¹Petrova, E.V.,¹Maksimova, A.A.,¹Chukin, A.V.,¹Oshtrakh, M.I.
Hyperfine Interactions 240, 42 Link to Article [DOI: 10.1007/s10751-019-1592-9]
¹Department of Experimental Physics, Institute of Physics and Technology, Ural Federal University, Ekaterinburg, 620002, Russian Federation

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¹Yoko Kebukawa,²Conel M. O’D. Alexander,¹George D. Cody
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13302]
¹Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road, Washington, District of Columbia, 20015 USA
²Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road, Washington, District of Columbia, 20015 USA
Published by arrangement with John Wiley & Sons

Past studies of the various separable carbonaceous fractions have been unable to account for all of C in primitive chondrites. In particular, up to 20–50% of the C is lost during acid leaching of bulk samples even after the C in carbonates and soluble organic matter is accounted for. To try to better characterize the nature of this “missing C,” we have compared the bulk infrared (IR) absorption spectra of a number of primitive chondrites with those of their previously reported insoluble organic matter (IOM). The aliphatic C–H stretching bands, in particular, allow us to compare the molecular structures of bulk C with that of IOM. The spectral differences between bulk C and IOM reflect “missing C” phases that were lost during acid leaching, although we cannot completely exclude the possibility that the OM was modified after demineralization. Comparing IR spectra of bulk meteorite powder and IOM suggests that the missing C varies in its molecular structure, and that mildly thermally metamorphosed type 3 chondrites tend to be richer in an aliphatic fraction with lower CH₂/CH₃ ratios, relative to IOM, compared to aqueously altered carbonaceous chondrites (CI/CM/CR). The missing C is most likely released from acid‐labile functional groups, such as esters, acetals, and amides, during demineralization, although it cannot be ruled out that some fraction of the missing C is in small grains that are difficult to recover from suspension, or in water‐soluble compounds trapped in phyllosilicates.

¹Anthony Gargano,²Zachary Sharp
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13303]
¹Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico, 87131‐0001 USA
²Center for Stable Isotopes, University of New Mexico, Albuquerque, New Mexico, 87131‐0001 USA
Published by arrangement with John Wiley & Sons

The bulk chlorine concentrations and isotopic compositions of a suite of non‐carbonaceous (NC) and carbonaceous (CC) iron meteorites were measured using gas source mass spectrometry. The δ37Cl values of magmatic irons range from −7.2 to 18.0‰ versus standard mean ocean chloride and are unrelated to their chlorine concentrations, which range from 0.3 to 161 ppm. Nonmagmatic IAB irons are comparatively Cl‐rich containing >161 ppm with δ37Cl values ranging from −6.1 to −3.2‰. The anomalously high and low δ37Cl values are inconsistent with a terrestrial source, and as Cl contents in magmatic irons are largely consistent with derivation from a chondrite‐like silicate complement, we suggest that Cl is indigenous to iron meteorites. Two NC irons, Cape York and Gibeon, have high cooling rates with anomalously high δ37Cl values of 13.4 and 18.0‰. We interpret these high isotopic compositions to result from Cl degassing during the disruption of their parent bodies, consistent with their low volatile contents (Ga, Ge, Ag). As no relevant mechanisms in iron meteorite parent bodies are expected to decrease δ37Cl values, whereas volatilization is known to increase δ37Cl values by the preferential loss of light isotopes, we interpret the low isotope values of <−5‰ and down to −7.2‰ to most closely represent the primordial isotopic composition of Cl in the solar nebula. Similar conclusions have been derived from low δ37Cl values down to −6, and −3.8‰ measured in Martian and Vestan meteorites, respectively. These low δ37Cl values are in contrast to those of chondrites which average around 0‰ previously explained by the incorporation of isotopically heavy HCl clathrate into chondrite parent bodies. The poor retention of low δ37Cl values in many differentiated planetary materials suggest that extensive devolatilization occurred during planet formation, which can explain Earth’s high δ37Cl value by the loss of approximately 60% of the initial Cl content.

