The Serrezuela Pluton: Carboniferous magmatic event in the northerm sector of the Sierra de Pocho, Córdoba, Argentina

Abstract

The Serrezuela granite is located at the Sierra de Serrezuela in the northern Sierra de Pocho, northwest Córdoba. It is a 16 km2 body, divided into two sectors by metamorphic outcrops. Structurally it is confined by several fractures related to major N-S regional lineaments. The Serrezuela pluton is composed of two main facies: biotite + muscovite monzogranite (BMM), and biotite tourmaline monzogranite (BTM). Both facies are calcalkaline peraluminous, with minor occurrences of a metaluminous biotite aplite. The BTM overlies the BMM facies with sharp contact, in a layer-like occurrence. The Serrezuela granitic stock is characterized by the presence of miarolitic cavities and widespread tourmalinization. A late quartz vein of considerable dimensions intrudes at the pluton boundary. Major element geochemistry shows some dispersion, whereas trace elements show a trend from biotite + muscovite monzogranite toward biotite tourmaline monzogranite. All rocks are strongly differentiated with the biotite + muscovite monzogranite being the least evolved and the most areally extended unit. A liquid fractionation mechanism is proposed for the differentiation and emplacement of the biotite tourmaline monzogranite. Changes in the foliation direction of the country rock, the presence of banded plagioclase and miarolitic cavities, suggests that the Serrezuela pluton had a forced emplacement into the country rocks at shallow crustal depth, along preexisting lineaments. Serrezuela pluton, is a Carboniferous K/Ar age granite (321± 7.4 Ma and 303± 2 Ma). It represents one of the youngest granitic magma pulses of this sector of the Eastern Sierras Pampeanas. This pluton is possibly recording the end of the magmatic cycle that generated the major neighboring Achala batholith and La Playa pluton under a collisional geotectonic regime.