Temporal, isotopic and spatial relations of early Paleozoic Gondwana-margin arc magmatism, Central Transantarctic Mountains, Antarctica

The Cambrian^Ordovician Ross Orogeny in Antarctica produced a voluminous magmatic belt composed mainly of post-orogenic granit-oids.This magmatic belt has strong calc-alkaline characteristics re-flecting a convergent-margin origin associated with subduction of paleo-Pacific oceanic lithosphere beneath cratonic East Antarctica. However, it is unclear how and when magmatism began, and to what degree magmatism was associated with syn-orogenic deform-ation and intra-arc extension. New U^Pb zircon ages, and whole-rock geochemical and Sr^Nd isotope data for granitoids sampled along a transect across the Ross Orogen in the Nimrod Glacier area of the central Transantarctic Mountains provide con-straints on the timing, spatial variation, and origin of the magma-tism in this area. This transect is one of the few places where the orogenic arc extends into the East Antarctic cratonic basement, thus helping to constrain both craton and arc evolution. New U^Pb age