| This research aims at developing a better understanding of the rheological and fluid dynamic processes that govern lava flow emplacement, both for terrestrial and extraterrestrial lavas. Two techniques are developed: fractal analysis and fluid dynamic modeling, both of which exploit the final shape of a flow as a source of information regarding flow rheology and dynamics. Analysis of terrestrial flow margins reveals systematic differences in the fractal properties of a'a and pahoehoe basaltic lava flows, as well as between basalts and more silicic lavas. These systematic differences have been developed into a remote sensing tool and applied to selected lava flows on Mars, Venus and the Moon. The vast majority of these extraterrestrial lavas have fractal properties indicating basalt, and have been further categorized into a'a, pahoehoe and transitional morphologies. For Venusian flows, this identification has been independently confirmed by radar measurements of surface roughness. Fractal analysis of extraterrestrial flood basalt margins suggests that these vast flow fields were emplaced at both high (a'a-like) and low (pahoehoe-like) eruption rates. Four flow margins on Mars were found to have fractal properties consistent with a rheology more viscous than typical basalt, possibly a more silicic composition. These results are in agreement with distal lobe width measurements, which indicate an andesitic composition.;Based on fluid dynamic modeling of lava flow emplacement, I generate an equation to describe gravity-driven flows on an inclined plane and solve it analytically. This solution models changes in flow depth and width with distance from the vent, based on different rheological characteristics. Consequently, by comparing known depth and width profiles with the model's output, these rheological characteristics can be determined. This approach resulted in the following conclusions: (1) The basaltic flows studied were generally non-Newtonian; and (2) Downstream viscosity increases for the flows studied were 2 to 4 orders of magnitude. These results are consistent with the results of several independent studies, attesting to the validity of the model. |
