Geochemistry of chlorite and biotite from contact metamorphism of phyllite by granites

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Authors:Neiva, A. M. R.
Author Affiliations:Primary:
Univ. Porto, Dep. Mineral. Geol., Porto, Portugal
Corporate Authors:Portugal, Universidade de Coimbra, Museu e Laboratório Mineralógico e Geólogico, Coimbra 3049
Volume Title:2<sup>e</sup> Encontro Nacional de Geociencías
Source:Memorias e Noticias, Publicacoes do Museu e Laboratorio Mineralogico e Geologico de Universidade de Coimbra, Vol.91-92, p.113-134; 2>e`Encontro nacional de geociencias, Coimbra, Portugal, Oct. 26-30, 1981, Portugal, Universidade de Coimbra, Museu e Laboratório Mineralógico e Geólogico, Coimbra 3049. Publisher: Universidade de Coimbra, Museu e Laboratorio Mineralogico e Geologico, Coimbra, Portugal. ISSN: 0373-6474
Publication Date:1981
Note:In English with Portuguese summary. 18 refs.; illus. incl. 55 anal., 6 tables
Summary:In the Alijo-Sanfins area of central N Portugal, regionally metamorphosed phyllites have been intruded by granites, producing a contact-metamorphic aureole; the chemistry of the rocks (10 major-element analyses) is discussed briefly. Major-, trace- and RE-element analyses for 7 chlorites and 12 biotites, from the country rocks and the outer and inner zones of contact metamorphism, show that with increased grade of metamorphism the chlorites are enriched in Si, Ti and K and impoverished in Al, Mg, Cr, V, Zn, Ni, Co, Sc and Er; the biotites are enriched in Si, Ti, Fe2+, K and H2O+ and impoverished in Al, Mg, Cr, V, Ni, Co and Ce - these changes being attributed to increase in T. Metasomatism is considered to be responsible for the enrichment of chlorite in Cl, F, Nb, Sn, Li, Ba, Rb, Tl and Cs, and of biotite in Cl, F, W, Nb, Zn, Sn, Li, Sc, Er, Y, Gd, Nd, Pb, Ba, Rb, Tl and Cs. The T of metamorphism is estimated from the biotite compositions as 450°C in the outer zone and 500°C in the inner zone. [R.A.H.]
Subjects:Biotite; Chlorite group; Contact metamorphism; Geochemistry; Gneisses; Granites; Igneous rocks; Intrusions; Major elements; Metagraywacke; Metamorphic rocks; Metamorphism; Metasedimentary rocks; Mica group; Phyllites; Plutonic rocks; Schists; Sheet silicates; Silicates; Trace elements; Variscan Orogeny; Europe; Iberian Peninsula; Portugal; Southern Europe; Vila Real Portugal
Abstract Numbers:84M/3159
Record ID:1986046887
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom, Reference includes data from PASCAL, Institute de l'Information Scientifique et Technique
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