AGU: Geophysical Research Letters

 

Editors' Highlight

A record of changing environmental conditions on Mars: Studies of clay-bearing deposits at Mawrth Vallis

Clay minerals such as montmorillonite and other smectites have been previously detected in layered outcrops in and around the Martian outflow channel Mawrth Vallis. Wray et al. (2008) have additionally identified kaolinite and oxide minerals such as hematite in the Mawrth Vallis outcrops and found that these diverse minerals occur in distinct stratigraphic horizons, implying either that they formed over time under different environmental conditions or that they have distinctly different sediment sources. The authors found that this pattern of layers occurs on both sides of the outflow channel and on its floor, with aluminum-rich clay-bearing layers typically overlying iron-rich clay deposits. This, combined with high-resolution topographic data, suggests that the aluminum-rich clay-bearing layers are younger than the outflow channel and may represent a later sedimentary or altered volcanic ash deposit that drapes the topography. Because of Mawrth Vallis's distinct layering history, the authors expect that this would make a good location for future surface missions to Mars to study geologic history and ancient habitable environments on Mars.

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