175 The Neoproterozoic Earth and Life Co-evolution, Part I

This session aims to enhance discussions and foster interdisciplinary collaborations to advance understanding of the Neoproterozoic Earth and life co-evolution. Contributions from paleontologists, geochemists, sedimentologists, Earth system modelers, and related fields are highly encouraged.

Tuesday, 21 October 2025
8:00 AM - 12:00 PM
HBGCC, 304A

Ediacaran Ultra-Weak Magnetic Field and the Avalon Explosion

Paper number: 175-11
Program: Technical Sessions
Time: 10:40 AM – 10:55 AM

Authors

Abstract

Earth’s magnetic field has typically been viewed as a shield, protecting life from harmful radiation from space that might otherwise thwart the development of life and evolution (Uffen, Nature, 1963; Sagan, Nature, 1965; Tarduno et al., Science, 2015). Recent data suggest that this relationship between the geomagnetic shield and evolution flipped 575 to 565 million years ago during the Avalon explosion (Shen et al., Science, 2008), when the first macroscopic mobile animals of the Ediacaran Period evolved (Tarduno, Phys. Today, 2025). At this time, Earth’s magnetic field was on the verge of collapse, more than 10 times weaker than the present-day. Concurrently, oxygenation of the atmosphere and oceans was increasing (Pogge von Strandmann et al., Nat. Commun., 2015). We have recently suggested that the weakened magnetic field allowed more atmospheric hydrogen to escape to space, leading to greater oxygenation of the atmosphere and ocean which in turn stimulated evolution (Huang et al., Commun. Earth & Environ., 2024; Tarduno et al., Natl. Sci. Rev., 2025). Key factors allowing H and related oxygenation are the exact strength of the magnetic field and the duration of the ultra-weak dynamo state. Here, we review and update the expanding paleointensity data set for this interval, including new data that suggest the field may have intermittently vanished in the Ediacaran and Cryogenian Periods. We also consider whether the renewal of the geodynamo and restoration of magnetic shielding in the latest Ediacaran/Cambrian (Zhou et al., Nat. Commun., 2022; ESPL, 2024), likely related to the onset of nucleation of Earth’s solid inner core, is reflected in the palaeontologic record.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-414476

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