Meso-Cenozoic extensional structures in the Northern Tarim Basin, NW China

Meso-Cenozoic extensional structures are important for understanding the tectonics of the Chinese Central Asia. This paper presents a systematic investigation on the Meso-Cenozoic extensional structures in the Northern Tarim Basin. Close interpretations of seismic data reveal that the Meso-Cenozoic extensional structures were widely developed in the Northern Tarim Basin. These extensional structures are regionally composed of many small normal faults, which usually group into left- or right-step en echelon and form several transtensional fault zones. Combinations of normal faults in profile become small graben-horst or staircase-like cross-sections. Based on the areal distribution, structural style, combination relationship, formation and evolution time, and formation mechanism of the extensional structures, we found that the Meso-Cenozoic extensional structures in Northern Tarim Basin can be classified into two conjugate normal fault systems, which were formed separately in Jurassic-Early Cretaceous and Late Cretaceous-Neogene. The former is likely associated with the stress relaxation after a collisional orogeny accompanied with a certain degree of anticlockwise rotation of the Tarim block relative to the South Tianshan; the latter is possibly induced by the east by south tectonic escape of the Tarim block with a certain degree of clockwise rotation relative to the South Tianshan triggered by the far-field effect of the Himalayan orogeny.