Print this pageA Neoproterozoic Submarine Fan in the Eastern of the Yangtze Block, China
Shuang-ying Li1, Liang Peng1, Cheng Cheng1, Guang-hua Cheng2, and De-en Wang3
1School of Resources and Environmental Engineering, Hefei University of Technology, Hefei, Anhui, China
2Nanjing Center of Chinese Geological Survey, Nanjing, China
3No. 332 Geological Team, Bureau of Geology and Mineral Resources of Anhui Province, Huangshan City, Anhui, China
Deposits of deep-sea fan systems represent potential hydrocarbon reservoirs and are a primary target for exploration in numerous basins, so the study on submarine fan systems has become one of the research hotspots. The eastern Neoproterozoic basin of the Yangtze Block, about sixty thousand square kilometers in size, develops accumulated about 5-6 km of deep-marine siliciclastic strata of the Cryogenian, which contributes to the deposits of a submarine fan. The strata are composed mostly of Shangxi and Xikou Groups (Li Shuangying et al., 2013). In the northern part of the basin, the major rock units are the Cryogenian Xiangdong and Yangzhanling Formations of the Shangxi Group, and in the southern part of the basin, the major rock units are the Cryogenian Zhangqian, Banqiao and Mukeng Formations of the Xikou Group.
The deposits of the Neoproterozoic submarine are composed of mostly sandstone and mudstone facies association, next conglomerate facies association. The former facies association includes thick-bedded sandstone, thinbedded sandstone, with minor pebbly sandstone, thin beds of mud clastbearing sandstone, massive mudstone and silt-rich mudstone types, which contribute to turbiditic and hemipelagic origin, and the latter facies association includes matrix-supported and clast-supported conglomerates, pebbly sandstone and silt-rich mudstone, which contribute to debris flow and hemipelagic origin.
The Neoproterozoic submarine fan formed during a transgressive-regressive cycle. In the transgressive stage, the submarine fan system developed a fining-upward sequence, about 3000 meters thick, which comprised deposits from inner-fan, middle-fan to outer-fan, and to basin plain, and the lobes (or sheet sands) develop extensively, but channel facies develop poorly; in the regressive stage, the fan developed a coarsing-upward sequence, above 2500 meters thick, which comprised deposits from the basin plain, to outer-fan, middle-fan, and inner-fan. In the latter stage, the lobes (or sheet sands) developed extensively, and the conglomerates and sandstones of channel facies, and slump deposits developed, which outcrop mostly on the northeast margin of the basin, about elongation of about 150 km from eastern Jixi to western Dongzhi of Anhui Province.
The Neoproterozoic submarine fan deposits in the basin formed during the continent rifting of South China, which was an immature passive-margin setting. Submarine fans develop primarily during periods of low sea level (Shanmugam and Moiola, 1988), so, the deposits of the Neoproterozoic submarine fan might record the events of the Kaigas and Sturtian iceage.
This study is supported by the funds from China Geological Survey (1212011121113) and the NSFC (40972082, 41172097).
AAPG Datapages/Search and Discovery Article #90180©AAPG/SEPM/China University of Petroleum/PetroChina-RIPED Joint Research Conference, Beijing, China, September 23-28, 2013