Microstructural evolution of silicate immiscible liquids in ferrobasalts
Abstract
An experimental study of the microstructural evolution of an immiscible basaltic emulsion shows that the Fe-rich liquid forms homogeneously nucleated droplets dispersed in a continuous Si-rich liquid, together with droplets heterogeneously nucleated on plagioclase, magnetite, and pyroxene. Heterogeneous nucleation is likely promoted by localised compositional heterogeneities around growing crystals. The wetting angle of Fe-rich droplets on both plagioclase and magnetite increases with decreasing temperature. Droplet coarsening occurs by a combination of diffusion-controlled growth and Ostwald ripening, with an insignificant contribution from coalescence. Characteristic microstructures resulting from the interaction of immiscible Fe-rich liquid with crystal grains during crystal growth can potentially be used as an indicator of liquid unmixing in fully crystallised natural samples. In magma bodies < 10 m in size, gravitationally driven segregation of immiscible Fe-rich droplets is unlikely to be significant.
- Publication:
-
Contributions to Mineralogy and Petrology
- Pub Date:
- September 2019
- DOI:
- 10.1007/s00410-019-1610-6
- Bibcode:
- 2019CoMP..174...77H
- Keywords:
-
- Immiscibility;
- Nucleation kinetics;
- Droplet size distributions;
- Wetting angle;
- Ferrobasalt;
- Binodal