Japan Geoscience Union Meeting 2015

Presentation information

Oral

Symbol M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS30] Evolution of the Pelagic Realm

Tue. May 26, 2015 9:00 AM - 10:45 AM 304 (3F)

Convener:*Atsushi Matsuoka(Department of Geology, Faculty of Science, Niigata University), Toshiyuki Kurihara(Graduate School of Science and Technology, Niigata University), Yasuhiro Kato(Department of Systems Innovation, Graduate School of Engineering, University of Tokyo), Tetsuji Onoue(Earth and Environmental Sciences, Graduate School of Science and Technology, Kumamoto University), Katsunori Kimoto(Japan Agency for Marine-Earth Science and Technology), Tatsuo Nozaki(Institute for Research on Earth Evolution, Japan Agency for Marine-Earth Science and Technology), Hayato Ueda(Department of Geology, Niigata University), Kenta Kobayashi(Department of Geology, Faculty of Science, Niigata University), Takashi Hasegawa(Division of Global Environmental Science and Engineering, Graduate School of Natural Science and Technology, Kanazawa University), Chair:Hayato Ueda(Department of Geology, Niigata University), Satoshi Takahashi(Department of Earth and Planetary Science, University of Tokyo)

10:15 AM - 10:30 AM

[MIS30-06] Deep-ocean acidification and volcanism across the Triassic-Jurassic extinction event

Masayuki IKEDA1, *S., Rie HORI2, Ryoichi NAKADA3, Yuki OKADA2 (1.Shizuoka Univerisity, 2.Ehime University, 3.Tokyo Institute of Technology)

Keywords:Triassic/Jurassic, acidification, volcanism, extinction

Triassic-Jurassic (T-J) extinction event marks one of the Big Five mass extinction events of the Phanerozoic. The emerging consensus points to volcanic activity at the Central Atlantic Magmatic Province (CAMP) as the ultimate cause of the extinction, yet the underlying nature of global environmental changes that accompanied the biotic turnover remain elusive. We present chemical and mineralogical studies across the T-J transition of the deep-sea chert sequence (Inuyama, Japan). Depleted hematite content normalized by terrigenous material occurred just before the T-J extinction with significant change in color from brick red to purple. This suggests the loss of authigenic hematite due to the deep-ocean acidification, which is consistent with the rock magnetic records of Abrajevitch et al. (2013). This timing is consistent with the CAMP volcanism, implying a catastrophic release of greenhouse gases as causes of deep-ocean acidification. Across the T-J transition, MgO/Al2O3, Fe2O3/Al2O3, and Al2O3/SiO2 increased with change in color from brick red to dusty red. These geochemical trends are consistent with those of weathered CAMP basalts in arid area (Dal Corso et al., 2014), implying that weathered CAMP basalts became the considerable source of aeolian dust in pelagic Panthalassa after the T-J extinction event.