Driving Mechanism of Tectonic Evolution in Key Paleozoic Period in Tarim Basin:Constraints from Tracing of Provenance Attributes in Keping Area
The dynamic source of the Paleozoic multistage tectonic pattern changes in Tarim basin,especially the reason for the sharp change of the basin tectonic pattern in the Middle and Late Early Paleozoic,has always been the focus of controversy among many scholars.Based on the analysis of heavy mineral assemblages,in this paper it conducts a detailed U-Pb chronological study of detrital zircons from the Furongian to the Cisuralian sandstone samples in Keping area,northwest margin of Tarim basin,in order to determine the provenance system of Keping area,and describe the sedimentary tectonic evolution process of this area.The results show that the detrital zircon samples recorded five tectonic thermal events at 500-420 Ma,870-710 Ma,1 100-880 Ma,2 000-1 710 Ma,and 2 570-2 400 Ma,with the previous three periods being the main age.Compared with the potential provenance areas,the palaeouplift in Tarim basin has always been an important provenance area in Keping area during the Furongian;In addition to the palaeouplift within the basin,there may also be two source areas during the Silurian to the Devonian.The northern source area is the northern margin of the Tarim craton,and the southern source area may be the West Kunlun orogenic belt.The main source of study area is the palaeouplift within the basin during the Carboniferous to the earliest Permian,which originated from the erosion of previous strata.Comprehensive research suggests that the Middle Tianshan terrane may have been connected to the Tarim craton before the Early and Middle Devonian.After this period,the Middle Tianshan terrane gradually separated from the Tarim craton,and the South Tianshan Ocean gradually formed.Correspondingly,due to the formation,subduction,closure of the ocean basin on the north side of the Tarim craton,the structural attributes of the northern margin of the basin have undergone multi-stage changes.
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