Quaternary folding of the eastern Tian Shan, northwest China

The Tian Shan, east-west trending more than 2000 km, is one of most active intracontinental mountain building belts that resulted from India-Eurasia collision during Cenozoic. In this study, Quaternary folding related to intracontinental mountain building of the Tian Shan orogenic belt is documented based on geologic interpretation and analyses of the satellite remote sensing images [Landsat Thematic Mapper (TM)/Enhanced Thematic Mapper (ETM) and India Remote Sensing (IRS) Pan] combined with field geologic and geomorphic observations and seismic reflection profiles. Analyses of spatial-temporal features of Quaternary folded structure indicate that the early Quaternary folds are widely distributed in both Piedmont and intermontane basins, whereas the late Quaternary active folds are mainly concentrated on the northern range-fronts. Field observations indicate that Quaternary folds are mainly characterized by fault-related folding. The formation and migration of Quaternary folding are likely related to decollement surfaces beneath the fold-and-fault zone as revealed by seismic reflection profiles. Moreover, analysis of growth strata indicates that the Quaternary folding began in late stage of early Pleistocene (2.1-1.2 Ma). Finally, tectonic evolution model of the Quaternary deformation in the Tian Shan is presented. This model shows that the Quaternary folding and faulting gradually migrate toward the range-fronts due to the continuous compression related to India-Eurasia collision during Quaternary time. As a result, the high topographic relief of the Tian Shan was formed. (C) 2003 Elsevier B.V. All rights reserved.