Formation mechanisms of ringwoodite: clues from the Martian meteorite Northwest Africa 8705
نویسندگان
چکیده
Abstract Ringwoodite and wadsleyite are the high-pressure polymorphs of olivine, which common in shocked meteorites. They major constituent minerals terrestrial mantle. NWA 8705, an olivine-phyric shergottite, was heavily shocked, producing shock-induced melt veins pockets associated with four occurrences ringwoodite: (1) lamellae intergrown host olivine adjacent to a pocket; (2) polycrystalline assemblages preserving shapes compositions pre-existing within vein (60 μm width); (3) rod-like grains coexisting clinopyroxene vein; (4) microlite clusters embedded silicate glass very thin (20 width). The first two ringwoodite likely formed via solid-state transformation from supported by their morphological features homogeneous (Mg# 64–62) similar 66–64). third occurrence might fractionally crystallize melt, based on its heterogeneous more FeO-enriched 76–51) than those 77–67) 66–64) this meteorite. coexistence ringwoodite, wadsleyite, suggests post-shock pressure 14–16 GPa temperature 1650–1750 °C. fourth compositional variation 72–58) crystallized at 16–18 1750–1850 presence probably due fast cooling rates and/or small pockets. In addition, higher Fa-contents (Fa 35–39 ) 8705 ordinary chondrites 16–32 makes olivine–ringwoodite prolong lower pressure.
منابع مشابه
EXPOSURE HISTORY OF LUNAR METEORITE NORTHWEST AFRICA 5000. K. Nishiizumi,
Caffee, N. Vogel, R. Wieler, M. D. Leclerc, and A. J. T. Jull, Space Sciences Laboratory, University of California, Berkeley, CA 94720-7450, USA ([email protected]), Department of Physics, Purdue University, West Lafayette, IN 47907-1396, USA ([email protected]), ETH-Zürich, CH-8092, Switzerland ([email protected], [email protected]), NSF Arizona AMS Facility, University of Arizona, Tuc...
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ژورنال
عنوان ژورنال: Earth, Planets and Space
سال: 2021
ISSN: ['1880-5981', '1343-8832']
DOI: https://doi.org/10.1186/s40623-021-01494-1