Sedimentary Features And Evolution Of Dongying Delta-Turbidite System

Dongying depression was one of the secondary tectonic unit in the east of Dongying Sag in Jiyang depression. Study area was in the southeast of Dongying depression. Dongying delta developed in Dongying depression during the deposition of Shahejie.Based on previous study and exploration data, using the integrated study well logging deta and drilling cores, we redraw the times of Dongying delta,and then we devide the deposition into 9 parasequence sets from bottom to top. We defined the identification marks of delta, lacustrine and turbidite. We identified two kinds of the turbidite. One was the secondary deposition of the delta front, and the other one was the seposition of the seasonal flooding. The first part of the turbidite was divided into three types: slip type; collapse type; distal type. We also analyzed the spatial combination relationship of facies, defined the development characteristics of sedimentary system, and established sedimentary model.Full use of the theory of sedimentation, we account the structure of Dongying delta. We also quantifies the relationship between sedimentary facies. We typical profiles of each simulation delta 9 of views within the front slope angle of slope Then we find out that the sedimentary evolution of the Dongying delta became flat from the beginning to the end in Shahejie.Finally, based on the engineering geological theory, we analyzed the balance of the slop sediments and find out the angle of the delta -turbidite systems. Then we find there are two reasons of the breake in the delta front.The first one is the delta front sediment characteristics including the namely size, mixed-based content, sorting, roundness, and sand and mud content.The second one is the external force such as earthquake.