--> ABSTRACT: Syn-Rift/Syn-Strike-Slip Sequence Stratigraphy of South Liaodong Bay, Bohai, Offshore China, by Li-Yuan Hsiao, Nat Tilander, Ed Griffin, and Stephan A. Graham; #90906(2001)

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Li-Yuan Hsiao1, Nat Tilander2, Ed Griffin2, Stephan A. Graham1

(1) Stanford University, Stanford, CA
(2) Chevron Overseas Petroleum Inc, San Ramon, CA

ABSTRACT: Syn-Rift/Syn-Strike-Slip Sequence Stratigraphy of South Liaodong Bay, Bohai, Offshore China

Liaodong Bay rift basin sits astride the Tan-Lu fault system of eastern China, one of the world°|s largest strike-slip fault systems. Integrated analysis of a high-quality industrial data set permits documentation of structural and stratigraphic development during Cenozoic evolution of the basin. The Tan-Lu fault was active during basin rifting, and its structural style seems to have been related to the mode of rifting. During the climax and the fading of the rifting, this fault system was characterized by positive and negative flower structures, respectively. These contrasting deformational styles exerted marked influence on syntectonic sedimentation. Transpressional tectonics created a local longitudinal structural high along the basin center that separated two major depositional systems and became a source of sediment provided to the basin. Subsequently, this structural system collapsed by transtensional tectonics.

Mode of continental rifting played the dominant role in the syn-rift stratigraphic development. During the climax of rifting, basin accommodation reached a maximum, and most sediments were trapped along the basin margins. The rift climax tectonic systems tract (Shahejie Sequence) is therefore dominated by deep lacustrine facies. In contrast, shallow lacustrine, deltaic and fluvial environments characterize late rifts tectonic systems tract (Dongying Sequences) due to fading of rifting and diminished accommodation. The late rift Lower Dongying Sequence is particularly interesting because it contains high-quality reservoirs reflecting its high-energy environment. Although their distribution is rather limited, high-quality sands can be recognized by oblique/truncational features in seismic reflection data. This provides a useful approach for identifying prospective reservoirs.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado