https://repositorio.ufba.br/handle/ri/5103
Tipo: | Artigo de Periódico |
Título: | The 2-Ga peraluminous magmatism of the Jacobina- Contendas Mirante belts (Bahia, Brazil) Geologic and isotopic constraints on the sources |
Título(s) alternativo(s): | Chemical Geology |
Autor(es): | Sabaté, Pierre Marinho, Moacyr M. Vidal, Philippe Vachette, Michelle Caen |
Autor(es): | Sabaté, Pierre Marinho, Moacyr M. Vidal, Philippe Vachette, Michelle Caen |
Abstract: | A 500-km north-south alignment of granitic intrusions cross-cuts the central part of the Silo Francisco craton. These late- to post-tectonic granitic bodies are emplaced between two Archean blocks (Jequié and Gaviio blocks) and cross-cut the Contendas Mirante volcano-sedimentary sequence and the metasedimentary rocks of the Serra de Jacobina. They are two-mica or muscovite-garnet-bearing peraluminous granites. Rb-Sr systematics show that these granites were emplaced during the Transamazonian orogeny ( ~ 1.9 Ga). The high initial STSr/86Sr ratios (0.706-0.748) and the very low £'Nd(t) ( -- 13 to -5) indicate a crustal origin. The possible sources are: ( 1 ) the Jequi6 block; (2) the Contendas Mirante sequence; and (3) the Gaviio block, including some early Archean domes [trondhjemitie-tonalitic-granodioritic (TTG), Boa Vista type ] which were tectonically emplaced within the volcano- sedimentary sequence. The currently available Rb--Sr and Sm-Nd data are not consistent with reworking of the 3.5-Ga TTG. The combination of field and isotopic constraints preclude the Jequi~ block and the Contendas Mirante sequence and favour instead the Gaviio block medium-grade terrains as the source for the peraluminous granitic line. The available data suggest that a continent-continent collision occurred during the Transamazonian orogeny, which followed subduetion/obduction marked by volcanism (are-tholeiitic, calc-alkaline and shoshonitic) and related plutonism. |
URI: | http://www.repositorio.ufba.br/ri/handle/ri/5103 |
Data do documento: | 1990 |
Aparece nas coleções: | Artigo Publicado em Periódico (IGEO) |
Arquivo | Descrição | Tamanho | Formato | |
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s2.0-000925419090288I-main.pdf | 1,23 MB | Adobe PDF | Visualizar/Abrir |
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