Abstract Records of large crustal masses in the northwest of Borborema Province (BP) spread over more than 300 km are found as numerous granitic bodies amid a high-grade metamorphic gneissic-migmatitic terrain. The Tamboril-Santa Quitéria Complex (TSQC) is a Neoproterozoic example of these records; it is located in the north of the Ceará Central Domain (CECD) and its origin is related to a continental magmatic arc at different evolutionary stages of the arc. The Uruburetama Granite (UG), object of this study, fits into this context and constitutes one of the most representative batholiths occupying an area of 1,500 km2. Dozens of other similar plutons have been recorded in cartographic works that show similarities which suggests the grouping of these bodies in the Uruburetama Granitic Suite (UGS), previously included in the TSQC. The UG consists of a variety of plutonic rocks associated with mafic-dioritic dikes and its metamorphic products. Six petrographic facies were identified among the plutonic rocks: biotite-hornblende monzogranites and syenogranitic varieties, biotite-hornblende granodiorites, in addition to quartz syenite, leucomonzogranites, and diorites rocks. These rocks are affected by deformation, with greater intensity at the edges of the batholith, where thrust shear zones with transcurrent components were installed, generating tectonic fabrics (mylonitic foliations, stretch lineation, almond feldspar porphyroclasts, and ribbon quartz). Despite the superimposed deformational effects, magmatic relict textures are partially preserved, mainly toward the central portion of the pluton. The UG and the associated plutons are hosted by migmatized orthogneisses, paragneisses with garnet, sillimanite or kyanite, marbles, calcium-silicate gneisses, micaschists, sillimanite quartzites, and amphibolite lenses. The contact relations are diffuse with gradation for migmatites, and in rare cases, intrusive contacts with gneiss mega-xenolites are registered. The geochronological data obtained by Pb-evaporation zircon in two samples of the UG show average ages of 655 ± 2 and 656 ± 1 Ma. U-Pb zircon data for the same samples showed slightly younger age values of 559 ± 10 and 634 ± 10 Ma, respectively. The ages obtained are considered as representative of the magmatic phases of UG crystallization in the context of the evolution of the Santa Quitéria Magmatic Arc (SQMA), with the main magmatic phase of the UG in the Cryogenian. However, the age of 559 Ma would represent a younger magmatic event in the evolution of the arch. Overall, these ages correspond to the “Pre-Collisional I” or “Early-Sin-Orogenic” phase of a large collisional belt in the west of BP, and the younger ages must represent events related to the continuity of the orogen convergence of the Latest-Pre-collisional I (634 Ma) and Post-Collisional I (559 Ma) phases. Sm-Nd whole-rock isotopes data showed εNd(t) values predominantly negative (-25.6 and −0.9), and Nd-TDM model ages of 2.90 and 1.2 Ga. The results of the Lu–Hf isotopes analysis for the Bt-Hbl monzogranite sample showed negative εHf values (-26.75 to −35.48) and Hf-TDMC model ages of 3.12 to 3.65 Ga while the results for Bt-Hbl granodiorite showed εHf values of −2.07 to +1.08 and Hf-TDMC model ages of 1.46 to 1.66 Ga. These data point to the existence of two distinct and older crustal sources in the generation of these granitoids, one in the Mesoarchean, and the other in the Mesoproterozoic. The Archean ages correspond to the basement in the south of the CECD (Tróia Massif and Granjeiro Complex); on the other hand, the Mesoproterozoic ages are up for discussion, since terrains with this type of age do not occur adjacent to the BP. On the other hand, it can be interpreted as a mixture of sources, one of them probably juvenile, neoproterozoic, with contamination of the Archean crust. Thus, the UG is considered one of the most important records of the beginning of the evolution of the Santa Quitéria Magmatic Arc associated with a wide collisional belt in the “West Gondwana Orogen” in the west of Borborema Province.

