Regional Unconformities and Structural Characteristics of the Kunsan

Abstract

We have identified and mapped three (latest Eocene, Early Miocene, and late Early Miocene) regional unconformities and the acoustic basement in the Kunsan Basin in the southern Yellow Sea from multi-channel seismic reflection data. The regional unconformities, tied to five exploratory wells, represent uplift, followed by erosion. Additional unconformities are seen in the deeper part of the basin fill but cannot be traced across the area. The latest Eocene unconformity is widespread in the central and northern part of the basin. It is cut by younger unconformities over basement highs and shallow basement. The Early Miocene unconformity cuts relatively small regions in the south central part of the area. The late Early Miocene unconformity is very angular, cutting a large region in the south central part of the area and many parts of the basin. The two-way traveltime depths of the top of the acoustic basement range from less than 0.4 s to over 3.5 s. The acoustic basement in the western part of the 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 SW Subbasin. The Central Subbasin is bounded to the south by the EW-trending normal fault with a vertical throw of more than 1.0 s TWTT.