^1,2Mike Meyer,³Peter J. Harries,⁴Roger W. Portell
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13299]
¹Earth and Environmental Science Department, Harrisburg University, Harrisburg, Pennsylvania, 17101 USA
²Geophysical Laboratory, Carnegie Institution for Science, Washington, DC, 20005 USA
³Department of Marine, Earth, and Atmospheric Sciences, North Carolina State University, Raleigh, North Carolina, 27695 USA
⁴Florida Museum of Natural History, University of Florida, Gainesville, Florida, 32611 USA
Published by arrangement with John Wiley & Sons

The Plio‐Pleistocene Upper Tamiami Formation (Pinecrest beds) of Florida is well known for its fossiliferous shell beds, but not for its extraterrestrial material. Here we report the first occurrence of tiny (~200 μm in diameter) silica‐rich microspherules from this unit and from the state. This material was analyzed using petrographic and elemental methods using energy dispersive X‐ray spectroscopy (EDS). The majority of microspherules are glassy and translucent in reflected light with some displaying “contact pairs” (equal‐sized micro‐spherules attached to each other). Broken microspherules cleave conchoidally, often with small internal spherical vesicles, but most lack any other evidence of internal features, such as layering. Using the EDS data, the microspherules were compared to volcanic rocks, microtektites, and cosmic spherules (micrometeorites). Based on their physical characteristics and elemental compositions these are likely microtektites or a closely related type of material. The high Na content in the examined material deviates significantly from the abundances usually found in micrometeorites and tektite material; this is enigmatic and requires further study. This material may be derived from a nearby previously unknown impact event; however, more material and sites are required to confirm the source of this material. Because of the focus on molluscan fossils in southwestern Florida shell beds, microtektite material has likely been overlooked in the past, and it is probable that these microspherules are in abundance elsewhere in these units and possibly throughout the region.

^1,2Nichols, C.I.O.,^1,3Einsle, J.F.,^4,5,6Im, M.-Y.,⁷Kasama, T.,^3,8Saghi, Z.,³Midgley, P.A.,¹Harrison, R.J.
Geochemistry, Geophysics, Geosystems 20, 1441-1453 Link to Article [DOI: 10.1029/2018GC008159]
¹Department of Earth Sciences, University of Cambridge, Cambridge, United Kingdom
²Department of Earth, Atmospheric and Planetary Sciences, MIT, Cambridge, MA, United States
³Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, United Kingdom
⁴Center for X-ray Optics, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
⁵Department of Emerging Materials Science, DGIST, Daegu, South Korea
⁶School of Materials Science and Engineering, Ulsan National Institute of Science and Technology, Ulsan, South Korea
⁷National Centre for Nano Fabrication and Characterisation, Technical University of Denmark, Kongens Lyngby, Denmark
⁸CEA, LETI, MINATEC Campus, Grenoble, France

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¹Hayashi, T.,¹Muramatsu, H.,¹Maehisa, K.,¹Yamasaki, N.Y.,¹Mitsuda, K.,²Maehata, K.,³Hara, T.
IEEE Transactions on Applied Superconductivity 29, #8654629 Link to Article [DOI: 10.1109/TASC.2019.2902304]
¹Institute of Space and Astronautical Science Japan Aerospace Exploration Agency (ISAS/JAXA), Kanagawa, 252-5210, Japan
²Department of Applied Quantum Physics and Nuclear Engineering, Kyushu University, Fukuoka, 819-0395, Japan
³National Institute for Materials Science (NIMS), Ibarakiken, 305-0044, Japan

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^1,2Miyahara, M.,²Ohtani, E.,³Nishijima, M.,⁴El Goresy, A.
Physics of the Earth and Planetary Interiors 291, 1-11 Link to Article [DOI: 10.1016/j.pepi.2019.04.001]
¹Department of Earth and Planetary Systems Science, Graduate School of Science, Hiroshima University, Higashi-Hiroshima, 739-8526, Japan
²Department of Earth Sciences, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan
³Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan
⁴Bayerisches Geoinstitut, Universität Bayreuth, Bayreuth, D-95440, Germany

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¹Oshtrakh, M.I.,¹Maksimova, A.A.,¹Chukin, A.V., Petrova,¹E.V.,²Jenniskens, P.,³Kuzmann, E.,¹Grokhovsky, V.I.,³Homonnay, Z.,¹Semionkin, V.A.
Spectrochimica Acta – Part A: Molecular and Biomolecular Spectroscopy 219, 206-224 Link to Article [DOI: 10.1016/j.saa.2019.03.036]
¹Institute of Physics and Technology, Ural Federal University, Ekaterinburg, 620002, Russian Federation
²SETI Institute, 189 Bernardo Avenue, Mountain View, CA 94043, United States
³Institute of Chemistry, Eötvös Loránd University, Pázmány sétány 1/A, Budapest, 1117, Hungary

