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The AAPG/Datapages Combined Publications Database

Journal of Sedimentary Research (SEPM)


Journal of Sedimentary Petrology
Vol. 29 (1959)No. 1. (March), Pages 16-29

Geology and Paleontology of Norwegian Sea Bottom Cores

Hans Holtedahl


Nine sediment cores from the southeastern part of the Norwegian Sea, collected from depths between about 700 m and 3000 m, have been examined. A gray, unsorted, sandy and pebbly clay, assumed to represent a glacial-marine sediment, is found to cover the surface of the sea bottom down to about 900 m depth, and to continue underneath more recent sediments at greater depths. These latter include a 10-15 cm thick top-layer of foraminiferal marl, with a CaCO3 content reaching 48 percent.

An examination of the Foraminifera distribution of a core collected from a depth of about 3000 m was carried out. The gray glacial clay is poor in Foraminifera, and the major part of the fauna consists of benthonic forms which live in lesser depths than where they are found, and therefore must be regarded as displaced. As this displaced fauna is restricted to the glacial-marine sediments of the core, it is assumed that it is transported to deep water by drifting ice. The low percentage of planktonic Foraminifera is thought to indicate rapid sedimentation of clastic material. The upper part of the glacial clay, which shows an increase in fineness upwards, also shows a marked decrease of the displaced benthonic fauna and a corresponding increase in the planktonic population. This is tho ght to indicate an amelioration of climate, with less ice-drift transportation, but still with rapid sedimentation of clastic material. The great increase in the Foraminifera population in the upper 30 cm of the core, especially of planktonic forms, indicates further amelioration of climate with clastic sedimentation having been of less importance.

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