Isotope geochemistry and geochronology of the Nico Pérez Terrane,Rio de la Plata Craton,Uruguay |
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| Institution: | 1. Laboratório de Geologia Isotópica, Instituto de Geociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS 91501–970, Brazil;2. Research School of Earth Sciences, Australian National University, Canberra, ACT 0200, Australia;1. Departamento de Geologia Aplicada, Instituto de Geociências e Ciências Exatas, Universidade Estadual Paulista, Avenida 24A, 1515, Rio Claro, 13506-900, Brazil;2. Departamento de Petrologia e Metalogenia, Instituto de Geociências e Ciências Exatas, Universidade Estadual Paulista, Avenida 24A, 1515, Rio Claro, 13506-900, Brazil;3. Departamento de Ecologia e Biologia Evolutiva, Universidade Federal de São Paulo, Rua Prof. Artur Riedel, 275, Diadema, 09972-270, Brazil;4. Instituto de Geociências, Universidade Federal de Minas Gerais, Avenida Antônio Carlos, 6627, Belo Horizonte, 31270-901, Brazil;1. Instituto de Geociências, Universidade Federal do Rio Grande do Sul, Avenida Bento Gonçalves, 9500, 91501-970 Porto Alegre, Rio Grande do Sul, Brazil;2. Departamento de Geologia, Escola de Minas, Universidade Federal de Ouro Preto, Morro do Cruzeiro, 35400-000 Ouro Preto, Minas Gerais, Brazil;1. Instituto de Geociências, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves, 9500, Porto Alegre, RS CEP 91501-970, Brazil;2. Companhia de Pesquisa de Recursos Minerais, São Paulo, Rua Costa, 55, SP CEP 01304-010, Brazil;3. Instituto de Geociências, Universidade de Brasília, Campus Universitário Darcy Ribeiro, Brasília, DF CEP 70904-970, Brazil;1. Geoscience Centre, Goettingen University, Germany;2. Geosciences Institute, University of São Paulo, Brazil;3. Geosciences Institute, Federal University of Santa Catarina, Brazil |
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| Abstract: | U–Pb SHRIMP zircon geochronology, bulk-rock geochemistry, and Sr–Nd isotopic data are herein presented in order to better constrain the tectonic evolution of the Nico Pérez Terrane (NPT), Uruguay. The studies are focused on two key geological units located in the southern part of the NPT, namely Carapé Complex (CC) and Lavalleja Metamorphic Complex (LMC). The Carapé Complex, previously interpreted as part of a remnant magmatic arc, formed at 1.75 Ga mainly by partial melting of Archean crust (TDM model ages between 2.8 and 3.0 Ga with strong negative ?Nd (t) values). The Lavalleja Metamorphic Complex, previously interpreted as a back-arc basin, has volcanic units formed at 0.59 Ga during the Brasiliano Cycle, but may also contain older (Paleoproterozoic) units. The geochemistry of the LMC meta-igneous rocks indicates a complex scenario. Two distinct signatures have been recognized, one similar to MORBs and the other similar OIBs. Sm–Nd TDM model ages of basic rocks present a bimodal (Paleoproterozoic and Archean) distribution, which is also recognized in several other units of the NPT. In the light of new results, we conclude that the NPT represents a cratonic margin setting, characterized by the stacking of lithotectonic assemblages with Archean, Paleoproterozoic, and Neoproterozoic age at the margin of the Rio de la Plata Craton. |
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