2023 Volume 77 Issue 4 Pages 127-145
The opinions on the generative process of the Japan Sea proposed since 1903 are classified into (1) block tilting, (2) opening and (3) vertical movement, being still controversial. The marginal sea was formed in some period during Paleogene to Miocene, so that its generative process should be recorded in the pre-Cenozoic basements in and around. The basements consist of the parallel-arranged three zones of volcano-plutonic, high-pressure metamorphic and “accretionary”, with no records of large-scale extension due to opening. A trial hypothesis proposed here attributes the Japan Sea genesis to crustal thinning/densification due to the upwelling of a DMM plume closest to upper continental crust.
