Petrogenesis and geochemical characteristics of the Zijinshan granitic complex from Fujian Province, South China

The Zijinshan granitic complex, including Jingmei, Wulongsi and Jinlongqiao plutons, located in the giant Zijinshan CuAu ore field in Fujian Province, was emplaced in the Late Jurassic (164 similar to 155Ma). This complex is composed of peraluminous granites, which are characterized by low REE, depleted in Ba, Nb, La, Ce, Sr, P, Ti, and enriched in Rb, Th, U, Pb. This complex shows various initial Sr-87/Sr-86 ratios and negative epsilon(Nd)(t) values (-10.3 to -6.8) of the whole rocks, and negative epsilon(Hf)(t) values (-19.0 to -7.1) of the zircons. Interpretation of the elemental and isotopic data suggests that the Zijinshan granitic complex was most likely derived from partial melting of the crust materials including Proterozoic orthometamorphic and parametamorphic rocks, and suffered assimilation and contamination by Indosinian granitoids. The initial magmas may have generated the Zijinshan complex through fractionation of feldspar, allanite, and apatite at a relatively low magmatic temperature. We suggest that a continental arc related to the paleo-Pacific plate subduction was the most likely geodynamic force for formation of the Jurassic Zijinshan complex in the Cathaysia Block.