Geochemistry and δ11B evolution of tourmaline from tourmalinite as a record of oceanic crust in the Tonian Ibaré ophiolite, southern Brasiliano Orogen.

Arena, Karine da RosaHartmann, Leo AfraneoLana, Cristiano de CarvalhoQueiroga, Gláucia NascimentoCastro, Marco Paulo de2021-08-162021-08-162020ARENA, K. da. R. et al. Geochemistry and δ11B evolution of tourmaline from tourmalinite as a record of oceanic crust in the Tonian Ibaré ophiolite, southern Brasiliano Orogen. Anais da Academia Brasileira de Ciências, v. 92, n. 1, p. e20180193, 2020. Disponível em: <https://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652020000100603>. Acesso em: 19 fev. 2021.1678-2690http://www.repositorio.ufop.br/jspui/handle/123456789/13483The 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 fi eld work with chemical analyses of tourmaline by electron microprobe (EPMA) and δ11B determinations via laser ablation inductively coupled plasma mass spectrometer (LA-ICP-MS). Remarkably massive tourmalinite (>90 vol.% tourmaline, some chlorite) enclosed in serpentinite has homogeneous dravite in chemical and isotopic composition (δ11B = +3.5 to +5.2‰). These results indicate a geotectonic environment in the altered oceanic crust for the origin of the tourmalinite. This fi rst δ11B characterization of tourmaline from tourmalinite sets limits to the evolution of the Neoproterozoic to Cambrian Brasiliano Orogen and Gondwana evolution.en-USabertoBoron isotopesGeochemistry and δ11B evolution of tourmaline from tourmalinite as a record of oceanic crust in the Tonian Ibaré ophiolite, southern Brasiliano Orogen.Artigo publicado em periodicoOs trabalhos publicados no periódico Anais da Academia Brasileira de Ciências, exceto onde identificado, estão sob uma licença Creative Commons que permite copiar, distribuir e transmitir o trabalho, desde que sejam citados o autor e o licenciante. Fonte: Anais da Academia Brasileira de Ciências <http://www.scielo.br/scielo.php?script=sci_serial&pid=0001-3765&lng=en&nrm=iso>. Acesso em: 23 jan. 2020.http://dx.doi.org/10.1590/0001-3765202020180193