Japan Geoscience Union Meeting 2018

convener:Inna Safonova(Novosibirsk State University), Tatsuki Tsujimori(Tohoku University), Yukio Isozaki(東京大学大学院総合文化研究科広域科学専攻広域システム科学系, 共同), Tsuyoshi Komiya(Department of Earth Science & Astronomy Graduate School of Arts and Sciences The University of Tokyo), Chairperson:Tsujimori Tatsuki, Komiya Tsuyoshi

Pacific-type convergent margins (ocean - continent) and their related orogenic belts exist/form over subduction zones, which are the only ways to deliver surface materials to the deep mantle. Pacific-type orogens keep records of the evolution of paleo-oceans, formation and transformation of continental crust at their active margins, and generation of hydrous-carbonated plumes in the mantle transition zone (MTZ) and its related intra-plate magmatism. An approach linking paleo-oceans, active margins and plume magmatism stands on three "whales": the model of Ocean Plate Stratigraphy (OPS), the parameters of active convergent margins and the model of hydrous-carbonated plumes. The OPS model was created by many detailed studies of western Pacific, in particular Japanese, accretionary complexes; it allows recognizing different oceanic plates within one paleo-ocean and evaluating their sizes and ages. Pacific-type convergent margins are places of major continental growth by island-arc juvenile magmatism and accretion, but they are also places of strong plate interactions and crust destruction. There are two contrast types of those margins: accreting ones accompanied by the formation of accretionary complexes, and eroding ones accompanied by the tectonic and subduction erosion of accretionary wedge, fore-arc prism and volcanic arc. The materials of oceanic and continental crust, which are eroded at Pacific-type convergent margins, can accumulate in the MTZ and affect mantle conditions. All those processes, the subduction of hydrated and carbonated oceanic crust, the destruction of continental crust at eroding margins, and the accumulation of mafic and sialic materials in the MTZ can synergistically trigger the generation of hydrous-carbonated mantle plumes in the MTZ, mantle melting and upwelling, and intra-plate continental magmatism. We welcome papers on results from Pacific-type orogenic belts worldwide and from Archean to Cenozoic ages.