The granulites of the Jequie complex and Atlantic Coast mobile belt, southern Bahia, Brazil - an expression of Archean/early Proterozoic plate convergence

Abstract

The study area can be divided in terms of lithology into three regions; northwest; southeast; and central. The lithology of each is described. Results strongly suggest a west dipping subduction zone below the southeastern zone and a collision zone in the central part. Mineral chemical data indicate that the main granulite metamorphism was of the high-temperature, intermediate-pressure type and that the metamorphic climax with age of approximately 2.0 Ga was reached after major ductile deformations ceased. Retrograde metamorphism can be identified and observations suggest that the amphibolite-granulite prograde reactions were isochemical. Nevertheless, evidence shows that K, Rb and Sr were mobilized during granulitic migmatization. -after Author