沾化凹陷东部长堤地区下第三系沉积体系研究

综合运用地质、测井、地震及分析化验等资料,对沾化凹陷东部长堤地区下第三系沉积体系进行了较为全面系统的研究,认为长堤地区下第三系发育有水下扇、滨浅湖滩坝、扇三角洲、浊积和辫状河等 5类沉积体系。并阐述了各类沉积体系在本区的亚相、微相类型及其特征,系统分析了早第三纪不同阶段的沉积相类型及其分布特征,探讨了不同时期物源区及古水流流向,总结了垂向上沉积体系的演化等。

Study on the Sedimentary System of Paleogene in Changdi Region of Zhanhua Sag

Changdi region is situated in the eastern part of Zhanhua sag in Jiyang depression. It belongs to one part of the Zhuangxi Gudong buried hill belt in structure,with area an about 160 km 2. Based on the synthetical analysis the geological, log, seismic and chemical analysis data,the authors believe 5 types of sedimentary system were developed in this area in Paleogene,that is, subsurface fan, beach and dam, fan delta, turbidity current and braided river. Subsurface fan can be divided 3 types of sub facieses,i.e, root fan, middle fan and fan edge by core and conglomerate distribution and etc. The middle fan can be divided 3 micro facies-braided channel, space between channel and front edge zone. In the braided channel, sediment grain is coatse. And it shows positive rhythm, SP curve with box type and etc. Surface of scour can be seen at the bottom of the channel. Beach and bar system were formed at the edge of lake, shallow platform and etc. They can be divided into 2 types,i.e.,terrigenous debris type and carbonate rock type. The terrigenous debris type was distributed mainly over the west edge of the study area, and carbonate rock type was distributed mainly in the middle part. About the fan delta system, there were prodelta and delta front in the area. The delta front subfaces consists of embranchment channel, channel mouth bar and etc.Judged by distribution of the sedimentary system, during the third member of Shahejie formation, researching area belongs to subsurface fan system. From the early stage to metaphase, the sediment range were widened gradually. In the later period, the range of lake and size of subsurface fan diminished. During the second member and the early stage of the first member of the Shahejie Formation, this area belonged to beach and bar system. In the third member of Dongying Formation, the study area belonged to fan delta system, and it stretched gradually from southeast to north.During the later period, the southeast part developed the fan delta plain.The delta front subfaces consisted of embranchment channel, channel mouth bar and etc. During the second member and the first member of the Dongying Formation, this area belonged to braided river system as a whole. There were a series of channel bar deposits. It was thought by synthetically analyzing the regularity of vertical evolution of sedimentary system was instinct. During the third and second member of the Shahejie Formation, the type of sedimentary system was subsurface fan near bank, the sediments came from Changdi lower upheaval. During the first member of the Shahejie Formation, it belonged to beach and bar system, while later period of the member, it was deep lake. From the third member of the Dongying Formation to the second and first member, the sediment system was fan delta, braided river, sediments mostly came from the Kendong-Qingtuozi upheaval.