Geomagnetic field variations in the past: an introduction

Abstract

In the last decades, palaeomagnetic research has provided us with a picture of the temporal and spatial behaviour of the Earth's magnetic field (EMF) from its origin up to the present day. Well-dated palaeomagnetic data offer important sources of information about the past variation of the geomagnetic field and have shown that it is characterized by temporal fluctuations such as reversals, excursions and spikes. Despite the advances in our understanding of EMF behaviour, the current dataset is biased towards high and northern latitudes and, therefore, several questions remain open to debate, such as the origin and evolution of the EMF and the frequency and spatial distribution of its variations. This Special Publication focuses on the study of the temporal and spatial evolution of the EMF in the past through new data from palaeomagnetic and rock magnetic studies of archaeological materials, sediments and lavas from Europe, Africa, Australia, New Zealand, India and Baltic Sea, and their applications in archaeology, stratigraphy and climate. This paper summarizes our current knowledge on geomagnetic field variations in the past, open questions and future challenges and gives an overview of the volume's context, which aims to disclose fundamental properties of the Earth's magnetic field evolution. EMF variation in the past: state of the art and open questions Reference data and mathematical models have shown that the EMF is characterized by continuous spatial

Simple stochastic model for geomagnetic excursions and reversals reproduces the temporal asymmetry of the axial dipole moment

“…Because it is not possible to obtain direct measurements of relevant parameters (internal magnetic field, fluid velocity, temperature, composition, etc.) of the outer core deep below the core-mantle boundary (CMB), the exact mechanisms that trigger a field reversal are still poorly known (1,2).…”