Sedimentary facies characteristics of the Cretaceous in southwestern Tarim Basin
Guo Qunying1, Li Yue2, Zhang Liang1, Zeng Changmin1, Guo Feng3, Wang Feng1
1 Research Institute of Exploration and Development,Tarim Oilfield Company,PetroChina,Korla 841000,Xinjiang; 2 Nanjing Institute of Geology and Palaeontology,Chinese Academy of Sciences,Nanjing 210008,Jiangsu; 3 School of Earth Science and Engineering, Xi′an Shiyou University,Xi′an 710065,Shaanxi
Abstract：In southwestern Tarim Basin, the Cretaceous was developed well with Upper and Lower. The Lower Cretaceous Kizilsu Group is subdivided into four members. They are dominated by terrestrial sedimentary rocks of brownish red glutenites intercalated with sandstones,silts,mudstones and conglomerates.The Upper Cretaceous Yengisar Group is composed of both marine and non-marine facies and summarized in ascending order.The Kukebai Formation is subdivided into two members and commonly composed of mudstones, gypsum beds and marine fossils. The Wuyitage Formation is characterized of red mudstones and muddy silts intercalated with sandstones.The Yigeziya Formation is rich in limestones, dolomitic limestones and marine fossils. The Tuyiluoke Formation is composed of brownish red mudstones,gypsum beds, sandstones, conglomerates and some marine fossils.Thestudy supplies an evolutionary process of the northwestern Tarim Block during the Cretaceous based on the temporal and spatial distribution of nine units covering the fore-land region of the Kunlun Mountains. The Kizilsu Group shows rapid terrestrial deposition spped in the western part, and delta and shoal facies in the eastern part where is short of clastic supplement.It is recognized as a wide facies of alluvial fan and braided river delta. The Kukebai Formation generally implies a transgression with a facies change from braided river to tidal falt.Tidal flat facies are mainly arrangement of the Wuyitage Formation. The Yigeziya Formation showed facies changed from carbonate platform to platform margin. The Tuyiluoke Formation is a persistence of a wide tidal flat environment.
