Abstract

The Tertiary stratigraphy and structure of southern Chile between 44" S and 47"s is poorly known yet is critical to the understanding of the evolution of the Andean Plate margin in this region, most speciiically the evolution of the Chile Triple Junction (Forsythe & Prior, 1992). Field studies carried out in the Cosmelli area ,10km east of Guadal, and in the Cerro Rocosso area, 15km south of Chile Chico, have provided new data relevant to the Tertiary evolution of southern Chile. Here we outline these reconnaissance studies together with some ideas as to their implications for the Tertiary plate dynamics of this region.