Timescales of alluvial fan development by precipitation on Mars
Article first published online: 9 SEP 2011
Copyright 2011 by the American Geophysical Union.
Geophysical Research Letters
Volume 38, Issue 17, September 2011
How to Cite
2011), Timescales of alluvial fan development by precipitation on Mars, Geophys. Res. Lett., 38, L17203, doi:10.1029/2011GL048907., , , and (
- Issue published online: 9 SEP 2011
- Article first published online: 9 SEP 2011
- Manuscript Accepted: 10 AUG 2011
- Manuscript Revised: 9 AUG 2011
- Manuscript Received: 14 JUL 2011
- Holden crater;
- alluvial fans;
- rain on Mars
 Dozens of large, low-gradient alluvial fans are present within impact crater basins on the cratered highlands of Mars. The timescales and climate conditions that were required to generate such fans are unknown, but testable through our understanding of terrestrial hill slope erosion in the presence of precipitation. Previous estimates of fan formation time vary from years to millions of years. Here, we use an idealised physical model of 2-D catchment-fan evolution to present a framework within which the development of Martian alluvial fans should be considered. We simplify the erosional and depositional system so that there are only three variables: erodibility due to gravity, amount of water runoff due to precipitation, and catchment-fan boundary elevation. Within this framework, to generate large, low-gradient (<6°) alluvial fans on Mars requires significant periods of erosion due to runoff. We suggest two climate scenarios, either: (1) rates of precipitation that are similar to arid terrestrial climates over timescales of 107 to 108 yr or (2) a shorter duration of semiarid to temperate climate conditions over a period on the order of 106 yr. Hyper-arid conditions generate low-gradient alluvial fans under conditions of a topographically lowered fan-catchment boundary and only over timescales >108 yr if the substrate is extremely erodible relative to terrestrial examples.