ABSTRACT
The Ribeira-Mantiqueira fold belt represents partly the southern continuation of the Aracuai belt. The term of orogeny was used because, in many Pan-African fold belts, the superstructure is reduced or missing, so it was difficult to apply the classical geosynclinal model. In the portion of Gondwana investigated here, the Pan-African and Brasiliano fold belts form a complicated network enclosing irregularly-shaped cratonic blocks. The whole appears as a gigantic puzzle or mosaic arranged around a backbone, the Congo-Sao Francisco craton. The characterization and location of the suture zones suggest that most Pan-African-Brasiliano orogens in western Gondwana are collisional in origin, with two exceptions: the West-Congo-Araçuai megabelt and most of the orogens forming the West-Africa Trans South-America festoon. Although a general eastward tectonic vergence should be expected, both eastward and westward vergences are observed in the field. Study of the Pan-African fold belts soon revealed that they were peculiar structures, different from Phanerozoic orogenic belts.
