Abstract:

Detrital zircon grains were collected from seven layers of sandstones along the paleomagnetically welldated Cenozoic sequence in the Jingou River section on the northern piedmont of the Tianshan Mountains. LAICPMS UPb dating of the zircon grains yields a large range of age spectrum with the Anjihaihe Fm. (paleomagnetic ages 2823.3 Ma) and Shawan Fm. (23.317.5 Ma) having peak zircon ages of 261328 Ma (PC), the Taxihe Fm. (17.513.2 Ma) 234311 Ma (TC) and 369403 Ma (DS), and the Dushanzi Fm. (13.26.0 Ma) and Xiyu Fm. (6.01 Ma) 264333 Ma. As compared with the lithostratigraphic distribution in the drainage reaches, it reveals that the central Tianshan Mountains began to uplift as a provenance and subjected to erosion in as late as  late Oligocene, then these processes extended to the southern margin of the northern Tianshan around the early Miocene, and finally to the whole northern Tianshan Mountains. Around mid and late Miocene the northern Tianshan Mountains began to prominently uplift and gradually impeded the supply of sediments from  central Tianshan Mountains and finally became the major provenance. The northward progressive uplift and erosion of  Tianshan reflect the distant responses of the collision  between India  and Eurasia Plates.

Key words: Junggar Basin, Tianshan Mountains, detrital zircon, Cenozoic, provenance, uplift and erosion