New 40Ar/39Ar ages and revised 40K/40Ar* data from nephelinitic–phonolitic volcanic successions of the Trindade Island (South Atlantic Ocean)

• Published in: Journal of Volcanology and Geothermal Research
• Main Authors: Pires, C., Bongiolo, E.M., Geraldes, C., Renac, C., Santos, A.C., Jourdan, F., Neumann, R.
• Other Authors: programa de pos-graduacao em geologia, insituto de geociencias, universidade federal do rio de janeiro, Universidade do Estado do Rio de Janeiro - Faculdade de Geologia, Géoazur (GEOAZUR 7329), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD France-Sud ), Western Australian Argon Isotope Facility (WAAIF), The Institute for Geoscience Research Perth (TIGeR), School of Earth and Planetary Science Perth - Curtin university, Curtin University Perth -Curtin University Perth -School of Earth and Planetary Science Perth - Curtin university, Curtin University Perth -Curtin University Perth, Centre for Mineral Technology (CETEM), Ministère de la Science et Technologie
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2016
• Subjects: [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; Morro; South Atlantic Ocean
• Online Access: https://hal.science/hal-01527342; https://doi.org/10.1016/j.jvolgeores.2016.09.020

International audience The Trindade Island is located in the South Atlantic Ocean, 1170 km from the Brazilian coast and represents the eastern end of the submarine E–W Vitória–Trindade Chain. This is interpreted as the Trindade plume track beneath the South American plate during the Cenozoic. Almeida (1961) recognized five volcanogenic successions at Trindade in decreasing age: the Trindade Complex (TC) and the Desejado (DF), Morro Vermelho (MV), Valado (VF) and Paredão (PF) formations, composed of nephelinitic to phonolitic effusive-pyroclastic deposits, dykes and necks. Here, we present new 40Ar/39Ar ages and re-evaluation of available 40K/40Ar* data that, coupled with previous petrological information, allowed us to reconstruct the volcanic history of the island (i.e., 3.9–0.25 Ma) distinguishing near synchronous volcanic episodes and solving several stratigraphic uncertainties reported in the literature.The geochronological dataset show that the nephelinitic–phonolitic volcanism at Trindade was discontinuous throught time, being marked by periods of high volcanic activity and periods of quiescence, which suggests variable melt production and eruption rates. The peak of the volcanic activity occurred between 3.9 and 2.5 Ma (i.e., Lower Pliocene to Lower Pleistocene) that is represented by the TC, which correspond to the largest volume of volcanic deposits preserved in the island. The volcanic activity slows down progressively from 2.5 Ma to cease at ca. 1.6 Ma, period that is represented by the DF. This volcanism was followed by a quiescent period that lasted until the ephemeral nephelinitic volcanism of the MV (no age), VA (no age) and PF (ca. 0.25 Ma). Thus, the volcanic activity in Trindade was ceased completely at ca. 0.25 Ma, event registered in the uppermost volcanic deposits of the PF and that represents the last volcanic activity in the Brazilian territory.