The basement of the Punta del Este Terrane (Uruguay): An African Mesoproterozoic fragment at the eastern border of the South American Río de La Plata craton

The Punta del Este Terrane (eastern Uruguay) lies in a complex Neoproterozoic (Brasiliano/Pan-African) orogenic zone considered to contain a suture between South American terranes to the west of Major Gercino-Sierra Ballena Suture Zone and eastern African affinities terranes. Zircon cores from Punta del Este Terrane basement orthogneisses have U-Pb ages of ca. 1,000 Ma, which indicate an lineage with the Namaqua Belt in Southwestern Africa. U-Pb zircon ages also provide the following information on the Punta del Este terrane: the orthogneisses containing the ca. 1,000 Ma inheritance formed at ca. 750 Ma; in contrast to the related terranes now in Africa, reworking of the Punta del Este Terrane during Brasiliano/Pan-African orogenesis was very intense, reaching granulite facies at ca. 640 Ma. The termination of the Brasiliano/Pan-African orogeny is marked by formation of acid volcanic and volcanoclastic rocks at ca. 570 Ma (Sierra de Aguirre Formation), formation of late sedimentary basins (San Carlos Formation) and then intrusion at ca. 535 Ma of post-tectonic granitoids (Santa Teresa and José Ignacio batholiths). The Punta del Este Terrane and unrelated western terranes represented by the Dom Feliciano Belt and the Río de La Plata Craton were in their present positions by ca. 535 Ma

A connection between the Neoproterozoic Dom Feliciano (Brazil/Uruguay) and Gariep (Namibia/South Africa) orogenic belts - evidence from a reconnaissance provenance study

A provenance study of Neoproterozoic siliciclastic successions in the stratigraphically and tectonically lowermost and uppermost parts of the Pan-African Gariep Belt (Stinkfontein Subgroup and Oranjemund Group, respectively) in southwestern Africa, as well as in the Rocha Group of the Punta del Este Terrane (DomFeliciano Belt) in Uruguay, revealed that the Oranjemund and Rocha Groups can be correlated and most likely formed in the same basin. Thus, the Rocha Group is considered to represent the fill of the westernmost part of a re-activated Ediacaran Gariep Basin. The lower parts of the Oranjemund and Rocha Groups reflect erosion of mafic rocks, whereas the upper parts are derived from a predominantly felsic source area. First major and trace element geochemical data are consistent with oceanic islands of within-plate geochemistry in the immediate vicinity as the most likely source of the mafic input into the lower part of the Oranjemund Group, whereas a combination of continental margin and island arc is indicated as source for the bulk of the younger sediments in the upper Oranjemund Group. Age spectra obtained by SHRIMP U–Pb analyses of detrital zircon grains from the Stinkfontein Subgroup (Port Nolloth Group), the Oranjemund Group, and the Rocha Group are very similar, except for a lack of the youngest age group around 600 Ma in the Stinkfontein Subgroup. In all three units, zircon grains of 1000–1200 Ma dominate, with a further peak in the age distribution between 1700 and 2000 Ma. These ages compare well with the pre-Gariep basement geology in southwestern Africa, where the former age range corresponds to magmatic and high-grade metamorphic activity in the Mesoproterozoic Namaqua-Natal Belt and the latter to an extensive Palaeoproterozoic Andean-type volcanic arc (Richtersveld Terrane). Comparable ages are conspicuously absent in the basement of the Rio de la Plata Craton in South America. Derivation of the Rocha Group sediments from a similar source as the contemporaneous Oranjemund Group sediments is therefore suggested. The most likely source of the youngest detrital zircon grains in these two stratigraphic units is the 640–590 Ma magmatic arc of the DomFeliciano Belt. This interpretation explains the continental island arc component in the sediment provenance and takes into account the absence of comparable magmatism in the Gariep Belt. Two stages of basin evolution are distinguished for the Gariep Basin, an early failed continental rift that subsequently became re-activated as back-arc basin related to the Cryogenian DomFeliciano arc. Consequently, the Gariep Basin does not represent the main suture between the Rio de la Plata and the Kalahari Cratons. This suture is now suspected to be west of the DomFeliciano volcanic arc, and might be connected with the Sierra Ballena – Major Gercino Lineament

The basement of the Punta del Este Terrane (Uruguay): an African Mesoproterozoic fragment at the eastern border of the South American Ri\u27o de La Plata craton

