ANTUNES, I.M.H.R. ; NEIVA, A.M.R. SILVA, M.M.V.G. (2003) - Geoquímica das rochas graníticas, seus feldspatos e micas da região de Segura, Centro de Portugal. In Congresso Ibérico de Geoquímica, 4. Semana de Geoquímica, 13, Coimbra, 14-18 de Julho - Resumos. Coimbra : Universidade de Coimbra. 3 p. Comunicação.
Title
Geoquímica das rochas graníticas, seus feldspatos e micas da região de Segura, Centro de Portugal
Subject
Rocha granítica Feldspato Mica
Date
2011-08-02T14:21:31Z 2011-08-02T14:21:31Z 2003
Description
At Segura, tin-bearing Hercynian two-mica granite, muscovite granite and aplite and granitic pegmatite veins and also granodiorite porphyry veins intruded the Cambrian schist-metagraywacke complex but aplite and pegmatite also intruded the granites. Variation diagramas of most major and trace elements of the rocks and muscovites show fractionation trends from muscovite granite to aplite and that the two granites are not related. They probably have origin in two distinct granite magmas derived from the muscovite granite by fractional crystallization of K-feldspar, quartz and ilmenite. Feldspars from this granite and aplite are the richest in P2O5 but K-feldpars retains the highest value. Variation diagramas of rocks and biotites and compositions of plagioclases show that granodiorite porphyry veins are not related. Variation diagrams of muscovites show fractionation trends from two-mica granite to pegmatite containing lepidolite, which replaces muscovite.
