A: Well, not neccesarily.
Let's start with the requirements of plate tectonics. First, there has to ba a driving force for plates to form and move. In our case, the driving force is the weight of our crust, and the heat from the interior. The heat makes the layer beneath the crust soft, allowing for convection currents that pull on the overlying crust. This heat is supplied by the radioactive decay of matter trapped in the core, a consequence of the large volume of matter that coalesced in Earth's early years. Heat may also be supplied by tidal forces from a nearby large body, such as those powering volcanism in Jupiter's moon Io. The tidal forces pull on the rocky material (such as how the moon pulls on our seas), creating friction that generates the heat.
Now let's tackle Mercury. Mercury does not have the sufficient mass and volume to have trapped much radioactive material necessary to power plate tectonics to this day. Tidal forces from the sun does effect Mercury's crust, but not enough to cause plate formation and movement. A 2008 survey of the planet has shown that it still has a molten core, but volcanism had ceased a long time ago. Chances that it still exhibits plate tectonics are slim.
Venus is another story. It has active volcanism, but present evidence cannot suggest that it has an active plate system. A theory proposed is that liquid water plays a role in plate tectonics, such that it "lubricates" subduction zones. A "wet" crust is also more likely to fail or create cracks and faults, since a dry crust can be strong enough to resist plate motion. The volcanoes of Venus are like the Hawaiian islands - volcanoes not connected to subduction zones.
These answers however, are based on plate tectonics as experienced here on Earth, which is why scientists were also surprised by the findings in Mars. Perhaps space geology still has a long way to go. No matter, what can be certain is that these planets did experience the familiar kind of plate tectoncis in their youth, when they were hotter and softer.
References:
http://www.umich.edu/~gs265/tecpaper.htm
http://www.news.cornell.edu/stories/May07/margot.mercury.html
http://csep10.phys.utk.edu/astr161/lect/mercury/surface.html
http://adsabs.harvard.edu/abs/2001AGUFM.U21A..09S
Prepared by: Benjamin Francis Rodriguez
Let's start with the requirements of plate tectonics. First, there has to ba a driving force for plates to form and move. In our case, the driving force is the weight of our crust, and the heat from the interior. The heat makes the layer beneath the crust soft, allowing for convection currents that pull on the overlying crust. This heat is supplied by the radioactive decay of matter trapped in the core, a consequence of the large volume of matter that coalesced in Earth's early years. Heat may also be supplied by tidal forces from a nearby large body, such as those powering volcanism in Jupiter's moon Io. The tidal forces pull on the rocky material (such as how the moon pulls on our seas), creating friction that generates the heat.
Now let's tackle Mercury. Mercury does not have the sufficient mass and volume to have trapped much radioactive material necessary to power plate tectonics to this day. Tidal forces from the sun does effect Mercury's crust, but not enough to cause plate formation and movement. A 2008 survey of the planet has shown that it still has a molten core, but volcanism had ceased a long time ago. Chances that it still exhibits plate tectonics are slim.
Venus is another story. It has active volcanism, but present evidence cannot suggest that it has an active plate system. A theory proposed is that liquid water plays a role in plate tectonics, such that it "lubricates" subduction zones. A "wet" crust is also more likely to fail or create cracks and faults, since a dry crust can be strong enough to resist plate motion. The volcanoes of Venus are like the Hawaiian islands - volcanoes not connected to subduction zones.
These answers however, are based on plate tectonics as experienced here on Earth, which is why scientists were also surprised by the findings in Mars. Perhaps space geology still has a long way to go. No matter, what can be certain is that these planets did experience the familiar kind of plate tectoncis in their youth, when they were hotter and softer.
References:
http://www.umich.edu/~gs265/tecpaper.htm
http://www.news.cornell.edu/stories/May07/margot.mercury.html
http://csep10.phys.utk.edu/astr161/lect/mercury/surface.html
http://adsabs.harvard.edu/abs/2001AGUFM.U21A..09S
Prepared by: Benjamin Francis Rodriguez
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