O pórfiro dacítico de Valverde (Alcácer do Sal) idade Rb-Sr e suas implicações

Abstract

Key-words: Vacite - Rb-Sr age - Upper Carboniferous - Valverde (Alcácer do Sal) - Portugal. The unexpected discovery of a small outcrop of igneous rock isolated within an extensive outcrop of Neogene and Quaternary sediments called for the attention of CEPUNL's researchers. The rock is a dacite whose Rb-Sr age (C. A. and M. H. C.) is 291 M. y. upper Carboniferous. Hence the dacite may be related to volcanism in the Santa Suzana tectonic basin.