page_title: Tectonics of Mars
section_title: Tectonic implications of magnetic anomalies
hierarchical_section_title: Tectonics of Mars / Tectonic implications of magnetic anomalies
caption_attribution_description: English: The global map is built up from many thousands of orbits at constant altitude (mapping orbit), and uses colors to represent the strength and direction of the field caused by crustal magnetization. It's originally in TIFF format. I transformed it into PNG format by Photoshop 7.0.1 to make it visible on the net.
context_page_description: Like the Earth, the crustal properties and structure of the surface of Mars are thought to have evolved through time; in other words, as on Earth, tectonic processes have shaped the planet. However, both the ways this change has happened and the properties of the planet's lithosphere are both very different when compared to the Earth. Today, Mars is believed to be largely tectonically inactive. However, observational evidence and its interpretation suggests that this was not the case further back in Mars' geological history.
  At the scale of the whole planet, two large scale physiographic features are apparent on the surface. The first is that the northern hemisphere of the planet is much lower than the southern, and has been more recently resurfaced – also implying that the crustal thickness beneath the surface is distinctly bimodal. This feature is referred to as the "hemispheric dichotomy". The second is the Tharsis rise, a massive volcanic province that has had major tectonic influences both on a regional and global scale in Mars' past.
context_section_description: The southern highlands of Mars display zones of intense crustal magnetization. The magnetic anomalies are weak or absent in the vicinity of large impact basins, the northern plains, and in volcanic regions, indicating that magnetization in these areas have been erased by thermal events. The presence of magnetic anomalies on Mars suggests that the planet maintained an intrinsic magnetic field early on in its history. The anomalies are linear in shape and of alternating polarity, which some authors have interpreted as a sequence of reversals and a process akin to seafloor spreading. The stripes are ten times wider than those found on Earth, indicating faster spreading or slower reversal rates. Although no spreading center has been identified, a map of the magnetic anomalies on Mars reveals that the lineations are concentric to the south pole.
caption: Map of crustal magnetic anomaly distribution on Mars, courtesy of NASA, 2005.
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