Paper No. 120-8
Presentation Time: 10:25 AM
A PALEOARCHAEAN CRATONIC NUCLEI NEIGHBORING THE ARCHAEAN VESTFOLD BLOCK, EAST ANTARCTICA: IMPLICATION FOR RECONSTRUCTIONS OF COLUMBIA AND RODINIA
In this presentation we provide systemic investigation of erratic rocks and sands in the Vestfold Hills, East Antarctica and new results to demonstrate that there must be an Archaean terrane with a Paleoarchaean cratonic nuclei neighboring the Vestfold Hills and the Rauer Group, East Antarctica. U-Pb ages of 14 samples from the southeastern and eastern Vestfold Hills, plus 26 sites of glacial erratic statistics demonstrate that the Archean terrane can be old in age up to 3533±8 Ma, which is the oldest terrane known in Antarctica and could be a provenance for the eastern Rauer Group high-grade metasedimentary rocks with Archean components. Two metamorphic trondhjemite clasts have prismatic igneous zircons and yield concordia cyrstalization ages of 3350 ± 6 Ma and 3380 ± 18 Ma, respectively. The εHf(t) values for the zircons of the trondhjemite clasts are predominantly negative although a few low negative values; and the two-stage Hf model (TDM2) ages of the zircons from the trondhjemite are between 3.6–4.2 Ga, demonstrating the trondhjemite having been derived from the remelting of older crustal protoliths. The Ar-Ar dating analyses on amphibole defined Pan-African ages of 585 ± 5 Ma and 522 ± 3 Ma for the two samples, reflecting the timing of the Pan-African (garnet)-epidote-amphibolite facies metamorphism. The results support the existence of ancient Paleoarchaean continental crust under the East Antarctica icecap, and provide new constraints on the reconstruction of the ancient supercontiments involving Columbia and Rodinia.