Supercontinent breakup: effect on eustatic sea level and the oceanic heat flux

Abstract

First-order sea-level highstands have occured only twice during Phanerozoic time and in both cases have followed supercontinent breakups by 50—100 Ma. We propose that a major control on first order sea-level cycles is the formation of new ocean basins and destruction of preexisting ocean basins. During breakup the global plate generation rate increases as new spreading ridges are created. As older basins are consumed, in order to conserve total ocean area, plate generation rates gradually decrease. Taken together, these variations in the global plate generation cause sea level, as well as the ocean heat flux, to first rise and then fall as new ocean basins open. The eustatic highstand generally occurs later than the oceanic heat flux maximum which, in turn, follows the time of peak plate generation rates. In contrast to other models, our mechanism does not require anomalously high spreading rates during the Late Cretaceous highstand.