Oxidation during magma mixing recorded by symplectites at Kusatsu–Shirane Volcano, Central Japan

Autor: Kenta Ueki, Mutsuko Inui, Kenta Matsunaga, Naoya Okamoto, Kazuki Oshio
Jazyk: angličtina
Rok vydání: 2020
Předmět:
Zdroj: Earth, Planets and Space, Vol 72, Iss 1, Pp 1-12 (2020)
Druh dokumentu: article
ISSN: 1880-5981
DOI: 10.1186/s40623-020-01192-4
Popis: Abstract Kusatsu–Shirane Volcano is an active Quaternary andesitic-to-dacitic volcano located in the Central Japan Arc. We conducted a detailed petrological investigation of orthopyroxene (opx)–magnetite (mt) symplectites associated with olivine in the Sessho lava, an andesitic lava flow from Kusatsu–Shirane. We concluded that the symplectites are pseudomorphs after olivine and were formed through the breakdown of olivine in a mafic magma as a result of oxidation during mixing with a felsic magma. Various olivines and opx–mt symplectites that show different stages of the progressive breakdown reaction of olivine coexist in a single lava flow. We suggest that basaltic recharge into the magma reservoir beneath Kusatsu–Shirane occurred repeatedly, leading to a hybrid andesite magma with different types of olivine and symplectite being erupted at Kusatsu–Shirane Volcano.
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