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The Itajaí Basin located in the southern border of the Luís Alves Microplate is considered as a peripheral foreland basin related to the Dom Feliciano Belt. It presents an excellent record of the Ediacaran period, and its upper parts display the best Brazilian example of Precambrian turbiditic deposits. The basal succession of Itajaí Group is represented by sandstones and conglomerates (Baú Formation) deposited in alluvial and deltaic-fan systems. The marine upper sequences correspond to the Ribeirão Carvalho (channelized and non-channelized proximal silty-argillaceous rhythmic turbidites), Ribeirão Neisse (arkosic sandstones and siltites), and Ribeirão do Bode (distal silty turbidites) formations. The Apiúna Formation felsic volcanic rocks crosscut the sedimentary succession. The Cambrian Subida leucosyenogranite represents the last felsic magmatic activity to affect the Itajaí Basin. The Brusque Group and the Florianópolis Batholith are proposed as source areas for the sediments of the upper sequence. For the lower continental units the source areas are the Santa Catarina, São Miguel and Camboriú complexes. The lack of any oceanic crust in the Itajaí Basin suggests that the marine units were deposited in a restricted, internal sea. The sedimentation started around 600 Ma and ended before 560 Ma as indicated by the emplacement of rhyolitic domes. The Itajaí Basin is temporally and tectonically correlated with the Camaquã Basin in Rio Grande do Sul and the Arroyo del Soldado/Piriápolis Basin in Uruguay. It also has several tectono-sedimentary characteristics in common with the African-equivalent Nama Basin.

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Palavras-chave: Cinturão Ribeira, batólitos graníticos, geocronologia, geoquímica isotópica. RESUMODurante a evolução da porção sul do Cinturão Ribeira no Estado do Paraná, o Ciclo Brasiliano-Pan Africano foi responsável pela geração de um grande volume de rochas graníticas com destaque para os batólitos Cunhaporanga (BCP) e Três Córregos (BTC). Estudos litoquímicos e isotópicos revelaram a existência de tipos graníticos distintos entre dois batólitos e internamente aos mesmos, definidos por unidades graníticas. A principal diferença entre os dois batólitos está no comportamento dos álcalis com o BCP, a NW mais potássico e o BTC, a SE mais sódico. Os dados isotópicos mostram claramente a participação de fontes infracrustais distintas de longa residência crustal, evidenciadas pelos isótopos de Pb em K-feldspato, pelos valores negativos de ε Nd (-11 a -13 para o BCP e -17 a -19 para o BTC) e pelas idades TDM (1,8 a 2,0 Ga para o BCP e 2,2 a 2,4 Ga para o BTC). Estas fontes estariam situadas em uma crosta continental paleoproterozóica com a participação de fontes mantélicas e supracrustais na gênese das rochas graníticas do BCP e BTC. A Unidade Ribeirão Butiá do BCP e as Unidades Arrieiros e Paina do BTC estão representadas predominantemente por monzogranitos e granodioritos e raros tonalitos, metaluminosos, cálcio-alcalinos de alto a médio K, formados entre 630 a 620 Ma em ambiente de margem continental ativa. As Unidades Piraí do Sul e Santa Rita do BCP são constituídas por monzogranitos fracamente peraluminosos, de alto K e as Unidades São Sebastião e Conceição do BTC são constituídas respectivamente por quartzo-monzonitos e monzo a sienogranitos fracamente metaluminosos, de alto K. Estas unidades foram formadas em ambiente sin-a tardi-colisional entre 620 e 590 Ma. ABSTRACTDuring evolution of the southern part of the Ribeira Belt in Paraná State, the Brasiliano-Pan-African Cycle was responsible for the generation of a large volume of granitic rocks among which the Cunhaporanga (BCP) and Três Córregos (BTC) batholiths stand out. Studies of rock chemistry and isotopic compositions show that differences exist both between and within the batholiths. The main difference between the batholiths is in the behaviour of the alkalies. The BCP is more potassic, while the BTC is more sodic. The isotopic data clearly show the participation of different lower crustal sources with long crustal residence times, given by the isotopic composition of Pb in K-feldspar, by the negative values of ε Nd (-11 to -13 for BCP and -17 to -19 for BTC), and by the model Nd T DM ages (1.8 -2.0 Ga for BCP and 2.2 -2.4 Ga for BTC). These sources are situated in Paleoproterozoic continental crust, and different proportions of mantle and crustal contributions are involved in the genesis of the BCP and BTC granites. The Ribeirão Butiá Unit of the BCP and the Arrieiros and Paina units of the BTC are mainly composed of monzogranite and granodiorite with rare tonalite, comprising metaluminous, medium-to high-K calc-alkaline rocks formed between 630...