Japan Geoscience Union Meeting 2018

Presentation information

[JJ] Oral

B (Biogeosciences) » B-CG Complex & General

[B-CG10] Phanerozoic biodiversity change: Extinction and diversification

Mon. May 21, 2018 9:00 AM - 10:30 AM 102 (1F International Conference Hall, Makuhari Messe)

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), Chairperson:Sawaki Yusuke(The University of Tokyo)

9:30 AM - 9:45 AM

[BCG10-03] δ88Sr and 87Sr/86Sr variations in Middle-Upper Permian seawater

*Tomomi Kani1, Yukio Isozaki2, Keiji Misawa3, Akira Ishikawa2, Shigekazu Yoneda4 (1.Earth and Environmental Science Kumamoto University, 2.The University of Tokyo, 3.National Institute of Polar Research, 4.National Museum of Nature and Science)

Keywords:carbonate, seawater, Sr isotope

The lowest value of seawater 87Sr/86Sr in the Phanerozoic called “the Capitanian minimum” represents an extremely unusual condition in the global Sr cycle, which may have been linked to the global environmental changes with major mass extinction at the end-Guadalupian (Middle Permian). We newly measured δ88/86Sr values of shallow marine carbonates for the same Middle-Upper Permian interval by TRITON TIMS, with correction of isotope fractionation during mass spectrometry with 87Sr-84Sr double spike. The δ88/86Sr values started to decrease in the Early Permian, and reached to the Phanerozoic lowest value at the end of Capitanian (Late Guadalupian). In turn, the values started to increase across the Middle-Late Permian boundary (G-LB), and kept increasing throughout the early Late Permian. This trend across the G-LB is similar to that of 87Sr/86Sr, even though there is no overall correlation between seawater δ88/86Sr and 87Sr/86Sr through the Phanerozoic. The extremely low δ88/86Sr value in seawater may reflect a unique balance between two fluxes to seawater from marine carbonate sources in global-scale; i.e., increase by dissolution and decrease by deposition of carbonates.