CHARACTERIZATION OF SCOUR PITS IN THE MEDUSAE FOSSAE FORMATION OF MARS

The Medusae Fossae Formation (MFF) is a region of Mars located to the southwest of Olympus Mons, between the two inactive volcanic centers surrounding the Tharsis Montes and Elysium Mons. Though still a topic of debate, there are several different hypotheses regarding the origin of the materials in this region, such as aeolian deposits, ashfall tuff, and ignimbrites. The MFF contains a variety of features indicative of aeolian activity, such as yardangs, and v-shaped depressions we refer to as “scour pits.” These wind-carved, erosional distinct from yardangs and relatively under-studied.

We identified more than 3,000 scour pits in our study region within the MFF. Using a gridded point count approach, 708 scour pits were selected for detailed investigation using the Java Mission-planning and Analysis for Remote Sensing (JMARS) program with ~6 m/px images from the Context Camera (CTX) onboard the Mars Reconnaissance Orbiter (MRO). We also used high-resolution (~25 cm/px) images from the High-Resolution Imaging Science Experiment (HiRISE) to study the morphology of the scour pits at a finer scale. We quantified the spatial distribution of the scour pits, their dimensions, orientation, and used these attributes to classify them into distinct morphological groups, to enable an improved understanding of these features. The classified morphologies are defined by: (1) central peaks, (2) barchan-shape, and (3) the absence of wings.

By comparing the dimensions of the features in each morphologic type, we conclude that there is a trend of increasing average size from the (1) central peak to (2) barchan-shape to (3) no-wing scour pit morphologies. The orientation of the scour pits also provides insight into the past wind dynamics across the MFF. A paleo-wind map was generated using the measured orientations of the pits, which are generally aligned northwest/west. We interpret that the classified morphologies of these features are related to the stages of evolution of the scour pits.