EARLY HOLOCENE DIATOM PULSE IN THE NORWEGIAN SEA AND ITS PALEOCEANOGRAPHIC SIGNIFICANCE

Abstract

A time synchronous mass abundance of sedimented marine planktonic diatom valves occurs in four cores from the western slopes of the Norwegian Basin and from the extinct Aegir Ridge in the middle of the Norwegian Basin. This mass abundance occurs shortly after the Saksunarvatn ash layer (9,000 to 9,100 y B.P.). Contrary to previous investigations we interpret the diatom pulse to represent a time synchronous event in the wider Norwegian Sea that has no direct relationship to a polar front movement but is related to “unique” oceanographic conditions favoring immense diatom production in the photic zone leading to the deposition of a sediment rich in diatom valves. The “unique” oceanographic condition may be related to a “switch on” of the Broecker conveyor belt coupled with an influx of surface and subsurface Atlantic waters rich in dissolved nutrients. Other Late Pleistocene and Holocene diatom peak abundances from the Skagerrak, from the Norwegian continental margin, from the western Barents Sea slope and from the Fram Strait are caused by local phenomena and cannot be associated with the −8,100 to 8,200 y B. P. diatom pulse.