Super-microstructure evolution caused by polysomatic reaction of Heishan hypersthene associated with

• 出 处: Chinese Science Bulletin
• 发表日期: 2005年14期
• 关键词: triple distinguished chains silicate Thompson HRTEM dimensions inevitable Nanjin

By means of transmission electron microscopy (TEM), the study on hypersthene megacryst and uralitized hypersthene from anorthosite complex of Chengde, Hebei Province of China shows that the layer silicate minerals such as talc and smectite would grow on the (100) under the con- dition of supergenesis. This kind of silicate is the product of the polysomatic reaction, and their evolution of growth from small to big was observed by TEM. In most cases, the layer silicate nucleus in the form of rhomb block firstly grow out of the interfaces of the augite exsolution lamellae in the hy- persthene matrix. The boundary faces of the rhomb blocks are parallel to {210} of hypersthene. The small blocks could link each other in the form of veins, and further in the form of flakes. It is proposed that the growth of layer silicates is constrained by the nucleation mechanism of polysomatic reaction. The characteristics of the super-microstructure for the uralitized hypersthenes show that the polysomatic reac- tion from pyroxene to amphiboles is caused by the bulk reac- tion mechanism.

By means of transmission electron microscopy (TEM), the study on hypersthene megacryst and uralitized hypersthene from anorthosite complex of Chengde, Hebei Province of China shows that the layer silicate minerals such as talc and smectite would grow on the (100) under the con- dition of supergenesis. This kind of silicate is the product of the polysomatic reaction, and their evolution of growth from small to big was was observed by TEM. In most cases, the layer silicate nucleus in the form of rhomb block first grow out of the interfaces of the augite exsolution lamellae in the hy- persthene matrix. The boundary faces of the rhomb blocks are parallel to {210} of hypersthene. The small blocks could link each other in the form of veins, and further in the form of flakes. It is proposed that the growth of layer silicates is constrained by the nucleation mechanism of polysomatic reaction. The characteristics of the super-microstructure for the uralitized hypersthenes show that the polysomati c reac- tion from pyroxene to amphiboles is caused by the bulk reac- tion mechanism.