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- Title
The anatomy of an albite-type granitic pegmatite from the Totoral pegmatite field, San Luis, Argentina.
- Authors
GALLISKI, Miguel Ángel; MÁRQUEZ-ZAVALÍA, María Florencia; ČERNÝ, Petr; OYARZÁBAL, Julio César; MUGAS LOBOS, Ana Cecilia
- Abstract
The Independencia Argentina albite-type granitic pegmatite is the most distal differentiate in the Cerro La Torre pegmatite group, located in the Eastern Pampean Ranges of Argentina. It is a zoned pegmatite formed at two main stages that probably shared the same origin but had separate evolutions. The product of the first stage was a pegmatite dominated by albite, quartz and muscovite, with rare K-feldspar and muscovite + albite pseudomorphs after spodumene, and accessory columbite-group minerals, beryl, fluorapatite and garnet. This first-stage pegmatite was emplaced forcefully and crystallized syn-kinematically. Resulting boudinage and necking-down produced the main body, bulbous in shape and asymmetric in zoning. This pegmatite was subsequently intruded by a melt that solidified to a very fine-grained, saccharoidal albite unit, composed in excess of 97 % by Ab99.1-99.6, with accessory columbite-group minerals and fluorapatite. The normative mineral composition of this unit corresponds very well with that of the experimental products of protracted fractionation of rare-element pegmatite melts, with high Na/K ratios and HFSE enrichment. The spatial and temporal association of the two pegmatitic melts, one enriched in H2O and the other one more evolved, Na-rich, almost alkaline and flux-bearing, strongly suggests that the two are cogenetic. They probably represent products of a rare-element pegmatite magma differentiation at depth that were extracted at different stages of its crystallization and emplaced at higher crustal levels.
- Subjects
SAN Luis (Argentina : Province); ALBITE; GRANITE; PEGMATITES; BIOLOGICAL evolution; MUSCOVITE
- Publication
Journal of Geosciences, 2015, Vol 60, Issue 1, p31
- ISSN
1802-6222
- Publication type
Article
- DOI
10.3190/jgeosci.187