MI2023 - 16 Andy Biggin: Do LLVPs leave signatures in the palaeomagnetic field?
Channel: MagNetZ
Date: 16/01/2023

Magnetic Interactions 2023 conference at the University of Cambridge
Session 4: Environmental Magnetism

Title: Do large low velocity provinces leave signatures in the palaeomagnetic field?
Author: Andy Biggin from the University of Liverpool, UK

Seismological studies provide detailed information about the present-day structure of Earth’s interior but are unable to probe its evolution through geological time. Two continental-scale large low velocity provinces (LLVPs) at the base of today’s mantle are a robust feature of seismic tomographic models but are enigmatic in terms of their composition, temperature, origin and longevity. An alternative source of information on such deep mantle structures is Earth’s magnetic field that is derived from the geodynamo operating in the underlying core and that is preserved, as the palaeomagnetic record, in rocks as they form through Earth’s history. Previous studies have suggested that a thermal signature of LLVPs is evident in palaeomagnetic behaviour but these have been limited to recent geological time and/or times of geomagnetic instability. Here we demonstrate that a new set of dynamo models subject to the thermal influence of LLVPs are uniquely able to reproduce palaeomagnetic observations, spanning recent times to several billion years ago, in the face of major changes to convective power as likely experienced by the geodynamo. We further show that the magnetic screening effect of the LLVPs produces a more Earth-like field when applied to the output of a wide range of simulations.

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00:00 - Intro
00:32 - Presentation
17:20 - Questions