U-Pb geochronology of the granite magmatism in the Embu Terrane: Implications for the evolution of the Central Ribeira Belt, SE Brazil

The Embu Domain represents the central part of the Ribeira Fold Belt in Sao Paulo, Brazil. It hosts several granitic occurrences of varied composition ranging from small granitic bodies that outcrop in a domain bounded by the intersection of two major sutures (Taxaquara and Guararema Faults) and batholitic masses outcropping to the east. Understanding the evolution of such granites is of vital importance to better constrain evolutionary models for the Ribeira Belt. In the present study, a set of samples from eleven main granite occurrences from the east of Sao Paulo state was selected for geochronological investigation using laser ablation-multicollector-inductively coupled plasma spectrometry (LA-MC-ICP-MS) and thermal ionization mass spectrometry (TIMS) U-Pb dating of zircon and monazite crystals, respectively. The results indicate a remarkable cluster of ages around 590 Ma with older events of granite magmatism between 660 and 600 Ma registered for four plutons, indicating a long history of crustal reworking and magma generation. The ages of reworked sources were evaluated from inherited zircon cores. Although highly discordant these point to the predominance of Paleoproterozoic (2.4-2.1 Ga) sources, with minor contributions from Mesoproterozoic (1.1-0.9 Ga) and Archean sources (similar to 3.1 Ga). The new data bring important insights into the role played by the Embu Domain on the paleogeography and evolution of the Ribeira Belt. (C) 2013 Elsevier B.V. All rights reserved.