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Four main classes of tectonic entities may be considered for the Ribeira Belt and southwest African counterparts: (1) cratonic fragments older than 1.8 Ga and their passive margin successions, (2) reworked basement terranes with Mesoproterozoic and/or Neoproterozoic deformed cover, (3) magmatic arc associations, (4) terranes with Palaeoproterozoic basement and deformed Neoproterozoic back-arc successions. Based on comparative investigation, a tectonic model of polyphase amalgamation is proposed with c. 790 and 630 -610 Ma major episodes of intra-oceanic and cordilleran arc magmatism along both sides of the Adamastor Ocean. Subsequent diachronous collision of the arc terranes and small plates followed at c. 630, 600, 580 and 530 Ma. The tectonic complexity reflects an accretionary evolution from Cryogenian to Cambrian times. The São Francisco-Congo and Angola palaeo-continents did probably not behave as one consolidated block, but rather may have accommodated considerable convergence during the Brasiliano/Pan-African episodes. The final docking of Cabo Frio and Kalahari in the Cambrian was coeval with the arrival of Amazonia on the opposite side, resulting in lateral reactivation and displacement between the previously amalgamated pieces. The transition between the Cambrian and the Ordovician is marked by the extensional collapse of the metamorphic core zones of the orogens.

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The Pan-African Damara orogenic system records Gondwana amalgamation involving serial suturing of the Congo-São Francisco and Río de la Plata cratons (North Gondwana) from 580 to 550 Ma, before amalgamation with the Kalahari -Antarctic cratons (South Gondwana) as part of the 530 Ma Kuunga-Damara orogeny. Closure of the Adamastor Ocean was diachronous from the Araçuaí Belt southwards, with peak sinistral transpressional deformation followed by craton overthrusting and foreland basin development at 580-550 Ma in the Kaoko Belt and at 545-530 Ma in the Gariep Belt. Peak deformation/metamorphism in the Damara Belt was at 530-500 Ma, with thrusting onto the Kalahari Craton from 495 Ma through to 480 Ma. Coupling of the Congo and Río de la Plata cratons occurred before final closure of the Mozambique and Khomas (Damara Belt) oceans with the consequence that the Kuunga suture extends into Africa as the Damara Belt, and the Lufilian Arc and Zambezi Belt of Zambia. Palaeomagnetic data indicate that the Gondwana cratonic components were in close proximity by c. 550 Ma, so the last stages of the Damara-Kuunga orogeny were intracratonic, and led to eventual outstepping of deformation/metamorphism to the Ross-Delamerian orogen (c. 520-500 Ma) along the leading edge of the Gondwana supercontinental margin.

The Brasília Belt comprises terranes and thrust-sheets that were tectonically transported towards the western passive margin of the São Francisco–Congo palaeocontinent during an orogenic episode resulting from collision of the Paranapanema and Goiás blocks and the Goiás magmatic arc against São Francisco–Congo at 0.64–0.61 Ga. The tectonic zones of the belt are, from east to west: a foreland zone with Archaean–Palaeoproterozoic granite–greenstone basement covered by Neoproterozoic anchimetamorphic sedimentary rocks (Bambuí Group); a low metamorphic grade thrust-fold belt of proximal shelf successions, mostly siliciclastic, containing rare basement slivers; metamorphic nappes in upper greenschist to granulite facies of distal shelf and slope metasediments and subordinate tholeiitic metabasalts; the Goiás massif, possibly a microcontinent; and the Goiás magmatic arc. The accretion of these terranes against the western margin of the São Francisco–Congo palaeocontinent took place during an early phase of Gondwana supercontinent amalgamation, when terranes accreted around São Francisco–Congo to create a proto-West Gondwana landmass, around which subsequent collisional and accretionary events followed, such as those in the Borborema–Trans-Saharan province (c. 0.62–0.60 Ga); in the Ribeira–Araçuaí belt (c. 0.58 Ga); along the Araguaia and Paraguay belts (collision of Amazonia, c. 0.54–0.52 Ga); and the accretion of Cabo Frio terrane in the Ribeira Belt (c. 0.53–0.50 Ga).

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EVOLUTION OF PROTERQZOIC BASINS AND THEIR BRASILIANO THERMAL-TECTONISM ALONG THE SOUTHERN MARGIN OF THE SÃO FRANCISCO CRÁTON Detailed mapping associated with the application of sequence stratigraphy, structural and petrographic analyses, permitted a reconstruction of the Meso to Neoproterozoic geológica evolution south of the craton. A major unconformity separates two main rock units, a pré l .8 Ga basement and its cover. The basement is composed of high grade gneisses, greenstpne belts and intrusives of variable composition. Four depositional cycles were recognised in the cover successions. In stratigraphic order these are: the Tiradentes and Lenheiro cycles, predominantly quartzitic, the Carandaí cycle with abundant pelites and carbonates, and the Andrelândia cycle with meta-sandstones and pelites. The analysis of these depositional cycles or sequences allowed the recognition of three depositional basins, the São João dei Rei basin, the Carandaí basin and the Andrelândia basin. The first two are intracontinental basins, whereas the last represents a passive continental margin of the São Francisco paleo-continent, that, at the time, extended futher southeast with relation to the present limit of the craton. A continental collision around 600 Ma, here considered equivalent to the collision that resulted in the Brasília belt further north, produced extensive thrusting with nappe formation and top to the east tectonic transport. The associated metamorphism (M B) was of relatively high pressure type, as testified by the local occurrence of retro-eclogites. It reached the granulite facies in the stability field of kyanite. A second tectonic event, related to the Ribeira belt, at about 570 Ma, produced crustal shortening with tectonic transport to the NNW in the southern part of the region. The related metamorphism (M R), characterised by sillimanite and cordierite, is of lower pressure type and produced a large number of anatectic granite bodies. Finally, important NE-SW transpressive dextral shear zones were generated in response to renewed E-W shortening.