湖南平江县仁里超大型伟晶岩型铌钽多金属矿床的发现及其意义

湖南平江县仁里铌钽多金属矿床是湖南省核工业地质局311大队新发现的高品位超大型伟晶岩型稀有多金属矿床,经过多年的地质勘查,在幕阜山复式花岗岩体西南缘的仁里矿区查明伟晶岩脉140条,发现铌钽矿脉14条。对主要矿脉进行了地表槽探和深部钻探验证,具有北铌钽南锂的特征,铌钽矿体具规模大、矿体形态简单、连续性好,矿化较均匀,品位富、埋藏浅,矿石质量优及资源潜力大等特点。矿区估算(333+334)Ta2O5资源量10791 t,Nb2O5:14057 t,平均品位Ta2O5:0.036%,Nb2O5:0.047%,达到超大型规模。仁里超大型铌钽多金属矿床的发现,突破以往对大岩基难以形成和找到超大型伟晶岩型稀有金属矿床的既往认识,提出幕阜山矿集区定位于构造岩浆隆起带,仁里矿床大型层状构造与燕山期岩浆岩联合控矿、含铌钽矿伟晶岩脉形成于区域后造山构造环境的伸展构造体制的新认识,分析了区域上的找矿方向,丰富和发展了稀有金属成矿理论,为华南地区稀有金属矿产找矿实现了重大突破,使幕阜山地区有望成为我国一个新的重要铌钽等稀有金属资源基地。

Discovery of Renli Superlarge Pegmatite-type Nb-Ta Polymetallic Deposit in Pingjiang,Hunan Province and its Significances

The Renli deposit is a high-grade superlarge pegmatite-type Nb-Ta polymetallic deposit newly discovered by 311 Team of Hunan Nuclear Geological Bureau. Through many years of geological exploration, 14 Nb-Ta-mineralized pegmatite dikes among the 140 pegmatite dikes were identified in the Renli ore field that locates in the southwestern margin of the Mufushan granitic batholith. Surface trenching and deep drilling of main ore veins revealed that Nb-Ta and Li are mainly distributed in the northern and southern parts of the Renli ore district, respectively. Nb-Ta ore bodies have features of large scale, simple shape, good continuity, uniform mineralization, high grade, low embedded depth, high quality and great resource potential. The estimated resources (333+334) and average grades of Ta2O5and Nb2O5are 10791 tons, 0.036% and 14057 tons, 0.047%, respectively, reaching scale of a superlarge sized deposit. Superlarge pegmatite type rare metal deposit related to batholith is rare, and the discovery of the Renli deposit is a big breakthrough in ore exploration. Our geological survey showed that the Nb-Ta-bearing pegmatite dikes in the Mufushan rare metal ore-concentration area, which is located in the Mesozoic tectono-magmatic uplift belt, were formed in a post-orogenic extensional tectonic environment, and controlled by large layered structures and Yanshanian magmatism. The exploration achievements and new conclusions enrich and develop the metallogenic theory of rare metal deposits. This new discovery revealed that the Mufushan area has the potential to become a new and important rare metal resource base in China, and therefore, more attention should be paid to the potential of batholith related rare metal mineralization in South China.