湖南香花岭复式碱长花岗岩体侵入期次关系的识别

IDENTIFICATION OF THE INTRUSIVE PHASES OF THE COMPOSITE ALKALI-FELDSPATHIC GRANITE IN XIANGHUALING,HUNAN

香花岭碱长花岗岩为一复式岩体。不同期次侵入体之间的接触关系、白色和绿色含铍条纹岩以及磁铁矿条纹岩与不同期次侵入体之间的对应关系、通天庙、塘官铺、太平和新风不同矿化组合与不同期次侵入体之间的成因联系以及遥感图像中的环形构造特点和差异明显的Rb-Sr同位素等时年龄表明该岩体是两期四次碱长花岗质岩浆侵入作用的产物,燕山早期的三次岩浆侵入与本区矿化关系密切;而燕山晚期的一次岩浆侵入与矿化无关。上述认识可对矿区的某些地质问题作出合理的解释。

Xianghualing alkali-feldspathic granite is a composite rock mass. The contact relation among different phases of intrusion, the corresponding relation among different phases of intrusion and white and green Be-bearing perthitic rocks as well as magnitic perthitic rock, the genetic connection among different phases of intrusion and the different mineralization assemblages in Tongtianmiao, Tangguanpu,Taiping and Xinfeng, the ring structure in remote sensing images and the distinct Rb-Sr isochronic ages indicate that the rock mass resulted from four phases of intrusion in twoepisodes of alkali-feldspathic granitic magmatic activity. The three phases in the early episode of Yanshanian Period are in close connection with the mineralization in this area; while the latist phase in the late episode of Yanshanian Period contributed nothing to mineralization. The above understanding can give rational explanation to some geologic problems remaining in suspense in the ore district.