Cenozoic tectonic migration characteristics in Qikou Sag of Bohai basin, China

摘要

Tectonic migration, a widespread geographic phenomenon prevailing in China basins, refers to that tectonic movement, sedimentation, magmatism and other geological process in basin have regularly migrated towards a particular direction in a certain geological evolution period, which are triggered by tectonization such as tectonic plate motion, mantle uplift and so on. Statistics obtained from elements of faults and materials on sedimentary and volcanic in Qikou sag are analyzed to study the movement and characteristics of tectonic migration. It is shown in the research that in Cenozoic fault activity, sedimentation and magmatism of the sag presented the characteristics of regular migration from the southwest to northeast. Besides, the faults strikes, controlling sedimentary fault strike and controlling magmatic activity structural trend changed from northeast in Sha-3 period to nearly east-west in Sha-1 period. And this phenomenon of migration is also common in other sags of Bohai basin. The regional geological background and thermodynamic characteristics of Qikou sag together demonstrate that this tectonic migration may be the performance of the deep mantle material activities on the superficial layer in Bohai basin as a result of both mantle motion and plate movement. In Qikou sag the tectonic migration has important influences on hydrocarbon accumulation.