Obliquity Forcing of Lake-Level Changes and Organic Carbon Burial During the Late Paleozoic Ice Age

The linkages between the astronomical forcing of sea-level oscillations, the environment, and climate change during the Late Paleozoic Ice Age (LPIA) add to our understanding of the complicated mechanisms and patterns of current global sea-level change, climate transition, and biological evolution. However, due to the complexity and internal nonlinearity of the Earth's climate system, the million-year-scale oceanic and continental moisture transport patterns and carbon cycle processes during icehouse states are still controversial. Here, we utilize highresolution gamma ray (GR), density (DEN) logs and total organic carbon (TOC) datasets to conduct a study on the cyclostratigraphy and organic carbon burial processes in the Lucaogou Formation of the Early Permian Junggar Basin in the Northern Hemisphere. An -4.2 Myr high-resolution astronomical time scale is developed by astronomical tuning of DEN log and TOC series to the stable 405-kyr long-eccentricity cycles. A comparative study of the sedimentary noise model and the SediRate-Fischer (SR-Fischer) plot finds similar patterns of lake-level changes for the first time, further demonstrating the utility and robustness of the sedimentary noise model and the SR-Fischer plot in tracking water-level variations. The antiphase correlation of sedimentary noise curve with the obliquity modulation and relative sea-level cycles demonstrates that the changes in land-ocean water exchange associated with variations in poleward flux of moisture dominated by s4-s3 obliquity amplitude modulation (AM) cycles may be a major driver for regulating inland lake levels in the Northern Hemisphere during the Late Paleozoic Ice Age. Additionally, we find a robust cyclicity of -170 kyr in the TOC series, which is modulated by the combined s4-s3 and s3-s6 astronomical signals and is nonlinearly amplified by internal climate responses of the carbon cycle under varying climate conditions. Our results strengthen knowledge of the connection of Myr-scale sea- and lake-level variations to astronomically induced climate change during the Late Paleozoic Ice Age and further elucidate the nonlinear climate feedback of the carbon cycle under obliquity forcing.