Geochemical characteristics, U-Pb dating of hydrothermal titanite from the Xingfengshan tungsten deposit in Hunan Province and their geological significance

The Xingfengshan skarn-type tungsten deposit, hosted in low grade metamorphic rocks, was discovered in Xiangzhong region recently. In this paper, major and trace element compositions, U-Pb dating of the hydrothermal titanite from the Xingfengshan skarn were analyzed by EPMA and LA-ICP-MS. The results show that the titanite possesses relatively low Sigma REE, TiO2 contents and Th/U ratio, and high Al2O3 and F contents, i.e., it belongs to typical hydrothermal titanite. The enrichment of W and depletion of Mo in the titanite suggest the hydrothermal fluid was rich in W and poor in Mo. The chondrite-normalized REE pattern of the titanite displays HREE enriched with obvious Ce and Eu positive anomalies, suggesting it formed under reduced environment. In-situ U-Pb dating of the titanite yields the intercept age of 215.2 +/- 2.7Ma, indicating the skarn tungsten deposit formed synchronously with the adjacent Baimashan ilmenite-type granitoid. Based on geological and geochronological evidences, we conclude that the deposit was genetically related to Baimashan magmatic-hydrothermal event in Indosinian. Combined with previous research, it is revealed that tungsten mineralization in Xiangzhong region is closely associated with Indosinian reduced granitoid and is a part of Late Indosinian regional mineralization event that took placed in the study region.