High-latitude continental evidence of the Jenkyns Event: Insights from the Southern Junggar Basin, NW China

The Jenkyns Event (Toarcian Oceanic Anoxic Event, T-OAE) represents a period of extreme global warming during the Early Jurassic. This study integrated geochronological, palynological, and elemental geochemical analyses on the Lower Jurassic Sangonghe Formation, a high-latitude lacustrine sequence exposed in the Honggou Section of the Junggar Basin. The results reveal a negative organic excursion in carbon isotopes, accompanied by significant enrichment in total organic carbon (TOC) within the Sangonghe mudstone. Combined with. Zircon UPb dating and age-diagnostic palynological assemblages, these findings suggest a probable correlation with the Jenkyns Event documented in both marine and terrestrial sediments. We reconstructed the climatic changes and environmental responses of the Junggar basin during the event. Elevated values of paleoclimatic proxies, including the C value and ln (Al₂O₃/Na₂O), along with an increased proportion of drought-tolerant palynomorph taxa, indicate an inland aridification occurring alongside intermittent humidity. Concurrent declines in the clastic input proxy (Ti/Al) and increases paleoproductivity proxy (Zn/Ti) suggest lake deepening and enhanced primary productivity, potentially resulting in water-column anoxia. This interpretation is supported by positive shifts in redox-sensitive indicators, including Mo_EF, U_EF, and C_org/P. Positive correlations between TOC and indicators of primary productivity and redox conditions suggest that increased primary productivity and development of anoxia jointly facilitated substantial organic carbon accumulation in high-latitude lake, making it a sink of organic carbon during the extreme thermal event. These findings provide a terrestrial evidence from high-latitude settings of climatic and environmental responses to the Jenkyns Event and offer new insights into its global significance.