Discovery of high-pressure polymorphs in the recent fall of Viñales (L6 ordinary chondrite): implications for collisions on its parent body

Abstract

Ordinary chondrites record impact-related features, including high-pressure (HP) minerals, usually occurring in melt veins (MVs), yielding constraints on shock conditions and hence parameters such as the size of colliding bodies, impact velocity, etc. Here, we report the first observations of HP mineral polymorphs in the recent L6 chondrite fall of Viñales (Cuba, 1st February 2019; proposed shock stage S3 [1] and partly S4 [2]). The investigated thin section shows at least nine major, subparallel, MVs (50-600 μm wide) and a few thinner MVs at an angle to these. It is unclear whether they are of a single or multiple generations. We have so far identified, within a single melt vein, a region hosting the HP polymorphs majorite and albitic jadeite. These observations define a definite pressure range for this meteorite and contribute to the shock record of the L-chondrites in general.