--> Structural Control on Development of Organic Facies in the Northern Part of Beibu Gulf Basin, South China Sea, by X. D. Ying and B. L. Deng; #90986 (1994).
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Abstract: Structural Control on Development of Organic Facies in the Northern Part of Beibu Gulf Basin, South China Sea

X. D. Ying, B. L. Deng

The development of syn-rift lacustrine organic fades in the Beibu Gulf Basin can be understood by interpreting pyrolytic organic geochemical and wireline log data within the structural framework outlined by complex association of Previous HithalfNext Hit grabens.

Several ENE trending major fault systems originated five major grabens or Previous HithalfNext Hit grabens separated by isolated ridges and/or interference ridges, which set the foundation for drainage systems and syn-rift basin fills in the basin. The SW Weizhou graben was bounded by an elevated rift should to the north and interference ridges to the east and south. To the west, the graben terminated at the junction of several major faults. The Wushi Previous HithalfNext Hit graben was separated by an isolated ridge to the south and an interference ridge to the north and was probably connected with another Previous HithalfNext Hit graben system to the east, providing a pathway for major sediment influx.

Rapid subsidence on the down-thrown blocks of the Previous HithalfTop grabens, limited sediment supply, and warm climate were major factors that conducive the formation of organic-rich fades and deposition of petroleum source rocks. Of the five grabens, the SW Weizhou and Wushi graben experienced very rapid subsidence and limited sediment influx which favored the accumulation of semi-deep lacustrine organic-carbon-rich dark shales during deposition of the Eocene Liushagang Formation. Success in exploration around the SW Weizhou graben has demonstrated the close relationship between the development of syn-rift petroleum source rocks and distribution of petroleum in the basin.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994