A combined zircon SHRIMP and Sm-Nd isotope study of high-grade paragneisses from the Mid-German Crystalline Rise: evidence for northern Gondwanan andGrenvillian provenance

SHRIMP analyses of detrital zircon cores front high-grade metasediments fro m the Mid-German Crystalline Rise,,which is situated between Eastern Avalon ia in the NW and Saxo-Thuringia in the SE. yield mostly ages of c. 550 Ma a nd c. 2.06 Ga, with minor c. 1.0 and 2.4-2.9 Ga components. The sedimentary protoliths were deposited during the Late Proterozoic to Early Cambrian, p robably prior to the break up of the northern Gondwana margin at 460-500 Ma . These data are consistent with the sediments' high epsilon Nd values (0.9 to -3.0), which are comparable to those of well-documented Late Proterozoi c sediments from other parts of Europe, The combined isotopic data suggest derivation of the sediments front at least three distinct crustal source re gions. Dominant sources were the Avalonian-Cadomian orogenic belt (c. 45%), situated at the northern margin of Gondwana during the Neoproterozoic, and the West African and/or eastern Amazonian cratons (c. 45%). The Grenvillia n belt was a minor source (c. 10%).