关键词: 歧口凹陷, 物源分析, 碎屑组分, 重矿物

Abstract:

In order to clarify the distributional feature of provenance and depositional systems of the second Member of Shahejie Formation in Qikou Sag, the surrounding provenances and their respective influence scopes on the deposition have been systematically studied by means of multiparameter analysis, such as detrital composition, heavy minerals, rare earth elements. The study indicates each parent rock type is mainly mediumbasic eruptive rock. There are three greater provenances in the study area, which could be divided into six distributary provenances, specifically north Yanshan, northwest Cangxian uplift, west Gangxi salient, west Gangdong salient, Zhaobei and Zhangdong. The distributary provenances of the north Yanshan and northwest Cangxian uplift control most delta deposits of the north part of Beidagang buried hill and Banqiao sag, mixed with west Gangxi salient distributary provenance in the center part of Beidagang buried hill controlling the nearby beach bar deposits. Distributary provenances, specifically Gangxian, Gangdong, Zhaobei and Zhangdong, only control nearby fan deltas and beach bar deposits. In general, the provenance has a good  allocating relationship with the depositional system, which provides a material base for the formation of lithologic stratigraphic reservoir of the second Member of Shahejie Formation.

Key words: Qikou Sag, provenance analysis, detrital composition, heavy mineral