鄂西北地区碱性岩—碳酸岩及相关铌钽—稀土矿研究与勘查进展

Research and Exploration Progress of Alkaline Carbonatite and Related NB-TA-REE Deposits in Northwest Hubei Province

鄂西北地区广泛发育一套碱性岩-碳酸岩,该套岩石与铌钽稀土矿成矿关系密切。湖北省地质局在鄂西北地区取得了丰硕的铌钽-稀土矿找矿成果,发现了庙垭铌稀土矿、天宝铌矿及土地岭铌钽矿等一批大-超大型矿床,使鄂西北地区成为中国重要的稀有稀土矿产资源后备基地。鄂西北地区碱性岩-碳酸岩形成于早志留世,其岩浆活动时间峰值范围为420~440 Ma,为幔源玄武质岩浆演化的产物,具有HIMU、EM1和EM2的混合源区特征,可能与壳源物质再循环进入软流圈地幔有关。该地区碱性岩-碳酸岩可能形成于被动大陆边缘裂谷环境。铌钽元素的富集与岩浆结晶分异作用有关;而稀土元素经历了早期碳酸岩岩浆结晶分异富集及岩浆演化晚期富含CO_(3)^(2-)、F^(-)以及REE的热液流体叠加富集作用,并在三叠纪接受了变质流体的活化和再富集作用。

A set of alkaline-carbonatite is widely developed in Northwest Hubei Province, which is closely related to NB TA,REE mineralization.The Geological Bureau of Hubei Province has made great achievements in prospecting niobium-tantalum-rare earth deposits in Northwest Hubei Province, and discovered a number of large and super large deposits, such as Miaoya niobium rare earth deposit, Tianbao niobium deposit and Tudiling niobium tantalum deposit, which makes northwest Hubei Province an important reserve base of rare earth mineral resources in China.The alkaline carbonatite in northwestern Hubei was formed in the Early Silurian.The peak time of magmatic activity ranges from 420~440 Ma.It is the product of the evolution of mantle derived basaltic magma.It has the characteristics of mixed sources of HIMU,EM1 and EM2,which may be related to the recycling of crust derived materials into the asthenosphere mantle.The alkaline carbonate rocks in this area may have been formed in a passive continental margin rift environment.The enrichment of Nb and TA is related to the crystallization differentiation of magma.The REE experienced crystallization differentiation and enrichment of early carbonated magma and superimposed enrichment of hydrothermal fluid rich in CO_(3)^(2-),F^(-) and REE in late magmatic evolution, and received activation and reenrichment of metamorphic fluid in Triassic.