4th International Conference of Palaeogeography

185 / 2019-06-11 19:06:36

Characteristics of sedimentary facies and sequence stratigraphy of Denglouku group in Xujiaweizi fault depression in Songliao basin,China

Xuxi sag, Xujiaweizi fault depression, Denglouku group, Sequence stratigraphic framework, Sequence boundary, Intermittent lacustrine facies, History of depositional evolution

According to the core data, the loggings, and the seismic reflection, use the technique of isochronic sequence stratigraphy and seismic sedimentology as the main technical means, divided the Denglouku Fomation of Xujiaweizi area in Songliao basin into 10 fourth order sequences, constraint the thickness within 70-80m for the first time (it was divided into 4 basic sequences, the thickness within 150-180m before). Recognized 3 basic sequence flooding surfaces as SB33、SB32 and SB31, 4 fourth order sequence flooding surfaces as D4-SB1、 D3-SB1、 D2-SB1 and D1-SB1. Modeling the recognition feature of the basic and fourth order sequence boundary, this was fit for the seismic and geological condition of the research area. And we also built the stratigraphic framework of the whole region. The analysis works shows the base level dropped down gradually from the bottom to the top of the whole Denglouku group. In member Deng 1st it developed lacustrine facies and fan delta facies, controlled by the sedimentary systems from the northeast and northwest. In member Deng 2nd and 3rd, it developed braided fluvial delta facies and intermittent lacustrine facies, the depositional environment in this period was controlled by the sedimentary systems from the north, the northeast, the east, the southwest, and the northwest. In member Deng 4th, it developed mainly braided fluvial facies, partly developed shallow lacustrine facies and braided fluvial delta plain facies, the main source is from the northeast, and a small amount of source is from the west. The precise recognition of the sedimentary facies in Denglouku group, Xuxi sag of Xujiaweizi fault depression is an important basis of the next exploration deployment in the research area, and has a positive significance.