Distribution, classification, and ages of martian impact crater lakes

Paleolakes in impact craters on Mars are characterized at global scale usin g the Viking Orbiter data. We identified 179 paleolakes in impact structure s formed by the influx of water and sediment derived from valley networks a nd channels that can be classified into three different fluviolacustrine sy stems: closed, open, and lake-chain systems. We show the hydrogeologic impl ications for each of the three systems and their significance in terms of d uration of fluviolacustrine activity. This study provides a catalog of areo graphic, physical, and physiographic data for each of the studied impact cr ater lakes, associated with the description of the sedimentary structures o bserved. It also identifies environments where life and/or precursors to li fe could have found favorable conditions to evolve. (C) 1999 Academic Press .