¹Ngyen, Ann N. et al. (>10)
Science Advances 9, eadh1003 Open Access Link to Article [DOI 10.1126/sciadv.adh1003]
¹Astromaterials Research and Exploration Science, NASA Johnson Space Center, Houston, 77058, TX, United States

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¹Huidobro J. et al. (>10)
Analytica Chimica Acta 1276, 341632 Open Access Link to Article [DOI 10.1016/j.aca.2023.341632]
¹IBeA Research Group, University of the Basque Country (UPV/EHU), Spain

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¹Liu, Weiyi, ²Zhang, Yigang, ¹Tissot, François L.H., ³Avice, Guillaume, ⁴Ye, Zhilin, ⁵Yin, Qing-Zhu
Science Advances 9, adg9213 Open Access Link to Article [DOI 10.1126/sciadv.adg9213]
¹The Isotoparium, Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, 91125, CA, United States
²Key Laboratory of Computational Geodynamics, College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
³Universite Paris Cite, Institut de physique du globe de Paris, CNRS, Paris, F-75005, France
⁴Key Laboratory of High-Temperature and High-Pressure Study of the Earth’s Interior, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, Guizhou, 550081, China
⁵Department of Earth and Planetary Sciences, University of California, Davis, 95616, CA, United States

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¹Nishi, Masayuki,¹Jin, Si,¹Kawano, Katsutoshi,²Kuwahara, Hideharu,^3,4Yamada, Akihiro, ⁵Kawaguchi, Shogo, ⁵Mori, Yuki, ¹Sakaiya, Tatsuhiro, ¹Kondo, Tadashi
Progress in Earth and Planetary Science 10, 41 Open Access Link to Article [DOI 10.1186/s40645-023-00572-0]
¹Department of Earth and Space Science, Osaka University, 1-1 Machikaneyama-cho, Osaka, Toyonaka, 560-0043, Japan
²Geodynamics Research Center, Ehime University, 2-5 Bunkyo-cho, Ehime, Matsuyama, 790-8577, Japan
³Department of Material Science, The University of Shiga Prefecture, Shiga, Hikone, Japan
⁴Center for Glass Science and Technology, The University of Shiga Prefecture, 2500, Hassaka-cho, Shiga, Hikone, 522-8533, Japan
⁵Japan Synchrotron Radiation Research Institute, Sayo-gun, Hyogo, 679-5198, Japan

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¹Gurpreet Kaur Bhatia
Planetary and Space Science (in Press) Link to Article [https://doi.org/10.1016/j.pss.2023.105783]
¹Department of Physics, MM Engineering College, Maharishi Markandeshwar (Deemed to be University), Mullana-Ambala, Haryana, 133207, India

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¹Lingqi Zeng,¹Jochen Gätjen,¹Manuel Reinhardt,^2,3,4Michael E. Böttcher,¹Andreas Reimer,¹Volker Karius,¹Volker Thiel,¹Gernot Arp
Geochmica et Cosmochimica acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2023.10.013]
¹Geoscience Center, University of Göttingen, D-37077 Göttingen, Germany
²Geochemistry and Isotope Biogeochemistry, Leibniz Institute for Baltic Sea Research (IOW), D-18119 Warnemünde, Germany
³Marine Geochemistry, University of Greifswald, D-17489 Greifswald, Germany
⁴Interdisciplinary Faculty, University of Rostock, D-18059 Rostock, Germany
Copyright Elsevier

