Paleosecular variation of the geomagnetic field during times of low reversal rates

• Grant number: 23/11998-4
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: June 01, 2024
• End date: May 31, 2028
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geophysics
• Principal Investigator: Daniele Cornellio de Paiva Caldeira Brandt
• Grantee: Julia Massucato Silva
• Host Institution: Instituto de Astronomia, Geofísica e Ciências Atmosféricas (IAG). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The main geomagnetic field, generated in the outer core, gradually changes over time. This variation, called secular variation, hasn't occurred in the same way throughout the geological time. The studies of the Earth's mean magnetic field's behavior and its long scale variations are conducted through the data of rocks' magnetization and from statistical models of the paleosecular variation. Many observations of the geomagnetic field for the past million years and for the periods of extreme reversal rates have been done, however, there is little knowledge about the transition of fields of high and low stability. For this reason, this project proposes a study of the geomagnetic field during the period of low, but not null, reversal rates that occurs after the high stability period called Cretaceous Normal Superchron (CNS). The period shortly after the CNS is the one that the reversal rates were low (maximum of 2 reversals per million years) and it has quite extensive paleomagnetic data that are not explored regarding the paleosecular variation. The main goals of this project are: (1) obtain new paleomagnetic data for the Itatiaia alkaline complex (~ 67.3 Ma) and combine them with previous results that were obtained for the same rock unit; (2) organize a new global database for the age interval between 45 and 80 Ma; (3) determine a new representative model for the Earth's magnetic field during the period after the CNS, using statistical models of the paleosecular variation. (AU)