Coupled sea-level and biodiversity dynamics during the Cambrian SPICE event

Abstract

The prominent Cambrian Steptoean Positive Carbon Isotope Excursion (SPICE) stands as one of Earth’s largest carbon cycle perturbations, marked by widespread marine anoxia, climatic upheaval, and biotic turnover, yet the complete extent and interplay of these environmental changes remain unclear. Here, we integrate high-resolution astrochronology, carbonate carbon isotope records from the North China Block and marine species richness to investigate sedimentary and biogeochemical responses during the SPICE interval. Time series analysis reveals a distinct ~2-million-year sedimentary rhythm that aligns with cycles in reconstructed sea-level fluctuations and biodiversity dynamics. We show that sea-level changes preceded shifts in benthic species richness by 70 kyr, linking astronomically paced eustatic oscillations to marine redox fluctuations and concurrent biodiversity turnover. These findings establish pivotal constraints on ocean-climate interactions during this critical interval, elucidating Earth system resilience to extreme climatic and biogeochemical perturbations.