The tectonics and petroleum system of the Qiulitagh fold and thrust belt, northern Tarim basin, NW China

Abstract

The timing of hydrocarbon charging relative to trap formation is a key factor for evaluating the exploration potential of the Qiulitagh fold and thrust belt (QFTB) on the north flank of the Tarim basin. Data obtained by this study indicate that structural traps were filled by hydrocarbons in two episodes. In this area, at least four major deformation events have been identified for the period of Late Cretaceous to Pliocene. The first event occurred in Late Cretaceous and led to the formation of paleo-uplift structures. The second event was characterized by thrust features and occurred in latest Oligocene. The third and fourth events were represented by compressional structures that were developed in Late Miocene and Late Pliocene, respectively. Based on oil and gas-source rock correlations and 1-D basin modeling, two episodes of hydrocarbon generation and migration are proposed to be responsible for oil and gas accumulations in the QFTB. The two episodes of hydrocarbon charging from a source kitchen north of the study area took place in Early Miocene and Pliocene, respectively. Since the QFTB was uplifted in Late Oligocene and Late Miocene, the hydrocarbon generated during all two periods could migrate toward this area to form oil and gas accumulations in suitable structures.