Geological and geochemical characteristics and tectonic and prospecting significance of the Shanxi-Guangshan intrusions in Lizhu area，Zhejiang Province

Abstract：Located in the northeastern part of the Qinhang metallogenic belt, Lizhu area in Zhejiang has developed a series of skarn type iron polymetallic deposits or ore spots, and mineralization is closely related to the late Jurassic intrusive rocks in the NE-trending fold-fault zone. Researches on the geological and geochemical characteristics of intrusive rocks show that the main rock types are middle-fine grained granodiorite and coarse-grained or fine-grained granite. The former type comprises amphibole-bearing calc-alkaline ( low potassium-high calcium) granitoids (ACG) characterized by low SiO2, K2O+Na2O and K2O/Na2O, rich CaO, MgO and FeOT, relative enrichment of K, Rb, Ba, Th, U, Zr, Hf, slight depletion of Sr, Ti, negative Eu anomalies along REE distribution curve with weakly right-oblique nature, similar geochemically to the I-type granite. The latter type consists of alkali-rich calc-alkaline (high potassium-low calcium) granitoids (KCG), characterized by high SiO2,K2O+Na2O and K2O/Na2O, low CaO, MgO and FeOT, enrichment of K, Rb, Th, U, Nb, Ta, Zr, Hf, strong depletion of Ba, Sr, Ti, and obvious negative Eu and "V"-type REE patterns, thus similar geochemically to the A-type granites. The petrogenetic tectonic environment was converted from the subduction collision to post-collision or post-orogeny, consistent with the conversion of the tectonic environment in South China, thus providing a new constraint for the tectonic-magmatic evolution in South China. Furthermore, both the two types of granites widespread in Zhejiang have good prospecting potential.