciences, Rutgers State University of New Jersey, Piscataway, New Jersey, 08854 USA
⁴Solar System Exploration Division, NASA Goddard Space Flight Center, Greenbelt, Maryland, 20771 USA
⁵Institute of Meteoritics, Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico, 87131 USA
Published by arrangement with John Wiley & Sons

We measured the multispectral images and a hyperspectral profile during the first dissection pass of core 73002, and here, we present preliminary results. Both multispectral images and hyperspectral data show systematic darkening and reddening from bottom to top of the core, indicating an increasing maturity from the subsurface to surface soils. Our estimated FeO and TiO2 abundances are 9 (±1) wt% and 1.8 (±0.5) wt%, and their homogeneous distributions imply no compositional stratigraphy was sampled by core 73002. The in situ regolith reworking depth is about 14 cm as inferred from the optical maturity (OMAT) profile, corresponding to a time range of about 61 million years. Mineralogy and Mg# (molar Mg/[Mg+Fe]) calculated using hyperspectral data and radiative transfer modeling show as expected the core is dominated by plagioclase and low-Ca pyroxene, and the average Mg# is 61 (±10). Our work shows that spectroscopy has a great potential to be applied in the preliminary examination of future extraterrestrial samples from outside of the glovebox.

¹Yves Marrocchi,²Marco Delbo,³Matthieu Gounelle
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13716]
¹Université de Lorraine, CNRS, Centre de Recherches Pétrographiques et Géochimiques (CRPG), UMR 7358, Vandoeuvre␣les␣Nancy, F-54501 France
²Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, Université Côte d’Azur, CS 34229, 06304 Nice, France
³IMPMC, Muséum national d’Histoire naturelle, CNRS, Sorbonne Universités, UMR 7590, 57 rue Cuvier, 75005 Paris, France
Published by arrangement with John Wiley & Sons

Chondrites are leftover solids from the early evolution of the solar protoplanetary disk that never experienced melting since their formation. They comprise unequilibrated assemblages of low- and high-temperature components, including volatile-rich, fine-grained matrices, Fe-Ni metal, sulfides, refractory inclusions, and chondrules. Consequently, chondrites are commonly described as pristine, primitive, or primordial rocks of the solar system. However, impact-generated secondary features are abundant in chondrites, suggesting that collisions among early-formed planetesimals and their fragmentation and reassembly have been effective throughout the evolution of the solar system. In this report, we review evidence of the major role of impacts in generating the current mineralogical and petrographic characteristics of chondrites. We provide perspective to these meteoritic features by discussing recent analyses of large-scale structures of the main asteroid belt and remote-sensing observations of asteroids. Observations at various spatial scales all attest that the “primitive” materials formed during the evolution of the solar system have largely been reprocessed, confirming previous studies that primitivity is relative, not absolute. This implies that (1) chondrites (and some differentiated meteorites) should systematically be envisioned as reprocessed and heterogeneous materials and (2) brecciated meteorites should be considered the norm and unbrecciated meteorites the exception.

¹Anicia Arredondo,¹Humberto Campins,²Noemi Pinilla-Alonso,^3,4Juliade León,³Vania Lorenzie,^5,6David Morat,^3,4Juan Luis Rizos,²Mário De Prá
Icarus (in Press) Link to Journal [https://doi.org/10.1016/j.icarus.2021.114619]
¹Physics Department, University of Central Florida, P.O. Box 162385, Orlando, FL 32816, USA
²Florida Space Institute, University of Central Florida, Orlando, FL 32816, USA
³Instituto de Astrofísica de Canarias, Tenerife, Spain
⁴Departamento de Astrofísica, Universidad de La Laguna, 38205 La Laguna, Tenerife, Spain
⁵Fundación Galileo Galilei – INAF, La Palma, Tenerife, Spain
⁶Observatório Nacional, Coordenação de Astronomia e Astrofísica, 20921-400 Rio de Janeiro, Brazil
Copyright Elsevier

