Abstract:
Cyclic sedimentary deposits characterize low-latitude late Paleozoic successions and preserve evidence of dynamic climate change on the Pangaean supercontinent. Although their orbitally paced glacioeustatic origins are widely accepted, their climatic signatures are open to interpretation. In this study, we utilize the GENESIS general circulation model (GCM) coupled to dynamic ice sheet and ecosystem components, to explore the response of low-latitude continental climate and high-latitude ice sheets to orbital and atmospheric pCO2 forcing. Our results suggest that atmospheric pCO2 concentration exerts the primary control over low-latitude continental climate and high-latitude glaciation. Our experiments constrain the atmospheric pCO2 window within which late Paleozoic climate was amenable to orbitally-driven glacial-interglacial fluctuations. The results suggest that both high-latitude ice-sheet accumulation and ablation and low-latitude climate change were paced by the eccentricity of Earth's orbit. Periods of high eccentricity amplified precession-driven changes in insolation and promoted high-latitude ice sheet volume fluctuations as well as increased low-latitude precipitation variability. When eccentricity was low, the amplification of precessionally-driven insolation fluctuations was reduced, which promoted high-latitude continental ice sheet stability and less variable low-latitude precipitation. Based on these modeling results we discuss the implications of eccentricity paced precessional-scale climatic changes on low-latitude Pangaean depositional environments.
