Surface morphology and origin of outflow channels in the valles marineris region

Neil M. Coleman, Victor R. Baker

Research output: Chapter in Book/Report/Conference proceedingChapter

19 Scopus citations

Abstract

Summary The outflow channels that emptied into Chryse Planitia provide the best evidence that great quantities of water once flowed on the Martian surface. Some channels were created when the cryosphere ruptured and ground-water discharged from chaos or from cavi along major fault zones. Some chaos formed on channel floors when fluvial erosion thinned the cryosphere, leading to catastrophic breakout of confined groundwater. These chaos can be used to estimate the cryosphere thickness, crustal heat flux and climate trends. At Iamuna Chaos the cryosphere was 700–1000 m thick when Ravi Vallis formed, indicating a cold, long-term climate similar to present-day Mars. The discovery of outflow channels at elevations >2500 m in Ophir Planum shows that Hesperian recharge likely occurred in upslope areas to the west (e.g. Sinai Planum, Tharsis highlands, Syria Planum). The larger circum-Chryse channels were carved by floods that issued directly from the ancestral canyons, which likely were smaller and less interconnected than today. A plausible mechanism for water release was catastrophic drainage of chasm lakes caused by the collapse of topographic barriers or ice-debris dams. We report evidence that a megaflood filled Capri Chasma and overtopped its eastern rim, carving two crossover channels and spectacular dry falls cataracts. This flooding may represent an initial outpouring of canyon lakes via a gateway in eastern Coprates Chasma. The recent discovery of hematite and abundant hydrated sulphates in the Valles Marineris canyons provides compelling evidence of a water-rich history.

Original languageEnglish (US)
Title of host publicationMegaflooding on Earth and Mars
PublisherCambridge University Press
Pages172-193
Number of pages22
ISBN (Electronic)9780511635632
ISBN (Print)9780521868525
DOIs
StatePublished - Jan 1 2009

ASJC Scopus subject areas

  • Earth and Planetary Sciences(all)

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    Coleman, N. M., & Baker, V. R. (2009). Surface morphology and origin of outflow channels in the valles marineris region. In Megaflooding on Earth and Mars (pp. 172-193). Cambridge University Press. https://doi.org/10.1017/CBO9780511635632.009