Evolution of fold-thrust belts and Cenozoic uplifting of the South Tianshan Mountain range in the Kuqa region, Northwest China

The evolution of the Kuqa fold-thrust belt is accompanied with the Cenozoic uplifting of South Tianshan Mountain range. The critical Coubomb wedge theory can be well applied to the structural evolution of the Kuqa fold-thrust belt where the decollement structures are well developed. Following the initial hypotheses of this theory, with the base of the taper wedge (not the sea level) as the reference level, we propose a geometric relationship between the evolution of fold-thrust belt and tectonic uplifting of orogen, and deduce a calculation formula between orogen tectonic uplifting amount (very different from the topographic uplifting) (partial derivative H), fold-thrust belt extending distance (partial derivative S) and crustal shortening amount (partial derivative L): partial derivative H = (partial derivative S - partial derivative L) *tan(alpha + partial derivative alpha) + [tan(alpha + partial derivative alpha) / tan alpha-1] (*) H-0. In this paper we select two representative seismic profiles across the Kuqa fold-thrust belt to reconstruct the structural evolution, and use the calculation formula to get the uplifting amount of the South Tianshan Mountain range in Kuqa region during two geological periods. The results showed: during the end of Miocene to the end of Pliocene, the uplifting amount of the South Tianshan Mountain range in the middle segment of Kuqa (partial derivative H-M1) is 4.1 km; during the end of Pliocene to the present, the uplifting amount of the South Tianshan Mountain range in the middle segment of Kuqa (partial derivative H-M2) is 4.7 km, and in the east segment of Kuqa (partial derivative H-E) is 5.0 km. (c) 2017 Elsevier Ltd. All rights reserved.