Tectono-sedimentary evolution of the Sinian in the Northwest Tarim Basin
Yang Yunkun1,2, Shi Kaibo1, Liu Bo3, Qin Shan1, Wang Jieqiong1,2, Zhang Xuefeng3
1. School of Earth and Space Sciences, Peking University, Beijing 100871;
2. PetroChina Research Institute of Petroleum Exploration and Development, Beijing 100083;
3. Institute of Oil and Gas, Peking University, Beijing 100871
Based on the field section survey and research of the Sinian in the Northwest Tarim Basin of China and the analysis of regional tectonic setting, it indicated that the Sugetbrak Formation of the Lower Sinian in Northwest Tarim Basin is main terrigenous clastic deposition, which composed of fluvial, lake, offshore and delta facies. And Chigebrak Formation of the Upper Sinian is a set of carbonates deposited on a restricted carbonate platform, which is dominated by tidal flat mudstones, beach grainstones and mixed tidal flat at the bottom. According to the characteristics of the assemblage of rocks and the carbon isotope evolution, the Sinian can be divided into three third-order sequences:ZSQ Ⅰ, ZSQ Ⅱ and ZSQ Ⅲ by the three unconformities. The three sequences reveal the depositional model and tectono-sedimentary evolution of the rift basin developed on the early plate margin. The early is the primary extensional stage, which is a group of coarse detrital rocks. Then the rapid extensional stage, which is composed of sandstone and mudstone of lake, offshore and delta accompanied by eruption of basalt. At the end, the steady subsidence stage with carbonate platform sediments developed.