Neoproterozoic-Early Devonian magmatism in the Antigonish Highlands, Avalon terrane, Nova Scotia: Tracking the evolution of the mantle and crustal sources during the evolution of the Rheic Ocean

Although the Sm-Nd isotopic data suggest that Avalonian basement and lithospheric mantle formed over the same time interval (0.8 to 1.1 Ga), the divergence of their respective envelopes with time reflects their differing εNd values and Sm/Nd ratios. We suggest that Avalonian crustal basement and its enriched mantle were both formed between 0.8 and 1.1 Ga in a Panthalassa-type ocean that surrounded the supercontinent Rodinia and were accreted to the northern Gondwanan margin at about 650 Ma, prior to the oldest magmatic event in the Antigonish Highlands.