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A geochronological and thermochronological approach to assess timing of deformation of Taxaquara Shear Zone, Ribeira Belt (Brazil)

Grant number: 18/16307-1
Support type:Scholarships abroad - Research Internship - Master's degree
Effective date (Start): March 11, 2019
Effective date (End): July 10, 2019
Field of knowledge:Physical Sciences and Mathematics - Geosciences
Principal Investigator:Ginaldo Ademar da Cruz Campanha
Grantee:Bruno Vieira Ribeiro
Supervisor abroad: Peter Cawood
Home Institution: Instituto de Geociências (IGC). Universidade de São Paulo (USP). São Paulo , SP, Brazil
Local de pesquisa : Monash University, Australia  
Associated to the scholarship:18/00320-9 - Crystallographic, deformational and thermocronological analysis of mylonites of Taxaquara shear zone (São Paulo), BP.MS

Abstract

The development of the Ribeira Belt, SE Brazil, is dominated by shear zone system established between Ediacarano and Cambrian and characterized by brittle-ductile to ductile shear zones. The Taxaquara Shear Zone (TSZ) was one of the first transcurrent structures of regional relevance identified in the Ribeira Belt, having been attributed to it great importance in the tectonic compartmentation of this tectonic entity. The deformational mechanisms of the shear zones, tectonic models and the period in which this system was installed are still subject of debate in the scientific literature. In spite of the importance attributed to it, the ZCT has been little studied since its definition, which makes it an interesting target to be reevaluated in the light of new concepts and techniques of investigation in microtectonics, structural geology and geochronology. Geochronological and thermochronological data regarding timing of deformation of this major shear zone system in the Ribeira belt are rare. This internship abroad' proposal to be executed at Monash University (Melbourne, Australia) aims to tentatively carry out apatite, monazite and zircon U-Pb analyses of mylonites and correlate rocks of TSZ. Apatite is a common phase in rocks related with TSZ and its thermochronological analysis is suitable due similarities between its closure temperature and deformation temperature of TSZ (H450°C). Apatite U-Pb geochronology, however, is rare in Brazil. Thus, this internship abroad will produce important data in order to proper understand timing of deformation of TSZ. U-Pb data, couple with 40Ar/39Ar e (U-Th)/He, will provide new data regarding timing of deformation and exhumation of TSZ and the shear zone system in Ribeira belt through regional correlations.