Postdoctoral Scholar Research Associate in Geology
Mount Sharp burial history Along with a record of depositional environment and surface water activity, the exposed stratigraphy of Mount Sharp also contains chemical and physical markers of burial and exhumation processes. There is extensive evidence of groundwater activity throughout the lower Mount Sharp strata but the source, duration, and eventual fate of groundwater in the Mars subsurface is still not well understood. We use deformation features (primarily fractures), cementation and vein fill chemistry, and mineral alteration phases to interpret burial depth and duration and the timing and nature of water activity during Gale Crater fill stage. Curiosity has observed pervasive fracture populations that are likely related to pore fluid overpressure in the buried stratigraphy. More complex fracture patters, such as shallowly dipping and sub-horizontal fractures, may be related to lateral exhumation of Mount Sharp or other more localized sources of stress. By measuring fracture orientations and reconstructing stress fields, I am working to determine the sources of stress for individual fracture populations and investigate changes in the fracture patterns and stress fields through the lower Mount Sharp stratigraphy. Variations in fracture patterns can give insight into rock properties, groundwater presence and migration, and the timing of burial and exhumation relative to fracture fill and other diagenetic markers. My work expands upon previous models of crater fill and exhumation to account for groundwater activity in modeling and interpreting subsurface conditions. Water-saturated pore space in clastic rocks raises the thermal conductivity of the rock, which results in lower burial temperatures at depth. Lower burial temperatures in a full crater fill model can help explain the absence of illite and other higher-temperature clay alteration phases in the lower Mount Sharp stratigraphy. Using time-variable burial models, I am investigating expected subsurface conditions for different scenarios of sediment fill and groundwater presence. By modeling expected burial conditions and related diagenetic markers, I will be able to determine the duration of groundwater presence in the subsurface during the burial and exhumation of Mount Sharp, which can help answer the question of how long liquid water lasted on Mars and how it disappeared.