Sprecher
Beschreibung
The Early–Middle Jurassic represents a key greenhouse interval marked by major environmental perturbations associated with the Karoo–Ferrar Large Igneous Province events (K–FLIPs) and the Pliensbachian–Toarcian boundary event. Although marine records have documented coupled carbon- and mercury-cycle disturbances during this interval, their expression in terrestrial ecosystems remains less well constrained.
Here, we present a plant-based, multi-proxy dataset derived from fossil ginkgo leaves collected from discrete stratigraphic horizons across an approximately 20-million-year interval in the Lower–Middle Jurassic succession of the Qaidam Basin, China. Fossil leaves were analysed for leaf morphology, stomatal characteristics, total organic carbon (TOC), carbon isotope composition (δ¹³C), atmospheric CO₂ reconstructed using a leaf gas-exchange model, and mercury (Hg) concentrations.
The results reveal stratigraphically coherent variations in δ¹³C values, Hg concentrations, and reconstructed atmospheric CO₂ across the studied interval. Intervals characterized by more negative δ¹³C values are commonly associated with elevated Hg concentrations and higher reconstructed CO₂ levels, whereas intervals with less negative δ¹³C values generally show lower Hg concentrations and lower reconstructed CO₂. Although alternative processes, including wildfire activity, cannot be entirely excluded, the observed coupling between carbon-isotope shifts, Hg enrichment, and reconstructed CO₂ is consistent with large-scale volcanic activity contributing to simultaneous perturbations of the carbon and mercury cycles.
These findings provide terrestrial plant-based evidence for coupled biogeochemical-cycle perturbations during an Early–Middle Jurassic greenhouse interval. More broadly, they highlight the value of fossil leaves as integrated archives for reconstructing atmospheric composition, mercury loading, and ecosystem-scale responses to extreme environmental events in deep time.