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Waste Disposal Practices of the Former Soviet Union in the Arctic Environment
Final rept. 1 Jan-15 Apr 1994
JOINT OCEANOGRAPHIC INSTITUTIONS INC WASHINGTON DC
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This paper summarizes major events in the tectonic evolution of the Arctic from a paleoceanographic perspective focused on the formation of oceanic basins in the Mesozoic and Cenozoic. Despite its present cold climate, the Arctic land masses once lay much farther to the south and were gradually carried northward by plate tectonic motions. For example, in the Late Carboniferous northern Greenland, which was part of Pangea, was situated at only 30 deg N with the Panthalassa Sea to the north. By Late Jurassic-Early Cretaceous, a series of allochthonous blocks had collided with both the North American and Siberian plates. The Pacific Ocean was separated from the Arctic Basin by rotation of the North-Slope Chukotka block counterclockwise away from the Canadian Arctic Islands by Mid Cretaceous. It is speculated, based on the magnetic patterns, that the Alpha-Mendeleev Ridge complex may either have been a separate precursor block or may represent oceanic crust modified by a hot spot. Sea floor spreading in Late Cretaceous or Early Paleocene rifted the present Makarov Basin in a wedge-shaped manner, with the Siberian end wider than the Canadian. The Eurasia Basin has a well-ordered set of magnetic anomalies, and thus this basin can be confidently dated to have been created just after the CretaceousTertiary boundary. Creation of the Eurasia Basin eventually opened the pathway for exchange of waters between the Arctic and Atlantic oceans. The cold-oxygen rich waters from the Arctic ventilate the worlds oceans and provide an important mechanism for global heat transfer and for the cycling of nutrients and carbon.
APPROVED FOR PUBLIC RELEASE