Abstract:

Beidagang salient tectonic belt is the important part of central uplift belt of Qikou Sag, which is also one of the key areas to the research of the Cenozoic structure evolution of Qikou Sag. Research on the formation and evolution of the salient are particularly important for both basin structure evolution research and petroleum exploration. The paper subtly descripts the structure characteristics of different segments in Beidagang salient tectonic belt with the latest threedimensional seismic data, statistically compares the fault activity of the tectonic belts main faults in each period of the Cenozoic and restores the Cenozoic structure evolution of Beidagang salient tectonic belt by using balanced section technology. It is considered that Beidagang salient tectonic belt shows different structure characteristics in different segments and shows the characteristic of “one culmination and one steep slope” in NE direction; fault activities mainly occurred in Sha3 period, Sha1 period, Dongying period and Neogene; the Liugangzhuang fault and Dazhangtuo fault are lateral connected, so do the Binhai fault and Gangdong fault; the strength of fault activity shows the migration from SW to NE. In the Paleogene the salient underwent three major tectonic uplift events: SW segment partial uplift activity in late Sha3 period, slowly uplifting in Sha1 period and intensive uplifting in late Dongying period; and the structure activity strength migrated from SW to NE with time. The evolution of Beidagang salient tectonic belt provides favorable conditions for hydrocarbon accumulation in Qikou Sag.

Key words: Qikou Sag, Beidagang salient tectonic belt, fault activity, tectonic evolution, petroleum significance