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The meaning of oxidized A-type post-orogenic granitic magmatism: petrogenesis of the Itupeva pluton, Itu batholith

Grant number: 18/06257-7
Support type:Scholarships in Brazil - Master
Effective date (Start): November 01, 2018
Effective date (End): September 30, 2020
Field of knowledge:Physical Sciences and Mathematics - Geosciences
Cooperation agreement: Coordination of Improvement of Higher Education Personnel (CAPES)
Principal Investigator:Valdecir de Assis Janasi
Grantee:Viviana Marcela Monsalve Hernández
Home Institution: Instituto de Geociências (IGC). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The magmatism associated to the post-orogenic period is characterized by the occurrence of plutons formed by undeformed granites, which usually have "A- type" characteristics and are associated with contemporary basic manifestations. The Itu batholith is one of the most expressive occurrences of the Itu Granitic Province, which is characterized by its unique character in the context of the Neoproterozoic tectonic evolution of southeast Brazil , given the presence of a considerable diversity of plutonic rocks: A- type granites of the aluminous series and calc-alkaline granites, besides abundant bodies of basic composition. Previous studies about the Itu Batholith concluded that a relatively oxidized character, high contents of lithophile elements and a distinct geochemical behavior distinguish the Itupeva Pluton from the other plutons. The main objectives of this project are to identify the crystallization conditions and source areas of the magmas that formed the Itupeva pluton, and understand its significance in the evolutionary context of the Itu Batholith and regional post-orogenic magmatism. The methods to be employed to investigate these questions consist of chemical analyses of mineral phases sensitive to crystallization conditions, i.e., P, T and fO2 (feldspar, mafic minerals and zircon), by electron microprobe (major elements) and LA-ICPMS (trace elements), and whole rock elemental (major and trace-elements) and isotope (Rb-Sr and Sm-Nd systems) geochemistry.