摘要
本文选择同属一个紫苏辉石堇青石花岗岩套,定位深度不同的花岗质岩石中的长石,通过偏光显微镜、费氏台测定和X光分析等于段进行研究、对比,得出结论为:随着岩石定位由深至浅(由混合花岗岩→深成花岗岩→浅成花岗岩→花岗斑岩),斜长石牌号增高,环带趋于发育,简单双晶和复合双晶比例增大,有序度减小(δ:0.9→0.3,Iss:1→0.1),残余成因的比例减少。钾长石中or分子减少,三斜度、有序度降低(S_T:0.88→0,△:1→0.22),由最大微斜长石→正长石;钾长石和斜长石的平衡温度升高,由720℃→800℃。证实了通过长石的研究可以判断花岗岩形成的条件。文章还对花岗岩中长石有序度和三斜度的决定因素,以及长石的研究方法等问题进行讨论。
Based on studies of feldspars from granitics at various emplacement depths in the same hypersthene cordierite granite suite by polarizing microscope, universal stage and X -ray analysis, conclusions are drawn as follows: with decrease in emplacement depths, as indicated by the occurrences of granite in the order of magmatitic granite, plutonic granite, hypabyssal granite, granite porphyry, there is (1) an increase in the number of plagioclase, the proportion of simple twins to complex twins, and the balance temperature of plagioclase and potash from 720 to 800℃ ; (2) a
decrease in the degree of order (i. e. , δ :0. 9--0. 3,Eis:l--0. 1), the residual components,
the orthoclase in potash feldspar, and the triclinicity and the degree of order of potash feldspar (Sr: 0. 88--0,△:1--0. 22); (3) a transformation from mierocline to orthoclase.
It is suggested that studies on feldspars may shed light on the forming -conditions of granites. Apart from what is described above, controls over the degree of order and triclinicity of feldspar and the methods applied to the studies of them are also discussed in this paper.
