Evolution of Mesozoic paleo-uplifts and differential control on sedimentation on the southern margin of Kuqa Depression, Tarim Basin

Abstract

The paleo-uplift is an important tectonic element which is key to control the sedimentary system in petroleum basins. The evolution of Mesozoic paleo-uplifts and differential control on sedimentation on the southern margin of Kuqa Depression, northern Tarim Basin, is still unclear, restricting successful petroleum exploration and development. Based on borehole and 3D seismic reflection data on the southern margin of the Kuqa Depression, the parameters of paleo-uplifts, such as residual thickness, eroded thickness, slope height, slope angle, slope height difference were extracted. Combined with the composition of the detrital minerals in the Cretaceous Shushanhe Formation which was one of the target layers and the Paleo-lithofacies map before the deposition of Cretaceous, the paleo-uplifts could be further divided into four sub-uplifts. The paleo-uplifts grew and extended in the Triassic to Jurassic, decreased in the Jurassic to Cretaceous, and transformed into subaqueous low uplift in the upper part of Cretaceous Shushanhe Formation. The evolution of paleo-uplifts controlled strata and facies, resulting in no Triassic strata were deposited in the north of Yaha-Kudong and Luntai sub-uplifts, while the Jurassic strata in the Xinhe and Qiaogu sub-uplifts experienced extensive erosion. The faults in the Xinhe sub-uplift and steep slopes in the Luntai sub-uplift controlled the deposition of alluvial fans and fan deltas, while the gentle slopes of Qiaogu and Yaha-Kudong sub-uplifts controlled the distribution of braided river deltas. The evolution of the paleo-uplifts was synchronized with regional tectonism, including the south Tianshan collision orogeny and the post-orogenic stress relaxation. This study will help elucidate the development and evolution of the paleo-uplifts on the southern margin of Kuqa Depression, northern Tarim Basin, clarify the relationship between provenance and sedimentary system, and guide the oil and gas exploration in Tarim Basin and other basins with the similar background globally.