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The Punta del Este Terrane, located in southeastern Brazil and eastern Uruguay, is a tectonostratigraphic terrane recognized in the Dom Feliciano Belt, the southern segment of Mantiqueira Province (Brasiliano Orogen). The northern sector of the terrane, called here by the Jaguarão Domain, is constituted by Arroio Telho, Arroio Grande, Matarazzo metamorphic complexes, and the Arroio Pedrado Gneisses. The first is composed of low to medium-grade metasedimentary rocks. Metasiliciclastic schists and marbles constitute the second, with serpentinites, magnesian schists, amphibolites, and metagabbros. The Matarazzo Complex comprises pure and siliceous dolomitic marble, metadolerite, and metagabbro. Arroio Pedrado unit comprises granodioritic to monzogranitic augen-gneisses. The rocks of the complexes were poly-deformed and intruded by high-K calc-alkaline peraluminous and metaluminous granitoids. The Pedro Osório, Arroio Grande, and Cerro Amaro dextral shear zones delimited the domain to the north. To the south and east, the units of the Jaguarão Domain were covered by coastal plain sediments. In gravimetric maps, the domain shows a high-density relief in contrast with the rocks of the granite belt (Pelotas Batholith). U-Pb zircon data from garnet-muscovite granites present crystallization ages of 587–568 Ma, which point to a widespread Ediacaran magmatism in the northern Punta del Este Terrane. U-Pb zircon provenance data of the metasedimentary sequences indicate main Meso- to Paleoproterozoic contribution, with subordinate Tonian to Cryogenian age populations. The geochronological results of the supracrustal rocks indicate a sedimentary deposition in an extensional setting, in which posterior deformation and metamorphism/magmatism compatible with a syn-orogenic setting in the context of the Dom Feliciano Belt framework. [ABSTRACT FROM AUTHOR]

A provenance and stratigraphic study of the Neoproterozoic Pontas do Salso Complex (PSC), western portion of the Dom Feliciano Belt (DFB), was conducted with U–Pb zircon geochronological analysis of the metasediments and the host rocks. The U–Pb isotopic data from detrital zircon of the metasediments indicate the source from the latest Middle Tonian to Late Cryogenian (between 897 and 684 Ma) and maximum depositional age of 685 ± 18 Ma in an arc-related basin setting adjacent in the Sao Gabriel Arc. The metasediments of the PSC form an elongated body in the N35°E direction and occur in the central portion of the São Gabriel Terrane (SGT), which is constituted by ophiolitic complexes and arc-related rocks, generated probably during the final consolidation of Rodinia supercontinent, although this question is still open. Low- to medium-K calc-alkaline, metaluminous affinity, and trace-element geochemistry suggest that the chemical composition of the protoliths was generated from metasomatized mantle sources in subduction zones. The PSC is composed of meta-arkoses, with subordinate metaconglomerates and metapelites. The meta-arkoses are disposed in plane-parallel layers, which also internally feature small-scale cross-bedding structures. The matrix has a blastopsammitic, poorly selected, fine to coarse texture, and hexagonal quartz and plagioclase porphyroclasts with superimposed thermal metamorphism. The polymict metaconglomerates are matrix-supported, with 15–55% of clasts of metavolcanic rocks, metasediments, undeformed granites, and quartz veins. The metapelites comprise mainly muscovite phyllites with syn-tectonic garnet and chloritoid porphyroblasts. The PSC represents a sedimentary succession deposited on an arc-related basin formed during the collapse and uplift of the SGT. [ABSTRACT FROM AUTHOR]

The Brusque Metamorphic Complex (BMC) is one of the main units of the Tijucas Terrain within the Dom Feliciano Belt, located in the state of Santa Catarina in southern Brazil. In the Itapema region, the BMC is composed chiefly of metasediments, including subordinate metabasalts, meta-ultramafic rocks, and clinoamphibole schists. The metavolcanic rocks form 4 m-thick lenses interlayered with metapelites and calc-silicate schists. Based on the observed textures and the associated structural, bulk-rock geochemical, and mineral chemical data, these metamafites and ultramafites were ancient lava flows of tholeiitic basalts and ultramafic cumulates. The mineral parageneses of the metabasalts are albite + actinolite + chlorite + epidote + titanite + magnetite and oligoclase + hornblende + epidote + titanite + magnetite, indicating progressive transformations produced under greenschist to amphibolite facies conditions. Volcanogenic metasediments show the same geochemical patterns as the metabasalts, whereas the metamorphosed ultramafic rocks consist of cumulates generated by crystal fractionation and flow segregation. The studied rocks show similar rare-earth element (REE) patterns, characterized by clearly higher normalized contents of light REEs compared with heavy REEs, without Eu anomalies in the metabasalts and positive Eu anomalies in meta-ultramafic rocks and volcanogenic metasediments. In accordance with the trace element contents that indicate a within-plate nature, the corresponding mafic melts apparently formed in the mantle by partial fusion and were subsequently enriched with crustal components during ascent into the sialic crust. The analysed 143Nd/144Nd and 87Sr/86Sr ratios lie between 0.5123 and 0.5126 and 0.7067 and 0.7086, respectively, and are thus typical of tholeiitic basalts of the continental plateau type. Initial ϵNd(936) values and derived model ages (T DM) between 1028 and 1762 million years support a mantle source or sources, with extraction and emplacement in the Neoproterozoic. Field relations and geochemical data (including isotopic data) indicate the generation of the studied mafic and ultramafic rocks in a continental rift. In the regional geologic context, the formation of the BMC volcanic and metasedimentary units marks a period of fragmentation of the Palaeoproterozoic continental crust. This extensional event is preserved regionally in gneisses from the Santa Catarina Granulitic Complex and the Camboriú Complex. [ABSTRACT FROM AUTHOR]