Ph.D. thesis
Abstract:
Isidis Planitia is a large impact basin on Mars. I have determined that the extensive numbers of sub-kilometre sized cones and cone chains in the basin are the result of deposition of sediments by retreating ice in a process analogous to terrestrial terminal moraine formation, along with the formation of pingos, mud- and cryovolcanoes by the expansion of freezing fronts into a subsurface containing liquid water. I have interpreted the sinuous ridges within the basin as analogous to terrestrial eskers. Much of the research I have carried out uses Mars Orbiter Laser Altimeter (MOLA) data to study the topography of the basin. I have interpolated and detrended the data in order to detect subtle variations in topography that are obscured by the the basin slope. I have analysed the large scale ridges within the basin, determining that they are the result of compressional tectonics forming normal faults, analogous to lunar wrinkle ridges. I have demonstrated that a model involving tectonic loading of the basin convincingly explains the division of ridges into an inner zone of concentric thrusting faults, and an outer zone of radially thrusting faults, and also provides an explanation for the gravitational anomaly found within the
basin. I have analysed the larger impact craters in the basin, and determined that they show evidence of interaction with buried volatiles at the time of their formation. I have also identified a number of previously unknown buried craters within the basin, and calculated the age of the buried unit in which they formed to be Lower-to-mid-Hesperian. I have investigated thermal and other surface properties of the basin surface. Finally, I have drawn the available evidence together to determine a history of events that have shaped the surface and subsurface of the basin during the Hesperian and Amazonian Epochs.