Abstract The northwestern region of Borborema Province is represented by the Ceara Central and Northwest Ceara crustal blocks connected by an extensive transcurrent shear zone that represents the northern portion of the Transbrasiliano Lineament in a complex geological context, which brings together geological units of nature, origin, and ages of the Archean to the Paleozoic. In this scenario, there is a large amount of granitic bodies, with different natures, age and tectonic environment, but predominantly representing a more intense granitogenesis in the Paleozoic Neoproterozoic and early Paleozoic, with plutons emplaced in different stages of the Brazilian Orogeny. In this context, the Chaval Granite corresponds to an isolated body in the extreme northwest of Borborema Province, located near the Atlantic coast, in the northern states of Ceará and Piauí. It is an intrusive batholith housed in Siderian orthogneisses (Granja Complex) and in Neoproterozoic supracrustal rocks (Martinopole Group), but is partly covered by sedimentary rocks from the Parnaíba Paleozoic Basin (Serra Grande Group), and coastal Cenozoic deposits. Field data and petrographic studies highlight the porphyritic texture with microcline megacrystals involved in coarce matrix as a remarkable feature. The predominant petrographic types are granodiorites, with variations for monzogranites and tonalites. The predominant primary mineral constituents are pertitic microcline, oligoclase, and quartz; biotite and rarely hornblende as qualified minerals and additionally titanite, apatite, zircon, alanite, and opaque minerals. Another peculiar characteristic is the deformational features related to the installation of the Santa Rosa Transcurrent Shear Zone along its eastern flank. The effects of the transcurrent shear deformation led to the modification of the original magmatic fabrics in much of the eastern half of the batolith, generating various types of mylonites. Thus, the typically igneous textures preserved in the western half of the pluton were gradually replaced by tectonic fabrics, which initially evolved into proto-mylonites in the central portion of the body, grading to mylonites eastward, highlighting strongly stretching, comminution associated with dynamic recrystallization, highlighting the formation of microcline and plagioclase porphyroclasts in a mylonitic matrix, which are involved by mylonitic foliation. Geochemical studies reveal compositional similarities, compatible with petrographic classifications, in which they mostly present granodioritic composition, followed by monzogranites and tonalites, classified as I-type granites, peraluminous with compatible with the calcium-alkaline series. The geochemical signatures of the Chaval Granite indicate the character of the tectonic magmatic arc environment. U-Pb zircon analysis by Mass Spectrometry (LA-ICP-MS) indicates crystallization age of 633 Ma, placing it in the Neoproterozoic, late Cryogenic-Early Ediacaran period, being one of the oldest granitoids in northwestern Borborema Province, correlated to the granites of the Santa Quitéria Magmatic Arc in the Ceara Central Domain. Hf-TDM model ages (2.65 to 2.13 Ga) and εHf(t = 633 Ma) values from -9.6 to -18.1 suggest incorporation of neoarchean and paleoproterozoic crustal sources in their formation with a long crustal residence time. Similar Sm-Nd data in whole-rock indicate Nd-TDM model ages of 1.27, 1.72 and 2.04 Ga and negative εNd(t = 633 Ma) values of -2.64 to -9.13, indicating paleoproterozoic and mesoproterozoic sources, with considerable crustal residence time implying a more evolved nature.

RESUMO: O Cráton São Luís compreende uma área entre o nordeste do estado do Pará e o noroeste do Maranhão que expõe suítes graníticas e sequências metavolcanossedimentares do Paleoproterozoico. No leste dessa unidade geotectônica, a cerca de 70 km ao sul da cidade de São Luís, há uma porção do Cráton São Luís representada pela Suíte Intrusiva Rosário. Este trabalho foi focado em rochas dessa suíte, incluindo estudos petrográficos, litoquímicos e geocronológicos para compreender a evolução crustal dessas rochas granitoides. O espectro de rochas varia de composições tonalíticas, granodioríticas, quartzo dioríticas e graníticas, que mostram alterações estruturais e mineralógicas parciais relacionadas à deformação ao longo das zonas de cisalhamento transcorrentes. Os estudos geoquímicos demonstram a natureza granítica metaluminosa caracterizando a série calcioalcalina com afinidade de granitos tipo I, típicos de ambiente de arco magmático. Os elementos terras raras apresentam fracionamento acentuado e ligeiras anomalias de Eu positivas ou negativas (Eu/Eu* = 0,82 a 1,1). Datações pelo método U-Pb em zircão forneceram idades consistentes de 2165 ± 7 Ma, 2170 ± 7 Ma, 2170 ± 7 Ma, 2161 ± 4 Ma e 2175 ± 8 Ma que representam a idade de cristalização dos zircões e de colocação desses granitoides no Paleoproterozoico (Riaciano). Os dados isotópicos Sm-Nd forneceram idades modelo (TDM) de 2,21 a 2,31 Ga, que são muito próximas às idades de cristalização, com valores positivos de εNd = +1,9 a +3,2 (t = 2,17 Ga), indicando fonte crustal dominantemente do Riaciano para os magmas parentais, similares aos encontrados em outros domínios do Cráton São Luís. Os dados deste estudo, integrados às informações geológicas e geocronológicas da literatura, indicam a ocorrência de um importante evento de formação de crosta continental nessa área, por meio de múltiplo alojamento de plútons graníticos da série calcioalcalina. A evolução paleoproterozoica entre 2,17 e 2,15 Ga está relacionada com a orogenia transamazônica, e os granitoides da Suíte Rosário representam a fase principal de acresção na evolução de um arco magmático continental juvenil, que tem continuidade para outras partes do Cráton São Luís e correlação com a porção noroeste do Cráton Amazônico, onde se têm registros de arcos magmáticos acrescionários riacianos que se amalgamaram em terrenos arqueanos, associados à orogenia transamazônica.

