Geological map of Aeolis fluvial sedimentary basin, Mars

The Aeolis Dorsa area (centered at about 151°E 3°S) is located along the dichotomy and opened into the Northern lowlands. It is a key zone for the analysis of an alluvial basin on Mars. Regional mapping of the area reveals... [ view full abstract ]

The Aeolis Dorsa area (centered at about 151°E 3°S) is located along the dichotomy and opened into the Northern lowlands. It is a key zone for the analysis of an alluvial basin on Mars. Regional mapping of the area reveals that the fluvial deposits extend over a large portion of the basin and deposition patterns are similar to terrestrial ones.
River network has been reconstructed through both exhumed (inverted) fluvial, alluvial and deltaic channels as differential Aeolian erosion has removed fine sediments and exposed remnants of more resistant and coarser channels as sinuous ridges [1]. A trunk river (or river systems) stretches longitudinally and alluvial fans, distributary systems and tributary rivers flows perpendicularly to the basin axis [2][3]. The presence of a large-scale fluvial system points to an extensive and long-lasting hydrological cycle.
Aeolis Dorsa was likely a sedimentary basin passing into the lowland body of standing water. The other sides of the basin consist of elevated plateaus consisting of volcanic basement rocks and Aeolian remnants. The basin infill can be investigated in eroded windows where younger deposits can get exposed. Three fluvial-related units have been recognized: a well-stratified unit can be observed in the deepest part of the sequence and is overlaid by different fluvial deposits that host large exhumed inverted meanderbelts which are in turn covered by another fluvial sub-unit. Alluvial fans are cone-shaped bodies that display straight preserved channels. They are probably stream-dominated alluvial fans that passed directly into rivers. The entire sequence is capped by heavily eroded aeolian deposit that lays on both fluvial and alluvial deposits in unconformity, while it is difficult to ascertain the nature of the contacts among the different fluvial subunits.
The Aeolis Dorsa alluvial plain displays an exceptional set of depositional environments and fluvial channels patterns that suggest the presence of large amount of surface and subsurface water. The plain can be confidently defined as a waterlogged environment. Its analysis may provide clues on the water history of the planet and the amount of water present on Mars.