Subduction zones serpentine

At greater depths, hydrous phases such as chlorite and serpentine are succeeded in cooler subduction zones by DHMSs. These DHMSs can transport water to the transition zone, where they may break down because of their lack of stability at high temperature. At these depths, however, wadsleyite would be able to accommodate the water released by these dehydration reactions. Further subduction may trigger H2O release at the wadsleyite —> ringwoodite transition, because of... 

Phipps-Morgan J., Ruepke L. H., Ranero C., and Hort M. (2002) Some geophysical and geochemical consequences of slab serpentinization at subduction zones. EOS, Trans., AGU Suppl. 83, abstract T51-E-13. 

Peacock S. M. (2001) Are the lower planes of double seismic zones caused by serpentine dehydration in subducting oceanic mantle Geology 29, 299-302. 

Figure 6 Major phase stability boundaries in H20-saturated peridotite and H2O contents stored in hydrous phases for harzburgite and Iherzolite (upper and lower number, respectively after Schmidt and Poli, 1998 and FumagaUi et ah, 2001). The gray field denotes stability fields of hydrous phases. Serpentinized peridotite following the coldest P-T-path will not dehydrate up to transition zone depths, as phase boundaries of phase A (and phase E at >11 GPa, Frost, 1999) are fiatter in P-T space than typical subduction P-T paths.

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