In this dissertation, the large-scale geophysical behaviour of the Earth, Venus and Mars are compared, using data collected by the Magellan spaceprobe (for Venus) and the Viking and Mars Global Surveyor (MGS) probes (for Mars). Neither Venus nor Mars show evidence of plate tectonics operating at the present day. On Venus, the lack of water means the frictional resistance at faults and the viscous drag on the base of the moving lithospheric plates are too high to be overcome by the driving forces for plate tectonics. The high elastic thickness of Mars results in a large frictional resistance to fault motion, although the faults themselves are probably no stronger than those on the Earth, and means large compressive stresses are required to initiate subduction. The likely high viscosity of the martian mantle, a consequence of its probable dryness and low temperature, may also result in large drag forces on the base of the lithosphere. Plate tectonics may have operated in the past on both planets, providing a possible explanation for the rapid resurfacing of Venus required by the crater counts and the linear magnetic anomalies recently discovered on Mars.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:596394 |
| Date | January 2001 |
| Creators | Barnett, D. N. |
| Publisher | University of Cambridge |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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