Gullies on Mars could have formed by melting of water ice during periods of high obliquity

• 成果类型: Article
• 署名作者: Dickson, J. L.; Palumbo, A. M.; Head, J. W.; Kerber, L.; Fassett, C. I.; Kreslavsky, M. A.
• 署名单位: California Institute of Technology; Brown University; National Aeronautics & Space Administration (NASA); NASA Jet Propulsion Laboratory (JPL); California Institute of Technology; National Aeronautics & Space Administration (NASA); University of California System; University of California Santa Cruz; Johns Hopkins University; Johns Hopkins University Applied Physics Laboratory
• 刊物名称: SCIENCE
• ISSN/ISSBN: 0036-9461
• DOI: 10.1126/science.abk2464
• 发表日期: 2023-06-23
• 页码: 1363-1367
• 关键词: martian gullies; midlatitude snowpacks; debris flows; liquid water; EVOLUTION; surface; ages

摘要

Gullies on Mars resemble water-carved channels on Earth, but they are mostly at elevations where liquid water is not expected under current climate conditions. It has been suggested that sublimation of carbon dioxide ice alone could have formed Martian gullies. We used a general circulation model to show that the highest-elevation Martian gullies coincide with the boundary of terrain that experienced pressures above the triple point of water when Mars' rotational axis tilt reached 35 degrees. Those conditions have occurred repeatedly over the past several million years, most recently similar to 630,000 years ago. Surface water ice, if present at these locations, could have melted when temperatures rose >273 kelvin. We propose a dual gully formation scenario that is driven by melting of water ice followed by carbon dioxide ice sublimation.