Sea-level change on a dynamic Earth

Large-scale and long-term sea-level variations on a dynamic, evolving Earth provide a natural connection between geophysics and geology, and they remain, after many decades of study, a subject of active interest. Research in this area is plagued by the classic problem of separating eustatic tie., globally uniform) signals from regional Variations linked to continental epeirogeny, and by uncertainties in the origin and magnitude of eustatic signals. In this article we review, in some detail, the principal issues involved in these debates, and we conduct numerical experiments that bear on both problems. First, we present numerical simulations of mantle convection that show that viscous now coupled to cold, subducting slabs is capable of inducing significant large-scale epeirogenic deformations of otherwise stable continental margins and interior platforms. The stratigraphic record indicates that the manifestations of this coupling, that is sedimentary basin formation and sea-level transgressions and regressions, are ubiquitous and we argue that this has likely biased past estimates of eustatic sea-level cycles. Second, we use a visco-elastic modelling procedure to demonstrate that sea-level variations driven by long-term wander of the rotation pole are potentially large and difficult to distinguish, on the basis of present observational constraints, from eustatic sea-level trends. This suggests that the origin and previously-inferred magnitudes of these trends may require re-appraisal.