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红山Cu多金属矿床位于滇西北义敦岛弧南端的中甸岛弧,一直以来被认为是印支期夕卡岩型矿床。但近年研究发现,矿区内还发育有燕山晚期斑岩型Cu-Mo矿化作用。本文首次在红山矿区发现了燕山晚期的花岗斑岩,花岗斑岩锆石LA-ICP-MS U-Pb定年研究确定其年龄为(81.1±0.5)Ma,与斑岩型Cu-Mo矿化年龄(77±2 Ma,辉钼矿Re-Os等时线年龄)在误差范围内非常接近,成岩与成矿作用之间具有密切的时空成因联系。红山Cu多金属矿床燕山晚期花岗斑岩成岩年龄与义敦岛弧造山后伸展环境下所形成的花岗岩浆成岩时代峰期(80 Ma左右)相一致,表明中甸红山地区除存在与俯冲作用密切相关的印支期Cu多金属成矿作用外,还存在燕山晚期形成于造山后伸展环境的花岗斑岩型Cu-Mo成矿作用。
The Hongshan Cu polymetallic deposit is located at the arc of Zhongdian Island on the southern tip of Yidun Island in northwestern Yunnan and has long been considered as the Indosinian skarn deposit. However, recent studies have found that there are also Yanshanian porphyry-type Cu-Mo mineralization in the mining area. In this paper, the late Yanshan granite porphyry was found in the Hongshan Mine for the first time. The LA-ICP-MS zircon dating of the granite porphyry determined that the age was (81.1 ± 0.5) Ma and was consistent with the porphyry Cu-Mo The mineralization age (77 ± 2 Ma, Re-Os isochron age of molybdenite) is very close to the error range, and the diagenesis and mineralization are closely related to each other in time and space. The diagenetic age of late Yanshan granite porphyry in the Hongshan Cu polymetallic deposit is consistent with that of the granitic magmatism (about 80 Ma) formed during the extensional environment of Yidong Island after arc orogen. It shows that except the Indosinian Cu polymetallic mineralization, which is closely related to subduction, is also related to the granite-porphyry Cu-Mo mineralization that formed in the post-orogenic extensional environment in late Yanshanian.