UCLA

Fundamental to the advancement of planetary geology is an understanding of the interaction between tectonic and aqueous processes on planetary surfaces. This dissertation examines this interaction within two geomorphologic processes: landslide emplacement, on Mars and on Earth, and the formation of seasonal slope features on Mars.

Long-runout landsliding in equatorial Valles Marineris, Mars is among the most prominent geomorphic occurrences shaping the canyon. However, the mechanism of landslide long-distance transport, and the highly debated role of water therein, remains elusive. Through systematic mapping of high-resolution satellite images, integrated with spectral analysis, we show that hydrated silicates played a decisive role in facilitating landslide transport by lubricating the basal sliding zone. This conclusion implies that clay minerals, generated by ancient water-rock interactions, exert a long-lasting influence on Mars surface processes.

The Eureka Valley (EV) landslide is an unexamined, well-preserved long-runout landslide in arid southeast Eureka Valley, California. The field, photogeologic, spectral, and luminescence dating investigation presented here support initiation as a result of fault-generated fracture during the mid to early Holocene at minimum, and transport lubricated by the presence of basal clays, characterized by 3-D internal deformation, as the most likely EV landslide emplacement mechanism. This geomorphological characterization may be applied to long-runout landslides on Earth and other planetary surfaces, suggesting that their emplacement likely does not require the participation of water.

Recurring slope lineae (RSL) are seasonal, narrow, low-albedo features extending down steep, equator-facing Mars slopes. RSL formation has been largely attributed to the seepage of near-surface water, though its source is not well understood. Through detailed analysis of high-resolution satellite images of RSL geologic contexts, we quantify the significant spatial correlation between RSL source regions and fractures in several geologic settings, indicating that fractures may act as conduits for fluid flow in the formation of RSL. This work provides insight into the hydrological cycle and the potential presence of habitable conditions on present-day Mars.

This new understanding of the formation processes of these planetary surface features implicates the persistent role of aqueous and tectonic processes in the formation of geomorphic features on widespread planetary surfaces throughout geologic time.