JpGU-AGU Joint Meeting 2026

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[E] Oral

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

[S-CG55] Oceanic plate as inputs to subduction zone and the subduction initiation

Thu. May 28, 2026 10:45 AM - 12:15 PM Convention Hall (CH-B) (International Conference Hall, Makuhari Messe)

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

This session focuses on two main topics: the oceanic plate as inputs to the subduction zone and the processes that initiate subduction. Subduction of oceanic plate drives various geodynamic phenomena, such as magma generation and fault formation, triggering volcanic and earthquake activity at subduction zones. Scales and distributions of such subduction zone-phenomena are controlled by physicochemical properties of subducting oceanic plates. In addition, oceanic plate-subduction processes transport surface materials such as water and carbon into the deep interior of Earth, playing an important role in global geochemical cycles. Physicochemical properties of oceanic plates as "subduction inputs" reflect their evolutionary histories from their formation at mid-ocean ridges until subduction at trenches. These characteristics are further modified by processes associated with plate bending prior to subduction, including fault development and petit-spot volcanism. Subduction initiation and the subsequent development of oceanic island arcs are poorly understood and remain an important unresolved problem in plate tectonics. Recent efforts to investigate geological record of subduction initiation along oceanic arcs and ophiolite have significantly improved understanding of processes associated with subduction initiation. This has also prompted extensive study utilizing tomography and numerical modeling to investigate requirements for the plate to subduct, and reconstruct tectonics for subduction initiation. We welcome contributions from a broad range of earth science (geophysics, geochemistry, geology, petrology, drilling science, and so on) discussing topics related to the nature of the subduction initiation of oceanic plate and their role as inputs to subduction zones.

11:15 AM - 11:30 AM

[SCG55-09] Hidden magmatism in old oceanic lithosphere revealed by International Ocean Drilling Programme (IODP3) Expedition 502

*Norikatsu Akizawa1, Kazuto Mikuni2, Jennifer Lington3, Christopher Yen4, Takashi Miyazaki5, Francesco Narduzzi6, Takanori Kagoshima7, Katie Preece8, Hayato Ueda9, Paola Vanucchi10, Lottie Atton11, Asuka Yamaguchi12, Hiroko Kitajima13, Naoto Hirano14, the Exp. 502 Science Team (1. Earth and Planetary System Science, Hiroshima University, 2. National Institute of Advanced Industrial Science and Technology, 3. University of Southampton, 4. University of Lausanne, 5. Japan Agency for Marine-Earth Science and Technology, 6. University of Pavia, 7. University of Toyama, 8. Swansea University, 9. Niigata University, 10. University of Florence, 11. University of Plymouth, 12. The University of Tokyo, 13. Texas A&M University, 14. Tohoku University)

11:30 AM - 11:45 AM

[SCG55-10] Lithostratigraphy and volcano-sedimentary facies at IODP3 Exp.502 site C0027 in a petit-spot field on the Japan Trench outer rise

*Hayato Ueda1, Paola Vannucchi2, Katie Preece3, Lottie Atton4, Kenji Matsuzaki5, Roberts Andrew6, Louisa Stokes7, Norikatsu Akizawa8, Jennifer Lington9, Kazuto Mikuni10, Christopher Yen11, Asuka Yamaguchi5, Hiroko Kitajima12, Natsumi Okutsu13, Exp. 502 Science Team IODP3 (1. Department of Geology, Niigata University, 2. University of Florence, 3. Swansea University, 4. University of Plymouth, 5. University of Tokyo, 6. Australian National University, 7. Curtin University, 8. Hiroshima University, 9. University of Southampton, 10. AIST, 11. University of Lausanne, 12. Texas A&M University, 13. JAMSTEC)

11:45 AM - 12:00 PM

[SCG55-11] Spatial stress field variations on the incoming Pacific Plate recorded by sediment-filled veins at Sites C0026, IODP Exp. 405, and C0027, IODP3 Exp. 502

*Hanaya Okuda1, Yu-Chun Chang2, Fuka Takuwa3, Taizo Uchida4, Olivier Fabbri5, Hiroko Kitajima6, Asuka Yamaguchi3, Natsumi Okutsu7, The IODP3 Expedition 502 Science Team (1. Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology, 2. Research Institute for Marine Geodynamics, Japan Agency for Marine-Earth Science and Technology, 3. Atmosphere and Ocean Research Institute, University of Tokyo, 4. Graduate School of Integrated Arts and Sciences, Kochi University, 5. Laboratoire Chrono-environment, Université de Marie-et-Louis-Pasteur, 6. Department of Geology and Geophysics, Texas A&M University, 7. Institute for Marine-Earth Exploration and Engineering, Japan Agency for Marine-Earth Science and Technology)

12:00 PM - 12:15 PM

[SCG55-12] CO2-rich hydrothermal reactions in petit-spot: experimental constraints on chemical and physical modification of pelagic sediments

*Keishiro Azami1, Kanta Koyama2, Takuya Saito3, Takazo Shibuya3, Syogo Kinoshita2, Shiki Machida1, Yasuhiro Kato4,1, Estuo Uchida2 (1. Ocean Resources Research Center ofr Next Generation, Chiba Institute of Technology, 2. Faculty of Science and Engineering, Waseda University, 3. Institute for Extra-cutting-edge Science and Technology Avant-grade, Japan Agency for Marine–Earth Science and Technology, 4. Department of Systems Innovation, School of Engineering, The University of Tokyo)

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