羌塘盆地中生代岩相古地理研究新进展OA北大核心CSTPCD

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.