Abstract

LOPEZ, José P; BELLOS, Laura  and  CASTRO, Antonio. The La Ovejería Tonalite is a N-Selongated body thatcrops outon the eastern side of the Sierra delAconquija, westof of Tafi delValle, Tucumán Province, Argentina. Ser. correl. geol. [online]. 2012, vol.28, n.1, pp.73-82. ISSN 1666-9479.

It is located just south of the larger, and probably genetically related, El Infiernillo Granodiorite . The studied pluton has a zoning determined by different grain sizes and mineralogies: the northern outcrops are medium-grained and composed of plagioclase, quartz scarce microcline, and biotite and pistacite (± tourmaline) as major accessories; the southern part of the intrusive is fine grained and composed of plagioclase, quartz scarce microcline, and biotite and sphene as accessory minerals. Two meter thick granitic dikes cross-cut the tonalites. The tonalite is calc-alkaline and peraluminous, with an ASI between 1.10 and 1.48. It intrudes metamorphic basement rocks composed of low grade schists that are characterized by an increase in static metamorphism, by syntectonic intrusions and by the intensity of flow folds. The emplacement of the La Ovejería Tonalite probably occurred during the Lower Paleozoic and was structurally controlled by the Tafi Megafracture, like the other intrusive bodies of the area. The El Infiernillo intrusive is composed of a two-mica (± tourmaline) equigranular granodiorite main facies and a biotite and epidote bearing (without primary muscovite) tonalitic border facies. According to field relations and petrographic, geochemical and structural data, the La Ovejería Tonalite may correspond to the northern border facies of the El Infiernillo intrusive.

Keywords : Petrography; Geochemistry; La Ovejeria Tonalite; El Infiernillo Granodiorite; Sierra del Aconquija.

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