Metasomatismo y potencial metalogenético de pegmatitas graníticas intruidas en rocas ultramáficas (Sierra de Comechingones, Córdoba)

MURATORI, MARÍA EUGENIA; DEMARTIS, MANUEL; CONIGLIO, JORGE ENRIQUE; ESTEBAN GUZMÁN, JOSÉ JULIÁN; BOFFADOSSI, MARÍA ALEJANDRA; MAFFINI, MARÍA NATALIA; D'ERAMO, FERNANDO JAVIER; PINOTTI, LUCIO PEDRO

Acta Geológica Lilloana

Fundación Miguel Lillo (Tucumán)

Lugar: San Miguel de Tucumán; Año: 2016 vol. 28 p. 235 - 240

0567-7513

Metasomatism and metallogenic potential of granitic pegmatites intruding ultramafic rocks (Sierra de Comechingones, Córdoba).In this contribution we present new geological data concerning granitic pegmatites that crop out in the eastern portion of the Sierra de Comechingones (Córdoba province) that have not been included into any other pegmatitic field of the Sierras Pampeanas. These pegmatites, with minor NYF features, belong to the LCT petrogenetic family. They intrude mostly within ultramafic and subordinately within metasedimentary rocks. They have tabular morphologies and frequent lobate contacts, and their dimensions do not exceed 10 m wide and 100 m long. When hosted in ultramafic rocks, at both sides of the pegmatite contacts a symmetric metasomatic zonation composed of vermiculite, phlogopite, tremolite-actinolite, chlorite and talc is invariably developed. Two alternatives are proposed to explain their origin. Firstly, fluids exsolved from the pegmatite melts lead to an intense geochemical exchange between pegmatites and ultramafic rocks generating these metasomatic zones, involving diffusion and infiltration mechanisms. Alternatively, rodingitization processes driven by circulation of fluids during serpentinization of the peridotites in the pegmatite-ultramafic rock boundaries are also proposed to explain such metasomatic zones. The special geological context of pegmatites intruding ultramafic rocks constitutes an ideal scenario for the occurrence of vermiculite, pink quartz, corundum and emerald, providing the study area with a particular metallogenic potential.