Structural, Stratigraphic, and Mineralogic Mapping of Noachian and Hesperian Aged Crust in Xanthe Terra, Mars

The Xanthe region of Mars (10N-17S, 300-345E) contains both Noachian-aged cratered highlands and Hesperian-aged plains and chasmata. In particular, the region is transected by the Capri Chasma running southwest to northeast. The total elevation relief is ~10 km due to the juxtaposition of both highlands and chasmata in this area. The variation in terrain type and elevation makes this region ideal for reconstructing the three-dimensional structure, stratigraphy, and lithology of the crust. This region also contains Aram Chaos, a well-studied site where kieserite and polyhydrated sulfates were identified from OMEGA data (Gendrin et al., 2005) and gray crystalline hematite was identified from TES data (Glotch and Christensen, 2005). Analysis of CRISM multispectral mapping strips (72 bands, 256 pixels/degree, covering ~30% of the study area) confirms the presence of both hydrated sulfate and hematite exposures in Aram Chaos. Phyllosilicate signatures were identified in the CRISM data by the presence of 1.9 and 2.3 μm absorption bands in the upper sections of the walls of Capri Chasma and Ganges Chasma where these chasmata cut across what are mapped as both Noachian Cratered Plains and Hesperian Ridged Plains (based on the geologic map by Scott and Tanaka, 1986). The multispectral data also show 2.3 μm absorptions that are tentatively assigned to a phyllosilicate signature in the chasma walls north of Hydraotes Chaos (1.5N, 325.5E) in a region that cuts across Noachian cratered terrain. Hydrated sulfates were identified in the walls of Hesperian-aged interior layered deposits (ILDs) superimposed on the floor of Capri Chasma (13S, 312E). Results show that within the study area the hydrated sulfates are younger than the phyllosilicates. Future plans include mapping pyroxene and olivine on the Noachian and Hesperian units, tracing the mineralogy to chasmata walls, and placing the phyllosilicate- and sulfate-bearing units in stratigraphic and structural context to help decipher the geologic evolution of the study site.