Abstract

LOPEZ, José Francisco et al. Magmatismo siliceo y niveles de emplazamiento durante el paleozoico inferior en el área de Tajamar-Quebradas de Agua de Castilla y Cajón, Salta. Rev. Asoc. Geol. Argent. [online]. 2016, vol.73, n.3, pp.348-368. ISSN 0004-4822.

In the Tajamar and Agua de Castilla-Cajón region, Ordovician igneous rocks crop out. These rocks constitute an association of acid plutonic, subvolcanic and volcanic units. Here, we characterize their field relationship, petrography and geochemistry. In the Tajamar area, a porphyritic granite intrusion, in turn intruded by granodiorites and porphyric rhyolite rocks crops out. In Cajón, a syenogranitic plutonic body constitutes an isolated intrusion with respect to the other intrusions. In the canyons of Agua de Castilla and Cajón isolated bodies of sills, cryptodomes and vulcacanite mantle intercalated with Arenig-Llanvirn sedimentary sequences are observed. The development of peperites in the contact between the volcanic body and sedimentary rocks suggests a magmatic-sedimentary contemporaneity. The magmatic units have geochemical signature calkalcaline and peraluminous. There is a group with relative enrichment of FeOT and MgO, and depletion in CaO, with respect to Cordilleran calkalcaline batholites. The field relationships and geochemistry link these rocks to the Faja Eruptiva de la Puna Oriental magmatism. This magmatism started in the Tremadoc with a peak at 470 Ma, and is characterized by successive plutonic and subvolcanic intrusions and volcanic extrusions. We propose a model of multiple emplacements of silicic magmas in shallow crustal levels, during the evolution of the Famatinian orogen. The ascent of these magmas was favored by ductil deformation zones to the development of ordovician basins.

Keywords : Silicic magmatism; Emplacement levels; Early Paleozoic.

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