Tectonics of one-plate planets

A general planetary shell model in spherical coordinates is developed that is capable of treating shells of arbitrary thickness and driving forces of arbitrary breadth. A methodology is then presented for finding the forces exerted on the shell from two processes. A treatment is developed for mantle convection driven by a density anomaly within a viscous mantle. This model is applied to the small moon of Uranus, Miranda, to study the three large coronae which dominate its surface and for which several competing hypotheses were offered, two of which invoked mantle convection driven by density anomalies of opposite sign. A general model is then developed for loading of the lithosphere and the effects of a range of loads breadths and lithosphere thicknesses are examined. The combinations of these two variables are mapped out where classical approximations such as the flat-plate and thin-shell models are applicable as well as the nature and extent of the transition between these two regimes are determined. Finite element modeling is employed to investigate the coronae on Venus, showing that morphological aspects of these features reported in the literature can be produced by flexure of the lithosphere beneath a volcanic load and gravitational sliding of a cooled crust off these volcanic mounds. Independent characteristic topographic profiles are produced for three of the more regular coronae which question how typical the reported morphologies are in the coronae in general