We present new near-infrared spectra of 55 objects observed using the NASA InfraRed Telescope Facility and the Telescopio Nazionale Galileo, along with visible spectra of 21 objects obtained from the SMASS and S3OS2 surveys, to explore the differences in spectral slope and curvature between the background and the families and to show that the background is a possible source for both Bennu and Ryugu. Within the background population there is spectral diversity in taxonomy, spectral slope, and absorption band parameters. Our sample of asteroids shows that the background looks spectrally similar to the families in the same region, i.e., the background and families may have originated from the same or similar composition parent bodies. Average band center (0.69 ± 0.02 μm, depth: 2.3 ± 0.9%) of an ~0.7 μm absorption feature attributed to aqueous alteration is present in 30% of our primitive background asteroid sample, similar to abundances observed in other primitive inner belt asteroid families. Both near-Earth asteroid sample return mission targets, (101955) Bennu and (162173) Ryugu, are thought to have originated from primitive asteroid populations in the inner main belt, specifically from the low inclination asteroid families. A population that has not been explored spectrally but is dynamically able to deliver asteroid fragments to near-Earth space is the background population, i.e., asteroids that do not cluster into families. Based on our spectral comparisons, the primordial background is a possible source for (162173) Ryugu, but not for (101955) Bennu.

^1,2H. C Bates,^2,3K. L. Donaldson Hanna,¹A. J. King,²N. E. Bowles,¹S. S. Russell
Journal of Geophysical Research, Planets (in Press) Link to Article [https://doi.org/10.1029/2021JE006827]
¹Department of Earth Sciences, Natural History Museum, London, SW7 5BD UK
²Atmospheric, Oceanic and Planetary Physics, Oxford University, Oxford, OX1 3PU UK
³Department of Physics, University of Central Florida, Orlando, Florida, 32816 US
Published by arrangement with John Wiley & Sons

Volatile-rich asteroids are crucial to understanding the transport of water and organics to the terrestrial planet forming region in the early Solar System. Observations of two such asteroids by Hayabusa2 and OSIRIS-REx suggest a relationship between these bodies and CI, CM and CY chondrites. To confirm this, meteorite spectra need to be collected under appropriate conditions for comparison with asteroid observations. We report mid-infrared (MIR) emissivity spectra (5.5 – 50 µm) obtained under ambient and simulated asteroid environment conditions and near-infrared (NIR) reflectance spectra (2 ‒ 5 µm) of CM and CY chondrite fine-particulate (<35 µm) powders for which bulk mineralogy was determined using X-ray diffraction. Reflectance spectra show a 3 µm feature associated with -OH/H2O that shifts from shorter (∼2.72 µm) to longer (∼2.90 µm) wavelengths and develops a rounder shape and reduced band area with increasing thermal metamorphism. In the MIR, the transparency feature (TF) and features in the Si-O bending region (>15 µm) can be used to infer the relative degree of aqueous alteration, and to resolve the effects of aqueous and thermal alteration, when combined with NIR spectral parameters. The MIR spectra of metamorphosed CY chondrites are distinct from CM chondrite spectra, including a plateau around the Christiansen feature (∼8.00 – 12.50 µm) and features at longer wavelengths in the Si-O bending region (for example, ∼25.50 µm compared to ∼24.30 µm in the CM spectra). We additionally report potential implications of the spectra and parameters determined in this study for the results from Hayabusa2 and OSIRIS-REx.

¹Noriyuki Kawasaki,²Shoichi Itoh,³Naoya Sakamoto,⁴Steven B. Simon,⁵Daiki Yamamoto,^1,3Hisayoshi Yurimoto
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13701]
¹Department of Natural History Sciences, Hokkaido University, Sapporo, 060-0810 Japan
²Department of Earth and Planetary Sciences, Kyoto University, Kyoto, 606-8502 Japan
³Isotope Imaging Laboratory, Creative Research Institution, Hokkaido University, Sapporo, 001-0021 Japan
⁴Institute of Meteoritics, University of New Mexico, Albuquerque, New Mexico, 87131 USA
⁵Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, 252-5210 Japan
Published by arrangement with John Wiley & Sons

