Geología y geocronología de las intrusiones laminares e irregulares predevónicas del sector central de las Sierras de Córdoba

BOFFADOSSI, M. ALEJANDRA; PINOTTI, LUCIO; MAFFINI, M. NATALIA; DEMARTIS, MANUEL; MURATORI, M. EUGENIA; D'ERAMO FERNANDO; CONIGLIO, JORGE; RADICE, STEFANÍA

Revista de la Asociación Geológica Argentina

Asociación Geológica Argentina

Lugar: Buenos Aires; Año: 2020 vol. 77 p. 551 - 570

1669-7316

A large amount of igneous intrusions hosted by a gneissic-migmatic metamorphic basement crop out in the central-north part of the Sierra Chica and eastern boundary of the Sierra Grande de Córdoba. In this contribution, five igneous lithologies were identified and grouped into two distinctive rock groups according to their morphologies, rheology and field relationships. The first group includes irregular-shaped monzogranites, tonalites and pegmatites (called type-I), having lobate and diffuse contacts with their surrounding host rocks. Field relationships suggest that these intrusions originated from crustal anatexis processes of different protoliths, correlated with similar processes occurred during the Pampean Orogeny. The second group includes laminar-shaped (dykes) tonalite-trondhjemites and pegmatites (called type-II), having straight and sharp contacts with their host rocks. They are spatially associated with narrow and localized shear zones stabilized in amphibolite facies. These igneous rocks invariably crosscut the irregular-shaped intrusives of the first group as well as gneissic and migmatic metamorphic host rocks of the basement, clearly reflecting a younger age of emplacement. According to their field relationships, their syn-kinematic emplacement with shear zones (stabilized in amphibolite facies) and 40Ar/39Ar ages obtained in this work (450.92 ± 1.41 Ma and 434.53 ± 3.16 Ma), the laminar-shaped intrusions of the second group would have been generated and emplaced during the Famatinian Orogeny.