Brian Kortz



GE 196-Oceans on Planets: Martian closed drainage crater basins: Tests for their origins using MOLA data and implications for the hydrologic cycle

Statement of the Problem:
-Forsythe and Blackwelder (1998) identified 144 crater basins in the Noachian highlands that have inflowing channel systems but no outflow channels.
-These basins are thought to represent the groundwater table at the time of their infilling.
-The channels are assumed to be formed by groundwater sapping methods. -The craters are believed to be a source of water vapor for the atmosphere through evaporation and sublimation processes. -The lowering of the local water table in the craters would then drive groundwater flow into the basins.
-This could have large impacts on the hydrologic cycle.

Questions:
-Do these crater basins actually represent the groundwater table? -Were all the channels formed by groundwater processes? Does surface runoff appear to be a possible mechanism for the origin of the channels? -After the impact that formed the craters, large amounts of heat and possibly impact melt would result. Could this alone be the cause of the channels?
-If the basins were a source of water vapor for the atmosphere, we would expect more precipitation at about this time. Is there a progression of older groundwater induced channels to younger runoff channels as precipitation possibly increased?
-What can MOLA data tell us? Can we delineate drainage divides, relief, topography, terraces, deltas, etc.?

Procedure:
-Choose a few crater basins to analyze based on Forsythe and Blackwelder's work.
-Obtain MOLA data for the areas.
-Examine the topography around and within the crater basins. -Study characteristics such as topography, relief, drainage density, etc. -Look for evidence of terraces, shorelines, evaporite deposits, deltas, impact melts, etc.