¹Petrova, E.V.,¹Grokhovsky, V.I.
Pure and Applied Chemistry 91, 1857-1867 Link to Article [DOI: 10.1515/pac-2018-1119]
¹Ural Federal University, Institute of Physics and Technology, Ekaterinburg, Russian Federation

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¹Åke V. Rosén,^1,2Beda A. Hofmann,³Moritz von Sivers,^3,4Marc Schumann
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13427]
¹Institute of Geological Sciences, University of Bern, Baltzerstrasse 1+3, 3012 Bern, Switzerland
²Natural History Museum Bern, Bernastrasse 15, 3005 Bern, Switzerland
³Albert Einstein Center for Fundamental Physics, University of Bern, Sidlerstrasse 5, 3012 Bern, Switzerland
⁴Institute of Physics, University of Freiburg, Hermann‐Herder‐Strasse 3, 79104 Freiburg, Germany
Published by arrangement with John Wiley & Sons

Radionuclide activities were measured in the low‐background gamma‐ray spectrometry facility GeMSE in eight meteorite falls (Lost City, Tamdakht, Huaxi, Boumdeid, Xining, Kamargaon, Degtevo, and Ouidiyat Sbaa) and two finds (SaU 606 and Mürtschenstock) to evaluate the use of radionuclides for terrestrial age estimates. Results indicate that these meteorites were all derived from small‐ (r < 25 cm) to medium‐sized (r < 65 cm) meteoroids. Short‐lived ⁴⁸V (t_1/2 = 16.0 d) and ⁵¹Cr (t_1/2 = 27.7 d) were only detected in Oudiyat Sbaa (EH), while ⁷Be (t_1/2 = 53.1 d) was also detected in Degtevo (H) and Kamargaon (L), in agreement with reported fall dates. The ²²Na/²⁶Al activity ratio in Huaxi agrees with the previously reported short cosmic‐ray exposure age of this meteorite while ²²Na/²⁶Al in Kamargaon likely records a complex exposure history. Bayesian statistical analysis verifies the detection of very low activities of ⁴⁴Ti (t_1/2 = 60 a) in the relatively large H chondrites (>100 g) Degtevo, Huaxi, Tamdakht, Lost City, and SaU 606. Additionally, large samples from Oudiyat Sbaa (EH) and Kamargaon (L) gave positive detections. For H chondrite target compositions, detected ⁴⁴Ti(Fe+Ni)/²⁶Al averaged 0.055 ± 0.013. Activities of ²²Na and ⁵⁴Mn in SaU 606 show that this meteorite fell between July and September 2012, making SaU 606 the second recent fall from Oman identified using gamma‐ray spectrometry. The upper activity limit of ²²Na in the Mürtschenstock meteorite shows that it fell prior to 1999 and is not related to a bolide observation in 2015. Mürtschenstock shows ¹³⁷Cs ~10× higher than previously determined in Oman meteorites, likely due to Chernobyl fallout.

¹J. Nava,^2,3M. D. Suttle,¹R. Spiess,²L. Folco,³J. Najorka,⁴C. Carli,¹M. Massironi
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13429]
¹Department of Geosciences, University of Padova, Via G.Gradenigo 6, 35131 Padova, Italy
²Dipartimento di Scienze della Terra, Università di Pisa, 56126 Pisa, Italy
³Core Research Laboratories, Department of Earth Science, The Natural History Museum, Cromwell Rd, London, SW7 5BD UK
⁴IAPS‐INAF, Istituto Nazionale di Astrofisica e Planetologia Spaziali, Roma, Italy
Published by arrangement with John Wiley & Sons

