--> Abstract: Sedimentary Attributes of Mesozoic Basins of Northwest China--Implications for Hydrocarbon Exploration in a Unique Foreland Setting, by M. S. Hendrix; #91012 (1992).

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ABSTRACT: Sedimentary Attributes of Mesozoic Basins of Northwest China--Implications for Hydrocarbon Exploration in a Unique Foreland Setting

HENDRIX, MARC S., Stanford University, Stanford, CA

Sedimentary facies, paleocurrent, and sandstone provenance data strongly suggest that the north Tarim and south Junggar basins of northwest China have been partitioned as discrete physiographic entities by the intervening Tian Shan (Heavenly Mountains) since the late Paleozoic. The Turpan basin, located within the Tian Shan, has been partitioned since the Triassic. Basinwide sediment accumulations, sediment dispersal patterns, and subsidence profiles indicate that, throughout their Mesozoic and Cenozoic history, each of these has been a foreland basin. Unlike the "classic" foreland basins of the Americas, which are built upon a substrate of cratonal crust, however, the Mesozoic-Cenozoic foreland basins of northwest China are constructed atop a series of accreted elements including arc , ophiolites, and microcontinents. This collage-like character of basement elements and the Mesozoic-Cenozoic accretionary history along the south Asian continental margin has resulted in episodic structural reactivation of terrane and basin-bounding faults adjacent to foreland basins of northwest China. Accompanying each structural reactivation was a physiographic rejuvenation of the Tian Shan, an acceleration of subsidence rates in adjacent sedimentary basins, and the progradation into each basin of a coarse alluvial sediment pulse.

Widespread Lower and Middle Jurassic organic-rich meandering fluvial and lacustrine deposits are present in each basin. Coals and organic-rich shales associated with these deposits contain high H.I. type I kerogens as well as type III kerogens. Kerogens are generally slightly immature to mature with respect to petroleum generation, though maturation indices vary according to sample location within each of the basins. Gas chromatography-mass spectrometry (GC-MS) analyses of bitumens indicate multiple sources of organic matter, including algae, bacteria, and higher plants, especially conifers. The abundance of Lower and Middle Jurassic organic-rich strata capable of liquid hydrocarbon generation, coupled with strong evidence supporting multiple Mesozoic episodes of subsidence-driven the mal maturation, provide a very optimistic exploration scenario for foreland basins of northwest China.

 

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)