摘要
采用X射线衍射法研究了16个碱性岩和碱性花岗岩体长石的结构态,获得了122个数据,并对样品进行探针或化学分析。这些富碱岩都以碱性长石为主,有单斜、三斜钾长石,以及由它们和钠长石组成的条纹长石。钾长石分属各种结构态,钠长石有中、低钠长石,钾、钠长石在一些岩体中体现了由高→低结构态有序化演化进程。长右结构态与矿物温度计所获得的资料得到了很好的对照,表明了长石Si/Al有序程度主要受结晶温度的影响。
Feldspars from 16 alkaline rocks and alkali granites have been studied.Of them alkali-feldspars are a main group in these alkali-rich rockbodies, whichconsist of monolinic and triclinic K-feldspars and albite. According to statistics,the highest opportunities of structural state in the above-mentioned feldsparsare listed as follows; t_(1o)=0.7～0.75 for monoclinic K-feldspar and t_1=0.95 fortriclinic K-feldspar and albite. Even in the same rockbody the structural statesof feldspars may range widely, sometimes from high to low. In general, for K-feldspars there exists a two-step ordering process, i. e., at first, with incre-asing value of t_1 in monoclinic feldspar and along with a trend line from t_(lm)-4× (t_(2o)+t_(2m)) to t_(2c). As to albite, a different ordering evolution tendency from t_(1m)-(t_(2o)+t_(2m)) to t_(1o) can be seen. In these alkaline rockbodies studied monoclinicK-feldspars are predominant. While in alkali granites, without any exception,only perthite, monoclinic or triclinic K-feldspars combined with albites, canbe observed. As for the formation temperatures of rockbodies, there is a coin-cidence between those estimated from feldspar structural states and those by min-eral thermometry in some rockbodies. Some valuable information can be obtai-ned from the study of Si-Al occupancy in feldspars.
出处
《矿物学报》
CAS
CSCD
北大核心
1993年第3期220-229,共10页
Acta Mineralogica Sinica
基金
国家自然科学基金
关键词
长石
结构态
碱性岩
碱性花岗岩
feldspar
structural state
alkaline rock
alkali granite
