水在硅酸盐熔体中的溶解度及研究意义

水是岩浆中主要的挥发份 ,而且其溶解作用强烈影响着熔体的物理和化学性质 ,因此对水在硅酸盐熔体中溶解度及溶解机制的研究是非常重要的。近年来研究表明 ,水在硅酸盐熔体中溶解度与压力、温度及熔体组分密切相关。具体而言 ,压力升高可使水的溶解度增大 ,而温度对溶解度的影响则与熔体组成有关。对于AbOrQ体系 ,在压力低于 4 0 0MPa时 ,溶解度与温度呈反相关 ;而在压力高于 50 0MPa时 ,则呈现出正相关。但是 ,温度对溶解度的影响要明显弱于压力的影响。至于水的溶解度与熔体组分的关系 ,通过对碱金属组分的研究表明水的溶解度按K ,Na ,Li的次序而增加。此外 ,根据碱金属组分对水在硅酸盐熔体中溶解度的影响对水的溶解机制进行了论述 ,这与Sykes等通过分子轨道计算和拉曼、红外光谱研究得出的水在铝硅酸盐熔体中的溶解机理是一致的。

THE SOLUBILITY OF WATER IN SILICATE MELT AND ITS SIGNIFICANCE

Water is major volatile in magma and its dissolution can influence the physical and chemical properties of melt significantly.Therefore it is very important to study the solubility and solubility mechanism of water in silicate melt. Recent studies have shown that the solubility of water is closely related to pressure,temperature and melt components. In other words, the increase of pressure can enhance the solubility and the influence of temperature is related to melt components. As for the system of AbOrQ, the correlation between temperature and solubility is negative when pressure being lower 400MPa and the relation is positive while pressure is higher 500MPa.And the influence of pressure is stronger than that of temperature. The solubility of water is also influenced by melt components. As for alkaline melts, the solubility increases in the order K,Na,Li. In addition, the solubility mechanism of water in silicate melts is also discussed on the basis of the influence of alkaline components on solubility of water. And this is accordance with Sykes' conclusion according to molecular orbital calculation and Raman,FTIR spectroscopy to research the solubility mechanism in aluminosilicate melts.