Geoquimica da biotite de rochas plutonicas  [Geochemistry of biotite in plutonic rocks]

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Alternate Title:Geochemistry of biotite in plutonic rocks
Authors:Neiva, A. M. R.
Author Affiliations:Primary:
Univ. Coimbra, Mus. e Lab. Mineral. e Geol., Coimbra, Portugal
Volume Title:Memorias e Noticias, Publicacoes do Museu e Laboratorio Mineralogico e Geologico da Universidade de Coimbra
Source:Memorias e Noticias, Publicacoes do Museu e Laboratorio Mineralogico e Geologico da Universidade de Coimbra, Vol.99, p.85-126. Publisher: Universidade de Coimbra, Museu e Laboratorio Mineralogico e Geologico, Coimbra, Portugal. ISSN: 0870-0397
Publication Date:1985
Note:In Portuguese. 56 refs.; illus. incl. 9 tables
Summary:Several factors control the variation trends of major and trace elements in the biotite of calc-alkaline rock series. Where fO2 is important, the trends differ according to whether it increases or decreases with T. There are links between the chemical composition of biotite, its paragenesis and the rock type in which it occurs. The biotite of calc-alkaline rocks can be distinguished from that in hybrid granitic rocks by: 1) Fe2O3 and Rb content, 2) variation trends in F, Gd, Pr, La, SIGMA Ce, SIGMA REE, and 3) thermodynamic conditions of crystallization. The biotite of Portuguese hybrid granitic rocks crystallized in metamorphic-metasomatic conditions. The biotite of S-type granites differs from that of I-types in that it has more Al2O3 and Li, and less Ba; in Caramulo and Gerez it has less Mg and F, and more Fe and Cl. Its high Sn content indicates the possibility of related tin and tungsten deposits. Although Cl is higher and Cu lower in the biotite of Cu-bearing granitic rocks, the difference is not enough to be a useful indicator of Cu mineralization. [R.E.S.]
Subjects:Biotite; Chemical composition; Igneous rocks; Mica group; Mineral composition; Petrology; Plutonic rocks; Sheet silicates; Silicates; Europe; Iberian Peninsula; Portugal; Southern Europe; Brufe-Gemesura tunnel; Caramulo; Gerez
Abstract Numbers:87M/4324
Record ID:1989031728
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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