Morphology and physico-chemical characteristics of an iron fragment from Chaco province

1,2Bucurica, I.A.,1,3Radulescu, C.,4Poinescu, A.A.,1,3,5Popescu, I.V.,1Nicolescu, C.M.,1Teodorescu, S.,3Bumbac, M.,6Pehoiu, G.,6Murarescu, O.
Romanian Journal of Physics 64, 906 Link to Article [http://www.nipne.ro/rjp/2019_64_7-8.html]
1Valahia University of Targoviste, Institute of Multidisciplinary Research for Science and Technology, Targoviste, 130004, Romania
2University of Bucharest, Faculty of Physics, Doctoral School of Physics, Bucharest, 050107, Romania
3Valahia University of Targoviste, Faculty of Sciences and Arts, Targoviste, 130004, Romania
4Valahia University of Targoviste, Faculty of Materials Engineering and Mechanics, Targoviste, 130004, Romania
5Academy of Romanian Scientists, Bucharest, 050094, Romania
6Valahia University of Targoviste, Faculty of Humanities, Targoviste, 130105, Romania

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Ferrovolcanism on metal worlds and the origin of pallasites

1Johnson, B.C.,2Sori, M.M.,3Evans, A.J.
Nature Astronomy (in Press) Link to Article [DOI: 10.1038/s41550-019-0885-x]
1Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, IN, United States
2Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, United States
3Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, RI, United States

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Timing and Origin of the Angrite Parent Body Inferred from Cr Isotopes

1Ke Zhu (朱柯),1,2Frédéric Moynier,3Daniel Wielandt,3Kirsten K. Larsen,4Jean-Alix Barrat,3Martin Bizzarro
The Astrophysical Journal Letters 877, L13 Link to Article [DOI
https://doi.org/10.3847/2041-8213/ab2044]
1Institut de Physique du Globe de Paris, Université de Paris, CNRS, 1 rue Jussieu, Paris F-75005, France
2Institut Universitaire de France, 103 boulevard Saint-Michel, Paris F-75005, France
3Centre for Star and Planet Formation and Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5–7, Copenhagen DK-1350, Denmark
4Laboratoire Géosciences Océan (UMR CNRS 6538), Université de Bretagne Occidentale et Institut Universitaire Européen de la Mer, Place Nicolas Copernic, F-29280 Plouzané, France

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The Heavy-element Content Trend of Planets: A Tracer of Their Formation Sites

1Yasuhiro Hasegawa,2Bradley M. S. Hansen,1Gautam Vasisht
The Astrophysical Journal Letters, 876, L32 Link to Article [https://doi.org/10.3847/2041-8213/ab1b5a]
1Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
2Mani L. Bhaumik Institute for Theoretical Physics, Department of Physics & Astronomy, University of California Los Angeles, Los Angeles, CA 90095, USA

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An interval of high salinity in ancient Gale crater lake on Mars

1W. Rapin,1,2B. L. Ehlmann,3G. Dromart,4J. Schieber,1N. H. Thomas,1W. W. Fischer,1V. K. Fox,1N. T. Stein,5M. Nachon,6B. C. Clark,7L. C. Kah,8L. Thompson,1H. A. Meyer,9T. S. J. Gabriel,9C. Hardgrove,10 N. Mangold,11F. Rivera-Hernandez,12R. C. Wiens,13A. R. Vasavada
Nature Geoscience 12, 889-895 Link to Article [https://doi.org/10.1038/s41561-019-0458-8]
1California Institute of Technology, Pasadena, CA, USA
2Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
3Laboratoire de Géologie de Lyon, Université de Lyon, Lyon, France
4Indiana University, Bloomington, IN, USA
5Texas A&M University, College Station, TX, USA
6Space Science Institute, Boulder, CO, USA
7University of Tennessee, Knoxville, TN, USA
8University of New Brunswick, Fredericton, Canada
9School of Earth and Space Exploration, Arizona State University, Tempe, AZ, USA
10Laboratoire de Planétologie et Géodynamique, UMR6112, CNRS,
Université Nantes, Université Angers, Nantes, France
11Dartmouth College, Hanover, NH, USA
12Los Alamos National Laboratory, Los Alamos, NM, USA
13Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA

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Rapid ocean acidification and protracted Earth system recovery followed the end-Cretaceous Chicxulub impact

