STRUCTURAL CHARACTERISTICS AND EVOLUTION IN THE LAIYANG DEPRESSION OF THE JIAOLAI BASIN

The Laiyang Depression is a secondary structural unit of the residual basin developed in the Cretaceous period.There are obvious differences in terms of different periods of the Cretaceous deposition,an angled unconformity surface existing between the Upper and the Lower Cretaceous,and well developed folds and faults in the depression.The structural evolution history may be divided into five stages including pull apart faulted depression during the Laiyang period,the extensional faulted depression during the Qingshan period,compressed folding at the end of the Qingshan period,re pull apart faulted depression during the Wangshi period and uplifted erosion during the Cenozoic.The tectonic activity during the Early Cretaceous provided conditions of deposition of hydrocarbon source rocks,and tectonic movement occurred in the Late Cretaceous and the Cenozoic resulted in formation and adjustment of oil and gas pools.