Characteristics and distribution of grain banks in the Cambrian Xixiangchi Group of Sichuan Basin and its adjacent areas
Zhao Aiwei1,2, Tan Xiucheng1,3, Li Ling2,3, Luo Bing4, Hong Haitao4, Liu Jiwei5, Wang Yong5, Duan Zhuo6
1 State Key Laboratory of Oil and Gas Reservoir Geology and Exploration, Southwest Petroleum University, Chengdu 610500, Sichuan 2 Sichuan Province Key Laboratory of Natural Gas Geology, Southwest Petroleum University, Chengdu 610500, Sichuan 3 The Sedimentary and Accumulation Department of Key Laboratory of Carbonate Reservoirs, PetroChina, Southwest Petroleum University, Chengdu 610500, Sichuan 4 Exploration & Exploitation Research Institute, PetroChina Southwest Oil and Gas Field Company, Chengdu 610051, Sichuan 5 Central Sichuan Mining District, PetroChina Southwest Oil and Gas Field Company, Suining 629000, Sichuan 6 Geophysical Prospecting Company, Chuanqing Drilling Company Limited, Chengdu 600213, Sichuan
Abstract：Based on comprehensive research on field outcrops,wells and the regional survey in 1︰200000 scale,the grain dolostone,grain limestone and fine- to mid-crystallized dolostone are found to constitute grain banks in the Cambrian Xixiangchi Group of Sichuan Basin and its adjacent areas. Sand-sized intraclast is the main type of intraclasts,and oolite,gravel-sized intraclast and minor bioclast follow in order. Three vertical sequences of upward-coarsening are identified,including lagoon-platform interior shoal-lagoon,lagoon-platform interior shoal-platform interior flat and tidal flat-tidal margin shoal-tidal flat. Each vertical cycle is commonly no more than 2.5 m thick and thin banks are frequently superimposed vertically in a relatively small scale, and the grain banks have small scale and bad continuity horizontally. The grain banks are mainly distributed on palaeo-uplifts and submarine highlands in the direction of northeast-southwest.Sea level fluctuation and sedimentary energy controlled the scale of grain banks,and the tectonic condition determined their lateral continuity and planar distribution.
Zhao Aiwei,Tan Xiucheng,Li Ling et al. Characteristics and distribution of grain banks in the Cambrian Xixiangchi Group of Sichuan Basin and its adjacent areas[J]. JOPC, 2015, 17(1): 21-32.