TAM5.29 is an extraterrestrial dust grain, collected on the Transantarctic Mountains (TAM). Its mineralogy is dominated by an Fe‐rich matrix composed of platy fayalitic olivines and clasts of andradite surrounded by diopside‐jarosite mantles; chondrules are absent. TAM5.29 records a complex geological history with evidence of extensive thermal metamorphism in the presence of fluids at T < 300 °C. Alteration was terminated by an impact, resulting in shock melt veins and compaction‐orientated foliation of olivine. A second episode of alteration at lower temperatures (<100 °C) occurred postimpact and is either parent body or terrestrial in origin and resulted in the formation of iddingsite. The lack of chondrules is explained by random subsampling of the parent body, with TAM5.29 representing a matrix‐only fragment. On the basis of bulk chemical composition, mineralogy, and geological history TAM5.29 demonstrates affinities to the CV_ox group with a mineralogical assemblage in between the Allende‐like and Bali‐like subgroups (CV_oxA and TAM5.29 are rich in andradite, magnetite, and FeNiS, but CV_oxA lacks hydrated minerals, common in TAM5.29; conversely, CV_oxB are rich in hydrated phyllosilicates but contain almost pure fayalite, not found in TAM5.29). In addition, TAM5.29 has a slightly different metasomatic history, in between the oxidized and reduced CV metamorphic grades while also recording higher oxidizing conditions as compared to the known CV chondrites. This study represents the third CV‐like cosmic dust particle, containing a unique composition, mineralogy, and fabric, demonstrating variation in the thermal metamorphic history of the CV parent body(‐ies).

¹Gary R. Huss,¹Elizabeth Koeman‐Shields,²Amy J. G. Jurewicz,³Donald S. Burnett,¹Kazuhide Nagashima,⁴Ryan Ogliore,⁵Chad T. Olinger
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13420]
¹Hawai‘i Institute of Geophysics and Planetology, University of Hawai‘i at Mānoa, 1680 East‐West Road, POST 504, Honolulu, Hawai‘i, 96822 USA
²Center for Meteorite Studies, Arizona State University, 781 E. Terrace Rd, ISTB4‐m/c 6004, Tempe, Arizona, 85287‐6004 USA
³Division of Geological and Planetary Science, California Institute of Technology, Mail Code 100‐23, 1200 E. California Blvd., Pasadena, California, 91125 USA
⁴Department of Physics, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri, 63130 USA
⁵GET‐NSA, LLC, AU‐62, 19901 Germantown Rd, Germantown, Maryland, 20875 USA
Published by arrangement with John Wiley & Sons

NASA’s Genesis mission was flown to capture samples of the solar wind and return them to the Earth for measurement. The purpose of the mission was to determine the chemical and isotopic composition of the Sun with significantly better precision than known before. Abundance data are now available for noble gases, magnesium, sodium, calcium, potassium, aluminum, chromium, iron, and other elements. Here, we report abundance data for hydrogen in four solar wind regimes collected by the Genesis mission (bulk solar wind, interstream low‐energy wind, coronal hole high‐energy wind, and coronal mass ejections). The mission was not designed to collect hydrogen, and in order to measure it, we had to overcome a variety of technical problems, as described herein. The relative hydrogen fluences among the four regimes should be accurate to better than ±5–6%, and the absolute fluences should be accurate to ±10%. We use the data to investigate elemental fractionations due to the first ionization potential during acceleration of the solar wind. We also use our data, combined with regime data for neon and argon, to estimate the solar neon and argon abundances, elements that cannot be measured spectroscopically in the solar photosphere.

¹A. A. Maksimova,¹E. V. Petrova,¹A. V. Chukin,¹ M. S. Karabanalov,²I. Felner,^1,3,4M. Gritsevich,¹M. I. Oshtrakh
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13423]
¹Institute of Physics and Technology, Ural Federal University, Ekaterinburg, 620002 Russian Federation
²Racah Institute of Physics, The Hebrew University, Jerusalem, 91904 Israel
³Department of Physics, University of Helsinki, Gustaf Hällströmin katu 2a, PO Box 64, FI‐00014 Helsinki, Finland
⁴Finnish Geospatial Research Institute, Geodeetinrinne 2, 02430 Masala, Finland
Published by arrangement with John Wiley & Sons

We studied the interior and the fusion crust of the recently recovered Ozerki L6 meteorite using optical microscopy, scanning electron microscopy (SEM) with energy dispersive spectroscopy, X‐ray diffraction (XRD), magnetization measurements, and Mössbauer spectroscopy. The phase composition of the interior and of the fusion crust was determined by means of SEM, XRD, and Mössbauer spectroscopy. The unit cell parameters for silicate crystals were evaluated from the X‐ray diffractograms and were found the same for the interior and the fusion crust. Magnetization measurements revealed a decrease of the saturation magnetic moment in the fusion crust due to a decrease of Fe‐Ni‐Co alloy content. Both XRD and Mössbauer spectroscopy show the presence of magnesioferrite in the fusion crust. The temperatures of cation equilibrium distribution between the M1 and M2 sites in silicates calculated using the data obtained from XRD and Mössbauer spectroscopy appeared to be in a good consistency: 553 and 479 K for olivine and 1213 and 1202 K for orthopyroxene.

