• 责任者：Li Bin (State Key Laboratory for Mineral Deposits Research ; School of Earth Sciences and Engineering ; Nanjing University ; Nanjing 210093 ; China) ; Zhao Kuidong
• 刊名：Acta Petrologica Sinica
• 出版年：2013
• 卷期：29(12)
• 关键词：铜矿 ; copper ores ; 金矿 ; gold ores ; 福建 ; Fujian Province
• 页码：p.4167-4185
• 图表：11 illus., 5 tables, 146 refs.
• 分类号：1001
• issnNo：ISSN1000-0569
• isbnNo：CN11-1922/P

     The Ermiaogou Cu-Au deposit is located within the Zijinshan ore field in southwestern Fujian Province. This deposit has similar styles of mineralization and alteration with the Zijinshan Cu-Au deposit. Mineralization was surrounded by acidic subvolcanic and closely related to porphyritic dacites and breccias, which suggested that both deposits may share similar genesis. Both the Ermiaogou Cu-Au deposit and the Zijinshan Cu-Au deposit belong to high-sulfidation epithermal low temperature hydrothermal deposits, which are significantly different from the Luoboling porphyry Cu-Mo deposit and the Yueyang low-sulfidation epithermal low temperature hydrothermal deposit. The Ermiaogou porphyritic dacites are closely related to the Cu-Au mineralization within the deposit. Our new precise zircon U-Pb dating results reveal that the Ermiaogou porphyritic dacite was emplaced in the Early Cretaceous （106~108Ma）, which are similar to those of porphyritic dacite in the Zijinshan deposit. These results suggest that both deposits were resulted from the same period of magmatism and the large-scale volcanic-intrusive activity related to mineralization in the Cretaceous. Geochemically, the Ermiaogou porphyritic dacite shows high Si and K contents and weakly peraluminous. The rocks are enriched in LILEs and LREE; depleted in Nb, Ta, P, Ti; no/weak negative Eu; and characterized by strongly fractionated REE pattern and high Sr/Y and La/Yb ratios. It also exhibits low initial 87Sr/86Sr ratios （0.712698 to 0.713174）, moderate εNd（t） （-6.26 to -4.94） and high zircon εHf（t） （-4.52 to 1.66） values. Interpretation of the elemental and isotopic data suggests that the Ermiaogou porphyritic dacite has some affinities with the adakite, and was most likely generated via a process including mixing of enriched mantle-derived mafic magmas and induced felsic magmas formed by partial melting of lower crust materials under a back-arc extensional environment that may have caused by the subduction of the Paleo-Pacific plate. Enriched mantle-derived melts have high oxygen fugacities and high H2O content, thus potentially are major sources for Cu-Au metals. Mafic magmas derived from enriched mantle can change their hydrous and redox state by mixing with crust-derived melts, and led to generate adakitic magma by magmatic differentiation under high pressure, which may further result in the relevant Cu-Au mineralization at Ermiaogou.