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Title: Stabilization of the southern portion of the São Francisco craton, SE Brazil, through a long-lived period of potassic magmatism.
Authors: Romano, Rafael Cotta
Lana, Cristiano de Carvalho
Alkmim, Fernando Flecha de
Stevens, Gary
Armstrong, Richard
Keywords: Brazil
São Francisco craton
Potassic grantoids
U-Pb geochronology
Issue Date: 2012
Citation: ROMANO, R. C. et al. Stabilization of the southern portion of the São Francisco craton, SE Brazil, through a long-lived period of potassic magmatism. Precambrian Research, v. 224, p.01-20, set. 2012. Disponível em: <>. Acesso em: 22 out. 2012.
Abstract: Although the southernportion of the SãoFranciscocraton in southeast Brazil encompasses one of the largest segments of Meso- to Neoarchaean crust in the South American plate, there is little understanding of the processes leading to cratonization of this region. Our combined field and U-Pb age data show that the crust experienced massive intrusions of potassic (K-rich) granitoids between 2750 and 2600 Ma, and that this magmatic event marked the beginning of a fundamental change in the tectonics of the terrain, with the ensuing billion years being dominated by the deposition of a series of thick clastic and chemical sedimentary successions. Thus, deep crustal partial melting and subsequent transport and intrusion of these granites in the upper crust is a likely mechanism by which this segment of the SãoFrancisco crust attained buoyancy to survive recycling. Regional mapping indicates that the potassic granitoids are distributed over an area of ∼25000 km2, and are related to one of the most prolific periods of potassicmagmatism in the craton. LA-ICP-MS and SHRIMP U-Pb data from 16 samples of potassic granitoids together with published TIMS ages suggest alonglivedperiod of magmatism from 2750 to 2700 Ma, and a small pulse of granite crystallisation at ca. 2612 Ma. The U-Pb SHRIMP and LA-ICP-MS data also indicate that the Archaean granitoids do not record evidence of U-Pb zircon resetting. Our interpretation is that partial melting and transport of granitoid melts (rich in heat producing elements) to the upper crust gave rise to a thermally stable lower crust and that this lower crustal segment (in the craton area) became sufficiently refractory and resistant to further partial melting.
ISSN: 03019268
metadata.dc.rights.license: O periódico Precambrian Research concede permissão para depósito deste artigo no Repositório Institucional da UFOP. Número da licença: 3315440594042.
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