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Sedimentary Processes on Earth and Mars: Canyon Erosion, Sand-Ripple Formation, and Mineral Composition


Lapôtre, Mathieu Gaetan Andre (2017) Sedimentary Processes on Earth and Mars: Canyon Erosion, Sand-Ripple Formation, and Mineral Composition. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/Z9RF5S2T.


Over the past few decades, orbiters, landers, and rovers have significantly expanded our understanding of Mars’ hydrology and climate; however, significant knowledge gaps stand in the way of our quest for martian life. In particular, the global drying of the planet remains one of the grandest unsolved mysteries in planetary science. To help unravel this puzzle, we develop new quantitative theories for sedimentary processes with implications for both Earth and Mars. This thesis revolves around three main sedimentary processes – erosion, deposition, and sediment transport. First, we focus on the erosion of bedrock canyons by water on Earth and Mars. After showing that groundwater seepage erosion is only efficient at carving canyons in restricted conditions, we develop a new hydraulic theory for flow focusing upstream of horseshoe-shaped waterfalls and combine it with waterfall-erosion mechanics to constrain the discharge, duration, and volume of canyon-carving floods on Earth and Mars. We show that martian Hesperian floods were large but short-lived. Second, we investigate fluid and sediment controls on the equilibrium size of bedforms. We develop a comprehensive scaling relation to predict the size of ripples forming in various sedimentary environments, including martian brines and methane flows on Titan, and show that the scaling relation predicts the size of large wind ripples forming under a thin martian atmosphere. This new theory, combined with observations of large-ripple cross-strata in wind-blown sandstones of the Burns formation at Victoria crater, suggests that Mars had a thin atmosphere around the Noachian-Hesperian boundary. Finally, we use orbiter-based inferences of the mineralogy of sands of the Bagnold dunes of Gale crater to disentangle the magnitude of wind sorting and local sediment sources. We develop a new probabilistic framework to invert for surface mineralogy, groundtruth our predictions with compositional datasets provided by the Curiosity rover, and discuss the implications of our findings for mineral sorting by martian winds and paleoenvironmental interpretations of martian wind-blown sandstones. Collectively, these results provide new mechanistic and quantitative constraints on the past hydrology and climate of Mars that are key to assess Mars’ astrobiological potential through space and time.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:canyons; ripples; sand; mineral composition; Mars; fluvial geomorphology; eolian geomorphology; spectroscopy
Degree Grantor:California Institute of Technology
Division:Geological and Planetary Sciences
Major Option:Geology
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Lamb, Michael P. (advisor)
  • Ehlmann, Bethany L. (co-advisor)
Group:Astronomy Department
Thesis Committee:
  • Ehlmann, Bethany L. (chair)
  • Lamb, Michael P.
  • Grotzinger, John P.
  • Farley, Kenneth A.
  • Golombek, Matthew P.
Defense Date:8 May 2017
Funding AgencyGrant Number
NASA Earth and Space Science Fellowship12-PLANET12F-0071
Record Number:CaltechTHESIS:05152017-105730412
Persistent URL:
Related URLs:
URLURL TypeDescription adapted for ch. 3 (Journal of Geophysical Research: Earth Surface) adapted for ch. 4 (Journal of Geophysical Research: Planets) adapted for ch. 5 (Science) adapted for ch. 6 (Geology) adapted for ch. 7 (Journal of Geophysical Research: Planets) adapted for ch. 8 (Journal of Geophysical Research: Planets)
Lapôtre, Mathieu Gaetan Andre0000-0001-9941-1552
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:10173
Deposited By: Mathieu Lapotre
Deposited On:23 May 2017 23:18
Last Modified:10 Mar 2020 23:49

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PDF (Ph.D. Thesis) - Final Version
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[img] Other (Chapter 6: Tables 6.4 and 6.5 (CSV file)) - Supplemental Material
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[img] Other (Chapter 6: Table 6.6 (CSV file)) - Supplemental Material
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