Structural analyses of the Qimugen fold-and-thrust belt along the southwestern Tarim Basin (China): implications for tectonics of eastern Pamir and hydrocarbon exploration planning

The India–Eurasia collision during the Cenozoic has established widespread fold-and-thrust belts in the Eurasia continental interiors, which are important for understanding the intracontinental convergence processes and have been proved to be rich in hydrocarbon resource. Despite the significance, the structures along the eastern Pamir foreland fold-and-thrust belts are blind and covered by the Cenozoic monocline, which hinders the mechanism of intracontinental convergence and the potential exploration targets to be comprehensively understood. In this study, we deciphered the blind structures along the Qimugen fold-and-thrust belt on the eastern Pamir foreland with interpretations of seismic reflection profiles and structural forward modelling. Our analyses indicate that the Qimugen fold-and-thrust belt features a structural wedge consisting of six thrust sheets, which involve the Paleozoic strata to form anticlinal fault-bend folds. During the late Cenozoic deformation, the structural wedge absorbs ∼56.39 km of horizontal shortening in total, of which ∼52 km is accommodated by the backthrust. These findings indicate lateral, eastward expansion of the Pamir in late Cenozoic, which was accommodated by westward underthrusting of the lower Tarim crust. We propose that the Carboniferous–Permian reservoirs in the anticlinal fault-bend folds of these thrust sheets are the favourable targets for the future hydrocarbon exploration, with the trap formation coinciding with the hydrocarbon generation, migration and accumulation. This study sheds light on the mechanism of convergence between eastern Pamir and Tarim Basin, and provides insights into the future hydrocarbon exploration planning for the Carboniferous–Permian plays in the southwestern Tarim Basin.