HUMMOCKY AND LOBATE DEPOSITS ON NORTH-FACING SLOPES IN ALBA PATERA, MARS

Alba Patera, Mars (40°N, 250°E) is the summit caldera complex of Albus Mons, a large (>1000 km basal diameter) volcano at the northern edge of the Tharsis region. Context Camera (CTX) and High-Resolution Imaging Science Experiment (HiRISE) images reveal that some north-facing slopes within Alba Patera are covered by different types of surficial deposits, which we interpret to be composed of ice-rich dust. Studying these materials could yield information on Martian climate cycles. The most commonly observed deposit on north-facing slopes within Alba Patera is characterized by hummocks ~40-50 m wide, which, locally, are arranged into downslope-trending ridges as long as ~200 m. These hummocky deposits are found on north-facing slopes including the southern caldera rim, in the southern portions of impact craters >500m in diameter, and on the north flanks of two conical hills found on the patera floor. The other, less common deposit is smoother, darker, has lobate margins, and is concentrated along the southern caldera rim. At the caldera wall, where they occur together, the hummocky deposits appear to overlie the smooth deposits, and the smooth materials extend as far as 2.8 km from the caldera rim whereas the hummocky materials only reach about a kilometer from the rim. We plan to create a map of these deposits, and any other surficial materials observed within Alba Patera. Additionally, we will search for similar deposits at the same latitude to determine how common they are beyond Alba Patera.