U-Pb age of the detrital zircon from the serteng formation in East Kunlun: constraints on its provenance and formation time

The Serteng Formation outcrops in the south part of the East Kunlun consisting mainly of metaclastic rocks, which experienced the regional metamorphism and contact metamorphism. From the bottom up, the sedimentary facies of the Serteng Formation are deepwater turbidite, shallow water sediment, and coastal-shallow water sedimentary, which constitute a regressive sequence. The sedimentary characteristics of the Serteng Formation indicate that it was formed during the closure of the Proto-Tethys. The ever existing controversy about the formation time of the Serteng Formation is primarily due to the absence of fossil. We expect to provide some valuable information about the provenance and stratigraphic formation time of the Serteng Formation through detrital zircon U-Pb dating. We have obtained five age ranges, such as >2500 Ma, 2300~2600 Ma, 1600~1800 Ma, 800~1200 Ma, and 421~600 Ma. The existence of zircon grains with ages older than 2500 Ma may indicate the existence of ancient crystalline basement in the East Kunlun. The rest age ranges indicate the source regions of the Serteng Formation have experienced complex multi-phase geological events, which corresponding to the Early Paleoproterozoic, Late Paleoproterozoic, Late Mesoproterozoic, Early Neoproterozoic and Early Paleozoic tectono-magmatic events, respectively. The paleocurrent direction abstracted from cross bedding indicates the clastics in the Serteng Formation are mainly from the north adjacent regions. Comparing the detrital zircon ages from the Serteng Formation with the adjacent stratigraphic units, we conclude that the Baishahe Group, Xiaomiao Group, Wanbaogou Group, granite formed during early Neoproterozoic tectono-magmatic event, and the evolution of the Proto-Tethys are the mainly provenance of the Serteng Formation. Combining the youngest zircon age 421±7 Ma and the age of rocks which intrude the Serteng Formation, we narrow the formation time of the Serteng Formation to 421~413 Ma. Furthermore, the Serteng Formation recorded the subduction to closure history of the Proto-Tethys in the East Kunlun, so we can use the stratigraphic formation to constraint the closure time of the Proto-Tethys in the East Kunlun. ©, 2015, Science Press. All right reserved.