Long-term behavior of the Earth’s magnetic field: How can we use paleomagnetism to understand the evolution of Earth’s deep interior?

The current understanding of the Earth’s deep interior is limited to recent time where we have direct observations from geophysical data. Fortunately, one source exists that records ancient signals from the deep interior, and that is paleomagnetic data. Variations in the magnetic field occur on a broad range of timescales. While most variations are attributed to stochastic processes in the outer core, long-term variations (> 10 Myr) have been suggested to be correlated to large-scale processes including planetary evolution (e.g., formation of the inner core) and changes in forcing arising from mantle convection. Although it is expected that both the mantle and the thermal evolution of the planet influence the outer core, the question that remains is whether the influence of these entities would result in changes to the magnetic field that are detectable in the paleomagnetic record. To help assess this question we have two key tools at our disposal: paleomagnetic data and numerical geodynamo simulations. If long-term variations can be properly identified in paleomagnetic records and tied to mechanisms predicted from numerical geodynamo simulations, together they can provide a means for studying changes in the deep interior over the course of Earth history. This presentation gives an overview of recent advances on this topic, including the characterization of long-term trends in paleomagnetic data, the assessment of “Earth-like” numerical geodynamo simulations, and other multidisciplinary approaches that are helping to clarify how paleomagnetic data can be used to understand the evolution of Earth’s deep interior.