Tectono-sedimentary evolution in central Tarim Basin during the early Cambrian: New insights from stratigraphic forward modeling

The Lower Cambrian carbonate platform sequences in the central Tarim Basin play an important role in controlling the development of hydrocarbon source rocks and reservoirs, as well as the formation and distribution of oil and gas. A large number of studies have been conducted on its formation and evolution, but most of them are based on qualitative analysis and paid little attention to the influence of differential deposition of the carbonate platform sequences.

Based on previous research findings and supplementary analysis of key seismic sections, outcrops, well logs, core, and cuttings, we have investigated the Early Cambrian paleoenvironment in the central Tarim Basin. By using the Earth System Science approach, we studied the Lower Cambrian carbonate platform sequences through stratigraphic forward modeling (SFM) by taking into consideration of key geological factors such as the initial paleo-topography, tectonic movement, high-frequency sea-level changes, carbonate growth/denudation, and clastic sediment input. The 3D stratigraphic forward model was calibrated and validated using a variety of geological data.

Through uncertainty analysis of different geological factors and variables, and combined with previous research findings, we have systematically analyzed the tectono-sedimentary evolution process responsible for the development of the carbonate platform margin facies in both time and depth domains and evaluated the contribution of key factors on the evolution of platform margin facies quantitatively, and finally clarified the formation mechanisms and evolution model of the platform margin facies in central Tarim Basin.

The study showed that the initial paleogeomorphology and tectonic subsidence jointly controlled the fluctuation of relative sea level, which determined the migration direction and internal structure of the carbonate platform margin. The differential stratigraphic architecture and stacking patterns of the carbonate sequences were primarily caused by the exposure duration and the slope angles of the platform margin collectively.