Coarse-grained, igneous Ca-Al-rich inclusions (CAIs) in CV chondrites formed through multiple melting events. We conducted in situ O-isotope analysis and Al-Mg systematics by secondary ion mass spectrometry of relict and overgrown minerals from a partial melting event in an Allende Type B CAI, Golfball. Golfball has a Type B CAI bulk composition and a unique structure: a fassaite-rich mantle enclosing a melilite-rich core. Many of the blocky melilite crystals in the core have irregularly shaped, Al-rich (Åk_5–15) cores enclosed in strongly zoned (Åk_30–70) overgrowths. Since the Al-rich melilite grains could not have formed from a melt of Golfball, they are interpreted as relict grains that survived later melting events. The O-isotopic compositions of the blocky melilite crystals plot along the carbonaceous chondrite anhydrous mineral line, ranging between Δ¹⁷O ~ −14‰ and −5‰. The Al-rich relict melilite grains and their overgrowths exhibit the same O-isotopic compositions, while the O-isotopic compositions are varied spatially among melilites. We found that the O-isotopic compositions steeply change across several melilite crystals within few tens of micrometers, indicating the O-isotopic compositions of the melt could not have been homogenized during the partial melting in that scale. According to the time scale of O self-diffusivity in the melt, the cooling rate of the partial melting event is calculated to be >6 × 10⁴ K h⁻¹. Al-Mg isotope data for core minerals plot on a straight line on an Al-Mg evolution diagram. A mineral isochron for Golfball gives initial ²⁶Al/²⁷Al of (4.42 ± 0.20) × 10^–5 and initial δ²⁶Mg* of −0.035 ± 0.050‰. The chemical and O-isotopic compositions of melilite and those initial values imply that its precursor consisted of fluffy Type A and/or fine-grained CAIs. The partial melting event for Golfball may have occurred in very short order after the precursor formation.

¹Alice Aléon-Toppani,¹Rosario Brunetto,²Jérôme Aléon,^1,3,4Zelia Dionnet,¹Stefano Rubino,^1,2Dan Levy,⁵David Troadec,⁶François Brisset,⁷Ferenc Borondics,⁷Andrew King
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13696]
¹Institut d’Astrophysique Spatiale, UMR 8617, CNRS, Univ. Paris-Saclay, Bât 120-121, 91405 Orsay Cedex, France
²Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, UMR 7590, Sorbonne Université, Museum
National d’Histoire Naturelle, CN RS, IRD, 61 rue Buffon, 75005 Paris, France
³INAF-IAPS, Rome, Italy
⁴DIST-Università Parthenope, Naples, Italy
⁵Institut d’électronique de microélectronique et de nanotechnologie, UMR 8520, Laboratoire central, Cité scientifique, Avenue Henri Poincaré, CS, 60069, 59652 Villeneuve d’Ascq Cedex, France
⁶Institut de Chimie Moléculaire et des Matériaux d’Orsay, CNRS, UMR 8182, Univ. Paris-Saclay, Orsay, France
⁷SOLEIL Synchrotron, Gif-sur-Yvette, France
Published by arrangement with John Wiley & Sons

With the recent and ongoing sample return missions and/or the developments of nano- to microscale 3-D and 2-D analytical techniques, it is necessary to develop sample preparation and analysis protocols that allow combination of different nanometer- to micrometer-scale resolution techniques and both maximize scientific outcome and minimize sample loss and contamination. Here, we present novel sample preparation and analytical procedures to extract a maximum of submicrometer structural, mineralogical, chemical, molecular, and isotopic information from micrometric heterogeneous samples. The sample protocol goes from a nondestructive infrared (IR) tomography of ~10 to ~70 µm-sized single grains, which provides the distribution and qualitative abundances of both mineral and organic phases, followed by its cutting in several slices at selected sites of interest for 2-D mineralogical analysis (e.g., transmission electron microscopy), molecular organic and mineral analysis (e.g., Raman and/or IR microspectroscopy), and isotopic/chemical analysis (e.g., NanoSIMS). We also discuss here the importance of the focused ion beam microscopy in the protocol, the problems of sample loss and contamination, and at last the possibility of combining successive different analyses in various orders on the same micrometric sample. Special care was notably taken to establish a protocol allowing correlated NanoSIMS/TEM/IR analyses with NanoSIMS performed first. Finally, we emphasize the interest of 3-D and 2-D IR analyses in studying the organics–minerals relationship in combination with more classical isotopic and mineralogical grain characterizations.