Evolução tectônica da margem ativa Neoproterozóica do Orógeno Gondwana Oeste na Província Borborema (NE-Brasil)

Abstract

AgradecimentosAo orientador desta Tese, Prof. Umberto G. Cordani meus profundos agradecimentos por acreditar neste projeto, me orientar e me ensinar a como se portar cientificamente, pela liberdade, e por abrir TODAS as portas necessárias para a realização desta pesquisa. Ao Prof. Miguel A. S. Basei pelo companheirismo e orientação indispensável na zirconologia. Ao Prof. Roberto F. Weinberg pela orientação nos migmatitos e granitóides, por estar sempre aberto e solicito a uma boa discussão geológica e por ser um incentivador de novas ideias científicas. Aos Profs. Daniela Rubatto e Joerg Hermman por me ensinarem que a geocronologia não é somente a busca de uma idade. Ao Prof. Renaud Caby por compartilhar comigo todo seu conhecimento geológico do NE do Brasil e suas correlações africanas. Ao Prof. Yao Agboussomondé pela aventura na coleta ! iv! AbstractThe Neoproterozoic West Gondwana Orogen (WGO), suggested in this Thesis, is a linear belt that extended for more than 5000 km from nowadays northwest Africa to Central Brazil. Traditional views suggest that this orogen resulted from the consumption and closure of the Goiás-Pharusian Ocean that culminated in a continent-continent collision involving mainly the conjoined Amazon and West African cratons against the SãoFrancisco-Congo and Saharan cratons. In this Thesis it has been investigated the crustal evolution of an important sector of the WGO in NE-Brazil at the northwestern portion of the Borborema Province as well as in some areas of Africa in Togo and Mali using a coherent approach. U-Pb Zircon geochronology of siliciclastic and igneous rocks indicates a long-lived convergent tectonics (up to 400 m.y) related to the comsumption of the Goiás-Pharusian Ocean. In the studied, particularly in NE-Brazil in the Ceára Central Domain, convergentrelated magmatism can be divided into three main periods: i) an early period comprising essentially juvenile arc magmatism at ca. 880-800 Ma and continuing to 650 Ma as evidenced indirectly by detrital zircons from synorogenic deposits, ii) a more mature arc period at ca. 660-630 Ma characterized by hybrid mantle-crustal magmatic rocks, and iii) crustal anatexis at 625-618 Ma continuing until ca. 600 Ma. Protracted tectonic evolution in the WGO and synchronicity of UHP metamorphism in NE-Brazil, Togo and Mali indicate that continental subduction, and hence continental collision, occurred simultaneously over at least 2500 km during the Ediacaran period (620-610 Ma). Here, it has been proposed that Borborema Province development from 620 to 570 Ma resulted from two discrete collisional events. Collision I, along the WGO, took place at ca. 620-610 Ma as the result of collision between the Parnaíba Block, as the forefront of the much larger AmazonianWest Africa Craton, and the old basement of the Borborema Province. The suture zone related to this collision was reactivated by a dextral transform zone (the Transbrasiliano Lineament), allowing the Borborema Province to approach and collide against the São Francisco Craton in the s...

U–Pb age of the coesite-bearing eclogite from NW Borborema Province, NE Brazil: Implications for western Gondwana assembly

“…4) (Rubatto and Gebauer, 2000). The retrograde eclogite from the FEZ dated by the U-Pb zircon SHRIMP displays similar results (616 ± 4 and 625 ± 8.5 Ma) with commonly low Th/U (mostly 0.01-0.05) and no significant Eu-anomaly (Araújo, 2014). Generally, coesite is preserved only in rocks that underwent very fast exhumation.…”

The Zona Transversal Domain of the Borborema Province, northeastern Brazil: Synthesis of the Archean to Cambrian evolution, and new tectonostratigraphic interpretation

“…Historically, the internal subdivision of TZD is treated with the definition of Tectonostratigraphic Terrains in several works (Santos , 1999Santos and Medeiros 1999), but there is still a lot of discussion regarding the tectonic evolution of BP (Santos 1999;Brito Neves et al 2000;Kozuch 2003;Santos et al 2010;Van Schmus et al 2008;Araujo 2014;Caxito et al 2020;Araujo et al 2021), where the term Terrain would not be compatible with all existing lines of thought for the province evolution (e.g. Neves et al 2006, 2015band Neves 2015.…”

“…The maximum sedimentation age of 637 ± 12 Ma can be attributed to the Barro complex (younger population weighted average). The Salgueiro Complex (Figure 13A) recorded a higher concentration of ages between 700 and 900 Ma, a period in which significant magmatic events were not characterized in TZD, in a way that this basin may have received a significant amount of debris from other BP domains, like Lagoa Caiçara Unit and Tamboril-Santa Quitéria Complex, in the northern sector of the province (Castro 2004;Teixeira 2005;Costa 2017;Araujo 2014;Pitombeira et al 2021). U-Pb dating performed in a metarhyolite associated with the Salgueiro complex suggest crystallization in 962 ± 12 Ma (Brito and Marinho 2017) that would correspond to the minimum sedimentation age of this basin.…”

“…The second model argues that the collage of crustal fragments occurred only during the Paleoproterozoic, being the rest of the configuration in a dominantly intracontinental environment, with episodes of crustal reworking until the province consolidation in the Ediacaran-Cambrian transition (Neves et al 2006, 2015band Neves 2015. Finally, a third model defends the rupture of a Paleoproterozoic continent, with opening of basins and formation of oceanic crust, and subsequent closure during the Brasiliano Orogeny, with associated arc magmatism in some parts of the province (Van Schmus et al 2008;Araujo 2014;Caxito et al 2020;Araujo et al 2021).…”

Litoestratigrafia e aspectos metalogenéticos do Complexo Máfico-Ultramáfico Estratiforme de Tucunduba, Província Borborema, Ceará – Brasil

“…A PB (Almeida et al, 1981) constitui o fragmento de um importante cinturão Brasiliano com tectônica acrescionária dominante, formando um megassistema orogênico neoproterozoico em reconstruções pre-drift (Arthaud et al, 2008;Ganade de Araújo, 2014;Caxito et al, 2020;Santos et al, 2022). Sua estruturação resulta da amalgamação dos crátons Amazônico, Oeste Africano-São Luís (Médio Coreaú-Dahomeyides-Gourma Tuareg Shield Oeste), São Francisco-Congo (Rio Preto-Riacho do Pontal-Sergipano-Yaoundé-África Central) e Saariano (Brito Neves e Cordani, 1991;Caxito et al, 2020).…”