Crustal Shortening on the Margins of the Tien Shan, Xinjiang, China

Abstract

We present the results of mapping selected cross-sections across the margins of the Chinese Tien Shan, an intracontinental mountain belt that formed in response to the India-Eurasia collision. This belt contains significant lateral variation in topography, structure, and stratigraphy at all scales, and our estimated rates of shortening also reveal a distribution of shortening that varies laterally. At the largest scale, it consists of two major high mountain ranges in the west that merge eastward into a complex, single high mountain belt with several distinct ranges, then separates farther eastward into several low mountain ranges in the south and a single narrow high mountain range in the north. Active fold-and-thrust belts along parts of the north and south flanks of the Tien Shan involve only Mesozoic and Cenozoic sedimentary cover, which varies in both stratigraphy and structure from east to west. The southern fold-and-thrust belt decreases in width and complexity from west to east and ends before rea...