Petrogenesis of Peraluminous Granites from the Fosdick Mountains, Marie Byrd Land, West Antarctica

Abstract

Granites from the Fosdick Mountains, West Antarctica were analyzed for major and trace elements as well as Sr-Nd isotopes ratios in order to investigate the sources and processes associated with granite formation at a former convergent margin. U-Pb ages from zircon separates are consistent with previous results and yield ages of ~360 Ma and ~100Ma. Major and trace elements indicate that paragneiss and orthogneiss samples are the high-grade equivalents of the Swanson Formation and the Ford Granodiorite site. Granites produced from the Devonian-Carboniferous melting event are derived primarily from the Ford Granodiorite suite while granites produced from the Cretaceous melting event are derived from melting of the Ford Granodiorite suite or mixing between the two putative sources. Cretaceous granites show evidence of early crystallized minerals. There is no chemical evidence for a source other than the Ford Granodiorite suite or the Swanson Formation.