黄骅坳陷沙河街组一段碎屑岩沉积特征及构造对沉积的控制作用

Depositional characteristics and tectonic control on sedimentation of the 1^(st) Member of Shahejie Formation in Huanghua Depression,Bohai Bay Basin

黄骅坳陷是渤海湾盆地内重要的含油气坳陷之一。综合运用岩心、岩性组合、沉积构造、古生物、地震等资料,对渤海湾盆地黄骅坳陷沙河街组一段沉积特征进行了研究,将黄骅坳陷古近系沙河街组一段分为沙一下(Es1(1))、沙一中(Es1(2))和沙一上(Es1(3))3个三级层序、9个体系域。研究认为,沙河街组一段碎屑岩沉积主要发育辫状河三角洲、曲流河三角洲、近岸水下扇、重力流和湖泊5种沉积相类型。同时研究了各沉积相类型的沉积特征和空间展布特征。辫状河三角洲主要发育在板桥凹陷、北塘凹陷和歧口凹陷西南部,曲流河三角洲主要发育在黄骅坳陷南区和埕宁隆起东南部,近岸水下扇主要发育在陡坡大断层沧县隆起的根部,重力流主要发育在歧北凹陷深湖区。最后指出,构造演化、断层陡缓和古地貌是控制黄骅坳陷沙河街组一段碎屑岩沉积体系的主控因素。

Huahua Depression is one of the most important petroliferous depressions in Bohai Bay Basin. Based on core observation,lithology association,sedimentary structure,paleontology and seismic data,this paper studied the depositional characteristics of the 1stMember of Shahejie Formation in Huanghua Depression. We divided the target formation into three 3rdorder sequences,namely Es1（ 1）,Es1（ 2）and Es1（ 3）,and nine system tracts. The results show that five facies including braided river delta,meandering delta,nearshore subaqueous fan,gravity flow and lacustrine facies develop in the 1stMember of Shahejie Formation. We also analyzed the depositional characteristics and the space distribution of each facies. The braided river delta facies distributes in Banqiao sag,Beitang sag and the southwest of Qikou sag. The meandering delta facies mainly develops in the south of Huanghua Depression and the southeast of Chengning Uplift. The nearshore subaqueous fan facies develops near the foot of the Cangxian Uplift with steep fault side. The gravity flow facies occurs in the deep lake of the Qibei sag. Tectonic evolution,steepness of fault and palaeomorphology are the main controlling factors on the clastic sedimentary system of the 1stMember of Shahejie Formation.