¹S. Marchi, ¹W. F. Bottke, ^2,6L. T. Elkins-Tanton, ³M. Bierhaus, ³K. Wuennemann, ⁴A. Morbidelli ⁵D. A. Kring

¹Southwest Research Institute, Boulder, Colorado 80302, USA
²Carnegie Institution for Science, Washington DC 20015, USA
³Museum für Naturkunde, Berlin 10115, Germany
⁴Observatoire de la Côte d’Azur, Nice 06304, France A. Morbidelli
⁵Universities Space Research Association, Lunar and Planetary Institute, Houston, Texas 77058, USA
⁶Present address: School of Earth and Space Exploration, Arizona State University, Tempe, Arizona 85287, USA

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

Reference
Marchi S, Bottke WF, Elkins-Tanton LT, Bierhaus M, Wünnemann K., Morbidelli A, Kring DA (2014) Widespread mixing and burial of Earth’s Hadean crust by asteroid impacts
Nature 511, 578–582

Link to Article [doi:10.1038/nature13539]

^1,2,3 Camille Cartier,^1,2,3Tahar Hammouda, ^1,2,3 Maud Boyet,^1,2,3 Mohamed Ali Bouhifd, ^1,2,3 Jean-Luc Devidal

¹ Clermont Université, Université Blaise Pascal, Laboratoire Magmas et Volcans, BP 10448, F-63000 Clermont-Ferrand, France
² CNRS, UMR 6524, LMV, F-63038 Clermont-Ferrand, France
³ IRD, R 163, LMV, F-63038 Clermont-Ferrand, France

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

Reference
Cartier C, Hammouda T, Boyet M, Bouhifd MA, DevidalJ-L (2014) Redox control of the fractionation of niobium and tantalum during planetary accretion and core formation. Nature Geoscience 7, 573–576

Link to Articel [doi:10.1038/ngeo2195]

¹E. Asphaug, ^1,2A. Reufer

¹ School of Earth and Space Exploration, Arizona State University, PO Box 876004, Tempe, Arizona 85287, USA
²Physics Institute, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland

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

Reference
Asphaug E, Reufer A (2014) Mercury and other iron-rich planetary bodies as relics of inefficient accretion. Nature Geoscience 7, 564–568

Link to Article [doi:10.1038/ngeo2189]

^1,2Masaaki Miyahara, ^1,3Eiji Ohtani, ⁴Akira Yamaguchi, ^1,4Shin Ozawa, ^1,5Takeshi Sakaia, ⁶Naohisa Hirao

¹ Institute of Mineralogy, Petrology and Economic Geology, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan;
² Department of Earth and Planetary Systems Science, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan;
³ V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch, Russian Academy of Sciences, Novosibirsk 630090, Russia;
⁴ National Institute of Polar Research, Tokyo 190-8518, Japan;
⁵ Geodynamics Research Center, Ehime University, Matsuyama 790-8577, Japan; and
⁶ Japan Synchrotron Radiation Research Institute, Hyogo 679-5198, Japan

Howardite–eucrite–diogenite meteorites (HEDs) probably originated from the asteroid 4 Vesta. We investigated one eucrite, Béréba, to clarify a dynamic event that occurred on 4 Vesta using a shock-induced high-pressure polymorph. We discovered high-pressure polymorphs of silica, coesite, and stishovite originating from quartz and/or cristobalite in and around the shock-melt veins of Béréba. Lamellar stishovite formed in silica grains through a solid-state phase transition. A network-like rupture was formed and melting took place along the rupture in the silica grains. Nanosized granular coesite grains crystallized from the silica melt. Based on shock-induced high-pressure polymorphs, the estimated shock-pressure condition ranged from ∼8 to ∼13 GPa. Considering radiometric ages and shock features, the dynamic event that led to the formation of coesite and stishovite occurred ca. 4.1 Ga ago, which corresponds to the late heavy bombardment period (ca. 3.8–4.1 Ga), deduced from the lunar cataclysm. There are two giant impact basins around the south pole of 4 Vesta. Although the origin of HEDs is thought to be related to dynamic events that formed the basins ca. 1.0 Ga ago, our findings are at variance with that idea.

Reference
Miyahara M, Ohtani E, Yamaguchi A, Ozawa S, Sakaia T, Hirao N (2014) Discovery of coesite and stishovite in eucrite. Proceedings of the National Academy of Sciences 111, 30.

Link to Article [doi: 10.1073/pnas.1404247111]