Fluvial valleys and Martian palaeoclimates

Theoretical models of early Martian atmospheric evolution describe the maintenance of a dense CO2 atmosphere and a warm, wet climate until the end of the heavy-bombardment phase of impacting. However, the presence of very young, earthlike fluvial valleys on the northern flank of Alba Patera conflict...

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Bibliographic Details
Published in:Nature (London) 1989-10, Vol.341 (6242), p.514-516
Main Authors: Gulick, Virginia C., Baker, Victor R.
Format: Article
Language:English
Subjects:
Climate
Cosmochemistry. Extraterrestrial geology
Earth sciences
Earth, ocean, space
Exact sciences and technology
Extraterrestrial geology
Geology
Hydrologic cycle
Lunar And Planetary Exploration
Mars
Paleoclimate
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Summary:Theoretical models of early Martian atmospheric evolution describe the maintenance of a dense CO2 atmosphere and a warm, wet climate until the end of the heavy-bombardment phase of impacting. However, the presence of very young, earthlike fluvial valleys on the northern flank of Alba Patera conflicts with this scenario. Whereas the widespread ancient Martian valleys generally have morphologies indicative of sapping erosion by the slow outflow of subsurface water, the local Alba valleys were probably formed by surface-runoff processes. Because subsurface water flow might be maintained by hydrothermal energy inputs and because surface-runoff valleys developed late in Martian history, it is not necessary to invoke drastically different planet-wide climatic conditions to explain valley development on Mars. The Alba fluvial valleys can be explained by hydrothermal activity or outflow-channel discharges that locally modified the atmosphere, including precipitation and local overland flow on low-permeability volcanic ash.
ISSN:0028-0836
1476-4687
DOI:10.1038/341514a0