断坳叠置湖盆岩相古地理研究方法——以沧东凹陷为例

通过对沧东凹陷及其周边区域钻孔资料和地震资料的分析，获得对沧东凹陷孔店组残留地层的空间分布和现今构造特征的认识。结合65口井1 120 m岩心、340余口井测井资料、600余口井录井资料和32条地震测线等资料指示的沉积特征，初步判定孔店组沉积期沧东凹陷湖盆演化总体经历了4个阶段，分别为：坳陷初期（孔店组三段沉积时期）、坳陷期（孔店组二段沉积时期）、坳陷末期（孔店组一段下亚段沉积时期）和断陷期（孔店组一段上亚段沉积时期）。4个阶段的湖盆古地理演化过程为：孔店组三段冲积扇-冲积平原（或辫状河三角洲）-滨浅湖沉积体系→孔店组二段辫状河三角洲-深湖沉积体系→孔店组一段下亚段冲积扇-冲积平原-滨浅湖沉积体系→孔店组一段上亚段冲积扇-冲积平原-膏盐湖沉积体系。

Paleogeography method of fault depression superposition lake basin: a case study of Cangdong sag

By analyzing the drilling data and seismic data of Cangdong Sag and its surrounding area, the spatial distribution and current structural feature of residual strata in the Kongdian Formation, Cangdong Sag is obtained. Combined with the sedimentary characteristics indicated by 1 120 m core from 65 wells, logging information from over 340 wells, mud logging information from over 600 wells, 32 seismic lines and other data, it is preliminarily considered that the lake basin in Kongdian Formation, Cangdong Sag overall experienced 4 stages in the depositional stage, i.e., early depression period(sedimentary period of the 3rd Member of Kongdian Formation), depression period(sedimentary period of the 2rd Member of Kongdian Formation), later depression period(sedimentary period of the lower sub-member of the 1st Member of Kongdian Formation) and faulted period(sedimentary period of the upper sub-member of the 1 st Member of Kongdian Formation). The 4 stages of paleogeography evolution in the lake basin is as below:alluvial fan-alluvial plain(or braided river delta) of the 3 rd Member of Kongdian Formation-shore-shallow lake sedimentary system→braided river delta-deep lake sedimentary system of the 2nd Member of Kongdian Formation→alluvial fan-alluvial plain-shore-shallow lake sedimentary system of the lower sub-member of the 1st Member of Kongdian Formation→alluvial fan-alluvial plain-gypsic saline lake sedimentary system of the upper sub-member of the 1st Member of Kongdian Formation.