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Distribution of trace elements in feldspars of granitic aplites and pegmatites from Alijó-Sanfins, northern Portugal

Published online by Cambridge University Press:  05 July 2018

A. M. R. Neiva
A. M. R. Neiva*
Affiliation:
Department of Earth Sciences, University of Coimbra, 3000 Coimbra, Portugal
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Abstract

At Alijó-Sanfins there are many granitic aplite and pegmatite veins crosscutting different petrographic facies of the Hercynian granite batholith and also mica-schists. They are tin-bearing granitic rocks. Thirty-four samples of K-feldspar and 34 of albite from these veins and host granites were analysed to establish the distribution of elements and their fractionation trends in the sequence of feldspar crystallization. Rubidium and Cs increase, and Ba, Sr, Ba/K, Sr/K and K/Rb decrease in K-feldspar, whereas Na increases and Sr and Ca decrease in albite, from granites to aplites and pegmatites. In a few aplite-pegmatite veins Rb, Rb/Ba and Rb/Sr increase and Ba, Sr, K/Rb and Ba/Sr decrease in K-feldspar, and Rb increases and Sr decreases in albite from aplite to coexisting pegmatite. Equilibrium was not attained for trace elements between coexisting feldspars.

Keywords

K-feldsparalbitegranitic pegmatiteaplitetrace elements
Type
Mineralogy
Information
Mineralogical Magazine , Volume 59 , Issue 394 , March 1995 , pp. 35 - 45
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1995

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