Atlantic paleobathymetry, paleoproductivity and paleocirculation in the late Albian: the benthic foraminiferal record

Spatial distribution patterns of benthic foraminifers in upper Albian sedim ents from 25 DSDP/ODP sites and 31 onshore sections of the North and South Atlantic Ocean are used to generate paleobathymetric reconstructions and to identify areas of high primary production such as coastal and equatorial u pwelling zones. New paleobathymetric estimates are provided for DSDP/ODP si tes and onshore locations that are not situated on oceanic crust. Paleobath ymetric reconstructions indicate shallow water exchange between the North a nd South Atlantic but show the existence of a deep-water connection between the western and eastern Tethys (> 2500 m) through the Gibraltar Gateway. S trikingly, there is no evidence for a strong latitudinal gradient in deep-w ater benthic foraminiferal distribution during the late Albian: South Atlan tic assemblages show close affinity to North Atlantic and Tethyan assemblag es, exhibiting only a minor degree of provincialism. Biogeographic patterns reveal a distinct asymmetry in late Albian paleoproductivity for the North Atlantic. As for the present day, the eastern margins of the Atlantic were generally more productive than the western margins, and a belt of enhanced carbon Aux export to the seafloor can be traced around the north African c oast, which probably corresponded to a zone of vigorous coastal upwelling. By contrast, assemblage composition in the South Atlantic generally reflect s mesotrophic to oligotrophic conditions. Benthic foraminiferal distributio n patterns, thus, provide robust proxy data to test predictions from paleoc irculation and paleobathymetric models for the mid-Cretaceous Atlantic Ocea n and adjacent margins. (C) 2001 Elsevier Science B.V. All rights reserved.