香花岭地区花岗岩类岩石稀土元素演化特点及其形成机理的探讨  

A PRELIMINARY STUDY ON THE REE EVOLUTION CHARACTERISTICS AND THEIR FORMATION MECHANISM OF THE GRANITOIDS IN XIANGHUALING (HSIANGHUALING) DISTRICT

作　　者：杜绍华[1] 邱瑞照[1] 

机构地区：[1]中国地质科学院宜昌地质矿产研究所

出　　处：《地球学报》1989年第1期131-142,共12页Acta Geoscientica Sinica

摘　　要：随着岩浆的演化,香花岭地区花岗岩类岩石的稀土元素总量不断下降,负铕异常减小,轻稀土相对于重稀土越来越富集,显示了与绝大多数花岗岩类岩石相反的逆向演化特点。造成本区花岗岩类稀土元素逆向演化的原因,除与本区花岗岩浆体系不同演化阶段的氧化还原条件不同外,最根本的是与该岩浆体系向贫Si、(K+Na),富Al、Li、F和H_2O的方向演化所造成的岩浆体系碱度的不断增强有关。in the Xianghualing (Hsianghualing) district, South Hunan, there are mainly three types of granitoids, i. e, the biotitegranite, zinnwaldite-albite-granite and Hsianghuagite. These granitoid rocks are formed by the same granitic magma in different stages and constitute a complete magmatic evolutionary series.With the magma evolving, the REE contents and negative Eu anomaly decrease progressively, and the LREE are more and more enriched as compared with HREE. Abovementioned facts show an evolutionary tendency of REE of the granitoids in the study district contrary to that of the granitoids elsewhere.The components of the granitic magma system become poorer in Si,(K + Na), richer in Al, Li, F and H2O+ during the evolution, which caused weaker acidity and stronger alkalinity. It may be the most important reason for the specific REE evolution of the granitoids in this district. In addition, the varied oxidation-reduction environments in different evolutionary stages of this magmatie system may be the other reason.

关 键 词：花岗岩类 演化特点 香花岭 铕异常 花岗岩体 形成机理 黑云母花岗岩 钠长石 地球化学行为 造岩矿物 

分 类 号：P5[天文地球—地质学]