The flood lavas of Kasei Valles, Mars

Abstract

Both the northern and southern arms of Kasei Valles are occupied by platy-ridged flood lavas. We have mapped these flows and examined their morphology to better understand their emplacement. The lavas were emplaced as high-flux, turbulent flows (exceeding 106 m3 s−1). Lava in southern Kasei Valles can be traced back up onto the Tharsis rise, which is also the likely source of lavas in the northern arm. These eruptions were similar to, but somewhat smaller than, the Athabasca Valles flood lava in Elysium Planitia, with estimated volumes of > 1200 km3 here and 5000 km3 in Athabasca Valles. The flood lavas in both Kasei and Athabasca Valles have evidence for distal inflation as well as widespread drainage or volume loss in medial areas; this may be an important characteristic of many large, recent Martian eruptions. Despite their great size and flux, the Kasei Valles flood lavas are only a late modification to the valley system capable of only modest local erosion. The more vigorous Athabasca Valles lava may have been capable of somewhat more erosion in its smaller valley system.