| Author's Name: SHEN Anjiang1,2,3, XIONG Shaoyun1,2,3, Hu Anping1,2,3, ZHANG Jianyong1,2,3 Xu Qiang4,
FU Xiaodong1,2,3, PAN Liyin1,2,3, WANG Xin1,2,3, LIU Siqi1,2,3, LI Xi1,2,3, DUAN Junmao1,2,3 |
| The overall research level of the Qiangtang Basin is at its primal stages due to lack of data and uneven
distribution, which makes the predictions of hydrocarbon source rocks and reservoirs imprecise. Based on the analysis of
basin attributes, sedimentary systems and their combination-coupling relationships, this article solves the problems of
multiple interpretations of sedimentary facies in regions with abundant data and lack of sedimentary model guidance in
regions lacking data. Hence, three geological acknowledgments are acquired as follows. First, we specify two distinct
consecutive stages of basin property of the north and the south subterrains in Qiangtang Basin based on the systematically
summarized closing history of the Koh Xil-Jinsha River Ocean, Bangong Lake-Nujiang Ocean and Longmuco-Shuanghu
Ocean. During the Late Triassic-Early Cretaceous epoch, the north Qiangtang terrain evolved from a compound foreland
basin to a weak-compressional in-land residual sea basin and entered into a rapid uplift-denudation period with multiple
folds and faults. The south Qiangtang terrain, meanwhile, transferred from a passive continental margin to an active
continental margin, and also entered into a rapid uplift denudation period with multiple folds and faults. Basin attributes of
eight key sedimentary periods are clarified. Second, we compile ten tectonic-lithofacies paleogeography maps in the Late
Triassic -Early Cretaceous epoch of Qiangtang Basin and distribution maps of igneous rocks of Nadigangri Formation
based on basin properties, sedimentary systems, and the coherent relationships among them. These maps reveal the
controlling effect of tectonic background on sedimentary process in Qiangtang Basin and enhance the precision of
sedimentary facies prediction in data-poor areas. Third, we figure out the tectonic-lithofacies paleogeography in
developing periods of hydrocarbon source rocks and reservoirs explicitly. The distribution of hydrocarbon source rocks of
Bolila Formation-Bagong Formation is controlled by foreland depression and deep-water shelf of the passive continental
margin, and that of Quse Formation is controlled by a back-arc extensional basin and weak-compressional in-land
residual sea basin. The dolomite reservoirs of the Buqu Formation are developed at the platform margin belt. With this
knowledge, we compile four distribution maps of hydrocarbon source rocks and reservoirs. All these new
acknowledgments will boost the oil-gas exploration process in the Qiangtang Basin. |
