Study on Density Discontinuous Layers of the Kunsan Basin in the Yellow Sea Using Satellite Altimetry Gravity Data

인공위성 해면고도계 중력자료를 이용한 황해 군산분지의 밀도 불연속면에 대한 연구

  • Kim, Kyong-O (Korea Institute of Geoscience and Mineral Resources) ;
  • Oh, Jae-Ho (Korea Institute of Geoscience and Mineral Resources)
  • Published : 2007.12.28

Abstract

To better understand the subsurface geological structure of the Kunsan Basin in the Yellow Sea, the mean depths of the density discontinuous layers (DDLs) of the Kunsan Basin were calculated by power spectrum analysis using satellite altimetry gravity data. The calculated mean depths of DDLs were -1.1km, -3.4km, -9.1km and -31.0km. The mean depth of -1.1km DDL was interpreted as regional unconformity shown in about 1 second in two way travel time (TWTT) in the seismic reflection profiles, and the mean depth of -3.4km DDL was also interpreted as top of the acoustic basement in the seismic reflection profiles. Comparing with well data, seismic reflection profiles and regional geology in the study area, the mean depth of -9.1km DDL was interpreted as top of the igneous origin basement. This means that the acoustic basement of the study area is composed mainly of sediments which are disregarded in previous study. The mean depth of -31.0km DDL was interpreted as the Moho discontinuity because this mean depth is similar to one of the normal continental crust thickness. The detection of top of the igneous origin basement suggests that oil gas potential analysis in Kunsan Basin needs to be extended to the deeper part of sediments (acoustic basement).

황해 군산분지의 지하 지질구조를 파악하기 위하여 인공위성 해면고도계 중력자료를 이용하여 파워 스펙트럼 분석(power spectrum analysis) 방법으로 밀도 불연속면의 평균 깊이를 계산하였다. 계산 결과에 의하면 군산분지를 포함한 본 연구지역에서는 각각 -1.1km, -3.4km, -9.1km 그리고 -31.0km의 평균 깊이를 가지는 밀도 불연속면이 검출되었다. -1.1km 평균 깊이의 밀도 불연속면은 본 연구지역의의 탄성파 단면에서 관찰되는 왕복 주시 1초 부근에서 나타나는 광역 부정합면으로 해석되었고, -3.4km 평균 깊이의 밀도 불연속면 또한 탄성파 단면에서 인지되는 음향기반암 상부면과 일치하는 것으로 해석되었다. -9.1km 평균 깊이의 밀도 불연속면은 본 연구지역의 시추공 자료, 탄성파 단면, 광역 지질 등을 고려하여 화성기원 기반암의 상부면으로 해석하였다. 이는 본 연구지역의 음향 기반암층은 기존의 연구에서 고려 대상이 되지 않았던 퇴적암으로 이루어져 있음을 의미한다. -31.0km의 평균 깊이를 가지는 밀도 불연속면은 일반적인 대륙지각의 평균 두께와 유사한 값을 보이므로 모호면으로 해석하였다. 화성기원 기반암 상부면으로 해석된 -9.1km 평균 깊이의 밀도 불연속면의 검출은 군산분지의 석유 가스 부존 가능성에 관한 연구에 있어 기존의 연구보다 심부층(음향 기반암층)에 대한 연구가 필요함을 시사하였다.

Keywords

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