Geochemistry of microgranular enclaves and host granite from Telões (Vila Pouca de Aguiar), Northern Portugal |
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| Authors: | MEP Gomes |
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| Institution: | aDepartment of Geology, University of Trás-os-Montes and Alto Douro, 5000-911 Vila Real, Portugal |
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| Abstract: | At Telões, a subaluminous medium- to coarse-grained porphyritic biotite granite, crops out along the Vila Real NNE–SSW fault. It is a post-tectonic granite of 299±3 Ma old given by U–Pb isotopic data on zircon. It contains metaluminous to subaluminous tonalitic, granodioritic and monzogranitic enclaves. All granitoids have Fe2+-biotite and some enclaves contain magnesiohornblende and subsolidus actinolite. Monzogranitic enclaves show obvious similarities to the host granite. Linear array between enclaves and host granite is observed in Rb–Sr typical isochron diagram and gives the age of 286±11 Ma and (87Sr/86Sr)0=0.7063±0.0011. Microgranular enclaves have δ18O values similar to those of the hosting granite. Microgranular enclaves are hybrid rocks probably formed by mixing between a tonalitic enclave magma and a host granite magma as supported by the modelling of major and trace elements. The similar isotopic signatures suggest a subsequent partial equilibration of the enclaves and granite magmas. |
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| Keywords: | Granite Microgranular enclaves Hybrid rocks Isotopic equilibration |
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