Blueschists and eclogites: a possible plate tectonic mechanism for their emplacement from the upper mantle

The most significant problem of blueschists and eclogite origin is explaining the mechanism by which they were transported from great depths to the surface. Three aspects of this problem are discussed: (1) prograde and retrograde trajectories in blueschist- and eclogite-bearing belts and the preservation conditions for such minerals as aragonite, lawsonite and coesite; (2) the mechanism by which low density crustal rocks (with coesite and...