No global-scale transgressive–regressive cycles in the Thanetian (Paleocene): Evidence from interregional correlation

A detailed examination of transgressions and regressions that occurred during the Thanetian (58.7–55.8 Ma) may provide an important constraint on the global palaeoenvironment. Seven tectonically “stable” regions (the eastern Russian Platform, Northwestern Europe, Northwestern Africa, Northeastern Africa, the Arabian Platform, the northern Gulf of Mexico, and Southern Australia), represent exceptional records of transgressive–regressive (T–R) cyclicity. Their chronostratigraphic frameworks are sufficiently well constrained to permit accurate correlation. Surprisingly, except for a generally regressive trend occurring in the late Thanetian, no common T–R cycles can be delineated, which indicates an absence of global-scale T–R cyclicity during the Thanetian. Furthermore, we find no clear correspondence between documented T–R patterns and previously reported eustatic changes. We suggest that a warm climate and an absence of major glaciations in the early-middle Thanetian, coupled with only slow eustatic change expected from tectonic processes, stabilized Thanetian eustatic sea level. Regional subsidence or uplift, possibly generated by mantle flow in the form of dynamic topography, governed transgressions and regressions locally and resulted in an inconsistency between T–R cycles in different parts of the globe. The late Thanetian regressive episode, which preceded the Paleocene–Eocene Thermal Maximum, may be linked to an advance of glaciation.