硅酸盐熔体包裹体均匀化过程的动力学性质

硅酸盐熔体包裹体的研究,和以模拟实验为主的实验岩石学,实验矿物学一样,已经成为现代岩浆岩石学,尤其是理论岩浆岩石学研究的一个必不可少的组成部分。均匀化测温研究,是硅酸盐熔体包裹体研究的一个重要组成部分。其方法是对于呈封闭系统的硅酸盐熔体包裹体进行加热,在反方向上,再造这些包裹体从结晶到熔融的所有阶段,直至其完全均匀化,也就是恢复到它们被生长着的矿物包含、捕获时的状态,借以测量矿物近液相线或固相线的结晶温度。

KINETIC BEHAVIOUR OF THE HOMOGENIZATION PROCESS OF SILICATE MELT INCLUSIONS

The homogenization thermometry is an important part of the study of silicate melt inclusions. Besides the Choice of convenient melt inclusions, it is necessary to establish a thermometric rule for the homogenization thermometry. The author has carried out a systematic study of the kinetics of homogenization process according to the chemical composition of included silicate liquid, in order to define and normalize the optimal conditions for useing of the thermometry. During heating the observation of disappearance of the shrinkage bubble permits to understand the kinetic of homogenization process. In light of the relation between the viscosity and the necessary time for the homogenization of inclusions, we can define the rate of homogenization equilibrium of different types of silicate melt inclusions. For the melt inclusions in basic lavas, the time necessary to realize the homogenization equilibrium is of the order of 5-10 minutes ; for the andesitic lavas and the intermediate alkali-lavas, it is about 20 minutes; for the acid lavas, about 1-2 hours. The viscosities of silicate liquids trapped by different types of inclusions have been also calculated. The curve of the relation between the viscosity and the necessary time for homogenization equilibrium shows that the lower the viscosity, the shorter the necessary time to realize the homogenization equilibrium.The total time of each experiment is: 2-4 hours for basic lavas, 4-8 hours for intermediate lavas and 6-12 hours for acid lavas.