Numerical modeling of tectonic and aeolian processes on Mars

This dissertation reports on two numerical studies for the surface evolution of Mars. The first study focuses on three models for the tectonic formation of the Valles Marineris. The second study models the disposition, transport pathways, and history of sand on Mars.; Three types of terrestrial rift models were formulated for the lithospheric conditions of the Valles Marineris to understand whether tectonism could be responsible for the observed troughs. Lithospheric conditions were determined from linked gravity and flexure studies performed for the Valles Marineris region. The calculated range of crustal thickness and heat flow were used to test two semi-analytic rift models, the first based on necking instabilities and the second on strength evolution, and one numerical finite element rift model. Although the necking model was primarily consistent with narrow rifting, and the strength-evolution model with wide rifting, results from the finite element model indicate that the assumptions of the analytical models severely limit their use for the interpretation of geologic structures. For the finite element model the depth of the troughs and size of trough flanks at Valles Marineris are consistent with fast extension, low heat flow, and moderate crustal thickness ({dollar}nu > .1{dollar} cm yr{dollar}sp{lcub}-1{rcub}{dollar}, {dollar}q < 40{dollar} mW m{dollar}sp2{dollar}, {dollar}H < 60{dollar} km). However, the width of the observed troughs are {dollar}sim{dollar}50% of the smallest troughs produced by the model, and are at best marginally consistent with moderate heat flux and low crustal thickness (q 40-60 mW m{dollar}sp2{dollar}, {dollar}H < 40{dollar} km). Lastly, observed multiple troughs are likely to have formed due velocity weakening or crustal heterogeneity.; A sand transport model using the Mars General Circulation Model was developed to understand the erosional sources, transport pathways, and depositional sinks of sand-sized particles on Mars. An initially uniform distribution of sand is regionally transported based on wind stress and saltation threshold, and accounting for topographic trapping of sand. Results are consistent with the observed polar and Hellespontus dunes, and with block size distributions modeled using thermal inertia data, but only for extremely low saltation threshold (.024 N/m{dollar}sp2{dollar}).