斜长角闪岩脱水熔融过程中熔体连通性的实验研究

The Experimental Study on the Connectivity of Melt in the Process of Partial Melting of Plagioclase Amphibolite

岩石的物理性质（弹性、电性等）明显受熔体连通性的制约。因此，研究熔体分布对理解深部地质作用、解释地球物理资料具有特殊意义。干高温高压条件下（T=850～1100℃，p=2．0～4．0GPa）在YJ3000吨六面顶砧压机上进行了天然块状斜长角闪岩的脱水部分熔融实验，测量了熔体与矿物相接触时所形成的二面角值。结果表明，熔体在低熔体系下（熔体体积百分比为5％），熔体以熔体薄膜形式存在于矿物相边界，二面角值〈60。时，熔体相互连通；不同固相矿物的二面角的分布有差别很大；二面角随温度升高而减小，因此温度升高有利干熔体形成连通体。表面张力和界面能的最小化是推动熔体连通的两个驱动力。通过测量二面角值可定性确定熔体的连通性及熔体连通的动力学机制。

The physical properties （e. g. elasticity and electrical conductivity） are obviously constrained by the connectivity of melt. Therefore, to study the distribution of melt has special significant meanings for properly understanding geological activities in depth and reasonably explaining geophysical data. An experiment of dehydration and partial melting of natural plagioclase amphibolite under high temperature and high pressure （t= 850-1100℃ ,P= 2.0-4.0 GPa） has been carried out by using YJ3000 ton press fitted with a wedge-type cubic anvil. Dihedral angels in the contact between the melt and the mineral have been measured. The results show that the melt exists in the grain boundary in form of melt film at low melt fraction （the volume percentage of melt up to 5%, while the melts are connected each other when the dihedral angel is less than 6°. The dihedral angels between the melt and different solid minerals could be obvious different. Because the dihedral angels are decreased with the rise of temperatures,the rise of temperature is favorable to the connection of melts. The minimizing of surface tension and interfacial energy are two forces for driving melts connected. Therefore,the measured dihedral angels can be used to qualitatively determine the connectivity of melt and to study the dynamics mechanism of the connection of melts.