南岭中段郴州一带中、晚侏罗世花岗岩浆的混合作用--来自镁铁质微粒包体的证据

镁铁质微粒包体在南岭中段中、晚侏罗世花岗岩中分布十分普遍，其分布规律是，岩体内同阶段较早次形成的岩石单元含量高，较晚次单元中含量少甚至无；与钨、锡、钼、铋等多金属矿有关的花岗岩体中微粒包体的含量高且个体大，而与矿化无关的岩体中含量少、个体小。对包体的颜色、形态、结构、成分、岩性等方面的综合研究表明，包体为岩浆成因。包体中出现明显的不平衡矿物组舍和结构，发育针状磷灰石晶体，出现嵌晶状石英和碱性长石，显示出岩浆混合的岩相学特征，表明该区中、晚侏罗世花岗岩的成因为壳一幔岩浆混合而成的。研究还表明，区内岩浆混合作用的强弱、基性物质加入的多少都与锡成矿作用的好坏有直接关系。

Middle-Late Jurassic granite magma-mixing in the middle segment of the Nanling Mountains, South China: Evidence from mafic microgranular enclaves

Mafic microgranular enclaves (MME) are distributed widely in Mid-Late Jurassic granite in the middle segment of the Nanling Mountains. There are more enclaves in the early-formed rock units than late-formed rock units in the same stage in the plutons. There are more and bigger enclaves in granites related to W-Sn-Mo-Bi polymetallic deposits and less and smaller enclaves in granites unrelated to mineralization. An integrated study of the colors, shapes, textures and structures, composition and lithology of the enclaves indicate that they are magmatic in origin. The occurrence of the disequilibrium mineral assemblage and textures and development of acicular apatite crystals and poikilitic quartz and alkali feldspar in the enclaves show the petrographic characteristics of magma-mixing, suggesting that the Mid-Late Jurassic granite formed by crust-mantle magma-mixing. In addition, study also indicates that Sn-mineralization is directly related to the degree of magma hybridization and the amount of introduced basic material.