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Paleoenvironmental reconstruction for termination stage of Superanoxia in Middle Triassic (Anisian) sedimentary sequence of the Mino belt, central Japan
Author(s) -
Soda Katsuhito,
Onoue Tetsuji
Publication year - 2018
Publication title -
island arc
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.554
H-Index - 58
eISSN - 1440-1738
pISSN - 1038-4871
DOI - 10.1111/iar.12262
Subject(s) - geology , permian , paleontology , extinction event , sedimentary rock , permian–triassic extinction event , early triassic , seafloor spreading , anoxic waters , stage (stratigraphy) , weathering , context (archaeology) , oceanography , biological dispersal , population , demography , structural basin , sociology
Superanoxia across the Permian/Triassic boundary, which is a long period of oceanic anoxia from the late Middle Permian to the early Middle Triassic, has been recognized and debated well in the context of the end Permian mass extinction. However, few studies have focused on the Middle Triassic anoxia because of limited application of geochemical proxies. To reconstruct paleoenvironmental changes during the termination stage of Superanoxia, various geochemical proxies were applied to chemical compositions of the Middle Triassic (Anisian) bedded chert sequence in the Mino belt, Japan, which accumulated in a deep seafloor environment in a low‐ to mid‐latitude zone of the Panthalassa Ocean. Three anoxic events were identified by statistically robust geochemical proxies during the middle Anisian. Degrees of calibrated‐chemical weathering intensity show higher values during these anoxic events, suggesting that the intensified continental weathering was a trigger mechanism for the oceanic anoxic events in the middle Anisian. Furthermore, our data indicate that the termination of Superanoxia in the Panthalassa Ocean was associated with a gradual decrease in continental weathering rates during the middle to late Anisian.