What Is Meant by the "Mantle Flush

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The Answer is It was once believed that the transition zone between the upper and lower mantle was an impenetrable barrier, and that slabs of dense, subducted lithosphere were consumed in the upper mantle. Recent studies using seismic tomography have suggested large accumulations of cold rocks above the mantle transition, substantial patches above the core- mantle boundary, and even a few areas where a cold slab appears to be passing through the transition zone. This 'flush' through the mantle is accompanied by a mantle plume of hot, buoyant material rising to take its place. This upward movement of mantle material may be partly responsible for the breakup of past supercontinents.

What Is Meant by the "Mantle Flush

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