Biostratigraphy and paleoceanography of the Cretaceous seaway between Norway and Greenland

The narrow seaway between Greenland and Norway, in Cretaceous time was over 1500 lan long and 300 + lan wide, and partly of bathyal water depth during Aptian through Campanian. It received a large volume of fine-grained, sili ciclastic sediments, with intercalated, gravity-flow sandstone wedges. As a conduit for heat transport between the low latitudes and polar region, Atl antic watermasses particularly affected the eastern, Norwegian margin of th is seaway. Despite its high-latitude setting, calcareous and few siliceous planktonic microfossils thus play an important role in regional stratigraph y and facies analysis, and a majority of fossil events correlate to NW Euro pean basins. The eastern margin sedimentary succession may be subdivided in several broad lithologic units: (1) Thin, multicolored, marry sediments of Hauterivian-Barremian age, with a shallow marine Falsogaudryina/nodosariid /ostracod assemblage; (2) Dark mudstones and minor sands, Aptian-early Ceno manian in age, with an upper bathyal, agglutinated assemblage, and monotypi c Hedbergella floods; (3) Thick mudstone facies with thin, slope-apron turb idite sands, and an impoverished benthic/planktonic assemblage of late Ceno manian-Coniacian age, deposited in an upper bathyal, oxic/dysaerobic enviro nment. Where Turonian sedimentation rates are low, a planktonic foraminifer al assemblage with Whiteinella, Hedbergella, Dicarinella, and Marginotrunca na occurs; (4) Grayish, laminated mudstones, Santonian-Campanian in age, wi th local sands in the north, a low diversity, middle to upper bathyal benth ic/planktonic foraminiferal assemblage, and an Inoceramus prisms and radiol arian/diatom flood; a Campanian agglutinated foraminiferal bloom also is kn own from the Atlantic oceanic realm; (5) More marry sediments of Maastricht ian age, with a low diversity planktonic/benthic foraminiferal assemblage. Using the distribution of 1755 foraminiferal and dinoflagellate microfossil events in over 30 exploration wells, a RASC (Ranking and Scaling) probabil istic zonation served as a template to build a Cretaceous zonal model with 19 assemblage and interval zones, including over 100 events. Variance analy sis ranks 72 events according to reliability in correlation. Three new inde x taxa include Uvigerinammina una and Ammoanita globorotaliaeformis (Albian ), and Fenestrella bellii (Campanian). Widespread planktonic flood events o ccur in late Albian through early Cenomanian, early-mid Turonian, late Sant onian-earliest Campanian and mid-Maastrichtian, the result of northwards sh ifts of warmer water masses, and disruptions in water stratification in the dysaerobic basins. An earliest Cretaceous hiatus separates Jurassic from C retaceous strata. Ongoing block-faulting, coupled to thermal subsidence and global sealevel rise increased water depth in Aptian-Albian time from neri tic to bathyal, and created sand accommodation space in dysaerobic, restric ted settings. In Cenomanian-Coniacian time, sedimentation rates in the 'cen tral basin' increased 10-fold, whereas paleo waterdepth did not deepen. Thi s relatively brief (less than 10 m.y.) tectonic episode, resulting in depos ition of deep water sands, is tentatively linked to stress re-orientation i n the Rockall area. A widespread upper Maastrichtian-Danian hiatus, the res ult of 'shoulder' uplift, reflects 'break-up', prior to the onset of Paleog ene seafloor spreading in the Norwegian Sea. (C) 1999 Elsevier Science B.V. All rights reserved.