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https://hdl.handle.net/1822/18619
Título: | Mantle and crustal sources in the genesis of late-hercynian granitoids (NW Portugal) : geochemical and Sr-Nd isotopic constraints |
Autor(es): | Dias, G. Simões, P. P. Ferreira, Narciso Leterrier, J. |
Palavras-chave: | Iberian peninsula Hercynian Hybrid granitoids Protoliths Geochemistry |
Data: | Abr-2002 |
Editora: | Elsevier 1 |
Revista: | Gondwana Research |
Resumo(s): | Large volumes of granitoids were emplaced in the Hercynian Central Iberian Zone during the last ductile deformation phase (D3, 300-320 Ma). The biotite-rich granitoids are the most abundant: (1) syn-D3 granodiorites-monzogranites (313-319 Ma) with calc-alkaline and aluminopotassic affinities; (2) late-D3 granodiorites-monzogranites (306-311 Ma), related to subalkaline and aluminopotassic series. These granitoids are associated with coeval gabbro-norite to granodiorite bodies and/or mafic microgranular enclaves. Both granitoids and basic-intermediate rocks show petrological, geochemical and isotopic evidence of interaction between felsic and mafic magmas. The mantle-derived melts, represented by shoshonitic gabbro-norites, were probably derived from an enriched and isotopically homogeneous source (Srl = 0.7049 to 0.7053, eNd= -2.1 to -2.5). In some syn- and late-D3 plutons there are evidences of essentially crustal granites, represented by moderately peraluminous monzogranites of aluminopotassic affinity. They have similar Nd model ages (1.4 Ga) but different isotopic compositions (Srl = 0.7089 to 0.7106, eNd= -5.6 to -6.8), revealing a heterogeneous crust. Potential protoliths are metasedimentary (immature sediments) and/or fclsic meta-igneous lower crust materials. Large amounts of hybrid magmas were generated by the interaction of these coeval mantle- and crust-derived liquids, giving rise to slightly peraluminous monzogranites/granodiorites of calc-alkaline and subalkaline affinities, which display more depleted isotopic compositions than the crustal end-members (Sr, = 0.7064 to 0.7085, eNd = -4.4 to -6.2). Petrogenetic processes involving mingling and/or mixing and fractional crystallization (at variable degrees) in multiple reservoirs are suggested. A major crustal growth event occurred in late-Hercynian times (305-320 Ma) related to the input of juvenile mantle magmas and leading to the genesis of composite calc-alkaline and subalkaline plutons, largely represented in the Central Iberian Zone. |
Tipo: | Artigo |
URI: | https://hdl.handle.net/1822/18619 |
DOI: | 10.1016/S1342-937X(05)70724-3 |
ISSN: | 1342-937X |
Versão da editora: | http://www.sciencedirect.com/science/article/pii/S1342937X05707243 |
Arbitragem científica: | yes |
Acesso: | Acesso aberto |
Aparece nas coleções: | CCT - Artigos (Papers)/Papers |
Ficheiros deste registo:
Ficheiro | Descrição | Tamanho | Formato | |
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2002_Dias et al_Gondwana.pdf | Documento principal | 2,2 MB | Adobe PDF | Ver/Abrir |