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The formation of Tharsis on Mars: What the line-of-sight gravity is telling us

Williams, Jean-Pierre and Nimmo, Francis and Moore, William B. and Paige, David A. (2008) The formation of Tharsis on Mars: What the line-of-sight gravity is telling us. Journal of Geophysical Research E, 113 (E10). E10011. ISSN 0148-0227. https://resolver.caltech.edu/CaltechAUTHORS:WILjgre08

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Abstract

Line-of-sight (LOS) spacecraft acceleration profiles from the Radio Science Experiment and topography from the Mars Orbiter Laser Altimeter (MOLA) instrument of the Mars Global Surveyor (MGS) are analyzed to estimate the effective elastic thickness (Te) for various regions of Tharsis. We identify a buried basin flanking the Thaumasia Highlands at the southeastern margin of Tharsis. Assuming that this basin results from lithospheric flexure from surface loading by the Thaumasia Highlands, we fit LOS profiles across the feature with a thin-shell, elastic flexure model and find the mountain belt to reflect a value of Te ∼ 20 km consistent with a Noachian formation age. We also determine admittances from LOS profiles for five regions across Tharsis and fit them with theoretical admittances calculated using the flexural model. Crater density, surface density, and predominant surface age are found to vary systematically across Tharsis while Te does not. The highest surface density and lowest Te values are obtained for the western portion of Tharsis where crater densities are lowest. Our results imply the majority of the topographic rise was emplaced within the Noachian irrespective of the surface ages. Topographic loading and resurfacing (i.e., volcanic activity) persisted into the Amazonian while becoming increasingly confined to the western margin where the youngest surface ages are found and the eruptive style transitioned from effusive volcanism to shield-forming volcanism as Te increased.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1029/2007JE003050DOIUNSPECIFIED
ORCID:
AuthorORCID
Williams, Jean-Pierre0000-0001-5058-695X
Nimmo, Francis0000-0003-3573-5915
Additional Information:Copyright 2008 by the American Geophysical Union. Received 27 November 2007; revised 26 June 2008; accepted 27 August 2008; published 31 October 2008. We thank Alistair Crosby and Bruce Banerdt for their thoughtful reviews. Jean-Pierre Williams was supported by the California Institute of Technology through the O.K. Earl Postdoctoral Fellowship and the National Science Foundations Astronomy and Astrophysics Research Grants program (AST-0709151).
Funders:
Funding AgencyGrant Number
O.K. Earl Postdoctoral Fellowship, CaltechUNSPECIFIED
National Science FoundationAST-0709151
Subject Keywords:Mars, Tharsis, gravity
Issue or Number:E10
Record Number:CaltechAUTHORS:WILjgre08
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:WILjgre08
Official Citation:Williams, J.-P., F. Nimmo, W. B. Moore, and D. A. Paige (2008), The formation of Tharsis on Mars: What the line-of-sight gravity is telling us, J. Geophys. Res., 113, E10011, doi:10.1029/2007JE003050.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:12885
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:08 Jan 2009 23:29
Last Modified:09 Mar 2020 13:19

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