Sedimentary characteristics and evolution of braided river delta of the Xujiahe Formation in Western Chongqing Area
In order to clarify the sedimentary characteristics and evolutionary patterns of the Upper Tri-assic Xujiahe Formation in the Western Chongqing Area In this study of the Xujiahe Formation in the Western Chongqing Area,based on drilling logging core field and seismic data,sedimentary charac-teristics and evolution patterns were investigated using techniques such as stratigraphic correlation,sedi-mentary facies analysis,and seismic attribute characterization.The results indicate that:the Xujiahe Formation in the Western Chongqing Area mainly consists of braided river delta deposits developed on the slope of the basin margin,with sedimentary microfacies including braided river delta plain braid channel,overbank deposits,subaqueous distributary channels,river mouth bars and distal sand bars,and a relatively limited distribution of lacustrine facies;the sedimentary evolution of the Xujiahe Forma-tion in the Western Chongqing Area is controlled by lake level changes and A/S ratio fluctuations under warm-humid to hot-dry ancient climatic conditions,establishing an evolution model for braided river del-tas in the region;during the deposition of the Xujiahe Formation,the climate was warm and humid in the Xu Ⅲ and Xu V stages,with deepening lake water and increasing A/S ratio,mainly developing front deposits of braided river deltas in the area;in the Xu Ⅳ and Xu Ⅵ stages,the climate was hot,with increased evaporation,shallowing lake basin,and decreasing A/S ratio,primarily developing delta plain of braided river deltas,during which thick sand bodies were continuously developed,forming the main reservoir intervals for tight sandstones in the area.The research results provide a theoretical basis for understanding the Late Triassic paleogeography of the Eastern Sichuan Area and the exploration of tight oil and gas in the Xujiahe Formation in the study area.
braided river deltatight sandstonesedimentary evolutionXujiahe FormationSichuan Ba-sinWestern Chongqing Area
万方数据
维普
