2011 Annual Science Report
Arizona State University Reporting | SEP 2010 – AUG 2011
Habitability of Water-Rich Environments, Task 1: Improve and Test Codes to Model Water-Rock Interactions
The goal of this task is to develop computer codes to model the chemistry and mineralogy of water-rock interactions on present and early Earth, and on extraterrestrial bodies with liquid water (ancient Mars, icy moons, early asteroids, and extrasolar planets). This year we developed and tested codes to model temporal changes in aqueous chemistry and mineralogy during vertical percolation of fluids through layered rocky materials. In particular, we were able to model neutralization of acidic fluids along with percolation together with changes in mineralogy of altered basalts. The model results closely match many observations.
The code to model kinetics of water-rock interaction was updated to increase its stability and to allow reading the results at each time step by other codes. The kinetic code was further tested in the models for basalt and granite alteration, and the corresponding paper is in press in Geochemistry International. The application of coupled kinetic-thermodynamic codes to fluid migration in mid-oceanic ridges led to promising results. The corresponding paper is published in journal Petrology.
New codes have been developed to model vertical percolation of fluids in weathering crusts with applications to processes on early Mars. The algorithm is also applicable to terrestrial environments. The new codes have been coupled with both equilibrium and chemical kinetic programs for water-rock interaction. These coupled codes have been used and tested in highly successful models for acid weathering of basaltic materials. The corresponding models closely reproduce observed mineral sequences formed during acid leaching. The results have been reported at the Goldschmidt conference in 2011.