Comment on 'The beginnings of hydrous mantle wedge melting', CB Till, TL Grove, AC Withers, Contributions to Mineralogy and Petrology, DOI 10.1007/s00410-011-0692-6

The paper by Till et al. (2011) reports new experiments on high pressure melting in the system (lherzolite ? water). In comparison with earlier published work, several appropriate methods of phase characterisation and experimental techniques, have not been reported. A result is that the authors’ conclusions are not substantiated for two important issues: the position in pressure, temperature (P, T) space of the hydrous vapour-saturated solidus and the compositions of near-solidus melts. The application of the experimental results to discussion of melting in the mantle wedge overlying subduction zones is therefore questionable.