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¹A.H.Peslier,² R.Hervig,³S.Yang,³M.Humayun,^4,5J.J.Barnes,⁶A.J.Irving,⁷A.D.Brandon
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2019.04.023]
¹Jacobs, NASA-Johnson Space Center, Mail Code X13, Houston TX 77058, USA
²School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287, USA
³National High Magnetic Field Lab, Florida State University, Tallahassee, FL 32310, USA
⁴ARES, NASA-Johnson Space Center, Houston, TX 77058, USA
⁵Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721, USA
⁶Dept. of Earth & Space Sciences, University of Washington, Seattle, WA, USA
⁷Dept. of Earth and Atmospheric Sciences, University of Houston, Houston, TX 77204, USA
Copyright Elsevier

Knowing the distribution and origin of water in terrestrial planets is crucial to understand their formation, evolution and the source of their atmospheres and surface water. The nakhlites represent a suite of minimally shocked meteorites that likely originated from lava flows from a single volcano or from a shallow intrusion or sill complex on Mars. Measuring the water contents and D/H ratios of their igneous minerals allows identification of phases that have preserved their magmatic hydrogen, and therefrom permits estimation of the water content of their mantle source. Pyroxene, olivine, melt inclusions and mesostasis of five nakhlites (NWA 998, Nakhla, Y 000593, MIL 03346 and NWA 6148) were analyzed in situ for water contents and H isotopes, and major and trace element contents. No water was detected in olivine grains except in Y 000593. The water content of pyroxenes is highly heterogeneous within individual grains and between grains within a single meteorite. Water concentrations in pyroxene (<0.1-387 ppm H2O), melt inclusions (26-4130 ppm H2O) and mesostasis (1130-7850 ppm H2O) decrease with increasing δD (from -268 to 4858 ‰) in all nakhlites. After ruling out significant influence from spallation, exchange with the martian atmosphere, shock, surface alteration, and hydrothermal processes, the H data of the pyroxenes can be explained by degassing and crystallization processes. Degassing is consistent with a decrease of water content from pyroxene interior to edge. Fractionation of H isotopes during degassing results in increases of δD during H loss from pyroxene but in decreases in δD during H2O-OH loss from a melt. Consequently, the low-water content, high-δD of most pyroxenes is best explained by degassing after the pyroxenes had crystallized. All melt and plagioclase inclusions analyzed are located in degassed pyroxenes and are also degassed. The lower δD of the mesostasis (24 ± 131 ‰) compared to that of the least-degassed pyroxenes (430 ± 172 ‰) is likely the result of melt degassing and interaction with hydrothermal fluids. Magmatic H, however, has been preserved in each nakhlite in some pyroxenes that are characterized by > 15 ppm H2O and δD < 700‰. The H composition of the least-degassed, most-Mg-rich augites can be interpreted in two ways. If Cl-bearing hydrothermal fluids were assimilated by the parent magma of nakhlites prior to pyroxene crystallization, the H composition could represent a crustal signature. If hydrothermal fluid assimilation occurred after pyroxenes start crystallizing, it could be a mantle signature. We favor the latter scenario, in which case the martian mantle sampled by the nakhlites is estimated to contain 59-184 ppm H2O and to have a δD of 430 ± 172 ‰. These water contents, similar to those of the upper part of the terrestrial mantle, represent those of a shallow depleted martian mantle reservoir. The two to four times higher δD of the martian mantle relative to that of Earth could have resulted from the two planets acquiring their water from different proportions and types of carbonaceous chondrite-like planetesimals.

^1,2Natsuki Hosono,³Shun-ichiro Karato,^2,4Junichiro Makino,^4,5Takayuki R. Saitoh
Nature Geoscience (in Press) Link to Article [https://doi.org/10.1038/s41561-019-0354-2]
¹Yokohama Institute for Earth Sciences, Japan Agency for Marine-Earth Science and Technology, Yokohama, Kanagawa, Japan
²RIKEN Center for Computational Science, Kobe, Hyogo, Japan
³Department of Geology and Geophysics, Yale University, New Haven, CT, USA
⁴Department of Planetology, Kobe University, Kobe, Hyogo, Japan
⁵Earth-Life Science Institute, Tokyo Institute of Technology, Meguro-ku, Tokyo, Japan

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