An unrecognized major collision of the Okhotomorsk Block with East Asia during the Late Cretaceous, constraints on the plate reorganization of the Northwest Pacific

摘要: Abstract Interactions at plate boundaries induce stresses that constitute critical controls on the structural evolution of intraplate regions. However, traditional tectonic model for East Asian margin during Mesozoic, invoking successive episodes paleo-Pacific oceanic subduction, does not provide an adequate context important Late Cretaceous dynamics across Asia, including: continental-scale orogenic processes, significant sinistral strike-slip faulting, and several others. The integration numerous documented field relations requires a new model, as proposed here. Okhotomorsk continental block, currently residing below Okhotsk Sea in Northeast was located interior Izanagi Plate before Cretaceous. It moved northwestward with collided South China Block about 100 Ma. indentation within Asia resulted formation fault system China, dextral North regional northwest–southeast shortening uplift Asia. Northeast-striking mountain belts over 500 km wide extended from Southeast to Southwest Japan Korea. peak metamorphism 89 Ma Sanbagawa high-pressure metamorphic belt probably related subduction beneath margin. Subsequently, north-northwestward change motion direction led northward movement along margin, forming transform boundary similar San Andreas California. rocks were rapidly exhumed through several-kilometer ductile shear zone lower crust upper mantle level. Accretionary complexes successively accumulated Jurassic–Early subdivided into narrow subparallel by crustal system. departure northeast-striking occurrence extensional setting magmatic west In Campanian, block Siberian At 77 Ma, occurred south Block, ending its long-distance motion. Based abundant Archean Early Proterozoic detrital zircons sandstones Kamchatka, Japan, Taiwan are interpreted have been sourced basement which possibly formed Proterozoic. suggests northward-moving average speed 22.5 cm/yr 89–77 Ma. is hypothesized Okhotomorsk–East collision 100–89 Ma slowed down Plate, while slab pull forces produced subducting redirected 90–89 Ma.