In impact crater lakes, the lacustrine sedimentary records may not solely reflect climatic changes but also potential erosional effects from lithologically distinct impactite formations. The hydrochemical and biogeochemical processes during the deposition of the Nördlinger Ries impact crater lake, which fall in the range of the mid-Miocene Climate Transition, were studied by analysing microcrystalline authigenic carbonates in a drill core succession, using stable oxygen and carbon isotopes in conjunction with biomarkers. These investigations revealed an early sulfidic interval characterized by thiophenes, iso- and anteiso-C15:0 acids derived from sulfate reducing bacteria, and dolomites with low to intermediate δ13Ccarb values. The subsequent distinctive interval is characterized by extremely 13C-enriched dolomite (δ13Ccarb up to +20.93 ± 0.05 ‰ V-PDB), decline of iso- and anteiso-C15:0 acids and is rich in an Archaea-derived archaeol that is 13C-enriched (-14.7‰), indicating extensive methanogenesis in sulfate-depleted lake porewater during early diagenesis. The sulfate decline results from successive sulfate reduction when replenishment of sulfate-bearing runoff water is limited. The carbonates exhibit enriched 18O due to pronounced evaporation in a long-resided water body and enriched 13C by methanogenesis. A change in provenance of water derived from the sulfur-rich suevite (impact melt-bearing breccia) and crystalline source rocks to the sulfur-poor Bunte Breccia (continuous ejecta blanket) is required. Intermittently high Si/Al and Zr/Al at the high δ13C interval suggests sporadic short-term runoff increase, leading to fluctuating physiochemical lake conditions. A subsequent decline in both δ13Ccarb and archaeol indicates a decreasing lake level with intermittent subaerial exposure events, supported by bioturbation and mud cracks. The concomitant lake oxygenation is well supported by increasing Pr/Ph ratios and lipids derived from aerobic methanotrophs (13C-depleted 3-methyl-hopanoids). In the youngest unit, allochthonous lignites and biomarkers from lacustrine/soil sources appear, high total sulphur contents and thiophenes recur, and stable C and O isotope values decrease again. These observations suggest another major provenance change of the inflowing solutes, with increasing influx from weathered pyrite-bearing Jurassic claystones. These findings demonstrate that the climatic record expected from the stable carbon and oxygen isotopes of the Ries carbonates is strongly overprinted by hydrochemical and biogeochemical processes due to changing ion influx from substrate rocks, along the course of the successive ejecta erosion and catchment changes. Such an intrinsic control of lacustrine biogeochemical processes is also expected for other hydrologically closed impact crater lake basins, where catchment rocks with distinctively different lithologies are present.

¹Lydie Bonal et al. (>10)
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2023.115826]
¹Institut de Planétologie et d’Astrophysique, Université Grenoble Alpes, 38000 Grenoble, France
Copyright Elsevier

This paper is focused on the characterization of the thermal history of C-type asteroid Ryugu through the structure of the polyaromatic carbonaceous matter in the returned samples determined by Raman spectroscopy. Both intact particles and extracted Insoluble Organic Matter (IOM) from the two sampling sites on Ryugu have been characterized. The main conclusions are that (i) there is no structural difference of the polyaromatic component probed by Raman spectroscopy between the two sampling sites, (ii) in a manner similar to type 1 and 2 chondrites, the characterized Ryugu particles did not experience significant long-duration thermal metamorphism related to the radioactive decay of elements such as 26Al; (iii) some structural variability is nevertheless observed within our particle set. It can be interpreted as some particles having experienced some short-duration and weak heating (R3 in the scale defined by Quirico et al. 2018 and TII or lower according to the scale defined by Nakamura, 2005).

^1,2Elias Wölfer,^2,3Gerrit Budde,^1,2Thorsten Kleine
Geochimica et Cosmochmica Acta (in Press) Open Access Link to Article [https://doi.org/10.1016/j.gca.2023.10.010]
¹Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
²Institut für Planetologie, University of Münster, Wilhelm-Klemm-Straße 10, 48149 Münster, Germany
³Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, RI 02912, USA
Copyright Elsevier

The carbonaceous Bencubbin-like (CB), high-metal (CH), and Renazzo-like (CR) chondrites are metal-rich chondrites that have been suggested to be genetically linked and are sometimes grouped together as the CR chondrite clan. Of these, the CB and CH chondrites are thought to have formed in an impact-generated vapor-melt plume from material that may be isotopically akin to CR chondrites. We report Mo, Ti, Cr, and Hf-W isotopic data for CB and CH chondrites in order to determine their formation time, to assess whether these chondrites are genetically related, and to evaluate their potential link to CR chondrites. An internal Hf-W isochron for the CH chondrite Acfer 182 yields an age of 3.8±1.2 Ma after formation of Ca-Al-rich inclusions, which is indistinguishable from the mean Hf-W model age for CB metal of 3.8±1.3 Ma. The Mo isotopic data for CB and CH chondrites indicate that both contain some of the same metal and silicate components, which themselves are isotopically distinct. As such, the different Mo isotopic compositions of bulk CB and CH chondrites reflect their distinct metal-to-silicate ratios. CR metal exhibits the same Mo isotopic composition as CB and CH metal, but CR silicates have distinct Mo and Ti isotopic compositions compared to CB and CH silicates, indicating that CB/CH chondrites may be genetically related to CR metal, but not to CR silicates. Together, the new isotopic data are consistent with formation of CB and CH chondrites in different regions of a common impact-generated vapor-melt plume and suggest that the CB and CH metal may derive from a metal-rich precursor genetically linked to CR chondrites. The Hf-W systematics of CH and CB chondrites indicate that the impact occurred at 3.8±0.8 Ma after the formation of Ca-Al-rich inclusions and, hence, up to ∼1 Ma earlier than previously inferred based on Pb-Pb chronology.

