GEOLOGICAL SKETCH OF LAGUNA POTROK AIKE AREA, PALI AIKE VOLCANIC FIELD, SOUTHERN PATAGONIA, ARGENTINA.

HUGO CORBELLA, PEDRO TIBERI, BETTINA ERCOLANO, ANDREA CORONATO

Buenos Aires

Workshop; Proyecto inerdisciplinario de la Patagonia Austral, 1er reunion internodos.; 2010

Proyecto PIPA-ANPCyT

The Laguna Potrok Aike (LPA) area is located in the western flank of the Pali Aike volcanic field, in the Magellan Basin, 300 kilometres East of the Andean volcanic front. Most of the Pali Aike basaltic outcrops are part of a Pliocene-Holocene back-arc volcanic field. In Pali Aike, the predominant fault systems have a NW direction, later followed by faults of E-W and ENE strike. The NW fault system coincides with the direction of the underlying Jurassic paleo-rift zone. The ENE and E-W structures were caused by a NW stretching due to a new stress field in the southern flank of the Magellan Basin. Finally, N-S lineaments seem to be younger structures in the area. The Potrok Aike maar is located in the vicinity of alignments belonging to these three structural systems. In the LPA area, structures with a NW direction controlled several volcanic alignments: Cuatro Marías, Carlota, Clouds and Flamencos. NW structures seem to have also controlled the old water way of the Bandurrias creek through the basaltic tableland, and a lineament detected by magnetometry on the LPA. One remarkable ENE structural feature crosses immediately North of LPA. This long structural alignment is especially noticeable on the geological cartography when a Digital Elevation Model is superimposed. Other notorious structures are oriented in E-W direction. One is the E-W structure that controlled the volcanic Rosario alignment; another is the normal fault that affected the deeply eroded Petrus tableland basalts 3 km North of LPA.