Unraveling evolution histories of large hydrothermal systems via garnet U-Pb dating, sulfide trace element and isotopic analyses: A case study of Shuikoushan polymetallic ore field, South China

Abstract

The Shuikoushan ore field is one of the largest Pb-Zn-Au polymetallic magmatic hydrothermal system in South China and hosts a significant metallogenic potential. In this study, detailed garnet U-Pb dating, sulfide trace element and sulfur isotopic analyses were conducted to reveal the features during ore formation. Chronologically, garnet U–Pb dating yields ore-forming ages of 158.8 ± 1.4 Ma for the Yagongtang deposit, 158.8 ± 2.5 Ma for the Kangjiawan deposit and 154 ± 18 Ma for the Laoyachao deposit, respectively. The ore formation history in the Shuikoushan ore field can be subdivided into four stages, and five types of sphalerite (Sp0 to Sp4), and three types of pyrite (Py to Py2) from early to late are identified. The distinct compostions indicate that sphalerite and pyrite were formed by different trace/minor element substitution mechanisms and oxidation state, although sulfur isotopes indicate a consistent sulfur origin. Combined with previously published studies, this work demonstrates that the Shuikoushan ore field belongs to a prolonged hydrothermal system. Its mineralization was genetically correlated with the emplacement of granodiorite, and the thermochemical sulfate reduction (TSR) process (Stage 2) and bacterial sulfate reduction (BSR) process (Stage 3) dominated the evolution of sulfur and facilitated the participation of sulfides within the Shuikoushan ore field.