Skarn mineralogy and trace elements of scheelite in Xianglushan tungsten deposit, Jiangxi Province, South China and their implications for mineralization process

The Xianglushan tungsten deposit is a large tonnage deposit with a resource of 0. 22Mt @ 0. 641% WO3. It is a typical skarn tungsten deposit formed in Early Cretaceous in the Jiangnan porphyry-skarn W polymetallic belt. Orebodies occur in the contact zone between the Yanshanian biotite granite and the Cambrian Yangliugang Formation which composed as muddy limestone in the form of stratiform and lenticulum. Based on detailed division of metallogenic stages and mineralogical work, trace elements of scheelite of different generations produced from different stages have been systematically studied via in situ LA-ICP-MS. Metallogenic stages of Xianglushan tungsten deposit can be divided into four stages: skarn stage, skarn retrograde stage, quartz-sulfide-scheelite stage and calcite -fluorite stage. According to mineral assemblage and paragenesis relationship with scheelite in each stage, four stages and six generations of scheelite have been divided, which are stage I scheelite ( in greisen), stage II a and stage II b scheelite ( in retrograde rock), stage M a and stage M b scheelite ( in sulfide band, M a is the core of scheelite, M b is the edge of scheelite) and stage IV scheelite ( in quartz-sulfide-scheelite vein). The chondrite-normalized REE distribution patterns for different types of scheelites are: concave ( stage I, II a, b), shallow negative ( stage IV) and shallow negative concave ( stage a). The trace element characteristics of scheelite at each stage indicate that, content of rare earth elements in scheelite of Xianglushan tungsten deposit is higher than that of most gold and tungsten deposits in the world, and it is also higher than that of scheelite of other tungstenpolymetallic deposits in South China. The main substitution mechanism of REE3+ and Ca2+ in scheelite is 3Ca(2+) = 2 REE3+ square Q Ca (square is a Ca vacancy). REE and Eu anomalies of scheelite are mainly determined by fluids and can be used to trace the evolution of fluids. Eu act mainly as Eu2+ Xianglushan tungsten deposit is a reduced deposit, and the variation of Mo in different stages of scheelite indicates that the reducibility of fluids in different stages fluctuates. The characteristics of rare earth and trace elements of scheelite in different stages of the deposit vary greatly. The highly enrichment mechanism of rare earth elements in Xianglushan scheelite remains to be further studied and discussed.