Investigating gully flow emplacement mechanisms using apex slopes

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

The origin of the martian gullies has been much debated since their discovery by the Mars Orbiter Camera (MOC, Malin, M.C., Edgett, K.S. [2000]. Science 288, 2330-2335). Several previous studies have looked at slope gradients in and around gullies, but none have used Digital Elevation Models (DEMs) from the High Resolution Imaging Science Experiment (HiRISE, McEwen, A.S., and 14 colleagues [2007]. J. Geophys. Res. 112 (E05), E0505S02), which has a pixel scale down to 25. cm/pixel. We use five 1. m/post HiRISE DEMs to measure gully apex slopes, the local channel gradient at the upslope extent of the gully debris apron, which marks a shift from erosion to deposition. The apex slope provides information about whether a flow was likely a typical dry granular flow (begins depositing on slopes ~21°) or fluidized by some extra mechanism (depositing on shallower slopes). We find that 72% of the 75 gully fans studied were likely emplaced by fluidized flows. Relatively old gullies appear more likely to have hosted fluidized flows than relatively fresh gullies. This suggests a time and location dependent fluidizing agent, possibly liquid water produced in a different climate as previously proposed. Our results do not provide evidence for water-rich flows in gullies today.

Original languageEnglish (US)
Pages (from-to)132-142
Number of pages11
JournalIcarus
Volume208
Issue number1
DOIs
StatePublished - Jul 2010

Fingerprint

gully
emplacement
apexes
slopes
digital elevation models
pixels
Mars Global Surveyor
gradients
water flow
digital elevation model
pixel
fans
debris
climate
erosion
shift
high resolution
Mars
liquids
water

Keywords

  • Geological processes
  • Mars, Climate
  • Mars, Surface

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Investigating gully flow emplacement mechanisms using apex slopes. / Kolb, Kelly Jean; McEwen, Alfred S.; Pelletier, Jon.

In: Icarus, Vol. 208, No. 1, 07.2010, p. 132-142.

Research output: Contribution to journalArticle

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