Monday, 27 August 2007 - 4:00 PM
1.P2.C-2
Jurassic silicic volcanism in the Transantarctic Mountains: was it related to plate margin processes or to Ferrar magmatism?
David H. Elliot1, T.H. Fleming2, K.A. Foland1, and C.M. Fanning3. (1) School of Earth Sciences, Ohio State University, 125 South Oval Mall, Columbus, OH 43210, (2) Earth Sciences, Southern Connecticut State University, New Haven, CT 06515, (3) Research School of Earth Sciences, Australian National University, Canberra, ACT 2000, Australia
Silicic volcanism in the Transantarctic Mountains , represented by rhyolitic tuff that mainly precedes emplacement of the Ferrar Large Igneous Province , is important in interpretation of the tectonic evolution of the Antarctic sector of Gondwana. Sr and Nd isotope data indicate that the tuffs are not directly related to Ferrar magmatism nor to melting of the underlying Ross orogen crust yet zircon gives a U-Pb age of 182.7±1.8 Ma, similar to the U/Pb age for the Ferrar. Distribution of the silicic tuffs along 1400 km of the Transantarctic Mountains suggests, alternatively, a relationship to the Gondwana plate margin. Although West Antarctica comprises Mesoproterozoic crustal terrains, few analyzed rocks are compatible isotopically with the Lower Jurassic tuffs. The source of the tuffs must lie in unexposed Early Jurassic magmatic centers in West Antarctica or an unexposed crustal terrain beneath the Transantarctic Mountains.