Paleocene-early Eocene post-subduction magmatism in Sikhote-Alin(Far East Russia):New constraints for the tectonic history of the Izanagi-Pacific ridge and the East Asian continental margin

• 作者: Andrei V.Grebennikov Igor V.Kemkin Alexander I.Khanchuk
• 来源期刊: 地学前缘（英文版）
• 年，卷（期）: 2021,（4）
• 所属期刊栏目: Research Paper
• 页码范围: 71-85
• 页数: 15页
• 语种: 英文

摘要

New isotopic,geochemical and geochronological data justify the widespread occurrence of middle Paleocene to early Eocene (60-53 Ma) post-subduction felsic magmatism across the entire Sikhote-Alin territory (southeast-ern Russia),conform with previous observations in Northeast China,the southern Korean Peninsula,and the Inner Zone of Japan.This igneous activity in East Asia coincided with the reactivation (after tectonic quiescence between-93-60 Ma) of left-lateral strike-slip displacements along the Tan-Lu and Central Sikhote-Alin faults and with the post-60 Ma cessation of subduction/accretion recorded in the Shimanto belt of SW Japan.The Sikhote-Alin post-subduction igneous A-type rocks present diverse mineralogical and geochemical features that suggest interactions of the subducting plate with anhydrous mantle upwelling through slab tears in the continental mar-gin.The middle Paleocene-early Eocene magmatism is not related to subduction but is synchronous with strike-slip tectonics and the termination of accretionary prism development,suggesting a shift in tectonic regime from oceanic plate subduction at a convergent margin to parallel sliding and initiation of a transform continental mar-gin.These new observations are inconsistent with the current tectonic model of 60-50 Ma Izanagi-Pacific ridge subduction beneath East Asian continental margin.