Provenance of Early Cretaceous Deposites in Kuqa Subbasin, the Southern Margin of Tianshan: Implication from Detrital

Key words: 
• Kuqa Subbasin

Abstract: There are some quite different disputes about the provenance types and tectonic attributes of early Cretaceous deposits in Kuqa Subbasin, northern margin of the Tarim Basin, with very complicated source rocks. In order to reveal further detailed information on the nature of the source terrains, a typical sandstone samples from the Yageliemu Formation in early Cretaceous strata is collected for UPb dating of 79 detrital zircons. The lower Cretaceous sample shows a complicated provenance geochronological constitution, with new peak ages of 427~389 Ma, 379~339 Ma, 321~283 Ma, 266~239 Ma, 162~150 Ma and some Precambrian basement zircons. Investigating on the rock attributes and age constitution of the Tian Shan Orogen, the potential source area, together with the previous results of sandstone framwork grains and detrital heavy minerals in Kuqa Subbasin, we suggest that the provenance supply is mainly resulted from denudation process of the South Tian Shan, the granitealkaline rocks belts in South Tian Shan and YiliCentral Tian Shan (including the Paleozoic granites and vocanic rocks at the southern margin of the Central Tian Shan)，related to the MiddleLate Jurassic volcanism and the OrdovicianPermian tectonic events. Additionly，the several clusters of ProterozoicArchean ages of this sample probably reflect that some provenance areas were deeply exhumated and the ArcheanProterozoic basement maybe exsist in the Tian Shan Orogen. In addition，the detrital zircons age spectra of 162～150Ma indicates that there was possible magma activity in late Jurassic in Tian Shan area, which require further work.