Late Neogene volcanism in the Cerro Blanco region of the Puna Austral Argentina, (~26.5°S, ~67.5°W).

KAY, S.M., COIRA, B., AND MPODOZIS, C.

Antofagasta, Chile.

Congreso; XI Congreso Geológico Chileno.; 2006

Sociedad Geológica de Chile-Universidad Católica del Norte

The Cerro Blanco Caldera near the southern edge of the Puna plateau has been of recent interest due to satellite radar interferograms that show the center is actively deflating (Pritchard and Simmons, 2002). The purpose of this abstract is to present K/Ar ages (Table 1) and chemical analyses (Table 2 and comparative ranges from our regional data set) of latest Miocene to Pleistocene volcanic rocks that put the Cerro Blanco region into an evolutionary tectono-magmatic context.                                                                 These volcanic rocks reflect the eastward migration of the arc front from the Maricunga Belt at ~ 7 Ma to the modern CVZ front at ~ 1. 5 Ma. Their chemical trends show similarities to those of southern Puna lavas that have been linked to Pliocene delamination of lower crust and mantle lithosphere (Kay et al., 1994). Five general magmatic stages can be recognized in the Cerro Blanco region.