Electronic Resource
Palo Alto, Calif.
:
Annual Reviews
Annual Review of Earth and Planetary Sciences
33 (2005), S. 133-161
ISSN:
0084-6597
Source:
Annual Reviews Electronic Back Volume Collection 1932-2001ff
Topics:
Geosciences
,
Physics
Notes:
The bulk of the Đ♯50-km-thick Martian crust formed at Đ♯4.5 Gyr B.P., perhaps from a magma ocean. This crust is probably a basaltic andesite or andesite and is enriched in incompatible and heat-producing elements. Later additions of denser basalt to the crust were volumetrically minor, but resurfaced significant portions of the Northern hemisphere. A significant fraction of the total thickness of the crust was magnetized prior to 4 Gyr B.P., with the magnetization later selectively removed by large impacts. Early large impacts also modified the hemispheric contrast in crustal thickness (the dichotomy), which was possibly caused by long-wavelength mantle convection. Subsequent Noachian modification of the crust included further impacts, significant fluvial erosion, and volcanism associated with the formation of the Tharsis rise. Remaining outstanding questions include the origin of the dichotomy and the nature of the magnetic anomalies.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1146/annurev.earth.33.092203.122637
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