2025-01-15 カリフォルニア工科大学 (Caltech)
＜関連情報＞
- https://www.caltech.edu/about/news/signatures-of-ice-free-ancient-ponds-and-lakes-found-on-mars
- https://www.science.org/doi/10.1126/sciadv.adr0010
火星のゲールクレーターにある氷のない古代の湖で形成された波紋 Wave ripples formed in ancient, ice-free lakes in Gale crater, Mars
Claire A. Mondro, Christopher M. Fedo, John P. Grotzinger, Michael P. Lamb, […], and Ashwin R. Vasavada
Science Advances Published:15 Jan 2025
DOI:https://doi.org/10.1126/sciadv.adr0010
Abstract
Symmetrical wave ripples identified with NASA’s Curiosity rover in ancient lake deposits at Gale crater provide a key paleoclimate constraint for early Mars: At the time of ripple formation, climate conditions must have supported ice-free liquid water on the surface of Mars. These features are the most definitive examples of wave ripples on another planet. The ripples occur in two stratigraphic intervals within the orbitally defined Layered Sulfate Unit: a thin but laterally extensive unit at the base of the Amapari member of the Mirador formation, and a sandstone lens within the Contigo member of the Mirador formation. In both locations, the ripples have an average wavelength of ~4.5 centimeters. Internal laminae and ripple morphology show an architecture common in wave-influenced environments where wind-generated surface gravity waves mobilize bottom sediment in oscillatory flows. Their presence suggests formation in a shallow-water (<2 meters) setting that was open to the atmosphere, which requires atmospheric conditions that allow stable surface water.
