There are various isotopic ages for four granitic plutons in the studied area, which respectively are as follows: Tangquan pluton 185 similar to 158 Ma; Zijinshan pluton 157 similar to 145 Ma; Caixi pluton 133 Ma; Sifang pluton 108 similar to 105. Tangquan and Zijinshan plutons are belonged to respectively Early-Middle-Jurassic and Late-Jurassic in Early-Mesozoic, and Caixi and Sifang plutons belong to Early-Cretaceous in Late-Mesozoic. Both Tangquan and Sifang plutons, which are the metaluminous granites with A/CNK < 1.0, are regarded to possess the geochemical characteristics of adakite rich in Sr, Ba and poor in HREE, Y, Yb, as the most potential host rocks of ore-bearing for the copper deposit. Zijinshan pluton is regarded as peraluminous granites with A/CNK > 1.1, and possesses the geoehemical feature of crust-derived mud materials by partial melting with enrichment in K, Rb, Th, Y, HREE and depletion in Sr, Ba, Ti. Caixi pluton is weak-peraluminous granites with A/CNK = 1.0 similar to 1.1, and its geochemical feature lies between the Zijinshan pluton and Sifang pluton. Tangquan pluton with higher Na, O content, which was formed by partial melts of the thickened lower-crust derived basic rock during Proterozoic, resulting from the underplating of mantle-derived basic magma, is the major host rocks of the metallogenic series of copper, iron and multiple metals deposits. Sifang pluton with higher K2O content, which was mixed between middle-lower crust-derived by granite magmas partial melting and mantle derived basic magma with high K, resulted in increase of K2O content in the melt and obtaining of a large amount of copper, other metals and sulphur from mantle, is the major host rocks of the metallogenic series of the porphyry copper, gold and multiple metal deposits. There have been the petrological records of lithosphere extension since Early-Middle-Jurassic (180 Ma) in the region, and formation of Zijinshan peraluminous granites is resulted from the extension mechanism. With the time past, the lithosphere extension-thinning and underplating is increased gradually, meanwhile the contribution of mantle to granite formation is increased gradually.
