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U-Pb dating and HF isotope geochemistry of zircon in the morro azul, Boa Vista and morro do pão granites (São Roque Domain, Ribeira Belt)

Grant number: 16/16418-2
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): October 01, 2016
Effective date (End): September 30, 2017
Field of knowledge:Physical Sciences and Mathematics - Geosciences
Principal Investigator:Valdecir de Assis Janasi
Grantee:Ingrid Souto Maia Lamoso
Home Institution: Instituto de Geociências (IGC). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The implementation techniques of in situ chemical and isotopic opened excellent prospects for solving fundamental problems of A particularly interesting application is the precise determination of the age of granites crystallization in which there is a significant proportion of inherited cores using the SHRIMP and LA-MC-ICPMS techniques for U-Pb zircon dating. These ages can be combined with in situ Hf isotope determinations by LA-MC-ICPMS of the same crystals, resulting in a powerful tool for identifying the age and characteristics of the sources of magmas. Previous studies in typical Neoproterozoic granites from the São Roque Domain (Ribeira Fold Belt) resulted in ages ~ 30 Ma younger than hitherto admitted to these events, and allowed identify an important change in the sources of de granite magmas, that become younger to the east. Thus, this project proposes a similar study in occurrences located at the eastern end of the San Roque Domain (Morro Azul, Morro do Pão and Boa Vista), whose ages are still uncertain, and potentially derived from the younger crustal sources of this domain.