Geomagnetic field intensity variations over the past 5 Myr

• Grant number: 25/14651-0
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• Start date: September 01, 2025
• End date: August 31, 2026
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geophysics
• Principal Investigator: Gelvam André Hartmann
• Grantee: Wellington Paulo de Oliveira
• Supervisor: Andrew John Biggin
• Host Institution: Instituto de Geociências (IG). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Institution abroad: University of Liverpool, England
• Associated to the scholarship: 23/13612-6 - Paleomagnetic field variability over the last 10 Ma: Evidence for the geomagnetic field hemispheric asymmetry, BP.PD

Abstract

The Earth's main magnetic field (EMF) varies spatially and temporally in different timescales, from years to billions of years. Integrated analysis of paleodirection and paleointensity data for periods of a few million years reveals geomagnetic features like the South Atlantic Magnetic Anomaly (SAA), which is characterized by the lowest total field intensities at Earth's surface and responsible for important Space Weather phenomena. However, the detailed EMF structure is largely limited by the geographic and temporal coverage of paleomagnetic data. The scarcity of these data is quite remarkable in the southern hemisphere and strongly implies the construction of paleomagnetic field models. The main objective of this research project is to investigate the paleomagnetic field intensity variations for the 0-5 Ma time interval, based on a selection of available paleointensity records from the literature, combined with a new paleointensity data set that will be obtained from volcanic rocks in Northwestern Argentina. To accomplish this, we intended: (i) to contribute to expanding the global paleointensity database with new records from Miocene-Holocene volcanic rock samples in the Antiplano-Puna Volcanic Complex (Northwestern Argentina) from a region largely lacking data coverage; (ii) to evaluate the low total field intensity of the EMF anomalies detected by targets located in the South Atlantic region extend to South America, based on mean virtual axial dipole moment (VADM) estimate of the new records, and (iii) to construct a new time-varying paleomagnetic dipole moment model spanning the 0-5 Ma interval, which will allow detecting patterns of minimum field intensity associated with geomagnetic reversals and excursions. Absolute paleointensity experiments will be determined by using both classical double-heating and the microwave methods; the last one is only available at the Geomagnetism Laboratory of the University of Liverpool (England) and will be performed in collaboration and supervision of Prof. Andrew Biggin. Statistical analyses of geomagnetic intensity variations will be performed applying the qualitative reliability criteria, which were defined by the Liverpool Geomagnetism group. This new dataset and statistical evaluations will provide insights into the paleomagnetic field variability over the past 5 Myr. (AU)