黄骅坳陷歧口凹陷沙河街组二段物源分析

为弄清歧口凹陷沙二段物源-沉积体系展布特征,通过碎屑组分、重矿物、稀土元素等多参数物源分析方法,对歧口凹陷周边源区分布及其各自对凹陷内部沉积的影响范围进行系统研究。发现各源区母岩岩石类型以中基性喷出岩为主。研究区存在北部、西部和南部3大物源区,可细分为北部燕山、西北沧县隆起、西部港西和港东凸起以及南部赵北和张东6个分支物源。其中北部燕山和西北沧县隆起分支物源控制了北大港潜山北部以及板桥凹陷一带的大部分三角洲沉积,并与西部港西凸起分支物源在港中一带形成混源滩坝沉积。而港西、港东、赵北和张东4分支物源仅控制其周边的扇三角洲和滩坝相沉积。总之,古物源区与沉积体系具有良好的空间配置关系,为沙二段岩性地层油气藏的形成提供了良好的物质基础。

Provenance Analysis of the Second Member of Shahejie Formation in Qikou Sag of Huanghua Depression

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.