Formation of Paleoproterozoic eclogitic mantle, Slave Province (Canada): Insights from in-situ Hf and U-Pb isotopic analyses of mantle zircons

The Jericho eclogites have previously been interpreted as representing remnants of metamorphosed oceanic crust, and their formation related to Paleoproterozoic subduction regimes along the western margin of the Archean Slave craton during the Wopmay orogeny. Hf isotope compositions and U-Pb results for the Jericho zircons reported here are in good agreement with a Paleoproterozoic subduction model, suggesting that generation of oceanic crust and eclogite formation occurred between 2.0 and 2.1 Ga. The slightly older Hf depleted mantle model ages (∼2.1 to 2.3 Ga) may be reconciled with this model by invoking mixing between 'crustal'-derived Hf from sediments and more radiogenic Hf associated with the oceanic crust during the ∼2 Ga subduction event. This results in intermediate Hf isotope compositions for the Jericho zircons that yield 'fictitiously' older Hf model ages.