Solubility of carbon dioxide in melts of andesite, tholeiite, and olivine nephelinite composition to 30 kbar pressure
✍ Scribed by Bjørn O. Mysen; R. J. Arculus; David H. Eggler
- Publisher
- Springer
- Year
- 1975
- Tongue
- English
- Weight
- 735 KB
- Volume
- 53
- Category
- Article
- ISSN
- 0010-7999
No coin nor oath required. For personal study only.
✦ Synopsis
Carbon dioxide solubilities in H20-free hydrous silicate melts of natural andesite (CA), tholeiite (K 1921), and olivine nephelinite (O M 1) compositions have been determined employing carbon-14 beta-track mapping techniques. The CO2 solubility increases with increasing pressure, temperature, and degree of silica-undersaturation of the silicate melt. At 1650 ~ C, CO2 solubility in CA increases from 1.48• wt % at 15 kbar to 1.95• wt % at 30 kbar. The respective solubilities in OM1 are 3.41 • 0.08 wt % and 7.11 • wt %. The CO2 solubility in K1921 is intermediate between those of CA and OM 1 compositions. At lower temperatures, the CO2 contents of these silicate melts are lower, and the pressure dependence of the solubility is less pronounced. The presence of H/O also affects the CO2 solubility (20-30% more CO2 dissolves in hydrous than in H20-free silicate melts); the solubility curves pass through an isothermal, isobaric maximum at an intermediate CO2/(CO2 + H20 ) composition of the volatile phase.
Under conditions within the upper mantle where carbonate minerals are not stable and CO2 and H20 are present a vapor phase must exist. Because the solubility of CO2 in silicate melts is lower than that of H20, volatiles must fractionate between the melt and vapor during partial melting of peridorite. Initial low-temperature melts will be more HzO-rich than later hightemperature melts, provided vapor is present during the melting.