Month: April 2021

Suevites and Tagamites of Zhamanshin Astrobleme: Distribution in the Crater and Petrographic Features

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1Sergienko, E.S.,1Yanson, S.Y.,1Kosterov, A.,2Kharitonskii, P.V.,3Frolov, A.M.
IOP Conference Series: Earth and Environmental Science 666, 042080 Link to Article [DOI: 10.1088/1755-1315/666/4/042080]
1St. Petersburg State University, Universitetskaya nab. 7-9, St. Petersburg, 199034, Russian Federation
2Saint Petersburg Electrotechnical University ‘Leti’, Prof. Popova str. 5, St.Petersburg, 197376, Russian Federation
3Far Eastern Federal University, Sukhanova str. 8, Vladivostok, 690950, Russian Federation

We currently do not have a copyright agreement with this publisher and cannot display the abstract here

Microtektites and glassy cosmic spherules from new sites in the Transantarctic Mountains, Antarctica

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1Lauren E. Brase,1Ralph Harvey,2,3Luigi Folco,2Martin D. Suttle,4E. Carrie McIntosh,4James M. D. Day,5Catherine M. Corrigan
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13634]
1Department of Earth, Environmental, and Planetary Sciences, Case Western Reserve University, Cleveland, Ohio, 44106 USA
2Dipartimento di Scienze della Terra, Università di Pisa, Via S. Maria 53, 56126 Pisa, Italy
3CISUP, Centro per l’Integrazione della Strumentazione dell’Università di Pisa, Lungarno Pacinotti 43, 56126 Pisa, Italy
4Scripps Institution of Oceanography, University of California San Diego, La Jolla, California, 92093 USA
5Department of Mineral Sciences, National Museum of Natural History, Smithsonian Institution, Washington, D.C., 20560 USA
Published by arrangement with John Wiley & Sons

We report on the geochemical analyses of glassy spherules from sediments at three Transantarctic Mountain locations and the discovery of Australasian microtektites at two of these sites. Australasian microtektites are present at Mt. Raymond (RY) in the Grosvenor Mountains and Meteorite Moraine (MM) at Walcott Névé, in the Beardmore Glacier region of Antarctica. The microtektites were identified based on their pale yellow appearance, the high concentrations of silica (SiO2 = 60 ± 7 wt%) and alumina (Al2O3 = 23 ± 4 wt%), and a K2O/Na2O > 1, which are all characteristics of microtektites and distinct from spherules of meteoritic origin. Additionally, trace element patterns for these microtektites match the upper continental crust compositions with enrichments in refractory elements and depletions in volatile elements, most likely as a result of melting and vaporization of source material. The presence of Australasian microtektites in RY sediment confirms the recent Australasian strewn field extension to Antarctica and the presence of highly volatile depleted microtektites. In addition to microtektites, thousands of chondritic spherules and a few unique differentiated cosmic spherules were identified in RY, MM, and Jacobs Nunatak sediments. Two unique spherules were calculated to have Fe/Mn ratios similar to micrometeorites assumed to be derived from Vesta (Fe/Mn 33.2 ± 0.5 atom%) and two other unique spherules are extremely rich in refractory components (Al2O3 ~ 30% and TiO2 = ~2%). The three sites examined are evidently successful cosmic dust and impact debris collectors, and thus are useful traps for recording and examining the nature of influx events.

Heat diffusion in numerically shocked ordinary chondrites and its contribution to shock melting

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1,2Moreau, J.-G.,3Schwinger, S.
Physics of the Earth and Planetary Interiors 310, 106630 Link to Article [DOI: 10.1016/j.pepi.2020.106630]
1Department of Geosciences and Geography, University of Helsinki, Finland
2Institute of Ecology and Earth Sciences, Department of Geology, University of Tartu, Estonia
3German Aerospace Center (DLR), Berlin, Germany

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Trace Element Conundrum of Natural Quasicrystals

