| Summary: | STRUCTURAL EVOLUTION OF THE ARCTIC-ATLANTIC BASIN DURING THE CENOZOIC Summary The paper gives a sketch of structural evolution of the Arctic-Atlantic Basin during the Cenozoic. The break-up of Laurasia continent close to the Cretaceous/Tertiary boundary proceeded north of Iceland along two major structural lines, the traces of which are now apparently the edges of continental shelves of Greenland and Norway-Svalbard: the Harland Line on the south, and the De Geer Line on the north. In a pre-drift position of the continents, the junction of these systems formed an obtuse angle of 120 degrees, and is still recognisable in sharp turns of continental margins at about 70°N on the eastern, and at 72-73°N on the western sides of the Greenland Sea. The separation of Norway and Greenland north of Iceland along the Harland Line began at about 60-70 Ma, as indicated by the study of magnetic anomalies on the Reykjanes Ridge. The active sea-floor spreading axis - the Aegir Ridge, was located along the line of abyssal hills (seamounts) in central Norwegian Sea and continued northward as buried volcanic ridge on the Vöring Marginal Plateau. About 60 Ma the Lomonosov Ridge began to separate from the northern margin of Eurasian shelf due to the growth of the Gakkel Ridge. During this stage of Early Tertiary extension, a huge pile of plateau basalts (tholeiites) was formed in East Greenland. In Svalbard, the main Tertiary sedimentary basin of Spitsbergen was formed subparallel to the De Gear Line. In the south-west part of the Barents Shelf, the Björnöyrenna-Hammerfest. Basins with probably Tertiary sediment fill, apparently mark a failed arm of a triple junction, the other and active arms being the De Geer and Harland lines. The succeeding stage of Early Tertiary compression (resp. transpression) is well evidenced in Svalbard as strong folding and thrusting of the west coast of Spitsbergen due to dextral translation of the Greenland block respective to the Svalbard-Barents block along the De Geer Line. The fold belt probably ...
|
|---|