OCEANIC-CRUST PRODUCTION AND CLIMATE DURING THE LAST 100-MYR

In order to evaluate the possible influence of oceanic crust production on climatic changes during the past 100 Myr variations in total oceanic crust for this period including production at mid-ocean ridges, oceanic plateaus, and back-arc basins were calculated using the most recent and accurate time-scales. The rates presented here differ from those of Larson (1991a, b) on Cenozoic fluctuations and show that (1) maximum production values occurred during the Cenomanian, Palaeocene, and late Oligocene-early Miocene and (2) minimum values occurred in Campanian-Maastrichtian, late Eocene, and middle Miocene. Significantly, variations of oceanic crust production correspond with variations in the deltaO-18 of deep-water benthic foraminifera: maximum values of oceanic crust production correspond with minimum values of deltaO-18, and minimum production values with maximum values of deltaO-18. This latter synchronism suggests that changes in land-sea relationships and atmospheric CO2 related to major fluctuations in oceanic crust production were the main cause of mid-Cretaceous warming and Late Cretaceous cooling, and of climatic quasi-cycles having a periodicity of 33-38 million years over the last 100 Myr. This is the first report showing variations of ocean crust production synchronized with the Cenozoic climate changes.