High-Resolution Sea and Lake Level Reconstructions of the Late Cretaceous: Evidence for a 'Seesaw' Ocean-Land Water Circulation Model

The investigation into water circulation mechanisms within greenhouse environments, particularly their link to orbital forcing and consequent impacts on organism-environment coevolution, is garnering increased attention. A key uncertainty is the nature of variations in continental and oceanic water reservoirs on an ice-free Earth and the primary factors driving sea level changes. Traditional approaches like sequence stratigraphy and sedimentology have provided rough and limited insights, hindering a detailed and comprehensive understanding of water circulation in deep time. Therefore, high-resolution inversion of sea and lake level changes is vital for studying global hydrological cycle. Employing advanced sedimentary noise models (DYNOT and ρ₁), based on astrochronology and time-series analysis, this research reconstructs detailed water-level variations in key regions: the continental Songliao Basin of Northeast China, the marine Basque-Cantabric Basin in Spain, and the marine Espírito Santo Basin in the western South Atlantic, covering the entire Maastrichtian Stage to the Cretaceous-Paleogene (K-Pg) boundary. These reconstructions, corroborated by sedimentary facies analysis and paleosol studies, reveal 1.2 Myr and 2.4 Myr periodic variations in sea and lake levels, exhibiting a 'seesaw' pattern of opposite trends. This indicates that sea level fluctuations might be influenced by changes in continental water reservoir content, providing new insights into the complex interplay between terrestrial and marine hydrological systems.