Palaeo-oceanography, margin stratigraphy and palaeophysiography of the Tertiary North Atlantic and Norwegian-Greenland seas

Abstract

The Tertiary was a period of dramatic changes of the palaeo-oceanography of the world’s oceans in general and of the North Atlantic in particular. These changes were caused by (1) the bathymetric evolution of ocean basins and intrabasin pathways (opening of the Norwegian-Greenland Seas and of the pathway to the Arctic Ocean, interruption of the circumglobal equatorial seaway); (2) the geographical development of the oceans and adjacent marginal basins in the context of rapid and intensive eustatic sea level fluctuations; and (3) the deterioration of the global climate throughout the Tertiary (change from a non-glacial to a glacial world, causing major changes in circulation of the surface and deep water). A biostratigraphy of Tertiary sediments deposited close to the continental margins has been developed by using remains of planktonic floras and faunas. Their presence in these sediments and their usefulness for long distance correlations of margin sediments, depend upon the circulation pattern and hydrographic gradients of the oceanic surface and deep water masses, the climatic regime over the continental border zones, and the probability of their post-depositional preservation.