MI2023 - 07 Evelyn Baker: Can we trust directional information from chemical remanent magnetisations
Channel: MagNetZ
Date: 2023-01-16

Magnetic Interactions 2023 conference at the University of Cambridge
Session 2: Rock and Mineral Magnetism

Title: Can we trust directional information from chemical remanent magnetisations in nature?
Author: Evelyn Baker from the Imperial College London, UK

In palaeomagnetism, there are three types of magnetic remanence: Thermoremanent magnetisations (TRM), detrital remanent magnetisations (DRM) and chemical remanent magnetisations (CRM). Determining directional information from magnetic remanences is an important aspect of palaeomagnetism, e.g., for studying the secular variation of the Earth’s magnetic field. TRMs and DRMs in nature have been proven to record directional information reliably. Despite CRMs being ubiquitous in nature, often dominating the magnetic remanence in sediments, it is unknown whether they can record the Earth’s magnetic field direction. To test whether CRMs in sediments can record directional information, we require a locality where the remanence is a CRM and the Earth’s magnetic field direction is known. This is the case for salt marshes in Norfolk, where greigite is currently forming. The salt marshes are less than 60 years old. Therefore, the greigite is expected to have recorded the current Earth magnetic field as a CRM during its formation. We conduct a magnetic study of these anoxic sediments to determine the magnetic carriers and whether they carry a CRM which has recorded the Earth’s magnetic field direction.

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00:00 - Intro
00:07 - Presentation
12:23 - Questions