Geochemistry, zircon U-Pb age, Lu-Hf isotopes and tectonic setting of the Early Paleozoic gneissic granites from the Nyainrong microcontinent, Tibet Plateau

The geochemistry of the Cambrian gneissic granite from the Nyainrong microcontinent, central Tibet, and its zircon LA-ICP-MS U-Pb ages and Hf isotope data are reported.The granite was formed at 516±3 Ma(n=20, MSWD=1.60), and belongs to high-K calc-alkaline I-type.It is characterized by negative Eu anomaly and right-dip chondrite-normalized rare-earth element patterns, enrichment of Rb, Th, and Pb, and depletion of Ba, Nb, Ta, Sr, P, and Ti.It exhibits negative zircon ε_Hf(t) values of -3.0~-0.1 and relatively high Mg^# values of 32~47, and yields old zircon Hf model age of 1472~1659 Ma, suggesting a magma source of Proterozoic sedimentary materials modified by mantle-derived magma.Based on the above study results and regional geological setting, it is suggested that the Cambrian gneissic granite from the Nyainrong microcontinent could be attributed to one part of the Andean-type magmatic arc along the northern margin of the Gondwana supercontinent.