Crystallographic and isotopic characterization of apatite mineral for age determination through Fission Track (FT) and U-Pb methods: Geochronology of the São José de Campestre region, Natal, RN, Brazil.

• Grant number: 23/18307-7
• Support Opportunities: Scholarships in Brazil - Master
• Start date: May 01, 2024
• Status: Discontinued
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geology
• Principal Investigator: Carlos Alberto Tello Sáenz
• Grantee: Camila Durães Ferreira dos Santos
• Host Institution: Faculdade de Ciências e Tecnologia (FCT). Universidade Estadual Paulista (UNESP). Campus de Presidente Prudente. Presidente Prudente , SP, Brazil
• Associated scholarship(s): 24/20042-4 - Triple Dating Method Development and Application in Apatite and Zircon from the Carajás Mineral Province, Pará, Brazil, BE.EP.MS

Abstract

This study aims to investigate the effects of chemical alteration on the crystallographic structure of apatite and its implications for Fission Track (FT) and U-Pb dating methods. The analyses will be conducted on apatite grains separated from three plutonic rocks and two basement rocks outcropping in the São José do Campestre tectonic unit, located in the northern part of the Borborema Province, Natal, RN, Brazil. The characterization of these apatites will involve Fission Track Analysis (FTA), U-Pb dating (isotopic characterization), Atomic Force Microscopy (AFM), micro-Raman spectroscopy, and Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM/EDS). Isotopic characterization will be performed using a Laser Ablation system coupled to a mass spectrometer (LA-ICPMS). By studying the physicochemical phenomena occurring during the natural crystallization of apatite, we aim to develop a novel protocol for the crystallographic characterization of apatite prior to determining its Fission Track age via LA-ICPMS and its simultaneous U-Pb age, both obtained from the same grain. This project will be carried out at the Nuclear Traces Detectors Research Group (DETRAN) at the Department of Physics (DF), UNESP Presidente Prudente, where a similar protocol is already in routine use for the mineral zircon. Grain ages will be obtained by measuring respective isotopic ratios, directing the laser to the microarea where the fission track density was previously determined, thus avoiding the time-consuming irradiation of the sample. Utilizing the mass spectrometer, both FTA and U-Pb ages can be determined for the same grain. Standard apatite samples, Durango and FCT (Fish Canyon Tuff), will be employed to establish this method in routine practice, allowing for a comparison of both crystallographic studies and the determination of FTA and U-Pb ages via LA-ICPMS.