Geochronology,Nd isotopes and reconnaissance geochemistry of volcanic and metavolcanic rocks of the São Luís Craton,northern Brazil: Implications for tectonic setting and crustal evolution |
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| Authors: | Evandro L Klein Renê Luzardo Candido AV Moura Denise C Lobato Reinaldo SC Brito Richard Armstrong |
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| Institution: | 1. Institute of the Earth’s Crust, Siberian Branch of the Russian Academy of Sciences, ul. Lermontova 128, Irkutsk, 664033, Russia;2. Geological Institute, Russian Academy of Sciences, Pyzhevskii per. 7, 119017, Moscow, Russia;3. School of Earth and Environmental Sciences, Seoul National University, Seoul 151–747, Korea;4. Division of Earth and Environmental Sciences, Korea Basic Science Institute, Ochang 363–883, Korea;1. A.P. Vinogradov Institute of Geochemistry, Siberian Branch of the Russian Academy of Sciences, ul. Favorskogo 1a, Irkutsk, 664033, Russia;2. Institute of Earth’s Crust, Siberian Branch of the Russian Academy of Sciences, ul. Lermontova 128, Irkutsk, 664033, Russia;3. Far Eastern Federal University, ul. Sukhanova 8, Vladivostok, 690950, Russia;4. V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia;5. Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090, Russia;6. Institute of Earth Sciences, Academia Sinica, 128, Academia Road, Sec. 2, Nangang, Taipei, 11529, Taiwan;7. Institute of Geology, Komi Science Center, Ural Branch of the Russian Academy of Sciences, ul. Pervomaiskaya 54, Syktyvkar, 167982, Russia;1. UA Petrología Experimental, CSIC-Universidad de Huelva, Facultad de Ciencias Experimentales, 21071 Huelva, Spain;2. Department of Geology, Payame Noor Universtiy, PO Box 19395-3697, Tehran, Iran;3. CiCEGE, Departamento de Ciências da Terra, Universidade Nova de Lisboa, Portugal;1. Department of Geology, Presidency University, 86/1 College Street, Kolkata 700073, West Bengal, India;2. Department of Geology and Geophysics, Indian Institute of Technology, Kharagpur, India;3. Centre for Earth Sciences, Indian Institute of Science, Bengaluru, India |
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| Abstract: | New field work, in addition to zircon geochronology, Nd isotopes and reconnaissance geochemical data allow the recognition of Paleoproterozoic volcanic and metavolcanic sequences in the São Luís Craton of northern Brazil. These sequences record at least five volcanic pulses occurring probably in three distinct epochs and in different tectonic settings. (1) The Pirocaua Formation of the Aurizona Group comprises early arc-related calc-alkaline metapyroclastic rocks of 2240 ± 5 Ma formed from juvenile protoliths in addition to minor older crustal components. (2) The Matará Formation of the Aurizona Group holds mafic tholeiitic and ultramafic metavolcanic rocks of back arc and/or island arc setting, which are likely coeval to the Pirocaua Formation. (3) The Serra do Jacaré volcanic unit is composed of tholeiitic basalts and predominantly metaluminous, normal- to high-K calc-alkaline andesites of 2164 ± 3 Ma formed in mature arc or active continental margin from juvenile protoliths along with subordinate older (Paleoproterozoic) materials and associated to the main calc-alkaline orogenic stage. (4) The Rio Diamante Formation consists of late-orogenic metaluminous, medium-K, calc-alkaline rhyolite to dacite and tuffs of 2160 ± 8 Ma formed in continental margin setting from reworked Paleoproterozoic crust (island arc) with incipient Archean contribution. (5) The Rosilha volcanic unit is composed of weakly peraluminous, medium-K, calc-alkaline dacite and tuff formed probably at about 2068 Ma from reworked crustal protoliths. As a whole the volcanic and metavolcanic rocks record and characterized better the previously proposed orogenic evolution of the São Luís Craton. |
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