The detrital zircon LA-ICP-MS U-Pb ages of Qudi Formation in southern Qiangtang basin, northern Tibet, and their significance

The southern Qiangtang basin is a set of tectonic accretionary geological bodies produced by Tethys subduction, and is also the key area for the study of early tectonic evolution in the Tibetan Plateau. In this basin, Carboniferous strata are rarely exposed. In this paper, the major compositions elements, trace elements and rare earth elements were studied by using two samples collected from the Late Paleozoic Qudi Formation. Zircon U-Pb dating through LA-ICP-MS isotope measurement shows that the ages have six peaks, i.e., 330~270Ma, 560~480Ma, 880~720Ma, 1750~1650Ma, 2400~2000Ma and 2800Ma. An analysis of geochemical characteristics suggests that the geotectonic background for the source region of Qudi Formation was passive continental margin and land arc, and the provenance of sediments had multi-source character, which, however, needs further research. It is inferred that the material source might have come from the northern Gondwana during Permian.