Paleomagnetic field variability over the last 10 Ma: Evidence for the geomagnetic field hemispheric asymmetry

• Grant number: 23/13612-6
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: May 01, 2024
• End date: April 30, 2026
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geophysics
• Principal Investigator: Gelvam André Hartmann
• Grantee: Wellington Paulo de Oliveira
• Host Institution: Instituto de Geociências (IG). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil

Abstract

The Earth's magnetic field (EMF) of internal origin exhibits variations on different timescales, from years to billions of years. Integrated analysis of paleodirection and paleointensity data for the last 10 Ma reveals non-dipole field features that appear similar to those observed in field models over timescales of centuries to millennia. The main non-dipole feature is the South Atlantic Magnetic Anomaly (SAA), which is characterized by the lowest total field intensities and responsible for important Space Weather phenomena. However, the EMF structure is largely limited by the spatial and temporal distributions 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 project is to investigate the paleosecular variation (PSV) behaviour and the time-averaged field (TAF) morphology for the 0-10 Ma time interval. To accomplish this, we intended: (i) to contribute with new paleodirection and paleointensity data in volcanic rock samples from two volcanoes in North Patagonia, Argentina; (ii) to evaluate the high PSV and low intensity EMF anomalies detected by targets located in the South Atlantic region extend to South America, based on estimates of the angular dispersion of virtual geomagnetic poles (VGPs) and average intensity of the geomagnetic field, and (iii) to ascertain whether the numerical simulations of geodynamo reproduce estimates of angular dispersion of geomagnetic poles and inclination anomaly as a function of latitude, which are compatible with the statistical PSV and TAF models for the period 0-10 Ma. This new dataset and statistical evaluations will provide information regarding structure and variability of the paleomagnetic field over the past 10 Ma.

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

DE OLIVEIRA, WELLINGTON P.; HARTMANN, GELVAM A.; TERRA-NOVA, FILIPE; PASQUALON, NATALIA G.; SAVIAN, JAIRO F.; LIMA, EVANDRO F.; DA LUZ, FERNANDO R.; TRINDADE, RICARDO I. F.. Long-term persistency of a strong non-dipole field in the South Atlantic. NATURE COMMUNICATIONS, v. 15, n. 1, p. 10-pg., 2024-11-01. (23/04179-7, 22/03086-2, 23/13612-6)