Geology and geochemistry of the only independent tellurium deposit in the world

Abstract

The article discusses both the regional and deposit geology including structure, strata, and igneous rocks, as well as the ore body and alteration of Dashuigou tellurium deposit at the Qinghai-Tibet Plateau, the only independent tellurium deposit in the world. There are over 30 minerals that make up the deposit‘s ore, including carbonates, silicates, oxides, sulfides including various tellurides and native element minerals. Euhedral, semi-euhedral, xenomorphic granular, metasomatic, metasomatic graphic, reaction rim, and solid solution separation are the main ore texture; while massive, vein/veinlet, stockwork, dissemination, breccia, and bird‘s-eye are the major ore structure of the deposit. Based on the ore structure, this deposit‘s ore can be divided into three categories: massive, veinlet-stockwork, and disseminated. The ores are further divided into eight subcategories in total based on the proportions of tellurium minerals, other sulfides, dolomite, quartz, and muscovite in it. Both geology and K-Ar isotope dating have confirmed that the pyritic (pyrrhotite + pyrite) vein and telluride vein are products of two different geological events that are far apart. The tellurium grade in the ores varies between 0.01% and 34.58%. All ores in this deposit are primary sulfide ores that have not been transformed by oxidation or weathering. Two paragenetic stages; namely, the pyritic stage and tellurium stage consisting of five sub-stages in total exist in the deposit. According to Laznicka‘s idea, the deposit‘s tonnage accumulation indices indicate that it is a super-large independent tellurium deposit.