Basal melting of snow on early Mars: A possible origin of some valley networks
نویسندگان
چکیده
[1] Valley networks appear to be cut by liquid water, yet simulations suggest that early Mars could not have been warmed enough by a CO2-H2O greenhouse to permit rainfall. The vulnerability of an early atmosphere to impact erosion, the likely rapid scavenging of CO2 from the atmosphere by weathering, and the lack of detection of weathering products all support a cold early Mars. We explore the hypothesis that valley networks could have formed as a result of basal melting of thick snow and ice deposits. Depending on the heat flow, an early snowpack a few hundred meters to a few kilometers thick could undergo basal melting, providing water to cut valley networks.
منابع مشابه
Valleys on Hecates Tholus, Mars: origin by basal melting of summit snowpack
Valley networks observed on the martian surface are found mostly on Noachian-aged highlands units, but a few occur on younger volcanic edifices. Enigmatically, they do not occur on all younger volcanoes of similar age or location. Using new data, we reanalyze the radially arrayed valleys on the flanks of Hecates Tholus, a Hesperian-aged shield volcano, and test the hypothesis that these valleys...
متن کاملCrater degradation in the Noachian highlands of Mars_ Assessing the hypothesis of regional snow and ice deposits on a cold and icy early Mars
The presence of valley networks and the highly degraded state of Noachian highland craters has led to the interpretation that Mars was once warmer and wetter. Recent climate models have suggested, however, that the extremely cold climate in the Noachian would be unlikely to support liquid water precipitation. The presence of a thicker atmosphere thermally coupled to the surface is predicted ins...
متن کاملLate Noachian and early Hesperian ridge systems in the south circumpolar Dorsa Argentea Formation, Mars_ Evidence for two stages of melting of an extensive late Noachian ice sheet
The Dorsa Argentea Formation (DAF), extending from 2701–1001 E and 701–901 S, is a huge circumpolar deposit surrounding and underlying the Late Amazonian South Polar Layered Deposits (SPLD) of Mars. Currently mapped as Early-Late Hesperian in age, the Dorsa Argentea Formation has been interpreted as volatile-rich, possibly representing the remnants of an ancient polar ice cap. Uncertain are its...
متن کاملSinton crater, Mars: Evidence for impact into a plateau icefield and melting to produce valley networks at the Hesperian–Amazonian boundary
a r t i c l e i n f o a b s t r a c t The majority of martian valley networks are found on Noachian-aged terrain and are attributed to be the result of a 'warm and wet' climate that prevailed early in Mars' history. Younger valleys have been identified, though these are largely interpreted to be the result of localized conditions associated with the melting of ice from endogenic heat sources. S...
متن کاملGully Formation on Mars: Testing the Snowpack Hypothesis from Analysis of Analogs in the Antarctic Dry Valleys
Introduction: Gullies, a class of unusually young features on Mars consisting of an alcove, a channel and a fan, were initially interpreted to have originated through processes related to the presence of liquid water, primarily through groundwater discharge [1,2]; the current metastability of liquid water on the surface of Mars generated a host of alternative explanations for the gullies [see s...
متن کامل