¹J.V. Clark,²B. Sutter,³A.C. McAdam,⁴E.B. Rampe,²P.D. Archer,⁴D.W. Ming,⁵R. Navarro‐Gonzalez,³P. Mahaffy,⁶T.J. Lapen
Journal of Geophysical Research, Planets (in Press) Link to Article [https://doi.org/10.1029/2019JE006173]
¹Geocontrols Systems – Jacobs JETS Contract at NASA Johnson Space Center, Houston, TX
²Jacobs JETS Contract at NASA Johnson Space Center, Houston, TX
³NASA Goddard Space Flight Center, Greenbelt, MD
⁴NASA Johnson Space Center, Houston, TX
⁵Universidad Nacional Autonoma de Mexico, Mexico City, Mexico
⁶University of Houston, Houston, TX
Published by arrangement with John Wiley & Sons

Evolved hydrogen chloride (HCl) detected by the Sample Analysis at Mars (SAM) instrument’s evolved gas analysis (EGA) mode on board the Mars Science Laboratory Curiosity rover has been attributed to oxychlorines (i.e., perchlorates and chlorates) or chlorides in Gale crater samples. Previous laboratory EGA studies of oxychlorines have been unable to reproduce the high‐temperature (>600 °C) HCl evolutions observed in most Gale crater samples. The objective of this work was to reproduce these high temperature HCl releases from laboratory mixtures of perchlorates and chlorides with phases that evolve water upon heating. Magnesium and sodium perchlorate and chloride were mixed with saponite, nontronite, and a basaltic glass and analyzed in a laboratory thermal evolved gas analyzer configured to operate similarly to the SAM instrument. Na perchlorate and chloride evolved HCl only when mixed with all three water‐producing phases. Mg perchlorate and chloride evolved a mid‐temperature HCl release (~450‐550 °C) and evolved an additional high‐temperature HCl release (~810‐820 °C) when mixed with saponite. This work demonstrated that chlorides, either originally present or from perchlorate decomposition, evolved high‐temperature HCl when reacting with water from water‐producing phases. The HCl release temperature was dependent on the mixture’s mineralogy and chemical composition. HCl releases detected by SAM were consistent with oxychlorines and/or chlorides in the presence of water‐producing phases. Additionally, this work provided constraints on the presence of oxychlorines or chlorides and their cation‐types, which has implications for past aqueous and diagenetic processes, the potential for past life, and detection of organics by EGA.

¹W. Crawford Elliott
American Mineralogist (2020) 105 (1): 1-2. Link to Article [https://doi.org/10.2138/am-2020-7312]
¹Department of Geosciences, Georgia State University, Atlanta, Georgia 30302-3965, U.S.A.

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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.