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465203 
Journal Article 
Neoproterozoic magmatism and high-grade metamorphism in the Goias Massif: New LA-MC-ICMPS U-Pb and Sm-Nd data and implications for collisional history of the Brasilia Belt 
Della Giustina, MES; de Oliveira, CG; Pimentel, MM; Buhn, B 
2009 
1 
Precambrian Research
ISSN: 0301-9268 
172 
1-2 
67-79 
English 
This paper presents the first U-Pb and Sm-Nd data for the gneisses of the high-grade Uruacu Complex, exposed in the northern part of the Neoproterozoic Brasilia Belt, central Brazil. Previous studies have interpreted this complex as the exposure of Archaean or Paleoproterozoic continental crust, included, therefore, in the so-called Goias Massif, a small Archaean/Paleoproterozoic allochthonous (?) block. The complex is located in the northern Brasilia Belt, adjacent to the eastern limit of the Goias Magmatic Arc, and comprises a variety of para- and orthogneisses metamorphosed under amphibolite to granulite facies. New U-Pb LA-MC-ICPMS data for zircon grains from felsic and mafic orthogneisses reveal ages ranging from ca. 690 to 650 Ma, interpreted as representative of the original igneous crystallization. Zircon overgrowths indicate metamorphic ages around 650 Ma, suggesting that the metamorphism was partly concomitant or only slightly younger than the intrusion of gramitoids and mafic bodies, as well as with the closure of the ocean between the Amazon and Sao Francisco continents at the end of the Neoproterozoic. The main geological characteristics of the Uruacu Complex, as well as the new U-Pb crystallization and provenance ages discussed in this work, are analogous to those observed in the Anapolis-Itaucu Complex, exposed in the southern Brasilia Belt. This may suggests the correlation between both complexes, resulting in a long granulitic belt developed to the east of the Goias Magmatic Arc during the main collisionall stage of evolution of the Brasilia Belt. High-grade metamorphism and associated igneous intrusions represented mainly by metagabbros and metagranites are, therefore, a conspicuous feature of the final stages of evolution of the Brasilia Belt and might be related to delamination, uplift and extension following ocean closure and continental collision. (C) 2009 Elsevier B.V. All rights reserved. 
Neoproterozoic; Brasiliano orogen; Uruacu Complex; U-Pb LA-MC-ICPMS; Metamorphic core; Delamination; anapolis-itaucu-complex; mara rosa arc; central brazil; crustal; accretion; niquelandia complex; tocantins province; id-tims; geochronology; evolution; shrimp