Laura Kotomaa, Markku Väisänen, Jussi S. Heinonen, Ermei Mäkilä, Hugh O'Brien, Arto Peltola
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引用次数: 0
Abstract
Löpönvaara is a rare new phosphorus-rich iron meteorite find from Löpönvaara, Finland. The ~164 g meteorite was discovered in 2017 from the same area as the ungrouped Lieksa pallasite. Löpönvaara was classified as an ungrouped iron meteorite due to its unusually high concentration of P (>4 wt%), coupled with a moderate concentration of Ni (~11 wt%), and Ga–Ge abundances in the “III” range. The meteorite consists of ~75 vol% kamacite and ~22 vol% schreibersite, with accessory troilite (<0.1 vol%), and minor terrestrial weathering products. The kamacite in Löpönvaara occurs as three different types: (1) rare, large 2–5 mm partially resorbed clasts; (2) round, ≤0.5 mm partially resorbed clasts; and (3) small, several tens of μm to sub-μm exsolution blebs and globules in the matrix. Schreibersite occurs solely as microscopic matrix material in between the type (1) and (2) kamacite clasts. The lack of taenite and the overall compositional and textural features of Löpönvaara suggest that it retained its composition possibly from a P-rich portion of immiscible melt at late stages of fractional crystallization, but its textural features suggest that the meteorite suffered impact-related metamorphism. The meteorite has no close textural or compositional affinities, which makes it unique and an important target for future studies.
期刊介绍:
First issued in 1953, the journal publishes research articles describing the latest results of new studies, invited reviews of major topics in planetary science, editorials on issues of current interest in the field, and book reviews. The publications are original, not considered for publication elsewhere, and undergo peer-review. The topics include the origin and history of the solar system, planets and natural satellites, interplanetary dust and interstellar medium, lunar samples, meteors, and meteorites, asteroids, comets, craters, and tektites. Our authors and editors are professional scientists representing numerous disciplines, including astronomy, astrophysics, physics, geophysics, chemistry, isotope geochemistry, mineralogy, earth science, geology, and biology. MAPS has subscribers in over 40 countries. Fifty percent of MAPS'' readers are based outside the USA. The journal is available in hard copy and online.