Majoritic garnets in Hawaiian xenoliths: Preliminary results

Abstract

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