Structural characteristics and genetic mechanism of Gaoyang low uplift in Jizhong Depression, Bohai Bay Basin

Abstract

As a secondary structural unit locating in the central Jizhong Depression of the Bohai Bay Basin, the formation and evolution of Gaoyang low uplift is closely related to the development of the adjacent Baoding and Raoyang sags. The understanding for the structural characteristics of the Gaoyang low uplift is valuable for the overall study of the extensional deformation system in the central Jizhong Depression. Based on abundant seismic data, the structural characteristics of the Gaoyang low uplift were determined by using structural analysis method. According to drilling data and regional stratigraphic correlation, the age of syndepositional formation and the time of tectonic activity were determined. By compiling balanced sections and analyzing regional tectonic evolution, the genetic mechanism of the Gaoyang low uplift was discussed in this paper. The Gaoyang low uplift is featured by a gentle anticline which narrows from the south to the north, and the west limb of the anticline is steeper than the east counnterpart. Several NW-SE trending faults with large heave and long plane extension distance developed in the east flank of the Gaoyang low uplift, while only a few small-scale faults were developed in the west flank. The age of the oldest syndepositional strata in the southern part of the studied area is the Late Mesozoic, while that in the north is Paleocene. The Gaoyang low uplift is a compound rollover anticline developed in the common hanging wall of the boundary faults on both sides of the central Jizhong Depression, and its formation was mainly controlled by the extension of the boundary faults. The southern Gaoyang low uplift began to develop earlier than the northern part.

Keywords

• extensional deformation system
• structural characteristics
• genetic mechanism
• gaoyang low uplift
• jizhong depression
• bohai bay basin