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.
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