- 责任者：Hu Shengqi (Faculty of Earth Sciences ; China University of Geosciences ; Wuhan 430074 ; China) ; Zhu Qiang
- 刊名：Mineral Deposits
- 出版年：2013
- 卷期：32(6)
- 关键词：斑岩铜矿床 ; porphyry copper deposit ; 斑岩钼矿床 ; porphyry molybdenum deposit ; 广东 ; Guangdong
- 页码：p.1139-1158
- 图表：11 illus., 4 tables, 102 refs.
- 分类号：1001
- issnNo：ISSN0258-7106
- isbnNo：CN11-1965/P
Located in Yuanzhuding area of Fengkai County in Guangdong Province, the Yuanzhuding Cu-Mo deposit lies on the northern margin of Dayaoshan uplift along the southern section of the Qinzhou-Hangzhou metallogenic belt. It is a large porphyry copper-molybdenum deposit. Based on the high-precise LA-ICP-MS zircon U-Pb isotope dating, the authors obtained an petrogenetic age of （154.3±1.7） Ma （n=12, MSWD=3.1） for the granite porphyry, suggesting that the intrusion was emplaced in Late Jurassic, corresponding to 155 Ma Cu-Mo mineralization age obtained by the Re-Os method. Rock geochemical analysis shows that Yuanzhuding porphyry granite has high silicon （SiO2=68.81%~70.21%）, high alkali （Na2O＋K2O=6.78%~8.01%）, calc-alkaline （Litman index σ=1.69~2.27）, and metaluminous to weakly peraluminous （A/CNK=0.96~1.04） characteristics. Geochemical characteristics of rare earth elements are ΣREE=142.15×10-6~170.83×10-6, ΣLREE=135.05×10-6~162.34×10-6, ΣHREE=7.10×10-6~8.48×10-6, （La/Yb）N=30.97~32.10, δEu=0.86 ~ 0.89. The chondrite-normalized REE patterns demonstrate right-oblique linear REE patterns with weak negative Eu anomaly and significant fractionation between LREE and HREE. As for trace elements in the primitive mantle normalized spider diagram, the rocks are relatively enriched in Rb, K and other large ion lithophile elements （LILE） and high field strength elements （HFSE） Th, U, Nb, Ta, P, and they are relatively depleted in Ti and high field strength elements and large ion lithophile elements Ba, Sr. In situ zircon LA-MC-ICP-MS Hf analysis shows that 176Hf/177Hf ratios vary from 0.282 500 to 0.282 801. εHf（t） values range from -6.27 to 4.19. Comprehensive analysis shows that Yuanzhuding granite porphyry is metaluminous to weakly peraluminous I-type granite, with crust-mantle mixed source. Zircon εHf（t） values suggest that the parental magmas of Yuanzhuding granite porphyry are rather complex. Zircon Hf isotopic composition suggests that the parental magmas of the rock bodies were mainly derived from a young mantle partly mixed with old continental crust rock during the evolution. Mantle material in the Yuanzhuding deposit played an important role in the formation of the granite porphyry. Combined with regional tectonic background and previous research results, the authors hold that the Yuanzhuding porphyry Cu-Mo deposit might have been controlled by the subduction of the Pacific plate continental margin in Late Jurassic. It is the syn-collision-post-collision granite, which reflects the characteristics of A type subduction and has the same tectonic background of the Yongping Cu deposit, formed in a plate subduction environment.