Light-toned deposit in the northeastern Hellas basin formed by terrain-conforming airfall sedimentation

Extensive exposures of a light-toned deposit (LTD) occurs on the northeastern interior slope Hellas basin. This is floors all but youngest craters greater than 30 km in diameter study region centered at 83°E and 30°S, as well crater exterior walls, intercrater plains, northern bordering slopes Navua Valles. Stratigraphic relationships indicate that LTD was emplaced terrain-conforming mantle several decameters thick. The more 5 range elevation consistent with deposition an airfall deposit, perhaps loess derived from wind erosion basin floor. during time period waning fluvial activity within region, tentatively dated to Early Middle Amazonian transition, thus serves stratigraphic marker bed. • Light toned deposits (LTDs) are widespread deposited probable volcanic ash origin Emplacement occurred epoch regional important marker.