Duration and rates of discharge: Maja Valles, Mars

Abstract

The 1600‐km‐long Maja Valles outflow system of Mars consists of three major divisions including the upper valley on Lunae Planum, the canyon section across Xanthe Terra, and the lower valley across western Chryse Planitia. Although water released from the source in Juventae Chasma could reach the terminus of the present day valley system within 40 hours, the original outflow did not traverse the Martian surface as an uninterrupted flow, nor was the source basin emptied instantaneously. The initial flood ponded on northern Lunae Planum and near the western edge of Chryse Planitia, significantly prolonging the lifetime of surface flow. Calculation of pond volumes and maximum discharge rates through various parts of the channel system, assuming full‐bank discharge, allows an estimate of minimum duration of water flow through the outflow complex. About four (terrestrial) months are required to empty Juventae Chasma, and another 10 months are required to drain the impoundment on Lunae Planum. Thus, the history of erosion and sedimentation in the lower reaches of the drainage system is potentially much more complex than that of outflow from the source region.