北秦岭光石沟地区含矿伟晶岩的成因问题,对于认识该区域铀成矿规律具有重要的指示作用.过去人们根据铀矿体的产出地质特征和与灰池子岩体的空间展布关系,普遍认为赋矿的花岗伟晶岩脉源自于灰池子岩体残余岩浆的分异作用.随着研究方法和测试技术的日渐成熟,专家学者们发现该区的花岗伟晶岩脉地球化学特征脱离了灰池子岩体的演化序列,暗示其物质来源另有途径.因此,笔者将区内的花岗伟晶岩脉以铀含量为标准分为含矿和非含矿两类,分别与秦岭群片麻岩和灰池子岩体进行对比分析研究,结果清晰表明,非含矿岩脉为灰池子岩体残余岩浆分异结晶所产生,而含矿岩脉则倾向于秦岭群片麻岩的部分重熔成因.这说明该地区伟晶岩脉具有多成因性,表现出复杂的多源特征.%Origin of the ore - bearing pegmatites in the Guangshigou area of the North Qinling orogeny is important to the instruction of the regional uranium mineralization. In the past, it was generally believed that the granitic pegmatite dikes were derived from the residual magma differentiation of the Huichizi pluton.With the growing maturity of testing techniques, more and more research result have revealed that the geochemical characteristics of the granitic pegmatite dikes in this area were separated from the evolutionary sequence of the Huichizi pluton which suggest that the source of the granitic granodiorite may be from the other rocks. The granite pegmatite dikes in the area can be divided into two categories: ore-bearing and non-ore-bearing according to the uranium content. By comparing with the gneiss of Qinling group and Huichizi pluton respectively, the non-ore-bearing dikes were found clearly be produced by the residual magma crystallization of the Huichizi puton, while the ore-bearing dikes tend to be the products of partially remelting of Qinling group, which means that the pegmatite dikes in the area were multi-genetic and of multi-source.
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