Majoritic garnets in Hawaiian xenoliths: preliminary results

In this report we present chemical, textural, and spectroscopic information on some mantle garnets from Oahu, Hawaii that have recorded the pyroxene d ouble left right arrow garnet transformation. Their textural and compositio nal characteristics indicate a high pressure origin, consistent with a dept h range of 180-270 km, which is much deeper than previously thought (< 100 km). One eclogitic xenolith is particularly interesting because its textura l and compositional characteristics suggest an origin in the deep upper man tle or the transition zone.