Origins of Xenolithic Eclogites and Pyroxenites from the Central Slave Craton, Canada

Major- and trace-element and Sr^Nd^Hf isotopic compositions of garnet and clinopyroxene in kimberlite-borne eclogite and pyroxe-nite xenoliths were used to establish their origins and evolution in the subcontinental lithospheric mantle beneath the central Slave Craton, Canada. The majority of eclogites can be assigned to three groups (high-Mg, high-Ca or low-Mg eclogites) that have distinct trace-element patterns. Although post-formation metasomatism involving high field strength element (HFSE) and light rare earth element (LREE) addition has partially obscured the primary compositional features of the high-Mg and high-Ca eclo-gites, trace-element features, such as unfractionated middle REE (MREE) to heavy REE (HREE) patterns suggestive of garnet-free residues and low Zr/Sm consistent with plagioclase accu-mulation, could indicate a subduction origin from a broadly gabbroic protolith. In this scenario, the low