Monazite petrochronology of high-pressure granulites from the Carvalhos Klippe via laser-ablation split stream (LASS) technique

• Grant number: 22/14877-0
• Support Opportunities: Scholarships abroad - Research Internship - Scientific Initiation
• Start date: April 15, 2023
• End date: July 14, 2023
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geology
• Principal Investigator: Brenda Chung da Rocha
• Grantee: Lorena de Toledo Queiroz
• Supervisor: Bruno Vieira Ribeiro
• Host Institution: Instituto de Geociências (IGC). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Institution abroad: Curtin University, Australia
• Associated to the scholarship: 22/07116-3 - Monazite petrochronology of the high-pressure granulites of the Carvalhos Klippe, BP.IC

Abstract

Monazite is a common accessory mineral in metapelites and metapsammites and has been extensively used as a geochronometer for dating high-grade metamorphic events. Compositional zoning and the trace element distribution in monazite, particularly Y and Th, reflects the growth and consumption of monazite in respect to major phases (e.g., garnet, biotite, melt), allowing the participation of monazite in metamorphic reactions to be assessed. Petrochronology involves the correlation between isotopic and chemical information from a datable accessory phase with its host mineral assemblage to establish the P-T-t paths. Monazite petrochronology has been widely used to define crystallization events in ultra-high temperature (UHT) rocks, but only a few studies explored the behavior of monazite in high-pressure (HP) rocks. The Southern Brasília Orogen exposes world-class high-pressure felsic granulites (e.g., Carvalhos Klippe), consisting of a rutile-kyanite-garnet-orthoclase gneiss with a variety of metamorphic textures and therefore offers a unique opportunity to investigate the formation of monazite in a high-pressure environment. This proposal aims to obtain monazite isotopic and trace element data from HP granulites of the Carvalhos Klippe, via laser ablation split-stream inductively coupled plasma mass spectrometry (LASS-ICP-MS) technique. This research will be carried out at Curtin University (Australia), under the supervision of Dr. Bruno Ribeiro. This will be the first study in the Carvalhos Klippe using a monazite LASS petrochronology approach, which has the potential to provide valuable insights into the timescales involved in metamorphic processes related to high pressure metamorphism in the Neoproterozoic. (AU)