Detrital zircon SHRIMP U-Pb dating of Carboniferous sandstone from the southern foot of the Harlik Mountains, eastern Xinjiang,and its geological implications

Abstract：Research into detrital zircons is an effective approach to the sources and provenance features of detrital materials and depositional ages and environment. The authors performed SHRIMP U-Pb dating of 47 detrital zircon grains from Carboniferous sandstone at the southern piedmont of the Harlik Mountains, eastern Xinjiang, and obtained ages of 388 to 949 Ma, clustering at 418 to 482 Ma. Based on these dating data, combined with the mineralogical characteristics and CL images of zircons as well as the regional geological data of the Harlik Mountains, we may draw the following conclusions: (1) the youngest detrital zircon age of the studied sandstone is 388±9 Ma, implying that this sequence of the strata is not older than Middle Devonian in age and possibly was deposited in the Late Carboniferous according to the regional geological correlation; (2) the detrital materials of the studied sandstone were mainly derived from magmatic rocks related to the Early Paleozoic arc of the Harlik Mountains; and (3)the tectonic evolution of the Harlik Mountains progressed through the Middle Ordovician to Early Silurian magmatic arc related to northward subduction of the oceanic lithospheric plate represented by the Kanggurtag oceanic crustal fragment, Carboniferous back-arc basin and terminal Late Carboniferous back-arc uplift. The last event was probably the main cause for the present difference in geological outcrops between the Harlik and Bogda mountains.