Tectonic Evolution of the Gyeongsang Basin, Southeastern Korea from 140 Ma to the Present, Based on a Strike-Slip and Block Rotation Tectonic Model

摘要

The geometric model involving two conjugate strike-slip fault sets with opposite-sense block rotations synthesized by structural, petrological, geochronologic, and paleomagnetic data from the Gyeongsang Basin from Cretaceous to Tertiary time is placed in the tectonic framework of East Asia. As a result, the birth and evolution of the Gyeongsang Basin might reflect a regional continental strike-slip zone in a convergent plate boundary such as the Tan-Lu wrench tectonic system. According to this model, we suggest six major geotectonic stages in the Gyeongsang Basin since the Cretaceous-e.g., 140-120, 120-110, 110-99, 99-80, 80-50, and after 50 Ma-which include the collision of an accretionary plateau with proto-Japan, subduction of the Izanagi-Pacific ridge, collision of India-Eurasia, northward approach of the Philippine plate, and the East Sea opening. Over more than 90 m.y., the Gyeongsang Basin apparently underwent three events of block rotations in opposite directions, and two events of clockwise rotation of the whole basin or the Korean Peninsula. The first series of events rotated with respect to Eurasia and the second rotated together with Eurasia. We present the tectonic evolution of the Gyeongsang Basin as a model for the tectonic development of East Asia from the Cretaceous to the present.