Incorporation of water into olivine during nebular condensation: Insights from density functional theory and thermodynamics and implications for phyllosilicate formation and terrestrial water inventory
Authors
Calculations of mineral-water interactions and molecular dynamic simulations by Abu Asaduzzaman, Krishna Muralidharan, and Jibamitra Ganguly (University of Arizona) support the idea that some of Earth's water could have originated in the solar nebula from the incorporation of water into olivine crystals.
The scenario they propose begins with olivine mineral surfaces saturated by adsorbed water with additional incorportation of water in the subsurface. Previous studies had only considered surface adsorption of water, so the new work extends water reactions to the subsurface. This leads to the formation of brucite molecules on the surface and serpentine molecules in the subsurface, which are amorphous materals that could crystallize into proper phyllosilicates. The idea that the amorphous materials precede crystalline phyllosilicates is compatible with observations made previously by other researchers of phyllosilicates associated with amorphous materials of similar compositions in the fine-grained matrices of some pristine carbonaceous chondrites (such as MET 00426 [Data Link from the Meteoritical Bulletin].
Asaduzzaman and coauthors say that there was plenty of time for the precursor amorphous materials to form during nebular condensation. They continue to study the thermodynamics of the process, hydration deeper into olivine crystals, and the activation energy of hydration.
Potential energy change associated with physical adsorption, and dissociative chemical adsorption of water on (010) surface of forsterite . Purple sphere: H; green, red and blue spheres: Mg, O and Si, respectively on forsterite surface. Hydrogen and oxygen in water molecule are enclosed in circles.
