High‐temperature HCl evolutions from mixtures of perchlorates and chlorides with water‐bearing phases: Implications for the Sample Analysis at Mars (SAM) instrument in Gale crater, Mars

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.

Radionuclide activities in recent chondrite falls determined by gamma‐ray spectrometry: Implications for terrestrial age estimates

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 (t1/2 = 16.0 d) and 51Cr (t1/2 = 27.7 d) were only detected in Oudiyat Sbaa (EH), while 7Be (t1/2 = 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 (t1/2 = 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.

Hydrothermal activity on the CV parent body: New perspectives from the giant Transantarctic Mountains minimeteorite TAM5.29

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 CVox group with a mineralogical assemblage in between the Allende‐like and Bali‐like subgroups (CVoxA and TAM5.29 are rich in andradite, magnetite, and FeNiS, but CVoxA lacks hydrated minerals, common in TAM5.29; conversely, CVoxB 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).

Hydrogen fluence in Genesis collectors: Implications for acceleration of solar wind and for solar metallicity

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.

Characterization of the matrix and fusion crust of the recent meteorite fall Ozerki L6

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.