Structural Evolution of the Kunsan Basin, Southern Yellow Sea

Abstract

We have identified and mapped nine regional unconformities including the top acoustic basement in the Kunsan Basin in the Southern Yellow Sea from multi-channel seismic reflection data. The depths of the acoustic basement range from less then 400 m in the southern part of the area to over 8000 m in the two depocenters. The acoustic basement in the western part of area is dominated by the EW- and NW-trending normal faults. The large fault cutting the basement in the northern part of the area turns southward in the east, forming the northern and eastern boundaries of the SE Subbasin in the northwestern part of the area. The Central Subbasin is bounded to the south by the EW-trending normal fault with a vertical throw of more than 1.0 second two-way travel time. Restoration of depth-converted seismic profiles suggests that the southern part of the SW Subbasin experienced rapid subsidence in the south during the Paleocene-Early Eocene, accommodating thick sediment accumulation, followed by a minor inversion in the north in the Middle-Late Eocene. In the Eocene, the southeastern part of the SW Subbasin and the area northwest of the depocenter of this subbasin underwent significant uplift. This contractional tectonic movement probably resumed briefly in the Early Miocene. The western part of the SW Subbasin appears to have remained shallow until the Middle Eocene (?). In the Late Eocene, significant uplift occurred over much of the western part of the SW Subbasin. An inversion continued locally in the south-southwestern part of the SW subbasin.