[B-CG05] Decoding the history of Earth: From Hadean to the present

[BCG05-14] Paleoenvironmental reconstruction based on the revised continuous stratigraphy across the Triassic-Jurassic boundary in the Mino Belt, central Japan

*Katsuhito Soda¹, Yuki Tomimatsu², Tetsuji Onoue², Minoru Ikehara¹ (1.Center for Advanced Marine Core Research, Department of Earth and Environmental Sciences, Faculty of Science, Kochi University, 2.Department of Earth and Planetary Sciences, Kyushu University)

The Triassic-Jurassic boundary (TJB) is marked by one of the big five biotic mass extinction events in the Phanerozoic. Anchoring at the TJB, previous stratigraphic framework in the Inuyama area of the Mino Belt established a floating astronomical time scale (ATS) converted from chert bed thickness variations. However, recent detailed stratigraphic studies indicated stratigraphic gaps by tectonic deformation across the TJB in the Inuyama ATS. Here we present paleoenvironmental reconstruction based on the revised continuous stratigraphy of the pelagic deep-sea rocks deposited in the Panthalassa across the TJB of the Mino Belt, central Japan. The several layers showed high Cr concentrations and low contents of redox sensitive elements in the latest Rhaetian, implying compositional effects from the Large Igneous Provinces and/or extraterrestrial impact. The Mg enrichment increased toward the Hettangian, suggesting enhanced inputs from the contemporaneous mafic materials like the Central Atlantic Magmatic Provinces. The low Mn enrichment indicated development of the reduced environment in the pelagic deep-sea realm of the Panthalassa during the latest Rhaetian.