HR: 17:10h
AN: S12F-05    [PDF]
TI: Theories of Mars' Interior: An alternative to plumes as the origin of Tharsis
AU: * Stegman, D
EM: dstegman@eps.berkeley.edu
AF: School of Mathematical Sciences, Monash University, Bldg 28, Monash University, Clayton, Vic 3800 Australia
AU: * Stegman, D
EM: dstegman@eps.berkeley.edu
AF: Theoretical Division, Los Alamos National Laboratory, Mail Stop B216, Los Alamos National Laboratory, Los Alamos, NM 87545 United States
AU: Jellinek, M
EM: markj@physics.utoronto.ca
AF: Dept. of Physics, University of Toronto, 60 St. George Street, Toronto, Ont M5S 1A7 Canada
AU: Richards, M
EM: markr@eps.berkeley.edu
AF: Dept. of Earth and Planetary Science, University of California, Berkeley, 307 McCone Hall, University of California, Berkeley, Berkeley, Ca 94720 United States
AU: Manga, M
EM: manga@eps.berkeley.edu
AF: Dept. of Earth and Planetary Science, University of California, Berkeley, 307 McCone Hall, University of California, Berkeley, Berkeley, Ca 94720 United States
AU: Baumgardner, J
EM: baumgardner@lanl.gov
AF: Theoretical Division, Los Alamos National Laboratory, Mail Stop B216, Los Alamos National Laboratory, Los Alamos, NM 87545 United States
AB: Mars' large-scale physiography is dominated by a hemispheric dichotomy (thin northern crust with low, smooth topography vs. thick southern crust with high, rugged topography) and by the Tharsis rise (an enormous volcanic plateau), both of which developed within the first ~1 Gyr of Martian history. Using a 3-D spherical mantle convection model with temperature-dependent viscosity, we explore the effect of hemispheric-scale crustal thickness variations on Martian mantle convection. Thickened crust in the "southern" hemisphere of the model causes insulation of that hemisphere which may effect the underlying mantle circulation. This leads to a transient, regional-scale partial melting event sufficient to generate the Tharsis rise during the first ~0.5-1.0 billion years following the formation of the crustal dichotomy. Our model avoids some problems of timing inherent in plume models, provides testable hypotheses regarding the history of Martian volcanism, and suggests a causal link between the formation of the N-S dichotomy and Tharsis.
DE: 5430 Interiors (8147)
DE: 5455 Origin and evolution
DE: 8121 Dynamics, convection currents and mantle plumes
DE: 8450 Planetary volcanism (5480)
SC: Seismology [S]
MN: 2003 Fall Meeting