Geodynamics of Venus
Episodic plate tectonics

Turcotte (1993) suggested that Venus has episodic tectonics, whereby short periods of rapid tectonics are separated by periods of surface inactivity lasting on the order of 500 Ma. During periods of inactivity, the lithosphere cools conductively and thickens to over 300 km. The active mode of plate tectonics occurs when the thick lithosphere detaches and founders into the interior of the planet. Large scale lithosphere recycling is thus invoked to explain resurfacing events. Episodic large scale overturns can occur due to a compositionally stratified mantle where there is competition between the compositional and thermal buoyancy of the upper mantle.
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