The Tiantai slope in the Xihu Sag, East China Sea Shelf Basin, has a special tectonic background with a deep NW-trending fault zone cutting through and adjusting/transforming the tectonic features of the Cenozoic in the southern and northern parts of the slope. Based on the detailed interpretation of 3D seismic data and restored balanced cross sections, this study establishes models for the development of deep and shallow faults, determines the tectonic attribute of the NW-trending transform zone and discusses the evolution history and genetic mechanisms of the transform zone against regional geological settings. The results show that the NW-trending extensional detachment faults, including the Tiantaixi fault and the Gushan fault, were developed in the Mesozoic of the Tiantai slope, and have played an accommodating and transforming role in shaping the geological framework and controlling fault development and extension intensity of the Cenozoic, resulting in a gentle and a steep slope respectively on the south and more stretched north parts of the slope. The faults of the Cenozoic in the northern slope obviously outnumber those in the southern slope. Arc fault systems are found to be developed in the hanging wall of the Gushan fault. The NW-trending tectonic transform zone bounded by the Tiantaixi fault and the Gushan fault differs greatly from that formed in the extensional setting, indicating a discrete type of tectonic transform zone. Influenced by the post-orogenic collision and extension between the Qinling and Dabie orogenic belts, and the collision and subduction of the Eurasian and Pacific plates, the transform zone in the Tiantai slope has experienced four evolutionary stages, including the gestation period from the Late Jurassic to the Early Cretaceous, the embryonic period from the middle Early Cretaceous to the Early Eocene, the maturation period from the middle Late Eocene to the Early Oligocene, and the quiescence stage from the Late Oligocene to present.

Igneous rock intrusions are extensively distributed in the western Shunbei area, Tarim Basin, playing a significant role in transforming stratigraphic architecture and petroliferous systems. However, there is a lack of clear understanding of their characteristics and coupling relationships with deep strike-slip fault zones. Using the latest 2D and 3D seismic data of the area, we present a fine-scale characterization of their morphological features, categorizing their types and combinations. Furthermore, we identify their developmental stages and define their coupling relationships with deep strike-slip faults. The results show that the igneous rock intrusions in the western Shunbei area exhibit multiple morphotypes, including stratum-concordant, tongue-, saucer-, and half-saucer-shaped intrusions. Individual intrusive sheets can combine to form sill complexes through processes of conjunction, connection, and fault-induced dislocation. The igneous intrusions in the Shunbei area predominantly occur between the tops of the Middle-Lower Ordovician and the Middle-Lower Devonian, with the activity types of intrusive sheets being categorized into single-stage and single-layer, single-stage and multi-layer, and multi-stage and multiple-layer types. Unconformities and faults, acting as magma conduits, dictate the quantity and scale of the igneous rock intrusions, leading to notable disparities in igneous rock intrusions between the southern and northern parts of the study area. Specifically, the northern part of the study area featuring the deep strike-slip faults serving as primary magma conduits, exhibits intense vertical magma intrusion. In contrast, the southern part featuring unconformities acting as magma conduits, shows stronger horizontal magma intrusion.