Geology of the Anecón Grande area, Patagonia (Río Negro), Argentina

Abstract

This contribution presents a 1:200,000 scale geologic map of the Anecón Grande area in northern Patagonia (41°00′–41°30′ S/70°00′–70°30′ W, Río Negro province, Argentina), covering around 2300 km2. The map results from a combination of classical visual stereoscopic interpretation of aerial photographs and remote sensing data, later corroborated by field surveys. The geology of the Anecón Grande is composed of a thick succession of intermediate to acidic volcanic and pyroclastic rocks (Late Triassic to Paleogene), and a thick pile of basaltic lava flows of the Somuncura Plateau (Neogene to Quaternary). Volcanic landforms, flat lava flows called ‘escoriales’, and regional peneplains are typical Patagonian landscapes in the Anecón Grande area. The map is of further interest for its socio-cultural relevance because the Anecón Grande area was settled by the Anikhon Grande Mapuche community, being one of the Native South American People and First Nations in Patagonia. Seven sites of geological interest are shown on the map which informs the reader of source areas of lithic materials (geodes, obsidian, peridotite mantle xenoliths) which may be potentially useful in the manufacturing of handicrafts by Mapuche people.