CONICET | Buscador de Institutos y Recursos Humanos

ABSTRACT. The Pampean Pegmatitic Prouince. 1: Tipology and distribution of its economic fields. The Pampean PegmatiticProvince ranges from 24°30´ S to 33°30´ S in northwestern Argentina. It comprises more than 95% of the pegmatitic mineralresources of the country. Since 1930 its pegmatites have been mined producing in excess of 25,000 t beryl, 45 t Nb-Ta ore, 1,000t Li minerals, Bi, U, mica, feldspars and quartz. This paper reviews the gealogy and tipology of its different economic {leida. Thepegmatites are classified in muscovite and rare element classes. The muscovite class pegmatitic fields are from cloral to south:Centenario, Quilmes, Ambato, Valle Fértil and Alta Gracia. They are placed in medium grade, medium pressure metamorphicrocks. These pegmatites are tabular, 200 m long, 2-10 m wide bodies, bearingmuscovite in theirintermediate zones. K-Ar agesshow a range from the Upper Precambrian to the Lower Silurian. The rare element pegmatite fields of LCT signature are: CerroBlanco, El Quemado, Calchaquf, Ancasti, Sierra Brava, Comechingones, Altautina, La Estanzuela, Conlara and Totoral. Theyforman 800 km long by 30-100 km wide segmented belt that runs parallel, eastward of the main muscovite clase fields. Thesepegmatites are placed in greyschists and gneisses of an Abukuma-type metamorphic belt. The most common pegmatite typesare: (1) beryl type in which both beryl-columbite and beryl-columbite-phosphate subtypes are present, (2) complex-type,spodumene-subtype, and (3) albite-spodumene type. Albite-type and lepidolite-subtype pegmatites are acaree. The pegmatitesof this belt have Cambrian-Ordovician K-Ar ages. The rare element pegmatite fields of mixed LCT-NYF signature are VelascoandPunilla. Theycontain beryl-columbite-phosphate subtype, rare element class pegmatites, placed in -or near- epizonal, high-K calcalkaline granitoids of Lower Carboniferous ages

enviar mensaje