In situ zircon Hf-O isotopic characteristics and petrogenesis of Late Cretaceous quartz diorite in the Narusongduo Pb-Zn mining area, Tibet

The accretion and evolution of the Lhasa Terrane is restricted by the subduction of the Neo-Tethys Ocean.The northward subduction of the Neo-Tethys Ocean started in the Mesozoic and formed the Late Cretaceous "magmatic burst" event in the south Lhasa Terrane.The Narusongduo Pb-Zn deposit is located in the southern margin of the central Lhasa Terrane.The nature of the magma source and petrogenesis of the quartz diorite in the mining district have not been well documented.The zircon SHRIMP U-Pb age and Hf-O isotopic characteristics of the quartz diorite are systematically reported in this study.The quartz diorite has SHRIMP U-Pb ages of 83.0 ±1.0 Ma, ε_Hf(t)values of -2.6 to 1.0(mean = -0.8)and the corresponding T_DM2 of 1088 Ma to 1312 Ma(mean=1253 Ma), and δ¹⁸O values between 6.5‰ and 7.9 ‰(average value = 7.2‰), indicative of an enriched source.In situ zircon Hf-O isotopic compositions display a binary mixing trend between mantle and continental crust, with the mixing calculations show in the mantle as a primary contributor.The Narusongduo quartz diorite has similar ages and geodynamic setting as the Late Cretaceous "magmatic burst" event in the southern part of Lhasa Terrane, implying that the Late Cretaceous magmatic activities triggered by the northward subduction of the Neo-Tethys Ocean were not limited in the south Lhasa Terrane and also extended to the central Lhasa Terrane.