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Shock‐induced formation of wüstite and fayalite in a magnetite‐quartz target rock

Henrichs, Leonard F.; Kontny, Agnes; Reznik, Boris; Gerhards, Uta; Göttlicher, Jörg; Genssle, Tim; Schilling, Frank

Abstract:
Projectile–target interactions as a result of a large bolide impact are important issues, as abundant extraterrestrial material has been delivered to the Earth throughout its history. Here, we report results of shock‐recovery experiments with a magnetite‐quartz target rock positioned in an ARMCO iron container. Petrography, synchrotron‐assisted X‐ray powder diffraction, and micro‐chemical analysis confirm the appearance of wüstite, fayalite, and iron in targets subjected to 30 GPa. The newly formed mineral phases occur along shock veins and melt pockets within the magnetite‐quartz aggregates, as well as along intergranular fractures. We suggest that iron melt formed locally at the contact between ARMCO container and target, and intruded the sample causing melt corrosion at the rims of intensely fractured magnetite and quartz. The strongly reducing iron melt, in the form of μm‐sized droplets, caused mainly a diffusion rim of wüstite with minor melt corrosion around magnetite. In contact with quartz, iron reacted to form an iron‐enriched silicate melt, from which fayalite crystallized rapidly as dendritic grains. The temperatures required for these transformations are estimated between 1200 and 1600 °C, indicating extreme local temperature spikes during the 30 GPa shock pressure experiments.

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Verlagsausgabe §
DOI: 10.5445/IR/1000104724
Veröffentlicht am 01.03.2021
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Angewandte Geowissenschaften (AGW)
Institut für Mikroverfahrenstechnik (IMVT)
Institut für Nanotechnologie (INT)
Institut für Photonenforschung und Synchrotronstrahlung (IPS)
KIT-Zentrum Klima und Umwelt (ZKU)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2020
Sprache Englisch
Identifikator ISSN: 1086-9379, 1945-5100
KITopen-ID: 1000104724
HGF-Programm 43.22.01 (POF III, LK 01) Functionality by Design
Weitere HGF-Programme 56.98.01 (POF III, LK 01) Betrieb in MML
Erschienen in Meteoritics & planetary science
Verlag John Wiley and Sons
Band 55
Heft 1
Seiten 56-66
Vorab online veröffentlicht am 17.12.2019
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