喜马拉雅琼嘉岗超大型伟晶岩型锂矿的发现及意义

近年来,喜马拉雅新生代淡色花岗岩的"高度分离结晶、异地深成侵入"成因,及其具有良好的稀有金属成矿潜力而倍受关注。已有野外调查和资源勘查工作表明该花岗岩带可能成为我国稀有金属重要的战略储备基地。目前带内金属组合以铍-铌-钽（锡-钨）组合为主（如错那洞大型锡-钨-铍矿床）,但尚未发现工业锂矿体的产出。本次工作在高喜马拉雅琼嘉岗地区发现了超大型伟晶岩型锂矿,并初步揭示该伟晶岩型锂矿的基本地质特征。琼嘉岗伟晶岩属于过铝质LCT型伟晶岩,稀有金属（REL）类REL-Li亚类钠长石-锂辉石型。含矿伟晶岩呈串珠状、囊状体产出在前寒武系肉切村群大理岩中,伟晶岩具有一定分带,目前主要包括细粒钠长石带、文象结构带、分层细晶岩带和块体微斜长石+锂辉石带,赋矿主体结构带为后两者。矿石矿物主要为锂辉石、铌铁矿-铌锰矿,以及少量锡石和绿柱石。59件样品中44件Li₂O含量在工业品位（0.80%）之上,平均1.30%。4条伟晶岩脉群资源量估算表明琼嘉岗锂资源可达超大型规模,琼嘉岗是喜马拉雅首例具有工业价值的伟晶岩型锂矿,其发现证实我国高喜马拉雅地区具有找寻大型-超大型花岗伟晶岩型锂（铍）矿的潜力。

Discovery of the Qongjiagang giant lithium pegmatite deposit in Himalaya, Tibet, China

In recent years, the genesis of highly fractionated Cenozoic Himalayan leucogranite, has attracted much attention because of its good potential for rare-metal mineralization. Field investigations and mineral resource surveys have pointed out that the Himalayan leucogranite belt may become an important strategic mineral reserve base for rare metals in China. At present, the discovered metal assemblages in the belt are dominated by beryllium-niobium-tantalum (tin-tungsten) assemblage (such as the Cuonadonglarge tin-tungsten-beryllium deposit), but no industrial lithium ore body has been found. The present work reports a newly discovered, superlarge-scale pegmatite-type lithium deposit in the Qongjiagang area of the Higher Himalayan belt, and we revealed the geological characteristics of the first pegmatite-type lithium deposit in the Himalaya. The Qongjiagang pegmatites belong to peraluminous LCT-family, REL-Li sub-type and albite-spodumene sub-style. The Qongjiagang rare-element pegmatite intruded into marble strata of the Pre-Cambrian Rouqiecun Group as pod-and lense-like bodies, and the ore minerals are mainly spodumene, columbite-group minerals, cassiterite and beryl. The Qongjiagang pegmatites have the internal zonation patterns from rim to core, including saccharoidal albite zone, layered aplite zone and massive microcline+spodumene zone, and the graphic pegmatite zone occurred in the border zone sometimes. Layered aplite zone and massive microcline+spodumene zone hosted a large proportion of spodumene. 44 samples out of 59 analyzed samples have the Li₂O contents higher than 0.80%, with average of 1.30%. Our resource estimate indicates the Qongjiagang Li deposit is the first pegmatitic lithium deposit with economic value in the Himalayan leucogranite belt, and its discovery confirms good potentials in the findings of large granitic pegmatitic lithium deposit in the Higher Himalayan region of China.