LA-ICP-MS trace element analysis of sphalerite and pyrite from the Beishan Pb-Zn ore district, south China: Implications for ore genesis.

[Display omitted] • Trace elements in sphalerite and pyrite distributed in the form of solid solutions or micro-inclusions. • The mineralization in the Beishan Pb-Zn ore district was under a low-temperature condition. • The Pb-Zn deposits in the Beishan Pb-Zn ore district are MVT deposits. The Beishan Pb-Zn ore district, located in northern Guangxi, China, is a giant carbonate-hosted Pb-Zn ore district. In-situ trace element analysis was performed using LA-ICP-MS on sphalerite and pyrite from three representative Pb-Zn deposits in the Beishan Pb-Zn ore district. The analysis of these trace elements reveals the trace element compositions of the sulfides, the distributions and the substitution mechanisms of trace elements, physicochemical characteristics of the ore-forming fluids, and ore genesis. Sphalerite is enriched in Mn, Fe, Ge, and Cd, while it is poor in Co, Ni, Ga, As, In. Pyrite is enriched in Co, Ni, As, Tl, Sb, and Pb, but poor in Mn, Ga, Ge, Cd, In, Sn. Mn, Fe, Cd, Ga, Ge, Sb, Ag, and As in sphalerite enter the mineral lattice mainly by simple or coupled substitution mechanisms, while Cu and Pb can enter the mineral lattice in the form of solid solution or micro-inclusions. Mn, Co, Ni, As, Tl, and Sb in pyrite substituted Fe2+ by simple or coupled mechanisms, while Pb can enter the mineral lattice in the form of solid solution or micro-inclusions. Studies of trace elements related to temperature (e.g., Mn, Fe, Ga, Ge, In) in sphalerite and pyrite indicated that mineralization in the Beishan Pb-Zn ore district occurred under a low-temperature condition. And according to the sphalerite GGIMFis geothermometer, the mineralization temperature of the Beishan Pb-Zn ore district was 55–268 °C (average 153 °C), of which 110–230 °C(average 153 °C) in Duchuan, 92–268 °C (average 149 °C) in Beishan, and 55–243 °C (average 167 °C) in Dongyong. The Mn, Fe, Ga, Ge, and In contents of sphalerite are similar to those of MVT deposits. The combination of some binary pattern diagrams, principal component analysis (PCA), and Co/Ni ratios of pyrite, with the geological features and physicochemical properties of the ore-forming fluids, indicates that the Beishan Pb-Zn ore district is an MVT district. This paper, combined with previous studies, shows that the Co/Ni ratio of pyrite has some guiding significance for mineral exploration of this kind of Pb-Zn deposit, with Co/Ni values around 0.1 indicating that the deposit has a better prospect of developing into a large deposit, and Co/Ni much less than 0.1 indicating that the deposit may not have a good prospect. [ABSTRACT FROM AUTHOR]