Structural characteristics analysis of Saihantala sag in Erlian Basin
Cheng San-you1, Liu Shao-feng2, Su San3, Ren Jin-li4
1. School of Earth Sciences and Resources, Chang'an University, Xi'an, Shaanxi 710054, China;
2. School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China;
3. Chevron Asia South, Beijing 100083, China;
4. Geophysical and Geochemical Exploration Team of the Shaanxi Bureau of Geology and Mineral Resourse, Xi'an, Shaanxi 710043, China
Abstract：By integrating structural geology method with stratigraphy analysis,multiple 2D seismic sections are interpreted,the structure is restored and balanced,and the extensional magnitude and rates are calculated.The results reveal the development process of Saihantala sag,and help to understand the general internal architecture and forming mechanism of Erlian Basin.The study indicates that the development of Saihantala sag mainly consists of three stages,that is,early stage of faulting/rifting,middle unbalanced stage with depression and uplift co-existed and late stage of regional depression with overlapping deposits.The early faulting mainly happens when Aershan formation and Tenggeer formation subunit 1 are deposited;while Tenggeer formation subunit 2 is deposited,the basin is undergoing differential depression and uplifting,with local subsidence still controlled by faulting.With the deposition of Tenggeer formation,the basin is characterized by regional depression and development of unconformity due to overlapping,and the basin is close to die out.The whole basin can be divided into three sub tectono-sequences or basin facies that are controlled by different tectonics,e.g.the lower rifting basin(Aershan formation and Tenggeer formation subunit 1),middle detachment basin(Tenggeer formation subunit 2 and Saihantala formation),and upper basin dominated by thermal decay or tectonic inversion.The result of this study will be beneficial to the hydrocarbon exploration in other sags in Erlian Basin with similar genesis and structure styles.
