Hydrological History of a Palaeolake and Valley System on the Planetary
Dichotomy in Arabia Terra, Mars
Abstract
Hundreds of ancient palaeolake basins have been identified and
catalogued on Mars, indicating the distribution and availability of
liquid water as well as sites of astrobiological potential. Palaeolakes
are widely distributed across the Noachian aged terrains of the southern
highlands, but Arabia Terra hosts few documented palaeolakes and even
fewer examples of open-basin palaeolakes. Here we present a detailed
topographic and geomorphological study of a previously unknown set of
seven open-basin palaeolakes adjacent to the planetary dichotomy in
western Arabia Terra. High resolution topographic data were used to aid
identification and characterisation of palaeolakes within subtle and
irregular basins, revealing two palaeolake systems terminating at the
dichotomy including a ~160 km chain of six palaeolakes
connected by short valley segments. Analysis and correlation of
multiple, temporally distinct palaeolake fill levels within each
palaeolake basin indicate a complex and prolonged hydrological history
during the Noachian. Drainage catchments and collapse features place
this system in the context of regional hydrology and the history of the
planetary dichotomy, showing evidence for the both groundwater sources
and surface accumulation. Furthermore, the arrangement of large
palaeolakes fed by far smaller palaeolakes, indicates a consistent flow
of water through the system, buffered by reservoirs, rather than a
catastrophic overflow of lakes cascading down through the system.