The Cambrian source rock is a key indicator that will guide future hydrocarbon explorations in ultra-deep strata. Despite its importance, the characteristics of paleotopography on the Precambrian basement and the distribution of source rocks above it remain unclear. The seismic and borehole data, isopach data, and the unconformity analysis are used to study the relations of the Cambrian source rock distribution to the paleotopography. The consistency of the strata thickness distribution maps of the Nanhua–Cambrian sequences show that the extensive thermal subsidence lasted the whole Sinian period, and makes the paleotopography of the Precambrian basement inherited from the landform after the Nanhua continental rifting. A major transgression caused by rapid subsidence of the Tarim Basin took place during the Cambrian. Shales were deposited offshore along the slopes of a paleo-uplift on the inherited paleotopography and formed the onlap in seismic profiles. The onlap on the inherited paleotopography reflects the distribution range of Yuertusi source rocks in the Cambrian.

Strike-slip deformation belts are interesting structures in the crust and are of significance in petroleum exploration. The Shunbei 5 fault belt (SB5), a long strike-slip deformation belt in the Tarim Basin, played an important role in the formation of a recently discovered major oilfield known as the Shunbei oilfield. In this study, models of plan view and vertical profile were established to interpret SB5 with multi-cycled tectonic activities. To this end, its structural framework, tectonic evolution, and associated plate tectonics were investigated using 2D and 3D seismic data. SB5 was formed as a dextral simple shear belt at the end of the Middle Ordovician. In the plan view, R-shears and P-shears with local transpressional and transtensional structures were observed. Along the vertical profiles, various structural styles occurred at various depths and strata in response to various stratigraphy mechanisms. Although these structures show clear boundaries between them, they correspond to the same formation time, indicating that they underwent deformation simultaneously. The second activity of SB5 occurred at the end of the late Ordovician, during which it was a dextral transtensional strike-slip deformation belt consisting of left-stepping en echelon R-shears. The R-shears were transtensional during the progressive deformation. Subsequently, SB5 underwent several strike slips of weak strength. Notably, SB5 cut through a deep Middle Cambrian gypsum salt layer and connected the deep Lower Cambrian source rock with deep Lower and Middle Ordovician carbonates to form the oil and gas reservoirs. The established models are of reference value in the interpretation of other subsurface strike-slip deformation belts.