Lu-Hf and Re-Os systematics for peridotite xenoliths from Spitsbergen, western Svalbard: Implications for mantle-crust coupling

Abstract

The timing of sub-continental lithospheric mantle (SCLM) differentiation beneath Spitsbergen, western Svalbard has been determined on spinel peridotite xenoliths using two complementary isotopic systems: Lu-Hf and Re-Os. The whole-rock Re-Os systematics (Re-Os errorchron, aluminochron, and Re-depletion age) define Paleoproterozoic/Neoarchean ages of isolation from the convecting mantle. We note that the age is independently supported by the Lu-Hf errorchron for the peridotite clinopyroxene grains, and average degree of melt depletion recorded in the samples. The obtained ages are indistinguishable with the oldest crustal ages recognized in western Spitsbergen, implying that the mantle lithosphere in this area is likely to have been genetically linked to the overlying crust. Our data suggest that the Spitsbergen lithosphere is unlikely to undergo bulk delamination in the tectonic regime varying from transpression to transtension since the Paleocene. We thus discount the delaminated and reactivated SCLM as a potential source for the Dupal-like enriched components in the Arctic upper mantle.