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

A new study reveals that the middle Paleocene to early Eocene (60–53 Ma) post-subduction magmatism in Sikhote-Alin, Far East Russia, was not linked to subduction but coincided with strike-slip tectonics and the cessation of accretionary prism development. This finding challenges the current tectonic model by suggesting a shift from oceanic plate subduction to parallel sliding and the initiation of a transform continental margin. The research integrates isotopic, geochemical, and geochronological data, indicating diverse mineralogical features in A-type igneous rocks that imply interactions between the subducting plate and anhydrous mantle upwelling through slab tears. This magmatic activity is also synchronous with tectonic reactivation along major faults and post-60 Ma termination of accretion in SW Japan.

Grebennikov, A. V., Kemkin, I. V., & Khanchuk, A. I. (2021). 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. Geoscience Frontiers, 12(4), 101142. https://doi.org/10.1016/j.gsf.2021.101142