Water in eclogite and pyroxenite xenoliths from the bottom 100 km of the Slave Craton (Canada) mantle root

Significant amounts of water can be stored in the mantle in nominally anhydrous minerals (NAMs) such as garnet, olivine, clino- and orthopyroxene as structural OH− ions. Water or, more precisely, hydrogen is incorporated as a trace element in the mineral structure. Subduction is the only conceivable mode to transport water into the mantle. The main goal of this study is to evaluate the water storage and transport capacity of garnet-clinopyroxene xenoliths (eclogite and pyroxenite, built by metamorphic processes during subduction of oceanic crust) and, in turn, the potential of subducted oceanic crust to recycle water into the mantle. For this purpose, 20 kimberlite-hosted xenoliths from the Diavik diamond mine, Canada, were investigated. The location is known for its abundance of well-preserved xenoliths. Previous studies have shown that the composition of garnet and clinopyroxene is highly variable (e.g., Aulbach et al., 2007), which is favorable for our study. Sample parameters, mineral composition, trace elements, and infrared data are listed in the attached tables.