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Old model Nd ages in Namibian Pan-African rocks

Abstract

The Nd-isotope analytical technique is a powerful tool for studying many geological processes: particularly the evolution of the upper mantle as seen through the isotope and trace element geochemistry of mantle-derived volcanic rocks1–3, and magmatic processes along destructive plate margins4,5. However, previous studies of continental crust6–8 have been largely restricted to Archaean examples and concerned primarily with dating their time of derivation from the upper mantle. In the present study we investigated the Nd- and Sr-isotope characteristics of rocks involved in a relatively young (800–450 Myr) orogenic event. Such events represent critical stages in the evolution of most of the Earth's continental crust—new material is added from the mantle, and pre-existing crust is remobilized by erosion and sedimentation, deformation and magmatic activity. Nd- and Sr-isotopes were used to outline the range in age and geochemical characteristics of rock sequences and provinces within both the upper mantle and the pre-existing crust which were sampled during the orogeny, and hence provided the major components of what is now a stable segment of continental crust.

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Hawkesworth, C., Kramers, J. & Miller, R. Old model Nd ages in Namibian Pan-African rocks. Nature 289, 278–282 (1981). https://doi.org/10.1038/289278a0

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