  A 54-km diameter Noachian-aged crater in the southern highlands of Mars
contains unusually well-preserved inverted fluvial channel networks and
lacustrine deposits, all of which formed completely inside the crater. This
closed-source drainage basin (CSDB) crater is distinct from previously
documented fluvially breached or groundwater-fed crater basin lakes on Mars. We
compare our observations to previously established models of crater
degradation, fluvial incision, and topographic inversion on Mars to assess the
most likely origins of the water that formed the fluvial and lacustrine
features. We favor top-down melting of a cold-based glacier as the source of
water in the CSDB crater, which would represent the first examples of
proglacial fluvial channels and lakes found on Noachian Mars.
