Japan Geoscience Union Meeting 2025

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[J] Oral

S (Solid Earth Sciences ) » S-CG Complex & General

[S-CG59] Oceanic plate as inputs to subduction zone: evolution process of the oceanic plate

Sun. May 25, 2025 3:30 PM - 5:00 PM 304 (International Conference Hall, Makuhari Messe)

convener:Takanori Kagoshima(University of Toyama), Naoto Hirano(Center for Northeast Asian Studies, Tohoku University), Gou Fujie(Japan Agency for Marine-Earth Science and Technology), Yuya Akamatsu(Japan Agency for Marine-Earth Science and Technology), Chairperson:Takanori Kagoshima(University of Toyama), Naoto Hirano(Center for Northeast Asian Studies, Tohoku University), Gou Fujie(Japan Agency for Marine-Earth Science and Technology), Yuya Akamatsu(Japan Agency for Marine-Earth Science and Technology)

4:15 PM - 4:30 PM

[SCG59-10] Off-Tohoku Petit-spot drilling: IODP Expedition 502

★Invited Papers

*Asuka Yamaguchi1, Hiroko Kitajima2, Natsumi Okutsu3, Sean Toczko3 (1.Atomosphere and Ocean Research Institute, The University of Tokyo, 2.Texas A&M University, 3.JAMSTEC)

Keywords:IODP3, petit spot, Japan Trench

International Ocean Drilling Programme (IODP3) Expedition 502 plans to explore the nature of the acoustic basement in the outer rise area of the NW Pacific subduction system, where layer-1 pelagic sediment of the subducting old (120–130 Ma) Pacific Plate is exceptionally thin. The hypothesis is that the acoustically thin sediment cover can be attributed to basalt sill intrusions or sheet lava extrusions in and on the pelagic sediment package by basalts fed by petit-spot magmatism. This hypothesis will be tested to see if petit-spot magmatism at the outer rise is more widely distributed than previously thought. The existence of widely-distributed petit-spots would strongly impact the subduction system, including rupture nucleation and slip propagation of plate boundary megathrust earthquakes, as well as effect changes to the geochemical cycle of arc magmatism and the global volatile cycle due to the differing materials associated with the subducted oceanic plate. In this presentation we will show the latest update of IODP3 Expedition 502.