Structural Interpretation from Seismic Data in the South Sea of Korea

Abstract

To investigate the geological structure based on the analysis of seismic, gravity and magnetic exploration data in the South Sea of Korea, we acquired 54-channel seismic and Chirp shallow seismic data, and magnetic and gravity data of 1,980 line-km as well as core sediments to analyze geological structure and the potential distribution area of marine resources. The study area lies at the northeastern part of the East China Sea Trough, a Tertiary back-arc basin. In this area there are transition zones such as the East China Sea Trough and Korea Strait straddled the boundary of Korea and Japan. Average water depth in the study area is about 100 m. KNOC drilled 11 exploratory wells in the study area and nearby on adjacent blocks. The sedimentary basin is formed by the graben and/or half-graben basin as rifted activities. Since basin subsidence was more widespread during the Oligocene-Early Miocene, the East China Sea Trough was formed as a single large basin. The sedimentary sequences were generally deposited in coastal plain to marginal marine environments. The sandstones are mainly channel deposits with some tidal influence. The sedimentary basin is composed of pre-rift, syn-rift and post-rift sediments bounded by regional unconformity. The pre-rift and syn-rift sediments consist of Eocene, Oligocene, early Miocene and middle Miocene sequence, whereas the post-rift sediments consist of late Miocene and Plio-Pleistocene sequences.