The evolution of granitic pegmatite from the Cenozoic Huangliangou beryllium deposit,West Yunnan and its implication for mineralization
The granitic pegmatite-type rare-metal deposits in China are mostly formed in Caledonian,Indosinian and Yanshanian periods,while the Cenozoic granitic pegmatite-type rare-metal deposits are rarely reported.The Huangliangou beryllium(Be)deposit is located in the rare-metal metallogenic belt of West Yunnan on the southeastern margin of the Tibeten Plateau.It is a typical Cenozoic granitic pegmatite-type rare-metal deposit developed in the West Yunnan.Strengthening the study of this deposit is of great significance to deeply understand the genesis of Cenozoic granitic pegmatite-type rare-metal deposits and enrich the metallogenic theory of granitic pegmatite-type rare-metals in China.U-Pb geochronological studies of columbite-tantalite group minerals(CGM)and cassiterites show that the rare-metal granitic pegmatites in this deposit is mainly formed between 64.0±0.8Ma and 66.0±0.3Ma,which is the product of the closure of the Neo-Tethys Ocean subduction during Cenozoic.Electron microprobe analysis(EMPA)and LA-ICP-MS in-situ elemental microanalysis showed that the concentration of trace elements such as Li,Cs,Rb and Be of muscovite,Mn of garnet,Ta and Ta/(Ta+Nb)of columbite-tantalite group minerals from K-feldspar pegmatite,albite-K-feldspar pegmatite and albite pegmatite display an increasing trend,indicating that their evolution degree has gradually increased.The occurrence of a large amount of hydrothermal turmaline in albite-K-feldspar pegmatite indicates that there was a magmatic system with plenty of volatile for the albite-K-feldspar pegmatite.The variation of FeO and MnO contents in garnet and the trend between Cs content and K/Rb ratios in muscovite suggest that the Huangliangou rare-metal pegmatites have evolved into the Be-Nb-Ta mineralization stage.The regional evolutionary history and mineralization characteristics of the Huangliangou beryllium deposit show that the granitic pegmatites in the southwest direction have higher degree of evolution,which may be the most important prospecting target area in the mining district.
West YunnanHuangliangou areaCenozoicRare metalsGranitic pegmatiteEvolutionary sequence
万方数据
维普