¹Nicolas Dauphas,¹Timo Hopp,²David Nesvorný
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2023.115805]
¹Origins Lab, The University of Chicago, 5734 South Ellis Ave, Chicago, IL 60637, USA
²Department of Space Studies, Southwest Research Institute, 1050 Walnut St., Suite 300, Boulder, CO 80302, USA
Copyright Elsevier

Elements with differing siderophile affinities provide insights into various stages of planetary accretion. The isotopic anomalies they exhibit offer a deeper understanding of the materials responsible for the formation of terrestrial planets. By analyzing new iron isotopic anomaly data from Martian meteorites and drawing insights from published data for O, Ca, Ti, Cr, Fe, Ni, Sr, Zr, Mo, Ru, and Si, we scrutinize potential changes in the isotopic composition of the material accreted by Mars and Earth during their formation. Our methodology employs a Bayesian inference method, executed using a Markov Chain Monte Carlo (MCMC) algorithm.

The Bayesian method helps us balance the task of emulating the compositions of the terrestrial planets (reflected in the likelihood) with the flexibility to explore the isotopic compositions of mixing components within permissible intervals (indicated by the priors of the nuisance parameters). A Principal Component Analysis of isotopic anomalies in meteorites identifies three main clusters (forming the three parts of the isotopic trichotomy): CI, CC=CM + CO + CV + CR, and NC = EH + EL + H + L + LL. We adopt CI, COCV, O, and E as endmember compositions in the mixtures. We are concerned here with explaining isotopic anomalies in Mars and Earth, not their chemical compositions. Previous studies have shown that Earth’s chemical composition could not be well explained by solely considering undifferentiated meteorites, as it requires incorporation of a refractory component enriched in forsterite. The endmember chondrite components considered here are assumed to be representative of isotopic reservoirs that were present in the solar nebula, but the actual building blocks could have had different chemical compositions, and we use cursive letters to denote those putative building blocks

Because Earth’s mantle composition is an endmember for some isotopic systems, it cannot be reproduced exactly by considering known chondrite groups only and requires involvement of a component that is missing from meteorite collections but is likely close to enstatite meteorites. With this caveat in mind, our results suggest that Earth is primarily an isotopic mixture of ~92%, 6%, and < 2% and . Mars, on the other hand, appears to be a mixture of ~65% , 33% , and < 2% and . We establish that Earth’s contribution substantially increased during the latter half of its accretion. Mars began accreting a mix of and but predominantly accreted later. Mars’ changing isotopic makeup during accretion can be explained if it underwent gas-driven type I migration from its origin near the – boundary to a location well within the region during the first few million years of solar system history. Earth’s later increased contribution may be attributed to the stochastic impact of an interloper carbonaceous embryo that moved inside the inner solar system region while nebular gas was still present, and subsequently participated in the stage of chaotic growth. The discovery that a significant portion of Earth’s building blocks closely resembles enstatite chondrites contrasts with recent findings of Si isotopic anomalies in enstatite chondrites when compared to terrestrial rocks. We suggest this discrepancy likely stems from insufficient correction for high-temperature equilibrium isotopic fractionation, whether of nebular or planetary origin. With appropriate adjustments for this influence, both the silicate Earth and enstatite chondrites exhibit comparable Si isotopic anomalies, reaffirming a genetic link between them.

¹Peter L. Olson,¹Zachary D. Sharp
Earth and Planetary Science Letters 622, 118418 Link to Article [https://doi.org/10.1016/j.epsl.2023.118418]
¹Earth and Planetary Sciences, University of New Mexico, United States of America
Copyright Elsevier

We combine calculations of pebble accretion and accretion by large and giant impacts to quantify the effects of pebbles on the hafnium-tungsten system during Earth formation. Our models include an early pebble accretion phase lasting 4–6 Myr with a global magma ocean and core segregation, a 20–50 Myr phase of large impacts, and a late giant impact representing the Moon-forming event. We consider various mass additions during each accretion phase, vary the metal-silicate partition coefficient for tungsten over a wide range, and track Hf180, Hf182, W182 and W184 in proto-Earth and impactor models over time using standard chondritic values for these isotopes in the pebbles. We find that an early phase of pebble accretion is compatible with the tungsten anomaly of Earth’s early mantle as well as the present-day Hf/W ratio, but under restricted conditions. In particular, the pebble mass of proto-Earth is limited to 0.7 Earth masses or less, the average metal-silicate partition coefficient for tungsten is 30–50, and because the metal-silicate equilibration efficiency for giant impacts is low, the equilibration efficiency must be high for the large impactors.