Martian lacustrine environments and their geological constraints on drilling operations for exobiological research

The richness of information regarding climate, hydrology and sedimentary deposition acquired from lakes and lacustrine environments
makes them among the most valuable targets for the Mars exploration. Moreover, terrestrial lacustrine deposits record a large variety of
biological traces and, thus, they are high potential candidates for exobiology study on Mars as well. Paleolakes have been recognized in
several settings and ages on the Martian surface. Crater lakes formed by channels debouching into impact craters are more common and
characteristic than the lakes in open topographic basins. On the basis of the morphological characteristics of crater lakes we studied along
with theoretical models, we suggest that two types of lacustrine basins could have occurred: deep-water lakes and dry lakes. Deep-water
lakes show terraces at their rims, Gilbert-type deltas at the mouth of in
owing channels, and a
at uniform
oor. Dry lakes are dry for
most of the time allowing chemical sediment accumulation. Evidence for this type of lakes is very rare on Mars but the high albedo tone
of some deposits suggests their presence. Mineralogical analysis is needed in order to identify this kind of deposits. The sedimentary
facies and lithology associated with these two types of lakes are dierent and they have important implications for drilling operations at
the landing sites. We describe the geological setting for each of these two types of lakes and their potential for the exobiology exploration