Petroleum Potential of North Qilian Overthrust
Belt
Qi Fei, Xiepei Wang
An extensive surface geological survey and seismic data show that the North
Qilian Range, northwest China, is composed of a series of northwest-trending
overthrust
faults, dips which change from steep at the surface to gentle at
depth forming an imbricated listric fault system. Most of the thrust faults
occur along plastic beds such as Carboniferous sandy shales, Lower Ordovician
tuffaceous rocks, clastic strata of Jurassic, Cretaceous, and Tertiary age, and
some unconformities. Since the Mesozoic-Cenozoic, North Qilian experienced at
least two stages of overthrusting. These tectonic movements were associated with
sinistral strike-slip displacement along the Alkin fault which controlled the
formation and development of the Jiuxi oil-bearing basin. According to the
balance profiles, the compression ration of the Qilian
overthrust
belt is
estimated to be 50%. Therefore, along the south rim of the Jiuxi basin, a
considerable package of Cretaceous source rocks lie buried beneath the
overthrusts along with a series of potentially favorable footwall oil and gas
traps. It is concluded that the foreland of North Qilian
overthrust
belt could
represent a new domain for oil and gas exploration.
AAPG Search and Discovery Article #91038©1987 AAPG Annual Convention, Los Angeles, California, June 7-10, 1987.