402 HEEZEN AND EWINO [CHAP. 16 



lies in the seismic belt and it could mark the continuation of the Ewing- 

 Heezen Rift north of Iceland and Jan Mayen". 



Recent exploration by Soviet shi]is su])ports the ])resent writers' interpretation 

 that the mid-oceanic ridge follows the seismic belt north between Spitsbergen 

 and Greenland. At the same time, the Soviet work refutes the traditional inter- 

 pretation of an east- west trans-oceanic ridge at Nansen's Sill. The strongly 

 north-south tectonic trends on Spitsbergen are in much closer agreement with 

 a north-south submarine pattern in the Nansen Sill region than with the 

 previously postulated east-w^est trend, which would have had to die out, or 

 turn 90° between the shelf break and the shoreline, in order to join the Spits- 

 bergen lineaments. 



A. Arctic Basin Seismic Belt 



The mid-oceanic seismic belt of the Atlantic Ocean and the Norwegian Sea 

 continues across the Arctic Ocean (Tams, 1922; Heck, 1938; Raiko and Linden, 

 1935; Hodgson, 1930). Unlike the Atlantic seismic belt, this Arctic continuation 

 does not symmetrically divide the Arctic Ocean basin into two equal parts. 

 Instead, the belt parallels the continental slope from Spitsbergen to Severnaya 

 Zemlya (Fig. 12), maintaining an almost constant distance of 250 nautical 

 miles seaward of the shelf break. Of thirty -two Arctic Ocean earthquakes shown 

 on Fig. 12, twenty-four epicenters lie along this belt. Two occurred on the con- 

 tinental slope between Spitsbergen and Franz Joseph Land, one lies north- 

 west of Banks Island, and three lie near the Bering Straits. 



B. Arctic Continaation of the 31 id-Oceanic Ridge 



Although the extension of the mid-oceanic seismic belt through the Arctic 

 Ocean has long been known, no clear evidence of a corresponding topographic 

 ridge has been reported. As Hope (1959) points out, the discovery of the 

 Lomonosov Ridge led some investigators to the conclusion that it was the 

 continuation of the mid-oceanic ridge but, as we have already shown, the seismic 

 belt lies parallel to the Lomonosov Ridge, about 250 miles distant, approxi- 

 mately bisecting the basin between the Lomonosov Ridge and the Barents 

 Shelf continental slope. Clearly, the Lomonosov Ridge is not (at the present, at 

 least) part of the mid-oceanic ridge system. 



The area between the Lomonosov Ridge and the continental margin of the 

 Barents and Kara shelves has usually been described as a single basin. We have, 

 however, good reason to expect a rifted ridge along the mid-oceanic seismic 

 belt. The ridge is shown in the contours of Fig. 12 in a new interpretation of the 

 soundings largely obtained from Fram and Sedov. In contouring the soundings 

 along the Arctic epicenter belt, Soviet investigators have generally shown broad 

 submarine canyons running across the belt toward the continental slope off the 

 Barents Shelf. The interpretation shown in this paper satisfies the soundings 

 and also preserves the world-wide pattern of rift, ridge and seismicity which we 

 have traced for over 40,000 miles. Post-war investigators have not added much 



