--> ABSTRACT: Tectonic and Climatic Controls on Mesozoic and Cenozoic Sedimentation and Hydrocarbon Generation in the Hexi Corridor, NW China, by Stephen J. Vincent, Mark B. Allen, Christine Brouet-Menzies, Zhao Xun; #91020 (1995).
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Tectonic and Climatic Controls on Mesozoic and Cenozoic Sedimentation and Hydrocarbon Generation in the Hexi Previous HitCorridorNext Hit, NW China

Stephen J. Vincent, Mark B. Allen, Christine Brouet-Menzies, Zhao Xun

An Early Palaeozoic collision accreted the island arcs and subduction complexes of the Qilian Shan to the cratonic basement of the Alashan (North China Block). The broad collision zone created by this event lies underneath the region known as the Hexi Previous HitCorridorNext Hit. Rift basins were created in and adjacent to the Hexi Previous HitCorridorNext Hit during the Late Jurassic and Early Cretaceous. Some are dextral pull-aparts (e.g. Minle). Others are the result of a more complex interplay of dextral and sinistral fault zones (e.g. Jiuquan and Bayanhaote).

Lakes developed within these basins provided favourable conditions for the preservation of organic matter. These organic-rich Upper Jurassic and Lower Cretaceous shales form the principal hydrocarbon source rocks of the region. The thickest shales developed in the northwestern basin of the Previous HitCorridorNext Hit (Jiuquan), with progressively decreasing thicknesses in basins to the southeast. The climate in this area seems to have been relatively humid at this time, a characteristic shared with the larger basins further east in China (e.g. Songliao). Mesozoic fluvial sandstones act as reservoir rocks, but the main reservoirs are developed in Neogene molasse. This Late Cenozoic deposition was a response to deformation generated by the India-Asia collision. The Qilian Shan has overthrust the southwest rn margin of the Previous HitCorridorNext Hit, and reactivated faults within it, in some cases with a component of sinistral transpression. The resulting structures form the main known hydrocarbon traps, and have considerable potential for further exploration.

The sedimentology and structure of the Minle Basin will be described to illustrate both the overall evolution of basins in the Hexi Previous HitCorridorTop, and the relative importance of tectonics and climate change in controlling base level, and hence source and reservoir distribution, in the fluvial-lacustrine systems.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995