Key host minerals for rare earth elements in kimberlite-borne eclogites
Rare earth elements are key geochemical tracers of crust-mantle interaction during the subduction of oceanic crust into the mantle. However, data on rare earth element concentrator minerals in mantle xenoliths are still fragmentary. The composition of mantle eclogites reconstructed on the basis of rock-forming minerals is often depleted by light rare earth elements (LREE), whereas the measured bulk composition does not demonstrate depletion in LREE. Such a difference may indicate the key role of accessory phases in the transfer of incompatible and high field strength elements. In this paper we present the first discovery of allanite and titanite in xenoliths of eclogites from kimberlites. Our data indicate that allanite and titanite are key mineral concentrators of light rare earth elements in mantle rocks.