Evidence of cross-cutting and redox reaction in Khatyrka meteorite reveals metallic-Al minerals formed in outer space

• Published in: Scientific Reports
• Main Authors: Chaney Lin, Lincoln S. Hollister, Glenn J. MacPherson, Luca Bindi, Chi Ma, Christopher L. Andronicos, Paul J. Steinhardt
• Format: Article in Journal/Newspaper
• Language: English
• Published: Nature Portfolio 2017
• Subjects: Medicine; R; Science; Q; Khatyrka; Chukotka; Koryak
• Online Access: https://doi.org/10.1038/s41598-017-01445-5; https://doaj.org/article/41f17fc0b0f34684a3333816f7f9e972

Abstract We report on a fragment of the quasicrystal-bearing CV3 carbonaceous chondrite Khatyrka recovered from fine-grained, clay-rich sediments in the Koryak Mountains, Chukotka (Russia). We show higher melting-point silicate glass cross-cutting lower melting-point Al-Cu-Fe alloys, as well as unambiguous evidence of a reduction-oxidation reaction history between Al-Cu-Fe alloys and silicate melt. The redox reactions involve reduction of FeO and SiO2 to Fe and Fe-Si metal, and oxidation of metallic Al to Al2O3, occurring where silicate melt was in contact with Al-Cu-Fe alloys. In the reaction zone, there are metallic Fe and Fe-Si beads, aluminous spinel rinds on the Al-Cu-Fe alloys, and Al2O3 enrichment in the silicate melt surrounding the alloys. From this and other evidence, we demonstrate that Khatyrka must have experienced at least two distinct events: first, an event as early as 4.564 Ga in which the first Al-Cu-Fe alloys formed; and, second, a more recent impact-induced shock in space that led to transformations of and reactions between the alloys and the meteorite matrix. The new evidence firmly establishes that the Al-Cu-Fe alloys (including quasicrystals) formed in outer space in a complex, multi-stage process.