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1Tommasini, S.,1,2Bindi, L.,3,6Petrelli, M.,4Asimow, P.D.,5Steinhardt, P.J.
ACS Earth and Space Chemistry (in Press) Link to Article [DOI: 10.1021/acsearthspacechem.1c00004]
1Dipartimento di Scienze della Terra, Università Degli Studi di Firenze, Via La Pira 4, Firenze, I-50121, Italy
2CNR-Istituto di Geoscienze e Georisorse, Sezione di Firenze, Via La Pira 4, Firenze, I-50121, Italy
3Dipartimento di Fisica e Geologia, Università Degli Studi di Perugia, Perugia, I-06123, Italy
4Division of Geological and Planetary Sciences, California Institute of Technology, 1200 E. California Blvd. M/C 170-25, Pasadena, CA 91125, United States
5Department of Physics, Princeton University, Jadwin Hall, Princeton, NJ 08544, United States
6INFN, Section of Perugia, Perugia, I-06123, Italy

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Potassium isotopic composition of various samples using a dual-path collision cell-capable multiple-collector inductively coupled plasma mass spectrometer, Nu instruments Sapphire

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1Moynier, F.,1Hu, Y.,2Wang, K.,3Zhao, Y.,3Gérard, Y.,1Deng, Z.,1Moureau, J.,4Li, W.,5Simon, J.I.,6Teng, F.-Z.
Chemical Geology 571, 120144 Link to Article [DOI: 10.1016/j.chemgeo.2021.120144]
1Université de Paris, Institut de Physique du Globe de Paris, CNRS, 1 rue Jussieu, Paris, 75005, France
2Department of Earth and Planetary Sciences, Washington University in St. Louis, St Louis, MO 63130, United States
3Nu Instruments, Unit 74 Clywedog Road South Wrexham Industrial Estate, Wrexham, LL13 9X, United Kingdom
4School of Earth Sciences, Nanjing University, Nanjing, China
5Center for Isotope Cosmochemistry and Geochronology, Astromaterials Research and Exploration Science division, NASA Johnson Space Center, Houston, TX 770058, United States
6Isotope Laboratory, Department of Earth and Space Sciences, University of Washington, Seattle, WA 98195, United States

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Bennu’s global surface and two candidate sample sites characterized by spectral clustering of OSIRIS-REx multispectral images

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1,2J.L.Rizos et al. (>10)
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2021.114467]
1Instituto de Astrofísica de Canarias, C/Vía Láctea s/n, E-38205 La Laguna, Tenerife, Spain
2Departamento de Astrofísica, Universidad de La Laguna, E-38206 La Laguna, Tenerife, Spain
Copyright Elsevier

The OSIRIS-REx spacecraft encountered the asteroid (101955) Bennu on December 3, 2018, and has since acquired extensive data from the payload of scientific instruments on board. In 2019, the OSIRIS-REx team selected primary and backup sample collection sites, called Nightingale and Osprey, respectively. On October 20, 2020, OSIRIS-REx successfully collected material from Nightingale. In this work, we apply an unsupervised machine learning classification through the K-Means algorithm to spectrophotometrically characterize the surface of Bennu, and in particular Nightingale and Osprey. We first analyze a global mosaic of Bennu, from which we find four clusters scattered across the surface, reduced to three when we normalize the images at 550 nm. The three spectral clusters are associated with boulders and show significant differences in spectral slope and UV value. We do not see evidence of latitudinal non-uniformity, which suggests that Bennu’s surface is well-mixed. In our higher-resolution analysis of the primary and backup sample sites, we find three representative normalized clusters, confirming an inverse correlation between reflectance and spectral slope (the darkest areas being the reddest ones) and between b’ normalized reflectance and slope. Nightingale and Osprey are redder than the global surface of Bennu by more than 1σ from average, consistent with previous findings, with Nightingale being the reddest (S′ = (−0.3 ± 1.0) × 10−3% per thousand angstroms). We see hints of a weak absorption band at 550 nm at the candidate sample sites and globally, which lends support to the proposed presence of magnetite on Bennu.