Astronomical constraints on the duration of the Early Jurassic Pliensbachian Stage and global climatic fluctuations

摘要: The Early Jurassic was marked by multiple periods of major global climatic and palaeoceanographic change, biotic turnover perturbed geochemical cycles, commonly linked to large igneous province volcanism. This epoch also characterised the initial break-up super-continent Pangaea opening formation shallow-marine basins ocean gateways, timing which are poorly constrained. Here, we show that Pliensbachian Stage Sinemurian–Pliensbachian carbon-cycle perturbation (marked a negative shift in δ13Cδ13C 2–4‰2–4‰), have respective durations ∼8.7 ∼2 Myr. We astronomically tune floating time scale 405 Kyr eccentricity solution (La2010d), propose revised with significantly shortened Sinemurian duration 6.9±0.4 Myr6.9±0.4 When calibrated against new scale, existing seawater 87Sr/86Sr record shows relatively stable values during first Myr Pliensbachian, superimposed on long-term decline 87Sr/86Sr. plateau coincides boundary perturbation. It is possibly late phase Central Atlantic Magmatic Province (CAMP) volcanism induced enhanced weathering continental crustal materials, leading an elevated radiogenic strontium flux ocean.