Zhuang RUAN¹, Bingsong YU¹, Lu NIU¹ & Cong ZHANG^1
1State Key Laboratory of Geological Process and Mineral Resources, China University of Geosciences, Beijing 100083, China. wofe0103@163.com

PROVENANCE SETTING AND EVOLUTION OF THE LOWER SILURIAN IN THE NORTHERN TARIM BASIN, NW CHINA: CONSTRAINS FROM DETRITAL ZIRCON U-PB DATING AND SANDSTONE COMPOSITION

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The Silurian system is a critical tectonic change period in the Tarim Basin. The study of the source and origin of the sediments is greatly significant in researching the tectonic evolution and the surrounding orogenic belts. Three representative samples of the Lower Silurian in different regions of the North Tarim basin were collected and the detrital zircon was analyzed by LA-ICP-MS for U-Pb dating. Results show that there are four accumulation age intervals in the Lower Silurian: 400~600Ma (Late Ordovician), 800~1200Ma (early stage of Late Proterozoic), 1800~2000 Ma (Early Mesoproterozoic) and 2400~2600Ma (late stage of Early Proterozoic). Combined with the analyses of geochemical data and sandstone components, the results indicate that the source of the Lower Silurian in the Keping region mainly came from the Precambrian basement in the Kuqe area forming in the continental island arc environment and the sources of those in other regions mainly came from the Late Ordovician igneous rock in Kuluketage area forming in the recycle orogen tectonic setting. Besides, Precambrian zircon ages reveal that the Tarim plate had a similar aggregation-breakup evolutionary history with the Rodinia super-continent during the Neoproterozoic and the North Tarim region had a matching structure-thermal event that occurred with the formation-cracking event of the Columbia super-continent during the Mesoproterozoic period.