大别杂岩中混合岩的矿物空间分布研究

介绍了矿物空间分布研究的基本原理及两种统计方法(接触频数法和线切法)。作者对混合岩矿物空间分布的研究表明:(1)前人提出的统计方法存在方法上的缺陷和应用上的局限性,作者推导出矿物接触类型的概率公式;(2)部分浅色体中矿物显示聚集分布的特征,而绝大部分的浅色体中矿物具有分散分布的特点。结合质量平衡和地球化学研究认为:大别杂岩中主体混合岩成因机制是重熔和交代作用。

The Spatial Distribution of Minerals in Migmatites of Dabie Complex

In this paper, the author introduces the basic principle of mineral spatialdistribution in migmatites, i. e. minerals in leucosomes which have reached themagmatic stage are spatially characterized by random distribution, whereasthose in leucosomes from solid materials exhibit aggregate distribution; besides, he presents two statistical methods, namely contact--frequency method andline-transection method. A study of mineral spatial distribution in migmatitessuggests that there exist defects and limitations in the statistical method Putforth by previous workers. The author has deduced the equation for calculatingprobabilities of mineral contact types and also defined the extreme dispersiondegree as the Probabilities of mineral contact types in the extremely dispersedstate of minerals within a rock. Minerals show aggregate distribution in a fewleucosomes, but are characterized by dispersed distribution in the overwhelmingmajority of leucosomes. The evidence obtained from mass balance calculation,geochemical studies and mineral thermobarometer reveals that the geneticmechanism of the migmatitic complex with thermal centers is anatexis andmatasomatism, with the genetic model being "the early stage metasomatisminduced by thermal anomalies, the main stage anatexis induced by the earlystage metasomatism, and the last stage post--anatexis metasomatism".