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Early Paleozoic Positive Basin Inversion of South China and its Implications for Petroleum Exploration

Wu, Long *1; Jia, Dong 2; Li, Haibin 2; Trudgill, Bruce D.1
(1) Department of Geology and Geological Engineering, Colorado School of Mines, Golden, CO.
(2) School of Earth Sciences and Engineering, Nanjing University, Nanjing, China.

South China can be divided into two parts by Jiangshao Fault Zone: Yangtze craton to the northwest and Wuyishan Fold Belt to the southeast. The late Neoproterozoic-Ordovician sediments in Yangtze area are shallow-marine platform strata (mainly carbonates) with some siliciclastic input on the southeastern margin, representing a typical passive margin setting. Coeval strata that preserved in the Wuyishan area developed on the Neoproterozoic Nanhua rift of South China, and are mainly composed of extensive ~10 km-thick basin facies terrigenous clastic turbidites. Coupled with lithofacies palaeogeography and palaeocurrent evidence, detrital zircon analysis of the thick succession in the proto-type rift basin indicates an outboard provenance terrane to the southeast of South China, which acted as a sustained source of the voluminous succession for ca. 150 Ma. In late Ordovician-Silurian, the tectonic setting of the rift basin inverted intensively and formed the Wuyishan Fold Belt. Our age statistics of early Paleozoic granitoids in South China indicate that the timing this orogenic event is ca. 460-395 Ma. Based on geological observation and U-Pb geochronology result, we propose that there was a latest Ordovician-Silurian foreland basin seated along the southern margin of Yangtze craton. Main evidences are: 1) rapid changing of sedimentary environment and depositional rate, 2) synorogenic sedimentary wedge, and 3) provenance analysis indicate that Silurian sediment largely derived from Wuyishan Fold Belt. The distribution of two important sets of black shale in Yangtze area, i.e., early Cambrian Niutitang Fm. and early Silurian Longmaxi Fm., have a close relationship with basin evolution. In this manner, our results not only improve the understanding of early Paleozoic basin evolution of South China, but also provide important geological implications on future exploration of hydrocarbons in southern margin of Yangtze craton.

 

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California