JpGU-AGU Joint Meeting 2017

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[JJ] Oral

M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS20] [JJ] Evolution of the Pelagic Realm

Thu. May 25, 2017 10:45 AM - 12:15 PM 201B (International Conference Hall 2F)

convener:Atsushi Matsuoka(Department of Geology, Faculty of Science, Niigata University), Toshiyuki Kurihara(Graduate School of Science and Technology, Niigata University), Tetsuji Onoue(Earth and Environmental Sciences, Graduate School of Science and Technology, Kumamoto University), Katsunori Kimoto(Japan Agency for Marine-Earth Science and Technology), Chairperson:Atsushi Matsuoka(Department of Geology, Faculty of Science, Niigata University), Chairperson:Toshiyuki Kurihara(Graduate School of Science and Technology, Niigata University)

11:00 AM - 11:15 AM

[MIS20-02] Jurassic/Cretaceous boundary and radiolarian bioevents

*Atsushi Matsuoka1 (1.Department of Geology, Faculty of Science, Niigata University)

Keywords:Jurassaic/Cretaceous boundary, GSSP, Radiolarians, evolutionary lineage, Pacific

The Global Boundary Stratotype Section and Point (GSSP) of the Jurassic/ Cretaceous (J/K) boundary is the last among the GSSPs in the Phanerozoic. It will be defined the base of the Berriasian Stage. The definition was decided as the evolutionary first appearance biohorizon of Calpionella alpina by the Berriasian Working Group in the International Subcommission on Cretaceous Stratigraphy. Unfortunately, the primary marker cannot be found in the Pacific and circum-Pacific areas since the distribution of Calpionella is limited to the western Tethys regions. To determine the base of the Berriasian outside of the western Tethys, alternative proxies are needed. Radiolarians are good candidates for determining the J/K boundary. Evolutionary series of several radiolarian lineages across the J/K boundary are reviewed and suitable bioevents, which are approximate to the J/K boundary, are proposed. These lineages include the genera Eucyrtidiellum, Cinguloturris, Ristola, Hemicryptocapsa, and Pseudodictyomitra.