FISSION-TRACK EVIDENCE FOR THE EXHUMATION HISTORY OF BOGDA - HARLIK MOUNTAINS, XINJIANG SINCE THE CRETACEOUS

Abstract

Fifteen apatite samples and five zircon samples from volcanic rocks and granites in Bogda - Harlik mountains were analysed. The apatite ages range from 109.3 to 11.9Ma and the zircon ages are within the range 81. 7-56.8 Ma. Results of calculation by paired-minerals indicate that the apparent exhumation rates range from 0.157 mm/a to 0.222 mm/a during the Late Cretaceous to Middle Cenozoic in above area. The thermal history modeled result shows four periods of exhumation in Bogda - Harlik mountains occurred in Early Cretaceous (119-105 Ma), late Late Cretaceous (67-65 Ma), Early - Middle Cenozoic (47-31 Ma) and Late Cenozoic (12-7 Ma) since Cretaceous. The deformation in Tianshan regions since Cretaceous is related to the multi-stage collisions and accretions of terranes with the south Asian continental margin.