Abstract:
Fuquanshan pluton is located in the Wannian-Dexing metallogenic belt within Qinzhou-Hangzhou belt, and it is also an important part of regional large volume of granitic magma.In this paper, we studied the geochronology, Hf isotopes and geochemistry of Fuquanshan pluton.Zircon LA-ICP-MS U-Pb dating yield the age of around 130 Ma, suggesting this pluton emplaced at Early Cretaceous.The geochemistry features of these rocks are rich in Si, Al, alkali and have low content of REE, implying they belong to high potassium calc alkaline series and peraluminous rocks (A/CNK>1.1).Combined with the characteristics of obvious negative Eu anomaly, high content of Rb, low content of Sr and Ba, low ratios of Nb/Ta (5.14~5.52) and Zr/Hf (31.22~39.09), depletion of high field strength elements (Nb, Ga, Y), we propose this pluton is highly fractionation S-type granite.Futhermore, the
εHf(
t) values of zircons range from -5.47 to -1.51 with
tDM2 values from 1255 Ma to 1668 Ma, implying the magma source is Mesoproterozoic lower-crust metasedimentary rocks.Comprehensive analysis shows that the Fuquanshan granite has the same tectonic setting as contemporary A-type granite in the region, and they generated by partial melting of Mesoproterozoic lower-crust metasedimentary induced by upwelling of asthenosphere in an extensional environment resulted from subduction of the paleo-Pacific plate to South China.