¹Kerry Sieh,¹Jason Herrin,²Brian Jicha, ¹Dayana Schonwalder Angel,¹James D. P. Moore, ¹Paramesh Banerjee,³Weerachat Wiwegwin, ⁴Vanpheng Sihavong,²Brad Singer,³Tawachai Chualaowanich,⁵Punya Charusiri
Proceedings of the National Academy of Sciences of the United States of America (PNAS)(In Press) Link to Article [DOI:https://doi.org/10.1073/pnas.1904368116]
¹Earth Observatory of Singapore, Nanyang Technological University, 639798 Singapore;
²Department of Geoscience, University of Wisconsin–Madison, Madison, WI 53706;
³Department of Mineral Resources, Ministry of Natural Resources and Environment, Ratchatewi, 10400 Bangkok, Thailand;
⁴Department of Geology and Mines, Ministry of Energy and Mines, Vientiane, Lao People’s Democratic Republic;
⁵Department of Geology, Chulalongkorn University, Khet Pathumwan, 10330 Bangkok, Thailand

The crater and proximal effects of the largest known young meteorite impact on Earth have eluded discovery for nearly a century. We present 4 lines of evidence that the 0.79-Ma impact crater of the Australasian tektites lies buried beneath lavas of a long-lived, 910-km³ volcanic field in Southern Laos: 1) Tektite geochemistry implies the presence of young, weathered basalts at the site at the time of the impact. 2) Geologic mapping and ⁴⁰Ar-³⁹Ar dates confirm that both pre- and postimpact basaltic lavas exist at the proposed impact site and that postimpact basalts wholly cover it. 3) A gravity anomaly there may also reflect the presence of a buried ∼17 × 13-km crater. 4) The nature of an outcrop of thick, crudely layered, bouldery sandstone and mudstone breccia 10–20 km from the center of the impact and fractured quartz grains within its boulder clasts support its being part of the proximal ejecta blanket.

¹A.B.Verchovsky,¹M.Anand,¹S.J.Barber,¹S.Sheridan,¹G.H.Morgan
Planetary and Space Science (in Press) Link to Article [https://doi.org/10.1016/j.pss.2019.104830]
¹School of Physical Sciences, The Open University, Milton Keynes, MK7 6AA, UK

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^1,2Leonard F. Henrichs,²Agnes Kontny,²Boris Reznik,³Uta Gerhards,⁴Jörg Göttlicher,²Tim Genssle,²Frank Schilling
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13422]
¹Karlsruhe Institute of Technology, Institute of Nanotechnology, Hermann‐von‐Helmholtz‐Platz 1, 76344 Eggenstein‐Leopoldshafen, Germany
²Karlsruhe Institute of Technology, Institute of Applied Geosciences, Adenauerring 20, 76131 Karlsruhe, Germany
³Karlsruhe Institute of Technology, Institute for Micro Process Engineering, Hermann‐von‐Helmholtz‐Platz 1, 76344 Eggenstein‐Leopoldshafen, Germany
⁴Karlsruhe Institute of Technology, Institute for Photon Science and Synchrotron Radiation (IPS), Hermann‐von‐Helmholtz‐Platz 1, 76344 Eggenstein‐Leopoldshafen, Germany
Published by arrangement with John Wiley & Sons

Projectile–target interactions as a result of a large bolide impact are important issues, as abundant extraterrestrial material has been delivered to the Earth throughout its history. Here, we report results of shock‐recovery experiments with a magnetite‐quartz target rock positioned in an ARMCO iron container. Petrography, synchrotron‐assisted X‐ray powder diffraction, and micro‐chemical analysis confirm the appearance of wüstite, fayalite, and iron in targets subjected to 30 GPa. The newly formed mineral phases occur along shock veins and melt pockets within the magnetite‐quartz aggregates, as well as along intergranular fractures. We suggest that iron melt formed locally at the contact between ARMCO container and target, and intruded the sample causing melt corrosion at the rims of intensely fractured magnetite and quartz. The strongly reducing iron melt, in the form of μm‐sized droplets, caused mainly a diffusion rim of wüstite with minor melt corrosion around magnetite. In contact with quartz, iron reacted to form an iron‐enriched silicate melt, from which fayalite crystallized rapidly as dendritic grains. The temperatures required for these transformations are estimated between 1200 and 1600 °C, indicating extreme local temperature spikes during the 30 GPa shock pressure experiments.

