--> Abstract: Dextral Shear In Cenozoic Hydrocarbon Basins Of East Asia, by M. B. Allen, D. I. M. Macdonald, R. Flecker, S. J. Vincent, and Z. Xun; #90928 (1999).

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ALLEN, MARK B.1, DAVID I. M. MacDONALD1, RACHEL FLECKER1, STEPHEN J. VINCENT1, and ZHAO XUN2
1Cambridge Arctic Shelf Programme, Department of Earth Sciences, Cambridge University, England
2Chinese Academy of Geological Sciences, Beijing, China

Abstract: Dextral shear in Cenozoic hydrocarbon basins of east Asia

Cenozoic extensional deformation in east Asia produced sedimentary basins from northeastern Russia to Indochina. The causes of extension thoughout this area are in dispute. Schemes for individual basins or sub-groups of basins relate extension to a far-field effect of the India-Asia collision, the action of subducting oceanic plates at Asia's continental margin, or a combination of the two mechanisms. Many of the basins are major hydrocarbon producers and/or exploration areas, such as the Sea of Okhotsk region and the Bohai, East China Sea, and Pearl River Mouth basins. Source and reservoir rocks are found in both syn- and post-rift successions. Pre-Cenozoic rocks form important reservoirs in footwall crests of half grabens in the Bohai Basin, for example in the Renqiu field.

Several of the major basins in this group, notably Bohai, the Sea of Okhotsk basins and the basins north of the South China Sea, possess components of dextral transtensional deformation in their structure. This is consistent with the sense of shear implied by the oblique convergence of the Pacific and Asian plates: an east-west convergence vector applied to a northeast-southwest trending plate boundary. The consistency of this shear along the Asian margin, and the initiation of extension prior to the India-Asia collision, support the subduction roll-back model for regional basin formation.

Plays involving dextral transtensional deformation contain elements not found in orthogonal rift systems, such as en echelon arrays of normal faults within larger half grabens: this is the setting for some of Bohai's most productive fields, including Renqiu.

AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas