Late Eocene-Oligocene Dinoflagellate Provincialism in the North Atlantic Ocean

Abstract

Diverse Eocene-Oligocene dinoflagellate assemblages occur in about four hundred and forty samples from twenty-three North Atlantic Deep Sea Drilling Project (DSDP) sites. The most complete sections are in the Priabonian, Rupelian and Chattian intervals, represented by samples from eleven coreholes on which the present study is based. Localities were grouped into five geographic regions: southwest North Atlantic (DSDP 540, 612; Alabama core); Newfoundland Basin (DSDP 112); Norwegian-Greenland Basin (DSDP 338, 345); Rockall Plateau-Porcupine Trough (DSDP 116, 117, 406, 549A); and offshore northwest Africa (DSDP 369A, 547A).Using this spatial and temporal framework, we have related species occurrences to paleoclimatic and paleooceanographic models for the Paleogene. The distribution of species occurring in the Priabonian appears to be influenced by both paleocurrents and paleolatitude. The existence of the proto-North Atlantic Current is supported by the relatively high percentage of species (20 %) which occur in all regions except the Newfoundland Basin, which was located north of the presumed path of the current. Priabonian species diversity decreases from low to high latitudes. The Rupelian has the highest percentage of species (64 % of the total assemblage) restricted to low latitudes. Middle-and high-latitude assemblages are notably less diverse, indicating a southward migration of taxa during this time; this is interpreted as. a response to the cooling event which took place across the Eocene-Oligocene boundary. In the Chattian, there is an increase in the number of cosmopolitan taxa, and the lowest species diversity occurs in the middle latitudes.

Early Oligocene dinocysts as a tool for palaeoenvironment reconstruction and stratigraphical framework – a case study from a North Sea well

“…Dybkjaer, 2004;Stover and Hardenbol, 1994), study temporal and spatial changes in assemblages (e.g. Damassa and Williams, 1994), or study changes in the assemblages together with palaeoclimatological proxies which can provide information about, Table 1. Alphabetical list of all identified dinocyst taxa identified in the 11/10-1 well.…”