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Localized Gravity/Topography Admittance and Correlation Spectra on Mars: Implications for Regional and Global Evolution[i] From gravity and topography data collected by the Mars Global Surveyor spacecraft we calculate gravity/topography admittances and correlations in the spectral domain and compare them to those predicted from models of lithospheric flexure. On the basis of these comparisons we estimate the thickness of the Martian elastic lithosphere (T(sub e)) required to support the observed topographic load since the time of loading. We convert T(sub e) to estimates of heat flux and thermal gradient in the lithosphere through a consideration of the response of an elastic/plastic shell. In regions of high topography on Mars (e.g., the Tharsis rise and associated shield volcanoes), the mass-sheet (small-amplitude) approximation for the calculation of gravity from topography is inadequate. A correction that accounts for finite-amplitude topography tends to increase the amplitude of the predicted gravity signal at spacecraft altitudes. Proper implementation of this correction requires the use of radii from the center of mass (collectively known as the planetary shape ) in lieu of topography referenced to a gravitational equipotential. Anomalously dense surface layers or buried excess masses are not required to explain the observed admittances for the Tharsis Montes or Olympus Mons volcanoes when this correction is applied. Derived T, values generally decrease with increasing age of the lithospheric load, in a manner consistent with a rapid decline of mantle heat flux during the Noachian and more modest rates of decline during subsequent epochs.
Document ID
20030071095
Acquisition Source
Headquarters
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
McGovern, Patrick J.
(Lunar and Planetary Inst. Houston, TX, United States)
Solomon, Sean C.
(Carnegie Institution of Washington Washington, DC, United States)
Smith, David E.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Zuber, Maria T.
(Massachusetts Inst. of Tech. Cambridge, MA, United States)
Simons, Mark
(California Inst. of Tech. Pasadena, CA, United States)
Wieczorek, Mark A.
(Massachusetts Inst. of Tech. Cambridge, MA, United States)
Phillips, Roger J.
(Washington Univ. Saint Louis, MO, United States)
Neumann, Gregory A.
(Massachusetts Inst. of Tech. Cambridge, MA, United States)
Aharonson, Oded
(Massachusetts Inst. of Tech. Cambridge, MA, United States)
Head, James W.
(Brown Univ. Providence, RI, United States)
Date Acquired
August 21, 2013
Publication Date
January 1, 2002
Publication Information
Publication: Journal of Geophysical Research
Publisher: American Geophysical Union
Volume: 107
Issue: E12
ISSN: 0148-0227
Subject Category
Lunar And Planetary Science And Exploration
Report/Patent Number
LPI-Contrib-1121
Funding Number(s)
CONTRACT_GRANT: NAG5-4077
CONTRACT_GRANT: NASW-4574
CONTRACT_GRANT: NAG5-10165
CONTRACT_GRANT: NAG5-4436
Distribution Limits
Public
Copyright
Other

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