Eocene Sedimentary Provenance Alteration In The South Margin Of The Tarim Basin Ant Its Constraining To The Uplift Of The Central Pamir

The Pamir Plateau forms a prominent tectonic salient,which separates the Tajik and Tarim basins.The building time of the Pamir Plateau remains elusive,and it acts the key role for the retreat of the Paratethys and aridification in the Central Asia.Based on the basin-range coupling theory,the Southwestern Tarim Basin and Tajik Basin at the mountain front of the Pamir Plateau are prime locations to decipher the building history of the Pamir Plateau.In this study,based on the previous high resolution magnetostratigraphy,the detrital apatite fission track and detrital zircon U-Pb ages are used to document the sedimentary provenance characteristics of the Keliyang section in the south margin of the Tarim Basin from Late Cretaceous to Oligocene.Detrital apatite fission track shows that the sedimentary provenance has three components of during,while sedimentary provenance has two components at least since the Oligocene.Detrital zircon U/Pb ages are mainly clustered between 400 Ma and 500 Ma during Late Cretaceous.While detrital zircon U/Pb ages are mainly concentrated at 40-70 Ma(at the peak of ?45 Ma)and 200-300 Ma since Eocene.The Late Cretaceous sediment are completely different from the two-component characteristic of the Oligocene.Combed with the apatite fission track dating and zircon U/Pb ages,an obvious sediments provenance variation had occurred at least during Eocene in the Keliyang area.Comparing these detrital zircon U-Pb ages with the surrounding tectonic units,we found that the Late Cretaceous zircon clusters of 400-500 Ma and 200-300 Ma have the affinities with the West Kunlun or SongpanGanzi terrane,and the Eocene zircon clusters of 40-70 Ma have the affinities with the Central Pamir terrane.Moreover,this Eocene provenance change from Central Pamir has been detected by previous studies both in the Tajik and Tarim basins,which means that the whole Central Pamir had experienced the almost quasi-simultaneous abrupt uplift and developed relative high landscapes during Eocene,which was caused by the northward of the Pamir Pleateau.