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The formation of the present-day morphostructural ensemble of the Arctic
basin was to a large extent controlled by sedimentological pattern that
was, in turn, strongly affected by the influence of the Atlantic and
Pacific oceans. Recently obtained new seismic data suggest several major
structural rearrangements in the region, the largest events occurring
during the Oligocene and the Late Miocene. Paleozoogeographic and
hydrological evidence of the connections between deep-sea basins and
surrounding shelves are of crucial importance for paleotectonic and
paleoenvironmental reconstructions.
Paleogene diatom assemblages from the Fram Strait constrain the evidence of
continental shelf environments in water depths not exceeding 300-400 m.
Freshwater diatoms are also common, indicating environments of coastal
marshes. The analysis of ODP materials from the Fram Strait shows that
in the Oligocene this basin was isolated from both the North Atlantic
and the Arctic basins. During the Miocene, this basin became deeper and
was characterized by higher sedimentation rates, thus providing
favorable environments for the preservation of benthic agglutinating
foraminifera assemblages.
Apparently, this basin was at that time isolated from the
Norwegian-Greenland Basin, as indicated by the absence here of the
typical North Atlantic carbonate fauna. On the Alpha Ridge,
Cretaceous-Eocene siliceous-rich sediments are overlain by late
Miocene-Pliocene deposits containing secretional fauna. This may
indicate a fundamental environmental change that began in the Oligocene
and reached its maximum during the Miocene. Further restructuring of the
Arctic Basin was signified by the appearance in the shelf and mainland
sedimentary records of both the Atlantic and North Pacific fauna and
flora assemblages and the onset of ice-house conditions imprinted in
replacement of the Miocene thermophilic diatoms by cool-water species.
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