ISLAS ILDEFONSO, TIERRA DEL FUEGO: DEPOSITOS DE ANTE ARCO DEL SISTEMA MAGALLANICO
Abstract
RESUMEN:Las Islas Ildefonso, ubicadas en la shelf magallanica al sur de Isla Hoste, estan constituidas por una secuencia sedimentaria de 100 m de espesor, donde se reconoce una sucesion de facies de turbiditas proximales, turbiditas distales y conglomerados de abanico submarino superior. La petrografia de esta serie corresponde, principalmente, a volcanitas y feldsarenitas derivadas de la erosion de un arco magmatico calco-alcalino. Si bien la edad de la secuencia es incierta, ella corresponde a los unicos afloramientos conocidos de la cuenca sedimentaria que ocupa la mayor parte del shelf magallanico al sur de Tierra del Fuego. Por su posicion geografica, las sedimentitas de Islas Ildefonso representan una asociacion de facies Meso-Cenozoicas de ante-arco del sistema magallanico.
ABSTRACT. Islas Ildefonso, located in the Magellan shelf, south of Isla Hoste, are built up by a 100 m thick, south dipping turbidite sequence where proximal fan sandstones, distal shale sandstone and upper fan or channel conglomerate facies are superposed. Petrographically the sandstones are arc-derived volcarenites and feldsarenites. Although the Islas Ildefonso sequence is still not well dated, it represents the only known outcrop of Meso-Cenozoic fore-arc sediments in the Magellan region.
ABSTRACT. Islas Ildefonso, located in the Magellan shelf, south of Isla Hoste, are built up by a 100 m thick, south dipping turbidite sequence where proximal fan sandstones, distal shale sandstone and upper fan or channel conglomerate facies are superposed. Petrographically the sandstones are arc-derived volcarenites and feldsarenites. Although the Islas Ildefonso sequence is still not well dated, it represents the only known outcrop of Meso-Cenozoic fore-arc sediments in the Magellan region.
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