New mantle model gets the water out.
Bercovici and his Yale colleague Shun-Ichiro Karato propose that when slow-rising mantle rock reaches within 400 kilometers of Earth's surface, the material sheds much of its water and partially melts. During that process, the scientists surmise, most trace elements leach out of the rock. This occurs mostly within a 10-km-thick layer of the mantle, and the resulting liquid later circulates back toward the planet's core.
Because mantle material in the hot-spot plumes rises quickly through the thin layer where leaching occurs, it doesn't lose as many of its trace elements as slow-rising rock does. The researchers describe their model in the Sept. 4 Nature.--S.P.
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|Title Annotation:||Earth Science|
|Article Type:||Brief Article|
|Date:||Sep 13, 2003|
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