Surface geology of Arsinoes Chaos: morphological and spectral aff nities across Chaotic terrains on Mars

We are mapping surface units on Arsinoes Chaos (Mars) based on morphological observations from
CTX and HiRISE experiments, as well as through spectral analyses of CRISM data. Strong analogies in
the depositional, erosional and collapse history suggest that the processes acting in Arsinoes Chaos may be
the same responsible for the formation of other Chaotic terrains such as Aram Chaos and Aureum Chaos. Aram and Aureum Chaos are characterized by a basaltic bedrock disrupted into kilometric polygonal
blocks and knobs, locally carved by outflow channels and stratigraphically underlying sedimentary units rich
in sulfates. Several interpretations were proposed in literature for the origin of such features; the common point between all the scenarios is the occurrence of a catastrophic collapse and consequent
outflow. In Arsinoes Chaos, in addition to the typical bedrock disruption in polygonal blocks and knobs, also
the layered sedimentary f ll displays morphological affinities with those occurring in the other Chaotic terrains.
If the spectral analyses will conf rm the mineralogical analogy between Arsinoes, Aram and Aureum Chaos,
we expect to observe the spectral signature of hydrated minerals (such as sulfates), plus possibly hematite. The
depositional environment inferred for the sedimentary units in Aram Chaos is water-rich with possible
evidences of hydrothermal or diagenetic processes. We are investigating the possible regional correlations
between Chaotic terrains, as well as the possible variability of tectonic and depositional processes within and
across them.