Module 3 - Shaping Planetary Surfaces

Mars Tectonism

In this page we'll examine if Mars has experienced tectonism.  And even though this may spoil it, we'll conclude that it certainly has undergone some tectonism, but not plate tectonics.  If we go back to the large scale topography, we see that the Martian dichotemy is the most prominent feature and it has been produced by an impact.  There are no planet-scale features that can be correlated to Earth-like plate tectonics.  And it is generally agreed that Mars never develop plate tectonics. We will later see that it has undergone the same contraction that we have seen on the Moon and on Mercury and as a result there are many wrinkle ridges on Mars.  But there is one major feature on Mars that is responsible for considerable amount of tectonic activity in Mar's early history.  That feature is the Tharsis bulge, the large ~10 km high plateau of volcanic rocks that have been placed on the surface of Mars. Placing a tremendous volume of rocks on top of the crust pushes it down. The local example for this would be to consider the thick icesheets that were present on top of Ontario during the last ice age.  They pushed the crust down and it is still in the process of coming back up (Hudson's Bay has risen 300 m over the last 800 years).


causes the rocks below and surrounding it to deform.  The surface of a planet

The reason for this is generally referred to as isostacy and rocks want to be in isostatic equilibrium.

  which in gology normally referes to the deisre



At present the Martian crust in the southern hemisphere has thickness in the range of 69 - 80 km, which is much thicker than Earth's.  It would be difficult to deform that crust. But in the distant geological past  (3 - 4 billion years ago)







 

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