The Characteristic And Prospecting Significance Of Tungsten-Bearing Granitoids Of Xintianling Skarn Scheelite Deposit, Southern Hunan Province, Nanling Range

Xintianling deposit is located in the southern Hunan Province, central part of the Nanling Range. The Xintianling scheelite skarn deposit was discovered recently whose reserves is330000tons of WO3. It have always been accepted that the Xintianling granite is one part of the Qitianling granite, and lack of research on Xintianling granite. The Xintianling granite is mainly composed of fine-to medium-grained biotite granite, which was cross-cut by the dikes of granite-porphyry. The precise dating of granitic emplacement and scheelite skarn mineralization indicate that scheelite skarn mineralization is related with the first phase of the biotite granites. The biotite granite is characterized by low Na2O content with relatively high K2O content, high initial Sr ratios (0.711587to0.719794), low value of εNd (t) and εHf (t) values (-7.1to-9.5,-8) and low forming temperature (～743℃). These features are similar to those of S-type granite. The characteristics of granite porphyry illustrate that it can be classified as A-type granite. The Harker diagrams and primitive mantle-normalized trace element spider diagrams reveal that two phases of granites have experienced strong crystallization differentiation. Additionally Xintianling biotite granite has similar two-stage model ages of Nd and Hf (～1.6Ga,～1.7Ga), which suggest that it may be formed by remelting of Mesoproterozoic crustal material. The studies of H-O isotope in quartz veins have shown that the ore-forming fluid is mainly derived from magmatic water mixed by atmospheric precipitation later. The S isotopic compositions of sulfide reveal that sulfur is mainly from magmatic sulfur mixed by sulfur from stratum.