摘要
The Dabaoshan porphyry Cu deposit(420 kilotons(kt)of Cu@0.36%)is located in South China.The newly discovered Cu orebodies are hosted in the dacite porphyry adjacent to a granodiorite porphyry.The alteration and mineralization timing and stages of the porphyry Cu deposit were not well-constrained.In this study,we combine field mapping,petrography,whole-rock geochemistry,hydrothermal rutile U-Pb dating and Cu isotopes to synthesize an ore model at Dabaoshan.In situ hydrothermal rutile U-Pb dating yields an age of 159±13 Ma,which brackets the timing of porphyry Cu mineralization.From top to bottom,the alteration zones in Dabaoshan are divided into quartz-sericite,biotite,chlorite-epidote,and chlorite-sericite subzones.Veins are classified into four stages(Stage 1 to 4)with Stage 4 quartz-sericite-chalcopyrite veins being the main Cu ore-bearing veins.The mineralized dacite porphyry has high SiO_(2),but low MgO,CaO,and Na_(2)O contents.The chalcopyrite hosted in veins exhibitsδ^(65)Cu=values ranging from−1.29‰to 0.51‰.Such copper isotope fractionation is attributed to vapor-brine phase separation,and mixing of fluids from different geochemical reservoirs.The timing of Cu mineralization and hydrothermal alteration support that the Jurassic granodiorite porphyry is an ore-forming intrusion at Dabaoshan.
基金
funded by the China Geological Survey(Grant Nos.DD20190379,DD20221695 and DD20221684)
a collaboration program(2019-2024)between the Institute of Mineral Resources(Chinese Academy of Geological Sciences)and the Guangdong Dabaoshan Mining Co.,Ltd.
