--> Abstract: High-Resolution Sequence Stratigraphic Framework of a Saline Lacustrine Basin, Qianjiang Formation, Jianghan Basin, Central China, by Chunju Huang, Paul Weimer, Kaiyuan Chen, and Zhixiong Fang; #90078 (2008)

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High-Resolution Sequence Stratigraphic Framework of a Saline Lacustrine Basin, Qianjiang Formation, Jianghan Basin, Central China

Chunju Huang1, Paul Weimer1, Kaiyuan Chen2, and Zhixiong Fang3
1Dept. of Geological Sciences, University of Colorado at Boulder, Boulder, CO
2Department of Energy Geology, China University of Geosciences, Beijing, China
3Jianghan Oilfield Company, China Petroleum & Chemical Corporation, Qianjiang, China

The Eocene Qianjiang Formation of the Jianghan Basin in central China comprises thick continental lacustrine strata. The maximum thickness of the formation is 4700 m and includes 1800 m of halite. Analyses of 2-D seismic data identified eight third-order depositional sequences based on truncation and onlap of sediments in the lakes. The main rock types are shoreline sandstones, dark mudstones, halite, and alternating mud and gypsum in low-relief place. This repeated vertical succession suggests distinct sediment cyclicity. Stratigraphic analysis indicates that the sediments were deposited in different kinds of lake systems. Specifically, the halite deposits developed in a saline lake-system, whereas the other deposits formed in fresh-water lakes. The alternating sediment types indicate this basin contained different types of lakes (fresh-water versus saline), and are probably due to changes in climate, sediment supply and accommodation. Specifically, within and between the eight sequences, the basin evolved from deep and shallow overfilled lakes, to deep and shallow balanced-fill lakes, and deep and shallow underfilled lakes (sensu Bohacs et al., 2000). The thick halite deposits are interpreted as deep-basin in origin based on interbedded dark mudstones. For the past thirty years, the Qianjiang Formation has produced petroleum from structural traps; exploration emphasis has now changed to stratigraphic traps. These new studies of the basin have focused on the origin of the thick salt deposits and their effects on petroleum generation and accumulation. Specially, the salt deposits have influenced the development of structural and stratigraphic traps, migration pathways, and possibly the timing of source rock maturation and generation.

 

AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas