Kuqa Depression, Eastern Cretaceous - Tertiary Sequence Stratigraphy And Depositional Systems

Kuche Depression, a foreland depression, is situated in the northen Tarim Basin. In the eastern Kuche Depression, Mesozoic Cretaceous and Cenozoic Tertiary are the main depositis. The lower cretaceous was composed of Yageliemu Formation and Sushanhe formation and is of coarse clastic rocks deposited in fan-delta and oxidation-lake evironments. The Kumugeliemu formation of Palaeogene is composed of coarse clastic rocks deposited in the coast-fan-delta, Suweiyi formation of palaeogene is depositd in alluvial-fan and oxidation-lake evironments. Jidike formation of Neogene is composed of sandstone and mudstone and gypsum deposited in wide and shallow salt-water lake evironments.There are abundant of microfossils such as ostracodes and charophytes found in these five formations.Seven sequence boundaries and six depositional sequence are recognized by the study of Crtaceus-Tertiary sequence stratagraphy in Kuche Depression. The sequence framwork of Cretaceous-Tertiary was established.Three parasequences were identified: base-level-rise parasequence, base-level-fall parasequence and composite parasequence.Main control factors of the sequence development wasdiscussed in this article, the main control factor is the tectonic movement.Five depositional system are recognized: fan-delta deposite system (Yageliemu Formation), coastal fan-delta depositional system (Kumugeliemu Formation), alluvial-Fan depositional system (Suweiyi Formation), oxidation-lake depositional system (Sushanhe Formation), wide and shallow salt-water lake depositional system (Jidike Formation).A correaltion of isochronous depositional faces is made on the basis of the study on sequences strate and depositional faces.The evolution of Cretaceous and Tertiary depositional system in the eastern Kuche Depression was summarised. And the coupling relationships among the Orogenic and sedimentary basins was discussedo...