The Punta del Este Terrane (eastern Uruguay) lies in a complex Neoproterozoic (Brasiliano/Pan-African) orogenic zone considered to contain a suture between South American terranes to the west of Major Gercino-Sierra Ballena Suture Zone and eastern African affinities terranes. Zircon cores from Punta del Este Terrane basement orthogneisses have U-Pb ages of ca. 1,000 Ma, which indicate an lineage with the Namaqua Belt in Southwestern Africa. U-Pb zircon ages also provide the following information on the Punta del Este terrane: the orthogneisses containing the ca. 1,000 Ma inheritance formed at ca. 750 Ma; in contrast to the related terranes now in Africa, reworking of the Punta del Este Terrane during Brasiliano/Pan-African orogenesis was very intense, reaching granulite facies at ca. 640 Ma. The termination of the Brasiliano/Pan-African orogeny is marked by formation of acid volcanic and volcanoclastic rocks at ca. 570 Ma (Sierra de Aguirre Formation), formation of late sedimentary basins (San Carlos Formation) and then intrusion at ca. 535 Ma of post-tectonic granitoids (Santa Teresa and Jose Ignacio batholiths). The Punta del Este Terrane and unrelated western terranes represented by the Dom Feliciano Belt and the Rio de La Plata Craton were in their present positions by ca. 535 Ma. C 2010 Springer-Verlag

A connection between the Neoproterozoic Dom Feliciano (Brazil/Uruguay) and Gariep (Namibia/South Africa) orogenic belts - evidence from a reconnaissance provence study

A provenance study of Neoproterozoic siliciclastic successions in the stratigraphically and tectonically lowermost and uppermost parts of the Pan-African Gariep Belt (Stinkfontein Subgroup and Oranjemund Group, respectively) in southwestern Africa, as well as in the Rocha Group of the Punta del Este Terrane (Dom Feliciano Belt) in Uruguay, revealed that the Oranjemund and Rocha Groups can be correlated and most likely formed in the same basin. Thus, the Rocha Group is considered to represent the fill of the westernmost part of a re-activated Ediacaran Gariep Basin. The lower parts of the Oranjemund and Rocha Groups reflect erosion of mafic rocks, whereas the upper parts are derived from a predominantly felsic source area. First major and trace element geochemical data are consistent with oceanic islands of within-plate geochemistry in the immediate vicinity as the most likely source of the mafic input into the lower part of the Oranjemund Group, whereas a combination of continental margin and island arc is indicated as source for the bulk of the younger sediments in the upper Oranjemund Group. Age spectra obtained by SHRIMP U-Pb analyses of detrital zircon grains from the Stinkfontein Subgroup (Port Nolloth Group), the Oranjemund Group, and the Rocha Group are very similar, except for a lack of the youngest age group around 600 Ma in the Stinkfontein Subgroup. In all three units, zircon grains of 1000-1200 Ma dominate, with a further peak in the age distribution between 1700 and 2000 Ma. These ages compare well with the pre-Gariep basement geology in southwestern Africa, where the former age range corresponds to magmatic and high-grade metamorphic activity in the Mesoproterozoic Namaqua-Natal Belt and the latter to an extensive Palaeoproterozoic Andean-type volcanic arc (Richtersveld Terrane). Comparable ages are conspicuously absent in the basement of the Rio de la Plata Craton in South America. Derivation of the Rocha Group sediments from a similar source as the contemporaneous Oranjemund Group sediments is therefore suggested. The most likely source of the youngest detrital zircon grains in these two stratigraphic units is the 640-590 Ma magmatic arc of the Dom Feliciano Belt. This interpretation explains the continental island arc component in the sediment provenance and takes into account the absence of comparable magmatism in the Gariep Belt. Two stages of basin evolution are distinguished for the Gariep Basin, an early failed continental rift that subsequently became re-activated as back-arc basin related to the Cryogenian Dom Feliciano arc. Consequently, the Gariep Basin does not represent the main suture between the Rio de la Plata and the Kalahari Cratons. This suture is now suspected to be west of the Dom Feliciano volcanic arc, and might be connected with the Sierra Ballena - Major Gercino Lineament

West Gondwana amalgamation based on detrital zircon ages from Neoproterozoic Ribeira and Dom Feliciano belts of South America and comparison with coeval sequences from SW Africa

<p>Neoproterozoic–Cambrian amalgamation of West Gondwana involved the collision of several terranes of older crust that are now in eastern South America and western Africa. U–Pb (SHRIMP) detrital zircon ages from representative metasedimentary units of the Ribeira and Dom Feliciano belts (South America) and Gariep and Damara belts (Africa) provide constraints on the possible sediment source areas across probable suture zones. Ribeira detrital zircons are Palaeoproterozoic and Archaean. For the Dom Feliciano Belt, a contribution of Meso- and Neoproterozoic zircons is present, which definitely indicate Neoproterozoic sedimentation. It is proposed that the inflow of material to the Ribeira basin was essentially derived from the Paranapanema and Rio de la Plata cratons, whereas for the Damara and Gariep–Rocha belts source areas were from the Namaqua Belt. The Dom Feliciano Belt received sediments from the South American side and to a lesser degree from African sources. These results highlight the differences in the detrital zircon signatures across a proposed West Gondwanan suture, with those in the west being derived from distinctive South American basement sources and those in the east from distinctive African sources. </p