Multiple-phase tectonic superposition and reworking in the Junggar Basin of northwestern China—Implications for deep-seated petroleum exploration

The Junggar Basin is one of the major petroliferous basins in Northwest China, where deeper hydrocarbon exploration has become an inevitable trend for resource development. In this paper, the structural features and tectonic evolution of the Junggar Basin are discussed based on seismic profiles, drilling data, isochore maps, and additional balanced cross sections. Our results suggest that the basin has undergone five extension-to-compression stages of tectonic evolution since the Permian. The Junggar Basin initially developed from several isolated continental rifts in the early Permian. At the beginning of the middle Permian, the basin developed into a more integrated terrigenous lake basin with the deposition of fine-grained, organic-rich lacustrine sediments; the basin inverted during the late Permian compressional uplifting. Then the sedimentary basin was superimposed and reworked by episodic Mesozoic to Cenozoic tectonic events, giving rise to the uplift and erosion at the basin margins while folding or tilting within the basin. At present, the basin presents a wedge-shaped geometry, with thickest strata in the south and thinnest strata in the north. The presence of source rocks, reservoirs, regional seals, and traps is closely related to the multiphase, basin-scale, extension-to-compression tectonic cycles of the basin. Episodic tectonic movements are also responsible for the adjustment and destruction of earlier-formed hydrocarbon pools and the formation of secondary pools. The preferential accumulation sites for prospective deep-seated petroleum exploration are also proposed.