Volcanic Centres in the Alta Sierra of Somún Curá and Surroundings, Patagonia, Argentina

REMESAL, M.B.; MARO, G.; MACKERN, A; PARICA, C.A.; SALANI, F.M.; CERREDO, M.E.

Heidelberg

Congreso; 22nd International Collquium on Latein Amerikan Earth Sciences; 2011

Ruprecht-Karls-Universität Heidelberg

In the north of the Extra-Andean Argentine Patagonia a large volcanism of Oligocene-Miocene age is emplaced. This is composed by the basaltic plateau of Somún Curá and the postplateau volcanism which are distributed in bimodal volcanic complexes (trachyte-basalt) or monogenetic basaltic centres. The NE region Somún Curá Plateau is covered by the post plateau sequence of the “Alta Sierra de Somún Curᔠ(High Range of Somun Cura) and the minor surrounding monogenetic vents. Even though in the “Alta Sierra de Somún Curᔠthe petrogenetic association is typical for the bimodal (basalt-trachyte) centres (Salani et al. 2008), most of the minor monogenetic vents which cover densely in the surroundings of the plateau are basaltic (Remesal et al, 2007) Recent regional and petrological recognitions on basaltic vents let to identify new varieties of basalts with high MgO and amphibole in disequilibria which complete the ones described before. Some lava flows makes evident that there are large effusions (>5km) with different rheological features than the originally supposed (spatter cones with short lava flows related). The analyse of the structural control based on satellite images (false colour and RGB bands combined) and the complement of aerial photos and field data, let to compile and classify close to 200 vents (41°50´20”S-66°14´04”W) into an area of 3000 Km2. The distribution of these craters defines two main directions, the first one on NE-SW and the second one SE-NW in agreement with the Abdala and Telsen alignments described by Franchi et al. (1977), Lapido & Page (1979), Cortés (1987) and also analyzed by Ardolino & Franchi (1996) for Marifil Complex (Mid Jurassic).