Geochemistry and zircon U-Pb age of the Xinlukou granite in JiangleCounty, Fujian Province and their mineralization significances

This study discussed the forming age and magmatic origin of the Xinlukou granite in Jiangle, Fujian Provine, and its relation to tungsten-tin mineralization using analysis of lithology, geochemisty and isotopic chronology. The results show that the Xinlukou granite is high in silicate, metaluminous-peraluminous, rich in alkaline, poor in iron and magnesium, strongly depleted in Ba, Sr, P, Ti and Nb. The chondrite normalized REE distribution diagram presents a seagull pattern with strong Eu depletion, suggesting highly fractionated S-type granite. Nd isotopic analysis shows the granite sourced mainly from crust. LA-ICP-MS zircon U-Pb dating indicates the granite formed at 147～145 Ma, Late Jurassic. The tungsten-tin deposit also formed in the Late Jurassic and was the product of the tectonic and magmatic activity in the extensional tectonic environment of Late Jurassic. Experiencing the Neoproterozoic and Silurian magmatism, the newly-formed W-Sn enriched residues was re-melted into Si-rich, alkali-rich and F-rich magma and hydrothermal fluid, from which W and Sn were extracted to accumulate in magmatic chambers. Fractional crystallization resulted in the formation of highly fractionated magma rich in ore-bearing materials, which migrated into along preferential structures and crystallize to form W- and Sn-beairng orebodies at shallow part.