广西栗木水溪庙不对称层状伟晶岩－细晶岩岩脉的成因讨论

水溪庙不对称层状伟晶岩─细晶岩岩脉生根于黄玉钠长石花岗岩中，其底板部分多以钠质细晶岩为主，顶板部分多以钾硅质伟晶岩为主，中间部分则往往以上述二种岩性的韵律式互层为主。笔者认为，岩脉的母岩浆应该与黄玉钠长石花岗岩的母岩浆相同，是一种富含Ｆ、Ｎａ的残余花岗质熔浆。岩脉自底板至顶板在组分和结构上的规律性变化，与这种特殊熔浆在岩脉环境下的分异演化、Ｆ含量的涨落和黄玉的周期性晶出以及熔浆结晶的动力学机制有关。

GENESIS OF ASYMMETRICALLY LAYERED PEGMATITEAPLITE DYKES OF SHUIXIMIAO MINE,LIMU DISTRICT,GUANGXI

The asymmetrically layered pegmatite-aplite dikes of Shuiximiao mine are rooted in topaz-albite granite cupola. Their footwall portions are mainly the albite aplite, their hangingwall portions are mainly the K feldspar-rich pegmatite, and their middle portions are usually the rhythmically intercalated pegmatite and aplite. It is considered that their initial magma be the F-and Na-rich residual granitic melt, the same as that for the albite-topaz granite of the cupola. The regular change in compositions and texture of the rocks from the footwall upwards to the hanging wall is related to the fractionation and evolution of this particular melt under the dike condition, the fluctuation of F concentration and periodic crystallization of topaz, and the kinetics of residual melt crystallization.