黑云母在富钠、氟、锂气成-高温热液作用下的实验研究  

EXPERIMENTAL STUDY ON BIOTITE IN THE Na-,F-AND Li-RICH PNEUMATOLYTO-HYPOTHERMAL PROCESSES

作　　者：郁云妹[1] 王玉荣[1] 

机构地区：[1]中国科学院地球化学研究所

出　　处：《地质论评》1987年第3期258-266,299,共10页Geological Review

摘　　要：本文叙述了用二组缓冲剂((NNO和CFG)研究黑云母在富钠、氟、锂气成-高温热液作用下发生变化的实验方法。实验结果显示:(1)在本实验条件下,黑云母均可以不稳定而形成新的稳定相。新稳定相矿物种类与fo_2值有关,较低的fo_2值形成富钠矿物(如霓石、钠长石),较高的fo_2值形成富锂云母。此结论与野外地质调查中发现的钠长石化在富锂云母化下方的地质事实吻合,暗示黑云母的碱交代可能提供了物质成分。(2)富锂云母的稳定性与形成环境中Mg^(2+)浓度有关,黑云母碱交代形成的环境决定于初始物黑云母中Mg^(2+)浓度,只有低镁的黑云母的碱交代才有利于稳定的富锂云母发育。(3)黑云母的不稳定有利于以类质同象存在其晶格中的成矿元素进入溶液。This paper describes the experimental method which is used to study thechanges of biotite taking place in the Na-, F- and Li-rich pneumatolito-hypothermalprocesses by using two buffers (NNO and CFG). The resolt reveals the following points. (1) Under the condition of this experiment biotite is unstable and may forma new stable facies, the variety of which is related to the value of fo_2. When thevalue of fo_2 is low, Na-rich minerals, such as aegirine and albite, are formed and Lienters the solutions; when the value of fo_2 is high, Li-rich minerals, andradite andgrossular and nepheline solid solutions are formed. The experimental result that theformation of albite and Li-rich mica is governed by fo_2 coincides in the main withthe geological fact that the occurrence of albitization beneath Li-rich micatizationas found in the field geological investigation, suggesting that the alkali-metasomati-sm of biotite connot directly produce albitization and Li-rich micatization but onlyprovides the constituent materials. (2) The stablity of Li-rich mica is related tothe Mg^(2+) concentration in the environment that the mica is formed. The environ-ment of low-Mg^(2+) concentration is advantageous to the development of low-Mg, Li-rich mica which is stable in nature, while the environment of high-Mg^(2+) concentra-tion can give rise to high-Mg, Li-rich mica which is unstable in nature. As for alkali-metasomatism of biotite, only the environment of alkali-metasomatism of low-Mgbiotite is favourable to the formation of stable Li-rich mica. The biotite used inthis experiment contains a low MgO content, but the Li-rich mica synthesized inthe experiment falls on the Mg-rich end in the b-Nm diagram. Maybe it is due tothe closed environment unedr which this experiment is run and to the absence ofother ions such as Cl^- which influence the Mg^(2+) concentration. When the Li-richmica forms under the environment of alkali-metasomatism of biotite, Mg^(2+) takes theplace of Fe^(2+) and the increase of Mg^(2+) in the lattics results in th

关 键 词：云母化 大隅石 黑鳞云母 矿物 钠长石化 钙铁榴石 石榴石 高温热液 成矿元素 碱交代作用 蓝闪石 角闪石 霓石 单斜辉石 NaF 偏光 地质论评 实验研究 

分 类 号：P61[天文地球—矿床学]