In Situ LA-ICP-MS U-Pb Geochronology, Sr-Nd-Hf Isotope and Trace Element Analysis of Volcanic Rocks from the Gacun Volcanic-Hosted Massive Sulfide Deposit in Sichuan, China

The Gacun deposit is a typical Volcanic Hosted Massive Sulfide (VHMS) associated with Late Triassic seafloor calc-alkaline felsic volcanics. Studies of zircon ages, petrology, major and trace element geochemistry, Sr-Nd-Hf isotope geochemistry volcanic rocks from the Northern Yidun arc were undertaken in this paper. We reshaped magmatic system activity time, defined origin magma evolution, proposed metallogenic model deposit. Whole-rock compositions island indicate that they are complete basalt–andesite–dacite–rhyolite assemblage, showing three obvious stages composition evolution. They enriched large-ion lithophile light rare earth elements, but depleted high field-strength heavy weak-to-negligible Eu anomalies (obvious rhyolite). These geochemical features based on ancient continental crust. Ganzi–Litang oceanic subduction induced mantle melting produced basaltic magma, while MASH processes at bottom crust andesitic magma. Part andesite erupted to form lava. remaining part was mixed via anatexis (approximately 20%–40% crustal component), forming ore-bearing rhyolite. Zircon U-Pb age data defines magmatic–hydrothermal mineralization sequence events: At 238 Ma, magmatism led formation eastern 233 zone (the western deposit), large-scale bimodal formed main rock series deposit, rhyolitic rocks. 221 eruptions tended end sub-volcanic intrusion occurred, lava dome, which located under dome acted as thermal engine promoted hydrothermal circulation. reached peak 217 ± 1 VHMS formed.