1,2Michael J. Henehan,3,4Andy Ridgwell,1,5Ellen Thomas,1Shuang Zhang,6Laia Alegret,7Daniela N. Schmidt,8James W. B. Rae,9,10James D. Witts,9Neil H. Landman,11Sarah E. Greene,12Brian T. Huber,1James R. Super,1Noah J. Planavsky,1Pincelli M. Hull
Proceedings of the National Academy of Sciences of teh United States of America (PNAS) (in Press) Link to to Article [https://doi.org/10.1073/pnas.1905989116]
1Department of Geology & Geophysics, Yale University, New Haven, CT 06520;
2Section 3.3, Deutsches GeoForschungsZentrum GFZ, 14473 Potsdam, Germany;
3School of Geographical Sciences, Bristol University, Bristol BS8 1SS, United Kingdom;
4Department of Earth Sciences, University of California, Riverside, CA 92521;
5Department of Earth and Environmental Sciences, Wesleyan University, Middletown, CT 06459;
6Instituto Universitario de Investigación en Ciencias Ambientales de Aragón, Departamento de Ciencias de la Tierra, Universidad de Zaragoza, 50009 Zaragoza, Spain;
7School of Earth Sciences, University of Bristol, Bristol BS8 1RJ, United Kingdom;
8School of Earth & Environmental Sciences, University of St. Andrews, St. Andrews KY16 9AL, United Kingdom;
9Division of Paleontology, American Museum of Natural History, New York, NY 10024;
10Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, NM 87131;
11School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham B15 2TT, United Kingdom;
12Department of Paleobiology, Smithsonian Institution, Washington, DC 20560

Mass extinction at the Cretaceous–Paleogene (K-Pg) boundary coincides with the Chicxulub bolide impact and also falls within the broader time frame of Deccan trap emplacement. Critically, though, empirical evidence as to how either of these factors could have driven observed extinction patterns and carbon cycle perturbations is still lacking. Here, using boron isotopes in foraminifera, we document a geologically rapid surface-ocean pH drop following the Chicxulub impact, supporting impact-induced ocean acidification as a mechanism for ecological collapse in the marine realm. Subsequently, surface water pH rebounded sharply with the extinction of marine calcifiers and the associated imbalance in the global carbon cycle. Our reconstructed water-column pH gradients, combined with Earth system modeling, indicate that a partial ∼50% reduction in global marine primary productivity is sufficient to explain observed marine carbon isotope patterns at the K-Pg, due to the underlying action of the solubility pump. While primary productivity recovered within a few tens of thousands of years, inefficiency in carbon export to the deep sea lasted much longer. This phased recovery scenario reconciles competing hypotheses previously put forward to explain the K-Pg carbon isotope records, and explains both spatially variable patterns of change in marine productivity across the event and a lack of extinction at the deep sea floor. In sum, we provide insights into the drivers of the last mass extinction, the recovery of marine carbon cycling in a postextinction world, and the way in which marine life imprints its isotopic signal onto the geological record.

Rapid condensation of the first Solar System solids

1Yves Marrocchi,1Johan Villeneuve,2Emmanuel Jacquet,1Maxime Piralla,3Marc Chaussidon
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.1912479116]
1Centre de Recherches Pétrographiques et Géochimiques (CRPG), CNRS, Université de Lorraine, UMR 7358, 54501 Vandoeuvre-lès-Nancy, France;
2Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), CNRS & Muséum national d’Histoire naturelle, UMR 7590, 75005 Paris, France;
3Institut de Physique du Globe de Paris, Université de Paris, CNRS, 75238 Paris, France

Chondritic meteorites are composed of primitive components formed during the evolution of the Solar protoplanetary disk. The oldest of these components formed by condensation, yet little is known about their formation mechanism because of secondary heating processes that erased their primordial signature. Amoeboid Olivine Aggregates (AOAs) have never been melted and underwent minimal thermal annealing, implying they might have retained the conditions under which they condensed. We performed a multiisotope (O, Si, Mg) characterization of AOAs to constrain the conditions under which they condensed and the information they bear on the structure and evolution of the Solar protoplanetary disk. High-precision silicon isotopic measurements of 7 AOAs from weakly metamorphosed carbonaceous chondrites show large, mass-dependent, light Si isotope enrichments (–9‰ < δ30Si < –1‰). Based on physical modeling of condensation within the protoplanetary disk, we attribute these isotopic compositions to the rapid condensation of AOAs over timescales of days to weeks. The same AOAs show slightly positive δ25Mg that suggest that Mg isotopic homogenization occurred during thermal annealing without affecting Si isotopes. Such short condensation times for AOAs are inconsistent with disk transport timescales, indicating that AOAs, and likely other high-temperature condensates, formed during brief localized high-temperature events.