Host: Japan Association of Mineralogical Sciences
The Fosdick Mountains of Marie Byrd Land, West Antarctica host subordinate migmatitic gneisses corresponding to the middle-to-lower crust (∼6-10 Kbar) and dominant granites. Based on petrography and geochemistry the granites are divided into silimanite-bearing low-Sr and silimanite-free high-Sr types. U-Pb geochronology on magmatic zircon from the granites reveals two periods of emplacement during Carboniferous and Cretaceous, consistent with a polyorogenic evolution of the region during Devonian-Carboniferous continental arc activity and Cretaceous continental rifting. The Cretaceous high-Sr granites, with U-Pb zircon ages and Sr-Nd isotope compositions comparable to the Cretaceous Byrd Coast Granite suite, are interpreted as a feeder zone for the shallow-level intrusions.
