内蒙古白云鄂博矿床铌分布规律、赋存状态和富集机制  

Spatial distribution,occurrence and enrichment of Nb in the giant Bayan Obo deposit,Inner Mongolia,China

作　　者：诸泽颖 柯昌辉[1] 赵永岗[2] 王登红[1] 张丽[2] 李以科[1] 赵剑 于洪[1] ZHU ZeYing;KE ChangHui;ZHAO YongGang;WANG DengHong;ZHANG Li;LI YiKe;ZHAO Jian;YU Hong(MNR Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resource CAGS,Beijing 100037,China;Bayan Obo Iron Mine of Baotou Iron and Steel Company,Baotou 014080,China;Barun Mining Branch Co.of Inner Mongolia Baotou Steel Union Co.,Ltd.,Baotou 014080,China)

机构地区：[1]自然资源部成矿作用与资源评价重点实验室,中国地质科学院矿产资源研究所,北京100037 [2]包钢(集团)公司白云鄂博铁矿,包头014080 [3]内蒙古包钢钢联股份有限公司巴润矿业分公司,包头014080

出　　处：《岩石学报》2025年第4期1170-1193,共24页Acta Petrologica Sinica

基　　金：国家重点研发计划(2022YFC2905301);国家自然科学基金项目(42072114);地质调查项目(DD20240075、DD20243486);中国地质科学院矿产资源研究所基本科研业务费(KK2419);科技成果转化项目(HE2228、HE2313、HE2332、HE2333、HE2334)联合资助.

摘　　要：内蒙古白云鄂博是我国第一大铌矿床,但含铌矿物颗粒细小,赋存状态以及空间分布规律不清导致铌成矿过程与成矿规律研究程度不深,严重影响了白云鄂博铌找矿以及综合利用。本文结合野外地质观察以及精细岩相学、矿物学等方法,详细描述了白云鄂博主矿、东矿、西矿和东介勒格勒矿区典型的铌矿体的空间分布,产出特征、矿石类型、铌的赋存形式及矿物共生组合。白云鄂博铌矿与稀土矿体具有同体共生和异体共生关系,其中异体共生的铌矿体为独立矿体,主要分布在西矿板岩内以及围岩接触带上,而同体共生为铌矿体位于稀土或铁矿体内部,见于主矿、东矿以及东介勒格勒中。根据岩相学、矿物学研究显示,白云鄂博矿区西矿主要的铌矿石为富云母霓长岩型,而主矿、东矿以及东介勒格勒主要的铌矿石分别为碳酸岩脉型、条带状霓长岩型以及条带状白云石碳酸岩型。白云鄂博主要的含铌矿物有易解石族矿物、铌铁矿族矿物、烧绿石、包头矿、褐钇铌矿,西矿以铌铁矿和烧绿石为主,主矿、东矿以及东介勒格勒以易解石为主。成矿差异可能与热液活动、构造活动以及围岩蚀变的类型不同有关,西矿与钾质霓长岩有关,主矿、东矿以钠质霓长岩有关。白云鄂博铌成矿具有岩浆和热液成因,其中岩浆成因的铌铁矿形成时代与火成碳酸岩侵位时间一致,铌来源于火成碳酸岩。而霓长岩化等热液作用有助于铌的活化富集再沉淀,在热液活动较强的区域形成铌的局部富集。碳酸岩岩浆的高度结晶分异同样促进了晚期铌与稀土的超常富集,在晚期碳酸岩脉以及东介勒格勒中形成热液成因的易解石。本研究通过明确含铌矿物的分布规律,厘清成矿过程,进一步提出白云鄂博铌与稀土具有耦合成矿的关系,为白云鄂博铌找矿以及综合利用提供一定的依据。Bayan Obo niobium deposit is the largest one in China.However,research work on the niobium mineralization process is rare due to the limited size of niobium-bearing minerals and their blurry regularities of distribution.To address these issues,this paper employs geological observations in conjunction with petrological and mineralogical studies to provide a detailed description of the spatial distribution of niobium orebodies,niobium-rich rock types,the occurrence of niobium-bearing minerals and their paragenetic associations in the West Mine,Main Mine,East Mine,and Dongjie Legele Mine within the Bayan Obo deposit.There exists a symbiotic and allo-symbiotic relationship between niobium(Nb)and rare earth element(REE)orebodies in Bayan Obo deposit.Symbiosis is predominantly observed in the West Mine,where Nb orebodies are distributed within slate formations or at the contact zones with surrounding rocks.Allo-symbiosis is mainly found in the Main Mine,East Mine and Dongjie Legele Mine,where Nb orebodies occur within REE orebodies.Petrographic and mineralogical observations reveal that the primary rock types hosting niobium in the West Mine are glimmerites,while in the Main Mine,West Mine and Dongjie Legele Mine,the dominant Nb-rich rocks are carbonatite veins,banded fenites and banded carbonatites,respectively.The major niobium-bearing minerals in Bayan Obo include aeschynite-group minerals,columbite-group minerals,pyrochlore-group minerals,baotite and fergusonite.In the West Mine,columbite and pyrochlore dominate as Nb-bearing minerals,whereas in the Main Mine,East Mine and Dongjie Legele Mine,aeschynite is overwhelming.These variations can be attributed to diverse fluid activities,tectonic settings and wall-rock interactions.The West Mine is associated with potassium fenites,while the East Mine is linked to sodium fenites.Niobium minerals exhibit both magmatic and hydrothermal origins.Magmatic columbite crystallization aligns with carbonatite emplacement,sourcing niobium from carbonatite melts.Hydrothermal processe

关 键 词：白云鄂博 铌铁矿 烧绿石 易解石 

分 类 号：P612[天文地球—矿床学] P618.79[天文地球—地质学]