ABSTRACT: The São Luís Cráton comprises an area between northeast Pará state and northwest Maranhão that exposes Paleoproterozoic granitic suites and meta-volcanosedimentary sequences. In the east of this geotectonic unit, about 70 km south of São Luís, there is a portion of the São Luís Craton, represented by the intrusive Rosario Suite (RS). This work is focused on rocks of this suite, including petrographic, lithochemical and geochronological studies to understand the crustal evolution of these granitoid rocks. The rock spectrum varies from tonalitic to granodioritic, quartz dioritic and granitic compositions, and there are partial structural and mineralogical changes related to deformation along transcurrent shear zones. The geochemical studies show granitic metaluminous compositions of the calc-alkaline series with I-type affinity typical of magmatic arc. Rare earth elements show marked fractionation and slight Eu positive or negative anomalies (Eu/Eu* = 0.82 to 1.1). Zircon U-Pb data provided consistent ages of 2165 ± 7 Ma, 2170 ± 7 Ma, 2170 ± 7 Ma, 2161 ± 4 Ma and 2175 ± 8 Ma, dating emplacement of these granitoids as Paleoproterozoic (Rhyacian). Sm-Nd isotopic data provided model ages (TDM) of 2.21 to 2.31 Ga with positive values of εNd +1.9 to +3.2 (t = 2.17 Ga), indicating predominantly Rhyacian crustal sources for the parental magmas, similar to those ones found in other areas of the São Luís Craton. The data, integrated with published geological and geochronological information, indicate the occurrence of an important continental crust formation event in this area. The Paleoproterozoic evolution between 2.17 and 2.15 Ga is related to the Transamazonian orogeny. The granitoids of the Rosario Suite represent the main phase of continental arc magmatism that has continuity in other parts of the São Luís Craton and can be correlated with Rhyacian accretionary magmatism in the northwestern portion of the Amazonian Craton that amalgamated Archean terrains during the Transamazonian orogeny.

RESUMO: O Complexo Granulítico Porangatu está exposto na porção central da Província Tocantins, do Neoproterozoico, no centro do Brasil, ao longo da fronteira entre o Cinturão Brasília, a leste, e o Cinturão Araguaia, a oeste. Esta região faz parte do sistema de cisalhamento transcontinental Transbrasiliano-Kandi. O complexo inclui enderbitos e charnockitos ricos em granada, gnaisses de alto grau metamórfico, bem como lentes de granada granulitos máficos ou granada anfibolitos, e charnockitos anatéticos in situ, o qual forma corpos alongados na direção NNE-SSW, ao longo da Zona de Cisalhamento Talismã (ZCT). Esse conjunto de rochas representam suítes de rochas ortoderivadas de afinidade cálcio-alcalina e pequenas contribuições de basaltos tholeíticos e paragnaisses aluminosos. O quadro estrutural registra componentes de cavalgamento relacionados provavelmente com os estágios iniciais de uma colisão oblíqua durante a evolução dos orógenos Brasilianos do Neoproterozoico e pode ser compreendido como envolvendo um sistema colisional de dois blocos crustais, inicialmente com componentes de cavalgamento que evoluiu em sua fase final para um sistema transcorrente com cinemática dextral. Isso levou à intensa imbricação, geração de foliação milonítica, lineação de estiramento, bandamento tectônico e rotação de estruturas e minerais. A deformação dúctil heterogênea e progressiva foi acompanhada por reequilíbrio metamórfico no Neoproterozoico tardio, que atingiu condições metamórficas máximas na fácies granulito a temperatura e pressão acima de 850ºC e 10 kbar, respectivamente, em ambiente quase anidro, atingindo a anatexia. As análises U-Pb SHRIMP em zircão realizadas em duas amostras de rochas selecionadas indicaram idade combinada de 580 ± 7 Ma para um charnockito e 548 ± 48 Ma para um granulito máfico do qual o charnockito foi derivado. O granulito máfico contém cristais de zircão datados de 2,1 Ga, indicando protólito ígneo do Paleoproterozoico envolvidos no metamorfismo de alto grau no Neoproterozoico. Além disso, os grãos de zircão mais antigos herdados de 3,1 e 2,0 Ga (idades 207Pb/206Pb) em charnockito também confirma a existência de material Arqueano e Paleoproterozoico nesta região, possivelmente derivado do Maciço de Goiás. Um grão de zircão herdado de 0,88 Ga é sugestivo de derivação do Arco Magmático de Goiás. Essa idade neoproterozoica para o metamorfismo de alto grau é substancialmente mais jovem do que a relatada para outros granulitos do Cinturão Brasília (cerca de 0,65 Ga), sugerindo que o Complexo Granulítico Porangatu está mais provavelmente associado à evolução do Cinturão Araguaia mais jovem. Os novos dados de campo, estruturais, petrográficos, e geocronológicos, sugerem que o Complexo Granulítico Porangatu foi envolvido em uma expressiva zona de cisalhamento transcorrente dúctil estabelecida em alta temperatura, que justapôs unidades de rochas de diferentes idades (Arqueano, Paleoproterozoico, Neoproterozoico), naturezas e níveis crustais (crosta continental inferior e média) fortemente retrabalhadas nos estágios finais da orogenia Brasiliano e representam as raízes expostas do Orógeno Tocantins.