富铁橄榄石的水溶性实验研究

The mechanical property of the upper mantle is controlled by the rheological properties of olivine. Water has great influence on the mechanical properties of olivine. Results showed that different temperatures and iron contents have influence on the water solubility of olivine. Therefore, the water solubility experiment was conducted on olivine with different iron contents at different temperatures in this paper. 'Hie olivine single crystals used in this study include natural San Carlo olivine single crystal FaI7 , Fa24 7 (Fena = 100 x molar Fe/( Mg + Fe) ) and synthetic olivine single crystal Fa22. Experiments were performed at temperatures between 1273K and 1473K with 50K increments at a confining pressure of 300MPa in a gas medium apparatus with oxygen fugacity buffered by the Ni : NiO. After the test, the olivine single crystal was double polished along b-plane. The composition was measured by Electron Probe, the orientation was determined by Electron Backscattered Diffraction ( EBSD) and the OH absorption spectra were recorded by infrared spectroscopy, respectively, for each of the single crystal. Results showed that, when the temperature changes from 1273K to 1473K, the water solubility of Fa17olivine varied from 600 to 1200 H/106 Si, Fal7 olivine from 1000 to 1300 H/106 Si and the synthetic Fa,,olivine from 500 to 900 H/106 Si, respectively. Therefore, the water solubility of the olivine with the same iron content increases with the increase of the temperature. The water solubility of the olivine at the same temperature increases with the increase of the iron content for natural San Carlo olivine. One percent increase in iron content resulted in ten percent increase in water solubility. In this paper, the water solubility in olivine at several Fe contents can be used to estimate the water storage in the upper mantle.