PerspectivePLATE TECTONICS

A Graveyard for Buoyant Slabs?

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Science  29 Jun 2001:
Vol. 292, Issue 5526, pp. 2445-2446
DOI: 10.1126/science.1062558

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Summary

Geoscientists have been debating whether convection deep inside Earth involves the whole mantle or is divided into two layers separated at 660-km depth. Compromise models suggest delayed penetration of the transition zone due to a phase change. In his Perspective, Green highlights a study by Chen and Brudzinski, who have found evidence for a buoyant cold slab in the transition zone between the upper and the lower mantle. The slab appears to be retained in the transition zone because of mineralogical differences between its interior and its surroundings.