LA-ICPMS Zircon U-Pb Geochronology and Hf Isotopic Compositions of Caledonian Granites From the Qingliu Area,Southwest Fujian

The LA-ICPMS zircon U-Pb geochronology and Hf isotopic compositions of two Caledonian granitic plutons,the Weibu and Ninghua granites,from the Qingliu area,southwest Fujian,are reported in this paper.The LA-ICP-MS zircon U-Pb dating for two representatively samples from the Weipu granite yielded the weighted mean 206Pb/238U ages of(429.9±3.0)Ma and(446.3±4.0)Ma,respectively.This suggests that the Weipu granite was crystallized at 429~446Ma Caledonian rather than Indosinian period as previously believed.Our dating results show that the Ninghua pluton gave a weighted mean 206Pb/238U ages of(448.2±2.5)Ma,suggestive of the Caledonian intrusion.Zircon Hf isotopic compositions for the Weipu and Ninghua granitic plutons exhibit the eHf values of-0.8~-10.4 and two-stage model ages(TDM2) ranging from 1.72Ga to 2.34Ga,indicative of the derivation from Proterozoic continental basement of the SCB.In conjunction with other published geochronological and geological data,it is proposed that the Caledonian granites in the hinterland of the South China Block,including Weibu and Ninghua plutons,are the derivation of the Cathaysian Proterozoic basement in response to the Caledonian intracontinental tectonic setting.It is also inferred that a significant reworking has been undergone for the South China basement during the Caledonian period.