Trace element partition coefficients of alkaline igneous rock-forming minerals: study of dikes related to Meso-Cenozoic magmatism in the southeastern part of South American platform

• Grant number: 12/25288-4
• Support Opportunities: Scholarships in Brazil - Master
• Start date: May 01, 2013
• End date: April 30, 2015
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geology
• Principal Investigator: Rogério Guitarrari Azzone
• Grantee: Mariana Robertti Ambrosio
• Host Institution: Instituto de Geociências (IGC). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 12/06082-6 - The Paraná-Etendeka magmatic province in Brazil: temporal and petrologic relationships between the tholeiitic and alkaline magmatism and geodynamic implications, AP.TEM

Abstract

This master's degree project aims to study the trace element partition coefficient of phenocrysts in chemical equilibrium with their matrix (aphanitic, glassy or phaneritic fine-grained ones). The main targets are alkaline dykes of different composition, as lamprophyres and phonolite, outcropping in São Paulo state, Brazil.To reach its objective, the former steps of this project are the sample selection and petrographic analysis by optical microscopy and scanning electron microscopy. Finally, the complete chemical analysis (major, minor and trace elements composition) of these minerals and of each lithotype will be done. Bulk geochemical compositions will be analyzed by spectrometry techniques as X-ray fluorescence (XRF), inductively coupled plasma optical emission spectrometry (ICP-OES), and inductively coupled plasma mass spectrometry (ICP-MS). Chemical compositions of minerals will be determined by in situ, punctual, microanalysis techniques, as wavelength-dispersive spectrometry (WDS) by electron microprobe and laser ablation ICP-MS.These new data will be treated and discussed focused on the trace element partitioning among coexisting mineral phases correlating the magnitude of their enrichments relatively to the bulk-chemistry of the system and to their crystalline structures. The theoretical treatment of the results will be based on the "crystal lattice strain" models. These models mention the influence of characteristic sites of crystalline structure of the different minerals in the partitioning behavior of trace elements. Finally, the study will lead to discussions of the variations in the behavior of trace elements in minerals crystallized in different liquid compositions.This mineralogical study will be of great importance for the interpretation magmatic evolution in the context of the alkaline magmatism in the southeastern part of Brazil, since there are few experimental studies reported in the literature investigating the trace element partitioning between mineral and alkaline magmas. The project represents a first approach to the theme from rocks related to the Meso-Cenozoic magmatism in the Brazilian Platform, adding an innovative theme to the traditional line of research associated with the petrological study of alkaline magmatism of the IGc-USP.

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

AMBROSIO, MARIANA ROBERTTI; AZZONE, ROGERIO GUITTARRARI. THE INFLUENCE OF CRYSTAL AND MELT COMPOSITIONS ON THE REE plus Y PARTITIONING BETWEEN CLINOPYROXENE AND BASANITIC/TEPHRITIC MELTS OF CRETACEOUS ALKALINE MAGMATISM ON THE SOUTHEASTERN PART OF THE SOUTH AMERICAN PLATFORM, SOUTHEAST BRAZIL. CANADIAN MINERALOGIST, v. 56, n. 3, p. 303-329, MAY 30 2018. (12/06082-6, 12/25288-4, 17/03768-8)

Academic Publications

(References retrieved automatically from State of São Paulo Research Institutions)

AMBROSIO, Mariana Robertti. . 2016. Master's Dissertation - Universidade de São Paulo (USP). Instituto de Geociências (IG/BT) São Paulo.