Stratigraphic correlation and sedimentology of the Ediacaran succession in the Tarim Basin, NW China: Implications for paleogeographic reconstruction and hydrocarbon exploration

The Late Neoproterozoic was an important period for the breakup of Rodinia and the assembly of Gondwana. The Neoproterozoic succession developed under the extensional setting is critical for understanding the early tectonosedimentary evolution of the Tarim Basin and possibly exhibits considerable hydrocarbon potential. In this paper, the stratigraphic correlation of the Ediacaran is conducted across the whole Tarim Basin, based on the latest wells, seismic data and field investigations. The paleogeographic distribution and hydrocarbon potential of the Ediacaran are thoroughly discussed. The Lower Ediacaran succession is mainly distributed in northern and southwestern Tarim Basin and marginal outcrop areas, but absent in the whole Central Rise. With sea level rising, the Upper Ediacaran succession gradually moved toward Central Rise with the exception of the Tazhong Uplift and the eastern Bachu Uplift. During Early Ediacaran, depositional environment in the Tarim Basin was mainly clastic shore-shelf, with a large denuded region extending from Bachu-Tazhong Uplift to Tadong Uplift. The range of the erosional area gradually diminished during Late Ediacaran. Accordingly, the Tarim Basin was dominated by carbonate platform and mixed shelf. Slope break belt between carbonate platform and mixed shelf was identified around the Manjar sag for the first time. The Ediacaran black mudstone and shale in northeastern and southwestern Tarim, which formed in deep-water environment and have relatively high values of TOC (mostly ranging from 0.3% to 1.2%), can serve as high-quality source rocks. The Upper Ediacaran dolostones altered by paleokarst could be potential reservoir rocks. Our research findings, combining with previous geological results, suggest that the Ediacaran succession in Tarim Basin has great potential for hydrocarbon exploration.