¹Friedrich Hörz,²Mark J. Cintala,¹Kathie L. Thomas‐Keprta,¹Daniel K. Ross,¹Simon J. Clemett
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13424]
¹Jacobs‐JETS, 2224 Bay Area Boulevard, Houston, Texas, 77058 USA
²Code XI3, NASA Johnson Space Center, 2101 NASA Parkway, Houston, Texas, 77058 USA
Published by arrangement with John Wiley & Sons

We shocked calcite in an unconfined environment by launching small marble cylinders at 0.8–5.5 km s−1 into aluminum or copper plates, producing shock stresses between 5 and 79 GPa. The resulting 5–20 mm craters contained intimately mixed clastic and molten projectile residues over the entire pressure range, with melting commencing already at 5 GPa. Stoichiometrically pure calcite melts were not observed as all melts contained target metal. Some of these residues were distinctly depleted in CO2 and some contained even tiny CaO crystals, thus illustrating partial to complete loss of CO2. We interpret a thin seam of finely crystalline calcite to be the product of back reactions between CaO and CO2. The amount of carbonate residue in these craters, especially those at low velocities (<2 km s−1), is dramatically less than that of silicate impactors in similar cratering experiments, and we suggest that this is due to substantial outgassing of CO2. Similarly, the volume of carbonate melts relative to the volume of limestone or dolomite in many terrestrial crater structures seems insignificant as well, as is the volume of carbonate melt compared to the volume of impact melts derived from silicates. These volume considerations suggest that volatilization of CO2 is the dominant process in carbonate‐containing targets. Because we have difficulties in explaining naturally occurring calcite melts by shock processes in dolomite‐dominated targets, we speculate—essentially via process of elimination—that such carbonate melt blebs might be condensation products from an impact‐produced vapor cloud.

^1,2N. G. Lunning,³A. Bischoff,²J. Gross,³M. Patzek,¹C. M. Corrigan,¹T. J. McCoy
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13430]
¹Department of Mineral Sciences, National Museum of Natural History, Smithsonian Institution, Washington, District of Columbia, 20560‐0119 USA
²Rutgers, Department of Earth and Planetary Sciences, The State University of New Jersey, 610 Taylor Road, Piscataway, New Jersey, 08854‐8066 USA
³Institut für Planetologie, Westfälische Wilhelms‐Universität Münster, Wilhelm‐Klemm‐Str. 10, D‐48149 Münster, Germany
Published by arrangement with John Wiley & Sons

Ancient, SiO₂‐rich achondrites have previously been proposed to have formed by disequilibrium partial melting of chondrites. Here, we test the alternative hypothesis that these achondrites formed by fractional crystallization of impact melts of Rumuruti (R) chondrites. We identified two new melt clasts in R chondrites, one in Pecora Escarpment (PCA) 91241 and one in LaPaz Icefield (LAP) 031275. We analyzed major, minor, and trace element concentrations, as well as oxygen isotopes, of these two clasts and a third one that had been previously recognized (Bischoff et al. 2011) as an impact melt in Dar al Gani (DaG) 013. The melt clast in PCA 91241 is an R chondrite impact melt closely resembling the one previously recognized in DaG 013. The melt clast in LAP 031275 has an L chondrite provenance. We show that SiO₂‐rich melts could form from the mesostases of R chondrite impact melts. However, their CI‐normalized rare earth element patterns are flat, whereas those of ancient SiO₂‐rich achondrites (Day et al. 2012; Srinivasan et al. 2018) and those of disequilibrium partial melts of chondrites (Feldstein et al. 2001) have positive Eu anomalies from preferential melting of plagioclase. Thus, we conclude that ancient SiO₂‐rich achondrites were probably formed by disequilibrium partial melting (due to an internal heat source on their parent bodies), rather than from impact melts.