Publication: Evidence of gully formation by regional groundwater flow
in the Gorgonum–Newton region (Mars)
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Publication Date
2005
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Elsevier Science B.V., Amsterdam
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Abstract
The discovery of gullies on Mars suggests liquid water activity near the surface of the planet in recent times. Since liquid water is unstable
under the present-day P–T martian conditions, the formation mechanisms of the gullies, and the source of the putative water, have been
a matter of debate for the last years. To provide new insights into these matters, we have approached the problem studying the gullies in
relation to their regional setting. A major point in our study relates to the geographic orientation of gullies, an aspect that has been previously
regarded as a crucial matter in different models, and has profound implications regarding their origin. We present a comprehensive and
detailed survey of the Gorgonum–Newton region, and a study of the Dao and Nirgal Vallis regions. The survey was carried out with the aid
of 965 high-resolution MOC images (752 for Gorgonum–Newton, 102 for Nirgal Vallis and 111 for Dao Vallis regions), and MOLA-derived
DEMs.We found that gullies display a clear regional pattern, geographically and topographically consistent with a decreasing regional slope.
We interpret the results in terms of the existence of several groundwater flow systems operating at different scales, which ultimately may
have led to gully formation by seepage at the slopes of craters and canyons. We suggest that aquifers discharging at gully systems may have
recharged from the surface, in response to the melting of young partially eroded ice-rich deposits.