Lithofacies palaeogeography of the Early Paleozoic black rock series in Dabashan region and their shale-gas geological significance
Xiong Guoqing1, 2, 3, Wang Jian1, 2, 3, Li Yuanyuan4, Yu Qian2, 3, Men Yupeng2, 3, Zhou Xiaolin1, 2, 3, Xiong Xiaohui2, 3, Zhou Yexin1, 2, 3, Yang Xiao1, 2, 3
1 College of Earth Science,Chengdu University of Technology,Chengdu 610059,Sichuan; 2 Chengdu Center of Geological Survey,China Geological Survey,Chengdu 610081,Sichuan; 3 Key Laboratory of Sedimentary Basin & Oil and Gas Resources,MLR,Chengdu 610081,Sichuan; 4 Shandong Institute of Geophysical & Geochemical Exploration,Jinan 250013,Shandong
Abstract Two suites of black rock series of the Lower Cambrian Shuijingtuo Formation(the Bashan Formation to the Lujiaping Formation)and the Upper Ordovician Wufeng Formation to the Lower Silurian Longmaxi Formation were developed in the Dabashan region in the Early Paleozoic. Sedimentological research reveals that the black rock series were deposited in a passive continental margin basin in the northern margin of the Yangtze Plate. Their sedimentary environments were mainly a deep shelf due to rapid transgression during the earlier period and gradually changed into the shallow shelf with sea-level decline during the later period with some local reefs and shoals. The Early Cambrian and Late Ordovician to Early Silurian basements of the passive continental margin basin in the study area were not flat,which would result in the multi-island obstructively palaeogeographical pattern in continental margin. But their formation mechanisms are totally different. The Early Cambrian palaeogeographic pattern was inherited from graben-horst pattern of the Doushantuo Stage,and local uplift or submerged uplift remained in garben;but foreland uplift during the Late Ordovician to Early Silurian developed in passive continental margin basin in the northern margin of Yangtze Plate was related to Yangtze Plate subduction to North China Plate. The restricted stagnant ocean is more conducive to high-quality shale formation with heavy thickness,high TOC(2%~6%)and high content of brittle mineral(40%~65%),which are usually sweet target layers for shale-gas exploration,but it is necessary to enforce structural research of preservation conditions.
Fund:Financially supported by the National Natural Science Foundation of China(Nos.41672112,41372124)
Corresponding Authors:
Wang Jian,born in 1962,is a Ph.D. supervisor and research fellow. Now he is mainly engaged in researches of sedimentary geotectonic,petroleum geology and sedimentary basin analysis. E-mail: w1962jian@163.com.
About author: Xiong Guoqing,born in 1975,is a Ph.D. candidate in College of Earth Science,Chengdu University of Technology. Now he is a senior engineer and is mainly engaged in researches of sedimentary facies and palaeogeography,sedimentology,and petroleum geology. E-mail: hsiungq@163.com.
Cite this article:
Xiong Guoqing,Wang Jian,Li Yuanyuan et al. Lithofacies palaeogeography of the Early Paleozoic black rock series in Dabashan region and their shale-gas geological significance[J]. JOPC, 2017, 19(6): 965-986.
Xiong Guoqing,Wang Jian,Li Yuanyuan et al. Lithofacies palaeogeography of the Early Paleozoic black rock series in Dabashan region and their shale-gas geological significance[J]. JOPC, 2017, 19(6): 965-986.
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