Pire Mahuida volcanic field: a bimodal complex in northern Patagonia. Argentina.

SALANI, F. M.

Nisyros, Grecia

Workshop; IAV-Nisyros Volcanology School; 2009

Italian Association of Volcanology - National and Kapodistrian University of Athens and the Institute of Geology and Mineral Exploration of Greece.

The Pire Mahuida Complex (PMC), located in the extra Andean region of the southern part of Argentina, is a bimodal volcanic field developed during Miocene times, likely related to an extensional regime. The complex covers about 800 km2 and shows a volume of 100 km3. It makes the bulk of the 60 km long-20 width of the Sierra Pire Mahuida (68º 30´W, 42ºS, figure 1). The PMC is the westernmost of the post-shield complexes (i.e. Apas, Talagapa, Barril Niyeu, Agua de la Piedra) which partially surrounds the southern border of the mainly Oligocene Somuncurá basaltic plateau (figure 1). Although the PMC shares some characteristics with these post-shield complexes (i.e. chronology, typical bimodal nature), the huge volume of acidic rocks and the acidic/basic ratio distinguish this complex from the remainder post-plateau associations (Salani et al. 2008).