Water solubility in majoritic garnet in subducting oceanic crust

[1] Water in majoritic garnet synthesized in the mid-oceanic ridge basalt (MORB) + H2O composition at 20 GPa and 1400-1500degreesC was measured by secondary ion mass spectrometry (SIMS) and infrared spectroscopy. We found that the majorite contains 1130 to 1250 ppm OH by weight. The infrared absorption band showed that incorporation of the hydroxyl in majorite is most likely due to the hydrogarnet substitution. Our results indicate that water can be transported into the mantle transition zone by nominally anhydrous minerals such as omphacite and majorite in the subducting basaltic crust. Such water may have great influences on the physical properties of slab in the transition zone.