Abstract

SARDI, Fernando Guillermo; HEIMANN, Adriana  and  SARAPURA MARTINEZ, Janet. Geología local y mineralogía accesoria de las pegmatitas berilíferas del Distrito Velasco y rocas graníticas asociadas , Provincia Pegmatítica Pampeana , Noroeste de Argentina. Ser. correl. geol. [online]. 2015, vol.31, n.1. ISSN 1666-9479.

A study of the internal structure of the pegmatites and its mineralogy and associated gra-nitic rocks from the Velasco district of the Pampean Pegmatite Province (Argentina) is presented. The pegmatites belong to the Rare Elements class, beryl type, beryl-columbite-phosphate subtype. They have spatial and genetic relationship to Carboniferous A-type granites. The pegmatites have ellipsoidal, elongated and semi-circular morphologies, being the major axis/minor axis ratio between 1 and 4.7. The direction of the major axis is variable for each pegmatite. The zoning is simple. From the outside inwards, the following internal zones could be recog-nized in the pegmatites: border zone, intermediate zone and quartz core. The graphic and pertitic microcline of the intermediate zone is replaced by plagioclase in some pegmatites. The accessory mineralogy is: for the parental granites, biotite, muscovite, apatite, fuorite, zircon, ilmenite, magnetite, uraninite and xenotime; for the border of the pegmatites, muscovite, biotite, apatite, zircon, monazite, fuorite, columbite-tantalite, ilmenite, rutile, pyrite, chalcopyrite, thorite; and for the intermediate zone, muscovite, biotite, beryl, apatite, triplite, tourmaline, garnet.

Keywords : Internal structure; Zoned pegmatites; Intragranitic pegmatites. Velasco District.

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