Petrogenesis of Tangjiaping granite porphyry in northern Dabie: Evidence from Zircon LA-ICPMS U-Pb dating and geochemical characteristics

Tangjiaping granite porphyry is located in the northern part of Dabie orogen. Zircon LA-ICPMS U-Pb dating of 20 zircon grains from Tangjiaping granite porphyry gives a concordant age of 121. 6 +/- 4. 6Ma, the later stage of Early Cretaceous. The granite porphyry is petrochemicaly charlacterized by high silica (SiO2 > 72%) and alkali (Na2O + K2O > 7. 4%) with ACNK values between 0.99 and 1. 18. The rocks are enriched in light-REE and show an obviously fractionation between light- and heavy-REE elements and serious negative abnonnity of Eu (delta E-u = 0.40 similar to 0.58), Sr, Ba, Nb. P2O5 increases with increasing SiO2; Pb decreases with increasing SiO2; Y and Th decrease with increasing Rb. Combined with petrological and geochemical characteristics, Tangjiaping granite porphyry can be classified as the highly fractionated S-type granite. The intrusion has clearly negative epsilon(Hf)(t) value (-17. 6 similar to -10.4) and epsilon(Nd)(t) value (-15.5 similar to -13. 7), and the Hf and Nd model age are 1843 similar to 2281Ma and 2034 similar to 2178Ma, respectively suggesting that the Tangjiaping granite was formed by partial melting of the crust. The moderate 'Sr ratios indicate that the magma source should include low-mature crust. In combination with the characteristics of REE, we argue that Tangjiaping granite was formed by the lower crust.