Diatomeen-Taphozoenosen als Anzeiger palaeo-ozeanographischer Entwicklungen im pliozaenen und quartaeren Nordatlantik

Quantitative diatom analyses of samples from DSDP-Hole 610 A (Feni Drift), ODP-Hole 646 B (Labrador Sea), and Core K 708-7 (Rockall Plateau) enable us to reconstruct paleoceanographic changes. Late Pliocene changes in paleoceanography of the North Atlantic are characterized by the transition from a preglacial to a glacial ocean at about 2.6 Ma. This transition was accompanied by a decrease of the sedimentation of siliceous biogens. Diatoms are the most important components of siliceous biogens and were analysed for Upper Pliocene sections of Holes 610 A and 646 B. Investigations on Core K708-7 were made to compare the preglacial and glacial mode of paleoceanography. The known preference of modern diatom species for benthic, netic or oceanic environments and their tropical/subtropical, polar/subpolar or cosmopolitan distribution have been used to arrange the observed species in seven categories. These are named benthic species, neritic coldwater species, neritic warmwater species, neritic cosmopolitans, oceanic coldwater species, oceanic warmwater species, and oceanic cosmopolitans respectively. Reworked species and Chaetoceros-spores are additional categories. In order to display the differences of the diatom taphocoenoses cluster analyses have been accomplished. Arithmetic averages of category percentages and additional data ( #delta#"1"8 O, coccolithophorids, cadmium, SSTw, %>63 #mu#m where available) are used to distinguish the clusters and interpret them as typical parameters of the observed taphocoenoses. (orig.)Available from TIB Hannover: RR 1846(24) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman