Magma mixing and crustal assimilation processes of basic alkaline magmas in a magmatic chamber environment: Pariquera-Açu alkaline complex, Ponta Grossa Arch Alkaline Province, SE Brazil

• Grant number: 20/15299-5
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: May 01, 2023
• End date: September 30, 2025
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geology
• Principal Investigator: Rogério Guitarrari Azzone
• Grantee: Lina Maria Cetina Tarazona
• Host Institution: Instituto de Geociências (IGC). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 19/22084-8 - The Paraná Magmatic Province: petrogenesis, chronology and environmental impact of Cretaceous tholeiitic, alkaline and silicic magmatism in the Brazilian Platform, AP.TEM
• Associated scholarship(s): 23/11826-9 - Trace element mapping of clinopyroxene and apatite, and in situ 87Sr/86Sr isotope analysis in apatite from the Pariquera-Açu K-alkaline complex: Study of magma mixing and crustal assimilation processes in a fossilised shallow magma chamber, BE.EP.DR

Abstract

The PhD Project aims to study how contamination processes in shallow crustal magma chamber environment influence the compositional variation of alkaline complexes. The selected target is the alkaline potassic intrusion of Pariquera-Açu Complex, located at the Arco de Ponta Grossa, mainly composed of shonkinites and malignites, and eventuality nepheline syenite pegmatite, alkaline ultramafic pyroxenite, and alkaline diabase dykes occurrences. The complex have been interpreted as a product of low-degree partial melting of a lithospheric, heterogeneous and metasomatic mantle source, with evolution mainly controlled by fractional crystallization processes. However, there is a lack in precise determinations for the age of crystallization, the emplacement depth and other intrinsic parameters (e.g. magma and crystallization temperature), as well as the role of contamination processes the formation of exotic lithotypes (shonkinites and malignites). The proposal study will try to understand how the crustal contamination processes can influence the mineralogical, chemical and isotopical variability of small alkaline complex, emplacement at a shallow depth. The project intends to contribute to the understanding of the Alkaline Pariquera-Açu Complex petrogenesis, related to the Meso-Cenozoic Magmatism of the Brazilian Plataform, from high resolution geochemical data and interpretations based on geochemical, thermodynamic and geochronological modelling, this focused on the study of crustal contamination processes acting in alkaline systems. (AU)