U-Pb zircon and Sm-Nd isotopic study of the Huangtuling granulite, Dabie-Sulu belt, China : Implication for the paleoproterozoic tectonic history of the Yangtze Craton

Abstract

SIMS data demonstrate Archean (2.9 to 2.7 Ga) and Paleoproterozoic (1991 ± 43 Ma) ages for rounded detrital zircon cores and unzoned rims respectively in a graulite sample collected from Huangtuling, Dabie-Sulu orogenic belt, China. The granulite rocks in this locality have pelitic compositions and represent an exposure of the northern margin of the Yangtze Craton. The rounded zircon cores show oscillatory zoning and have Th/U ratios (0.17 - 0.78) systematically higher than those of the unzoned luminescent rims (0.005 - 0.03). The age of the detrital zircon cores and whole rock Nd isotope model age suggest that the Huangtuling granulite was possibly derived from a provenance dominated by Archean rocks similar to the Kongling Complex exposed 200 km in the southwest. Multiple phases of metamorphism have been identified for the granulites, with the dominant granulite-facies mineral assemblage, defining an early clock-wise metamorphic P-T path. Orthopyroxene, plagioclase and whole-rock material define a linear trend in a 147Sm/ 144Nd - 143 Nd/ 144Nd diagram, corresponding to an age of 1926 ± 146 Ma. This result and the U-Pb data for the zircon rims suggest that a collisional event may have occurred along the northern margin of the Yangtze Craton at ∼2.0 Ga, inviting further study on whether the Yangtze Craton was involved in the assembly of the recently-proposed Paleo-Mesoproterozoic supercontinent Columbia.