INTRODUCTION TO THE NORTH ATLANTIC-ARCTIC GATEWAYS: PLATE TECTONIC-PALEOCEANOGRAPHIC HISTORY AND SIGNIFICANCE

Jörn Thiede and Annik M. Myhre

ABSTRACT

  The Arctic and Subarctic seas exert major influences on global climate and ocean systems. The oceanic pathways between the Arctic Ocean proper and the North Atlantic Ocean provide passages for shallow and deep-water exchange and thus contribute to patterns and variability of ocean and atmospheric circulation over this segment of the Northern Hemisphere. Because of the global importance of these processes, the Ocean Drilling Program (ODP) has designed a program to study the geological and paleoceanographic history of these passages defined as North Atlantic-Arctic Gateways (NAAG). Under the framework of this program, ODP Leg 151 investigated the western Norwegian-Greenland Sea (Iceland Plateau and East Greenland Margin), the Fram Strait (Hovgård Ridge and the deep sill between the Arctic Ocean and the Norwegian-Greenland Sea), and several locations on the Yermak Plateau to the north of Svalbard. ODP Leg 162 comprised the second part of this program and was carried out in late summer 1995. It concentrated on drill sites to the north and south of the Greenland-Scotland Ridge as well as in the Norwegian-Greenland Sea; it's northernmost location was to the west of Svalbard in an attempt to drill one of the trough-mouth fans of glacial origin.
  The major success of the NAAG drilling program has to be sought in (1) a complete and detailed coverage of the preglacial paleoceanography of the Norwegian-Greenland Sea; (2) the identification of the onset of the ice cover in the northern North Atlantic to the south of the Greenland-Scotland Ridge, in the western Norwegian-Greenland Sea, in Fram Strait, and on Yermak Plateau; and (3) the description of patterns of variability of sedimentation in response to the cyclical behavior of the depositional environment (Milankovitch frequencies). In this volume the scientific results of ODP Leg 151 (July to September 1993) are presented.

Date of initial receipt: 7 March 1996
Date of acceptance: 22 May 1996


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