Glacial Processes and Morphologies in the Southern Hemisphere of Mars

Hdl Handle:
http://hdl.handle.net/10150/193842
Title:
Glacial Processes and Morphologies in the Southern Hemisphere of Mars
Author:
Banks, Maria Elaine
Issue Date:
2009
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Understanding the history of ice on Mars provides important insight into Martian geologic and climatic history. A model capable of ice reconstruction that requires few input parameters, and a detailed analyses of landforms in an area with hypothesized glacial modification, Argyre Planitia, provide further understanding of Martian ice.A threshold-sliding model was developed to model perfectly-plastic deformation of ice that is applicable to ice bodies that deform when a threshold basal shear stress is exceeded. The model requires three inputs describing bed topography, ice margins, and a function defining the threshold basal shear stress. The model was tested by reconstructing the Greenland ice sheet and then used to reconstruct ice draping impact craters on the margins of the Martian South Polar Layered Deposits using a constant basal shear stress of ~0.6 bars for the majority of Martian examples. This result is ~1/3 the value calculated for the Greenland ice sheet. Reasons for the lower Martian basal shear stress are unclear but could involve the strain-weakening behavior of ice. The threshold-sliding model can be used for ice reconstruction and forward modeling of erosion and deposition to provide further insight into the history of ice on Mars.To test the glacial hypothesis in the Argyre region, landforms are examined using images from the High Resolution Imaging Science Experiment (HiRISE) camera and other Martian datasets. Linear grooves and streamlined hills are consistent with glacial erosion. Deep semi-circular embayments in mountains resemble cirques. U-shaped valleys have stepped longitudinal profiles and tributary valleys have hanging valley morphology similar to terrestrial glacial valleys. Boulders blanketing a valley floor resemble ground moraine. Sinuous ridges cross topography, have layers, occur in troughs, and have variations in height that appear related to the surrounding surface slope; these are characteristics consistent with terrestrial eskers. At least portions of Argyre appear to be modified by ice accumulation, flow, erosion, stagnation and ablation. The type and amount of bedrock erosion and presence of possible eskers suggests the ice was, at times, wet-based.
Type:
text; Electronic Dissertation
Keywords:
Argyre; geomorphology; Glaciation; Mars; modeling; water
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Geosciences; Graduate College
Degree Grantor:
University of Arizona
Committee Chair:
McEwen, Alfred S.

Full metadata record

DC FieldValue Language
dc.language.isoENen_US
dc.titleGlacial Processes and Morphologies in the Southern Hemisphere of Marsen_US
dc.creatorBanks, Maria Elaineen_US
dc.contributor.authorBanks, Maria Elaineen_US
dc.date.issued2009en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractUnderstanding the history of ice on Mars provides important insight into Martian geologic and climatic history. A model capable of ice reconstruction that requires few input parameters, and a detailed analyses of landforms in an area with hypothesized glacial modification, Argyre Planitia, provide further understanding of Martian ice.A threshold-sliding model was developed to model perfectly-plastic deformation of ice that is applicable to ice bodies that deform when a threshold basal shear stress is exceeded. The model requires three inputs describing bed topography, ice margins, and a function defining the threshold basal shear stress. The model was tested by reconstructing the Greenland ice sheet and then used to reconstruct ice draping impact craters on the margins of the Martian South Polar Layered Deposits using a constant basal shear stress of ~0.6 bars for the majority of Martian examples. This result is ~1/3 the value calculated for the Greenland ice sheet. Reasons for the lower Martian basal shear stress are unclear but could involve the strain-weakening behavior of ice. The threshold-sliding model can be used for ice reconstruction and forward modeling of erosion and deposition to provide further insight into the history of ice on Mars.To test the glacial hypothesis in the Argyre region, landforms are examined using images from the High Resolution Imaging Science Experiment (HiRISE) camera and other Martian datasets. Linear grooves and streamlined hills are consistent with glacial erosion. Deep semi-circular embayments in mountains resemble cirques. U-shaped valleys have stepped longitudinal profiles and tributary valleys have hanging valley morphology similar to terrestrial glacial valleys. Boulders blanketing a valley floor resemble ground moraine. Sinuous ridges cross topography, have layers, occur in troughs, and have variations in height that appear related to the surrounding surface slope; these are characteristics consistent with terrestrial eskers. At least portions of Argyre appear to be modified by ice accumulation, flow, erosion, stagnation and ablation. The type and amount of bedrock erosion and presence of possible eskers suggests the ice was, at times, wet-based.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectArgyreen_US
dc.subjectgeomorphologyen_US
dc.subjectGlaciationen_US
dc.subjectMarsen_US
dc.subjectmodelingen_US
dc.subjectwateren_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGeosciencesen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.chairMcEwen, Alfred S.en_US
dc.contributor.committeememberKargel, Jeffrey S.en_US
dc.contributor.committeememberStrom, Robert G.en_US
dc.contributor.committeememberBaker, Victor R.en_US
dc.contributor.committeememberPelletier, Jon D.en_US
dc.identifier.proquest10394en_US
dc.identifier.oclc659752010en_US
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