208 / 2025-04-14 22:41:38

Ediacaran equatorial dipole field revealed by multi-section magnetostratigraphy in South China and its potental link to early metazoan radiation

Ediacaran,Paleomagnetism,South China,Doushantuo Formation,Geomagnetic field

Theme 3: Earth-Life Co-evolution Through Time > Session 3b: Evolution of the Earth-Life System During the Neoproterozoic-Paleozoic Transition

Over the past decades, inconsistencies in Ediacaran paleomagnetic datasets have persistently challenged paleomagnetists. Our pioneering work (Zhong et al., 2024) established a continuous magnetostratigraphic section (ca. 567.3–572.8 Ma) in the upper part of Member 3 of the Doushantuo Formation from the Zhengjiatang section, South China, revealing rapid apparent polar wander (APW) supported by validation through high-resolution records in South China. This study verifies this foundation by analyzing two additional sections that span the δ¹³C excursion potentially associated with the Shuram negative excursion. Crucially, stratigraphic correlation demonstrates that Xiangerwan (XW) section and Southxiangerwan (SXW) section respectively correspond to the upper (ca. 567.6–569.5 Ma) and lower (ca. 569.9–572.8 Ma) intervals of the Zhengjiatang section. The three-section consistency test confirms regional geomagnetic signal coherence, effectively excluding local remagnetization artifacts. These findings collectively provide: 1) A comprehensive magnetostratigraphic framework with at least 13 geomagnetic reversals were identified; 2) Using the astronomical timescale of the Zhengjiatang section (Li et al., 2022), the acquired poles DST_3-1 and DST_3-2 were constrained to ca. 569.5–567.6 Ma and ca. 572.8–569.9 Ma, respectively; 3) The calculated APW rates of 223.4 ± 20.4° Myr⁻¹ (this study) and 243 ± 17° Myr⁻¹ (Zhengjiatang section) show statistical consistency that confirms the equatorial dipole field. The equatorial dipole configuration correlates temporally with metazoan radiation events (575–565 Ma), suggesting potential geomagnetic modulation of surface UV flux and biospheric evolution.