GEOL 212 Study Guide - Quiz Guide: Asthenosphere, Advection, Paroxysmal Attack
26 Dec 2017
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Venus, plate vs. blob tectonics - tectonics without subduction. Impact crater enigma - relatively young surface: volcanoes everywhere, venus" internal heat flow model, lithospheric overturn. On earth, plate tectonics involve: the subduction of cold lithospheric plates at convergent boundaries, subducting slabs are lubricated by partial melting of adjecent mantle rocks as a result of the infusion of water from the subducting slab. A: lithosphere doesn"t subduct because it is not relatively cool. That sums up the situation on venus, where there seems to be lithospheric movement, but no subduction zones or clear plate boundaries. Subductions zones and their volcanic arcs are the refineries at which continental and oceanic crust are differentiated. Lacking them, venus lacks the global dichotomy (maybe) of continents and ocean basins that characterize earth, even though it has continent-like elevated regions. (compare this image of earth surface elevations to this one of. Crater enigmas: venus has: surprisingly few impact craters.
