Mineral chemistry and trace element and rare earth analysis in pyroxenes of the Anel Norte Lujauritic-Khybinitic body from the Poços de Caldas Alkaline Massif (MG-SP)

• Grant number: 15/23532-3
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: March 01, 2016
• End date: September 30, 2016
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geology
• Principal Investigator: Silvio Roberto Farias Vlach
• Grantee: Ludmila Maria Fonseca Teixeira
• 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

The Anel Norte Lujauritic-Khibinitic Intrusive Body from the Poços de Caldas Alkaline Massif (MG-SP) is an important agpaitic occurrence in the massif. This intrusion is made up of five nepheline syenite petrographic facies (lujaurites and khibinites), whose mineralogy is constituted by alkali-feldspar, nepheline, pyroxenes (aegirine and aegirine-augite formed during different crystallization stages, one syn-magmatic, other post-magmatic, contrasted mainly by their textural relationships), arfvedsonite, sodalite and eudyalite, among several others rare accessories. Up to date, in spite of the expressive data concerning to the mineralogy, geochemistry and petrology of these rocks in the literature, there are no chemical data for trace element (including the rare earths) for the contrasted textural pyroxene generations, whose chemical evolution is essential to built a comprehensive approach for the intrusion magmatic evolution, due their great chemical variability, as already evidenced by the available data for major and minor elements. This project, being a subproject of the main Thematic Project FAPESP 12/06082-6, has as its main goal to cover this data gap by obtaining Laser-Probe Inductively Coupled Plasma Mass Spectrometry (LA-ICPMS) analyses of selected samples, to complement the available chemical data and allow better founded petrogenetic interpretations.