The Neogene Barril Niyeu Volcanic Complex. Somún Curá Magmatic Province. Northern Extra Andean Patagonia. Argentina

SALANI, F. M.; REMESAL M. B; CERREDO, M.E.

Mar del plata

Conferencia; INTERNATIONAL GEOLOGICAL CONGRESS ON THE SOUTHERN HEMISPHERE 2010; 2010

INTERNATIONAL GEOLOGICAL CONGRESS ON THE SOUTHERN HEMISPHERE

The mainly Oligocene (25-28Ma) Somún Curá basaltic plateau covers about 25000 km2 in the north of Extra Andean Patagonia (Argentina, Fig. 1). Several eruptive centers of different complexities were built over the basaltic plateau during Late Oligocene-(Early) Miocene which, according to the wide compositional and eruptive diversity may be grouped in two main types: a) large bimodal complexes and b) monogenetic eruptive centers. The former are characterized by their alkaline nature associated with a typical gap in the ~ 53-60% SiO2 range. Most of the large bimodal complexes are aligned along a WNW-ESE trending belt (Fig. 1). A prominent transcurrent fault of roughly WNW-ESE orientation was identified offshore the northern Extra Andean Patagonia (Urien and Zambrano, 1996), where it bounds the Cenozoic Valdez and Rawson basins. On land, the Telsen fault (Ciciarelli, 1990), and further W the alignment of large bimodal complexes, might represent the continuation of this major onshore-offshore wrench structure. From NW to SE: Agua de la Piedra, Pire Mahuida, Barril Niyeu, Talagapa, Apas and Telsen volcanic complexes (Salani et al, 2008) form a fairly well defined mountain chain which cuts across the main Somún Curá plateau