Shizhuyuan large-scale skarn type tungsten and tin polymetallic ore deposit is located at Chenzhou County, Hunan Province, which occurred in the southern margin of the Qianlishan alkali feldspar granite body. The stockwork in skarn includes different types of veins, mostly alkali metamorphic vein (AMV), a few granite vein and greisen veins. The early stage AMV consists of granite vein in the central part, and K-feldspar-fluorite-wolframite in the margins, with garnet-diopside skarn alteration around the vein. The late stage AMV consists of K-feldspar, fluorite, minor actinolite, epidote, magnetite, scheelite, molybdenite, and bismuthinite. The AMV occurs only in the skarn and the skarnization marble, but is lack in the granite. The contents of CaO, TiO2, W, Bi, Mo, Cu, Pb, Zn, Sr and Ba show an increase trend from the granite, granite vein, AMV, to skarn, which may indicate an enrichment of ore materials from the magma to hydrothermal fluids. Evidence from the structure of granite vein in the center and the K-feldspar-fluorite in the margins, together with occurrence of melt or melt-fluid inclusions in the AMV indicate that the veins may have formed from a unique fluid transition from magma to hydrothermal. The evolution of this fluid is continuous from magmatic to hydrothermal process, and the mineralization started before the magma fully consolidation. We suggest the following mineralization model; Firstly, the pegmatite, massive greisen and banded wollastone-garnet skarn formed in the top and outboard of the granite in the latest magmatic stage; then in the prograde stage after widespread hydrothermal-brecciation, magma or the magma-hydrothermal transition fluid flow along the fractures of the carbonate rocks, which formed the stockwork mineralization and cause alteration of K-feldspar and garnet-diopside skarn. In the retrograde stage after magma consolidation, the mineral assemblage includes actinolite, magnetite, scheelite, molybdenum, and bismuth sulfides. In the latest sulfide stage, the temperature and fluid salinity decreased further on, and the Pb-Zn sulfides precipitate in the carbonate rocks outside the skarn.
