Trace element compositions of galena in an MVT deposit from the Sichuan-Yunnan-Guizhou metallogenic province, SW China: Constraints from LA-ICP-MS spot analysis and elemental mapping

Abstract

Galena trace element signatures and element partitioning between associated sulfides are poorly constrained, especially in Mississippi Valley-type (MVT) Zn-Pb deposits. This study reports laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) spot analysis data of different stages of galena as well as elemental mapping results of typical sulfide assemblages in the Daliangzi Zn-Pb deposit, one of the largest MVT deposits in the Sichuan-Yunnan-Guizhou (SYG) metallogenic province, SW China. The galena is generally enriched in Sb and Ag, with minor Cd, Cu, and As, but depleted in Bi. Antimony was generally incorporated into galena lattice via Sb3+ + Ag+ ↔ 2Pb2+, and the substitution of 2Sb3+ + □ (vacancy) ↔ 3Pb2+ also occurred at high Sb content level (>1200 ppm). Direct substitution is the main way for Cd incorporation, while Cu and As may exist via coupled substitution. Micro-inclusions also play important roles in the incorporation of Sb, As, and Cu in some cases. The elemental distribution maps show that Sb, Ag, and Tl are dominantly incorporated into galena, while Cd, Fe, Mn, Cu, As, Ga, and Ge are primarily concentrated in sphalerite. However, when present tennantite-tetrahedrite will become the preferential host phase of Sb, Ag, Cu, and As. This elemental partitioning verifies that the preferential host sulfide for trace elements is controlled by intrinsic factors (e.g., oxidation state and ion radius) rather than external factors (e.g., metal sources, pressure, temperature, and redox conditions). External factors, such as temperature, may be vital for the partitioning of a given element (e.g., Cd) between priority and subordinate hosts. Additionally, the galena trace element characteristics are found to vary significantly with the ore genetic types, which appears to imply the applicability of galena geochemistry in the ore type discrimination.