华南诸广山复式岩体中段花岗岩的碱交代蚀变

诸广山复式花岗岩体中段某大型铀矿田中的部分花岗岩广泛发育碱交代蚀变作用。据对３１３个碱交代蚀变花岗岩样品的岩石化学分析资料及岩相学研究结果表明，该地碱交代蚀变是以钠长石化为主的多阶段钾、钠叠加交代（即混合交代），蚀变强度大多较弱，局部可较强并生成二长石岩、钠长石岩等交代蚀变岩。测得该碱交代蚀变岩石的Ｒｂ－Ｓｒ等时线年龄为１３２．１±５．８Ｍａ，在时序上它与主体侵入的似斑状黑云母花岗岩（Ｒｂ－Ｓｒ等时线成岩年龄为２１５．２±６．３Ｍａ）、补体侵入的细粒少斑黑云母花岗岩（测得Ｒｂ－Ｓｒ等时线成岩年龄为１５５．２±５．４５Ｍａ）构成一连续演化序列，推测碱质可能源自该产铀花岗岩岩浆演化钠转折分异阶段的产物；该蚀变岩属铀成矿前已遭剥蚀的钨、锡矿化矿根相，成为随后工业铀矿化（Ｕ－Ｐｂ法测得成矿年龄为１０３．２±０．６Ｍａ）的有利围岩。

Alkali Metasomatic Alteration of the Granite in Middle Chuguang Mountain, South China

Based on chemical and Rb Sr isotopic data, it is shown that alkali metasomatic alteration of granite in Middle Zhuguang Mountain, South China, is multi stage potassium sodium metasomatism with dominant sodium metasomatic alteration. In general, the alkali metasomatism is rather weak in strength and resulted from tectono magma evolution. The alkali metasomatic granite is ore root facies of tungsten ,tin mineralization prior to uranium mineralization in granitoid in South China. The alkali was probably derived from the differential granitic magma.