Glacial and gully erosion on Mars: A terrestrial perspective

摘要: The mid- to high latitudes of Mars host assemblages landforms consistent with a receding glacial landscape on Earth. These are postulated have formed >5 Ma under different climate regime when Mars' orbital obliquity was average 10° higher than today. Here, we investigate the spatiotemporal relationship between gullies and landforms, both common in mid-latitudes. Gullies kilometre-scale source alcove, transportation channel, depositional apron. comprise (1) extant viscous flow features (VFF) that extend from base crater walls into interior floors widely interpreted as debris-covered glaciers containing ice, (2) such arcuate ridges at been relicts more recent, less extensive advances focussed walls. We measure headwall retreat associated date their host-craters constrain minimum rates. record rates up ~102 m My−1 for youngest suite equivalent erosion wet-based Earth martian bedrock gully systems. find evidence single erosional episode dating 5–10 Ma, which postdates emplacement majority VFF but seems predate formation gullies. propose glaciation rather melting ice deposits (VFF). This is our observations wall morphologies, including presence terrestrial glaciotectonic require liquid water form, textural alteration eroded surface ice-segregation frost-shattering, downslope pasted-on terrain, tentatively here till sourced wall. terrain usually thicker, latitude-dependant mantle located sloping airfall nucleated dust, suggest it has reworked by predominantly origin. Although results cannot substantiate produced meltwater, discovery this wet event does provide widespread meltwater generation recent history.