A mid-Cretaceous age for the Palmer Land event, Antarctic Peninsula: implications for terrane accretion timing and Gondwana palaeolatitudes

Abstract

New structural and age data suggest that West Gondwana may have been at lower palaeolatitudes than previously interpreted from Albian sequences in Gondwana marginal suspect terranes. The Palmer Land event, which juxtaposed Mesozoic terranes on the Gondwana margin, deformed granitoids in the southern Antarctic Peninsula. U-Pb SHRIMP dating of zircons from a microgranite dyke yields a crystallization age of 106.9 ± 1.1 Ma. This result and re-interpretation of the structural position of another granite pluton date the Palmer Land event, and probable terrane collision, as late Early Cretaceous, and not latest Jurassic as formerly interpreted.