Along-arc variations in lithospheric mantle compositions in Kamchatka, Russia: First trace element data on mantle xenoliths from the Klyuchevskoy Group volcanoes

► Harzburgite xenoliths sample lithospheric arc mantle initially formed by high-degree melt extraction. ► Coarse orthopyroxene (opx) in the harzburgites has spoon-shaped trace element patterns and is enriched in light REE. ► The opx in the Bezymyanny xenoliths has greater LREE enrichments than opx in xenoliths from Avacha, southern Kamchatka. ► The Bezymyanny xenoliths show petrographic and chemical differences with peridotite xenoliths from Shiveluch volcano. ► Metasomatism and melt-rock reactions in sub-arc mantle in northern Kamchatka are enhanced by the proximity to plate edge.