JpGU-AGU Joint Meeting 2020

Presentation information

[E] Oral

B (Biogeosciences ) » B-CG Complex & General

[B-CG07] Phanerozoic biodiversity change: radiation and extinction

convener:Yukio Isozaki(Department of Earth Science and Astronomy, Multi-disciplinary Sciences - General Systems Studies, Graduate School of Arts and Sciences, The University of Tokyo), Yusuke Sawaki(The University of Tokyo)

[BCG07-05] Permian Panthalassan Sr budget change

*Tomomi Kani1, Yukio Isozaki2, Keiji Misawa3, Akira Ishikawa4, Shigekazu Yoneda5 (1.Department of Earth and Environmental Sciences, Kumamoto University, 2.The University of Tokyo, 3.National Institute of Polar Research, 4.Tokyo Institute of Technology, 5.National Museum of Nature and Science )

Keywords: δ88Sr, 87Sr/86Sr, carbonate, seawater

The radiogenic Sr isotopic composition (87Sr/86Sr) of the Phanerozoic seawater has been fluctuated according to global tectonics and/or climate change. The major Sr fluxes to drive 87Sr/86Sr in seawater are three-fold; i.e., weathering of highly radiogenic continental silicates, non-radiogenic submarine hydrothermal fluid, and weathering of less radiogenic carbonates and basalts from island arc/oceanic island. During the Phanerozic, seawater 87Sr/86Sr changed most dramatically around the Middle/Late Permian boundary marked by a major mass extinction. Stable Sr isotope (δ88Sr) in seawater is recently recognized as an useful proxy for estimating ancientburial/dissolution of marine carbonate. The δ88Sr values were consistently low in the Middle Permian and began to increase during the Late Permian. The timing of thistrend change across the G-LB corresponds to that of 87Sr/86Sr. This significant change of ocean Sr budget in the Phanerozoic might be explained by increase/decrease of carbonate weathering on continental shelves with respect to the long-term cooling/warming associated with global sea level change.