In Situ U—Pb Dating and Trace Element Analysis of Garnet in the Tongshanling Cu Polymetallic Deposit, South China

The grossular–andradite garnet is an ideal mineral for indicating the formation age of skarn, which also pretends to constrain skarn processes because its higher REE (rare earth elements) content. Tongshanling deposit a medium-sized reduced Cu–W–Pb–Zn associated with highly evolved I-type granodiorite intrusion in Nanling metallogenic belt, South China. Different assemblages, microscopic characteristics, and BSE images distinguish two kinds garnets prograde retrograde stages. grains from stage have U–Pb isochron 165.4 ± 3.8 Ma (MSWD = 0.7) that 159.5 1.7 1.8), implying thermal metamorphism hydrothermal metasomatism mainly occurred middle Upper Jurassic. total amount rare elements (∑REE+Y) gradually decreased patterns shifted enriched HREE Eu negative anomaly HREE-depleted positive anomaly. decreasing U content increasing indicate redox environment change oxidation reduction. However, different elevations within same (+90 m, +5 −35 −200 −400 m) exhibit similar patterns, despite weak cooling significant depressurization confirmed by fluid inclusion microthermography. As result, are dominated species parent fluids, changed over time symbiotic REE-enriched precipitation environment, while being slightly affected pressure. Grossular garnets, rich REEs, found deposits, can chronology reveal spatio-temporal zonal characteristics.