Hydrous albite magmas at lower crustal pressure: new results on liquidus H2O content, solubility, and H2O activity in the system NaAlSi3O8–H2O–NaCl at 1.0 GPa
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- 作者：A. R. Makhluf ; R. C. Newton ; C. E. Manning
- 刊名：Contributions to Mineralogy and Petrology
- 出版年：2016
- 出版时间：September 2016
- 年：2016
- 卷：171
- 期：8-9
- 全文大小：2,134 KB
- 刊物类别：Earth and Environmental Science
- 刊物主题：Earth sciences
Geology
Mineral Resources
Mineralogy - 出版者：Springer Berlin / Heidelberg
- ISSN：1432-0967
- 卷排序：171
文摘
The system albite–H2O serves as an important model for the generation of granitic magmas, yet relatively few experimental investigations have focused on phase relations at high pressure. This study reports new experimental results, at 1.0 GPa and 690–1050 °C, on the temperature and liquid composition at vapor-saturated melting, the H2O content of undersaturated silicate liquids in equilibrium with albite, the solubility of albite in H2O–NaCl fluids immediately below the solidus, and the activity of H2O in hydrous NaAlSi3O8 liquids along the liquidus. Albite melts and dissolves congruently at all temperatures and salinities. In the NaCl-absent system, the temperature of vapor-saturated melting of low albite, confirmed by X-ray diffraction, is 695 ± 5 °C and the liquid composition is 18.14 ± 1.35 wt% H2O. The temperature dependence of the fluid-undersaturated liquidus curve in the system NaAlSi3O8–H2O varies with H2O wt% (\(w_{{{\text{H}}_{2} {\text{O}}}}\)) according to $$T = - 2.0331 \times 10^{ - 3} w_{{{\text{H}}_{2} {\text{O}}}}^{3} + 1.6497w_{{{\text{H}}_{2} {\text{O}}}}^{2} {-} 58.963w_{{{\text{H}}_{2} {\text{O}}}} + 1235.5\,^{ \circ } {\text{C}}$$