MORE SWEAT: DISCOVERY OF MESOPROTEROZOIC AND PALEOPROTEROZOIC IGNEOUS CRUST IN EAST ANTARCTICA STRENGTHENS THE CASE FOR LAURENTIA-ANTARCTICA CONNECTIONS IN RODINIA

Several lines of geologic evidence in East Antarctica support crustal-scale correlation with southwestern Laurentia: (1) εHf(i) and εNd(i) values of ~1.4 Ga A-type granitoid glacial clasts, and Hf isotopic compositions of ~1.4 Ga Antarctic-margin detrital zircons, match those in Laurentian granites of similar age, indicating the presence of granites in East Antarctica with the same age, geochemical properties, and isotopic signatures as the distinctive granite belt in Laurentia; (2) high-grade, lower-crustal metamorphism and magmatism of 1.73-1.72 Ga age reflects collisional assembly of pre-existing Neoarchean crust; (3) upper Neoproterozoic rift-margin siliciclastic rocks contain large populations of 1.8-1.6 and 1.2-0.9 Ga detrital zircons, indicating Paleo- and Mesoproterozoic igneous and/or metamorphic source terrains in East Antarctica; (4) the same rift successions have Nd-isotope compositions matching those in western Laurentia and 670-650 Ma intercalated volcanic rocks define similar depositional ages; (5) Nd-isotope compositions in basement and early Paleozoic granites define crustal-age provinces of 2.1-2.0, 1.9-1.6, ~1.4, and 1.2-1.1 Ga; (6) ~1.06 Ga metaigneous glacial clasts in East Antarctica reveal the presence of a previously unrecognized Grenville-age igneous province at the margin of older Proterozoic crust. New U-Pb zircon ages from a large suite of igneous clasts collected from broad glacial drainages crossing the Transantarctic Mountains further demonstrate that the crust in central East Antarctica was formed by a series of 2.00-1.90, 1.88-1.85, 1.75-1.73, 1.58-1.55, 1.48-1.43, and 1.20-1.10 Ga magmatic events. The dominant igneous populations are 1.85, 1.45 and 1.18 Ga, with some showing metamorphic overprinting at 1.15-1.18 Ga. Together, these disparate and unique lines of evidence indicate the presence in cratonic East Antarctica of a large, composite Proterozoic igneous province that reflects crustal growth across central East Gondwana, and they provide direct geologic support for the SWEAT reconstruction of Rodinia. The persistence of ~1.1 Ga Grenville-age igneous and metamorphic signatures in the interior may reflect the latest stages of Rodinia assembly, and may provide the best sampling to date of crust underlying the Gamburtsev Subglacial Mountains.