地质通报2018，Vol.37Issue(4)：669-681,13.
北祁连甘肃毛藏寺铜-钼矿床花岗质岩石锆石U-Pb年龄、地球化学特征及其地质意义
Zircon U-Pb age,geochemical characteristics and geo-logical significance of granitoids in the Maozangsi deposit,Northern Qilian Mountain
摘要
Abstract
The Maozangsi Cu-Mo deposit in Gansu is a porphyry type deposit related to granitoids.Maozangsi granitoids are com-posed of porphyritoid monzogranite and granodiorite. In this paper, zircon U-Pb dating and geochemical study of the Maozangsi granitoids were conducted to constrain its geochronology and discuss petrogenesis and its relationship with mineralization. Zircon LA-ICP-MS dating yielded concordant ages of 455.8±3.1Ma and 425.0±2.8Ma respectively,indicating that the two plutons were formed in Late Ordovician and late Silurian respectively. Geochemical data show that porphyritoid monzogranite is a peraluminous granite and belongs to the calc-alkaline series,whereas granodiorite is a aluminous granite and belongs to the high-K calc-alkaline series. They are characterized by enrichment of LILEs and depletion of HFSEs, with REE patterns exhibiting the right-deviation type and strong fractionation with LREE enrichment.The porphyritoid monzogranite show weak positive Eu anomalies(δEu=1.18~1.24)and geochemical affinity to adakite,probably resulting from the slab melting(including marine sediments)of the subduction of North Qilian Ocean with the residual minerals of garnet in the source.The granodiorite shows weak negative Eu anomalies and was generated in a post-collisional extension setting and derived from partial melting of basaltic rocks in the lower crust induced by asthe-nosphere after the breakup of previously subducted North Qilian oceanic slab.The features of porphyritoid monzogranite are in ac-cordance with the characteristics of ore-forming period adakitic rocks and thus suggest good mineralization conditions.In combina-tion with data obtained from previous studies,the authors hold that it is possible to find Cu-Mo-Au deposits related to adakites in the eastern section of the Northern Qilian Mountain.关键词
花岗质岩石/地球化学/LA-ICP-MS锆石U-Pb年龄/毛藏寺铜钼矿/北祁连Key words
granitoids/geochemistry/LA-ICP-MS zircon U-Pb age/Maozangsi Cu-Mo deposit/Northern Qilian分类
天文与地球科学引用本文复制引用
赵辛敏,郭周平,王育习,高永伟,张乐,白赟,杨生飞..北祁连甘肃毛藏寺铜-钼矿床花岗质岩石锆石U-Pb年龄、地球化学特征及其地质意义[J].地质通报,2018,37(4):669-681,13.基金项目
中国地质调查局项目《祁连成矿带肃南—大柴旦地区地质矿产调查》(编号:DD20160012) （编号:DD20160012）
