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Abstract

More than 50 % of the world’s total reserves of tungsten are in China, and most tungsten deposits are located in the Nanling range (Cathaysia block, southeast China). This study explores the genetic relationship between W-specific magmatic events and shallow (W)-Ag-Pb-Zn deposits in the Nanling range based on data from the Wutong deposit, Guangxi Province. Because the temperatures obtained from mineral thermometry and homogenization temperatures of fluid inclusions are the same (~300°C), the fluid inclusion homogenization temperatures are interpreted to be approximately equal to the trapping temperatures, indicating formation at low pressures, i.e., slightly above the liquid-vapor curve. This, in turn,indicates that the deposit formed at relatively shallow levels. The C-O-S-Sr-Pb isotopic composition of minerals indicate that one single fluid was responsible for mineralization. The chemical composition of fluid inclusions indicates that the fluid evolved from a fractionated magma. Therefore, the Wutong deposit is likely to represent the shallow expression of a magmatic-hydrothermal system. The Sr-Pb isotopic data indicate that the magmatic fluids are associated with melting of crustal rocks of the Cathaysia block. The age of the Wutong mineralization, obtained from hübnerite dating, is Late Yanshanian (Cretaceous). Most Ag-Pb-Zn deposits in this region are typically attributed to Late Jurassic mineralization. In contrast, Wutong is a Cretaceous system formed during the Cretaceous mineralization peak in south China. As this relatively shallow hydrothermal system is related to deeper magmatism, Cretaceous mineralization is not limitted to the western limit of Cathaysia but may extend eastward at least to the Nanling range. Furthermore, regional grouping of the age of granite-related magmatism indicates that the same kind of crustal source has been melted repeatedly, possibly in different tectonic settings.