CONICET | Buscador de Institutos y Recursos Humanos

The Argentine Patagonian region is characterized by a predominantly acidic Jurassic volcanism that stretches from the Andean to the extrandean region, where it forms an extensive volcanic field referred to as the Chon Aike Province, part of a larger silicic LIP and related to the Gondwana breakup. The effusion of the acidic volcanites is linked either to calderas or to large fractures or, most likely, to the combination of both. In the Deseado Massif, southern Patagonia, this volcanism is known to bear gold and silver epithermal deposits which has traditionally constituted an additional interest for its study.Among the main caldera structures so far identified in the Deseado Massif are e.g., in the extra-Andean zone, the La Josefina, Cerro 1º de Abril, El Dorado-Monserrat and Cerro Torta Calderas, and in the Andean region, the La Peligrosa Caldera.Based on the premise of the existence of additional, unexposed and, hence, still unidentified, calderas in the Deseado Massif, so as to justify the huge volume of Chon Aike ignimbrites, we have scrutized the aeromagnetic data available for this region, with a view to detect new caldera structures. As a result, we have firstly identified two large calderas concealed under thin Cenozoic sedimentary deposits in the Río Seco area, and secondly we have newly identified three additional calderas and a number of associated lava domes in the Los Manantiales area. All of these five structures, with dimensions of ?14 to 30km? takentogether define a caldera field herein referred to as the Santa Cruz Central Caldera Field, extending roughly in an E-W direction for at least 150 km, and occuring in the context of a structural corridor of the same orientation. The discovery of this Caldera Field may well open a new frontier in the exploration for Au-Ag mineralization in the Deseado Massif.