Geochemistry and δ11 B evolution of tourmaline from tourmalinite as a record of oceanic crust in the Tonian Ibaré ophiolite, southern Brasiliano Orogen.

The isotopic and geochemical evolution of tourmaline constrain the processes of paleo-oceanic lithosphere in ophiolites. The Brasiliano Orogen is a major structure of South America and requires characterization for the understanding of Gondwana supercontinent evolution. We made a pioneering investigation of tourmaline from a tourmalinite in the Ibaré ophiolite by integrating field work with chemical analyses of tourmaline by electron microprobe (EPMA) and δ11B determinations via laser ablation inductively coupled plasma mass spectrometer (LA-ICP-MS).