|
Read Full Article (file size: 116219 bytes) Cited by
GEOPHYSICAL RESEARCH LETTERS,
VOL. 32,
L22201,
doi:10.1029/2005GL024260,
2005
Buried mass anomalies along the hemispheric dichotomy in eastern Mars: Implications for the origin and evolution of the dichotomy
Walter S. Kiefer
Lunar and Planetary Institute, Houston, Texas, USA
Abstract
Gravity observations indicate the presence of buried, high-density material along the hemispheric dichotomy in eastern Mars.
This material is unrelated to present-day topography and is probably the result of localized thinning of the crust. This thinning
may be the result of an epoch of edge-driven convection that occurred shortly after the dichotomy formed. Initiation of edge-driven
convection requires that lateral variations in lithospheric structure be created on a timescale that is shorter than the conductive
cooling time for the lithosphere, a few tens of million years at most. This timescale cannot be achieved if the dichotomy
boundary is created solely by large-scale convective flow. Formation or modification of the boundary by large impact basins
such as Utopia can create the required lithospheric structure in a geologic instant. This suggests that large impacts were
important in shaping the dichotomy, at least on a regional scale.
Received 29
July
2005;
accepted 12
October
2005;
published 17
November
2005.
Index Terms: 5417 Planetary Sciences: Solid Surface Planets: Gravitational fields (1221); 5475 Planetary Sciences: Solid Surface Planets: Tectonics (8149); 6225 Planetary Sciences: Solar System Objects: Mars; 8120 Tectonophysics: Dynamics of lithosphere and mantle: general (1213); 8121 Tectonophysics: Dynamics: convection currents, and mantle plumes.
Read Full Article (file size: 116219 bytes) Cited by
Citation: Kiefer, W. S.
(2005),
Buried mass anomalies along the hemispheric dichotomy in eastern Mars: Implications for the origin and evolution of the dichotomy,
Geophys. Res. Lett.,
32,
L22201,
doi:10.1029/2005GL024260.
Copyright 2005 by the American Geophysical Union.
|