Thursday, October 15, 2015

Evidence of Enhanced Erosion During Amazonian Eon Glaciations on Mars

Enhanced erosion rates on Mars during Amazonian glaciation


Levy et al


Observations of Mars from the surface and from orbit suggest that erosion rates over the last ∼3 Gyr (the Amazonian) have been as slow as 10−5 m/Myr and have been dominated by aeolian processes, while ancient (Noachian) erosion rates may have been orders of magnitude higher due to impact bombardment and fluvial activity. Amazonian-aged glacial deposits are widespread on Mars, but rates of erosion responsible for contributing debris to these remnant glacial deposits have not been constrained. Here, we calculate erosion rates during Amazonian glaciations using a catalog of mid-latitude glacial landforms coupled with observational and theoretical constraints on the duration of glaciation. These calculations suggest that erosion rates for scarps that contributed debris to glacial landforms are 4–7 orders of magnitude higher than average Amazonian rates in non-glaciated, low-slope regions. These erosion rates are similar to terrestrial cold-based glacier erosion and entrainment rates, consistent with cold-based glacier modification of parts of Mars.

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