Environmental drivers of biotic turnover: Insight from tectono-sedimentary environment transition during the terminal Ediacaran to Early Cambrian

Abstract

Biotic turnover and innovation during the terminal Ediacaran to Early Cambrian have been widely linked to tectonic, sedimentary, climatic, and oceanic environmental changes due to their temporal coincidence. However, the precise interconnections between these environmental factors and biological co-evolution remain uncertain. The Yangtze Block preserves essential records to investigate this issue. In this study, we use lithostratigraphic logs and correlations of the terminal Ediacaran to Early Cambrian successions across the upper Yangtze Block to suggest that, the significant lithological change from dolomite to siliciclastic-dominated sedimentation indicates the tectono-sedimentary environment transition from a shallow-water carbonate platform to a deep-water siliciclastic basin. Extensional tectonic activities, enhanced continental weathering, and rising sea levels led to rapid subsidence and extensive siliciclastic sediment accumulation during the Early Cambrian, facilitating this transformation. This sedimentary environment transition also correlates with marine transgression on a global scale. Further, qualitative comparisons of detrital zircon age spectra from this period place the Yangtze Block near northern India, confirming its paleogeographic and material connections with Gondwana. By integrating these findings and geological data on tectonism, sedimentation, marine environment, and biological evolution, this paper constructs a synthetic framework to propose that enhanced continental weathering and marine transgression during the assembly of Gondwana initially triggered changes in lithofacies and seawater conditions, potentially driving early bio-evolution. Our research highlights the interactions among multiple environmental factors during this critical geological period, which contributes to understanding the trigger of the Cambrian explosion.