Geologic Concepts of Arctic Ocean Basin: ABSTRACT

Abstract

Geologic concepts of the Arctic Ocean basin fall into two groups. The basin is either (1) a permanent or old feature of the Earth's crust, dating from at least the early Paleozoic and probably from the Proterozoic, or (2) it is a relatively young feature (Mesozoic and/or Cenozoic), formed by subsidence of continental crust or by continental drift, through a process of rifting and/or sea-floor spreading. When the Arctic basin is considered as a whole, the large differences between different parts of the basin indicate that its overall tectonic history has been far too complicated to be explainable by either hypothesis. Oceanographic and geophysical studies indicate that the Arctic Ocean basin is not a uniformly deep basin isolated from the world ocean system by epicontinental seas but is divided into separate basins by submarine mountain ranges. The Eurasian basin, separated from the Canada basin by the Lomonosov Ridge, is connected to the northern Atlantic by a deep trough. The Nansen Cordillera which crosses the Eurasian basin as an extension of the Mid-Atlantic Ridge, has volcanic and seismic activity that can be related to sea-floor spreading. Paleozoic geologic trends along the Arctic coast of Eurasia are oblique to the margin of the Eurasian basin. The shape of the Lomonosov Ridge shows a good fit with the continental margin of Eurasia, and appears to be a narrow fragment of Eurasia that has drifted passively into the center of the Arctic basin, as the Eurasian basin spread. The Canada basin, on the other side of the Lomonosov Ridge, contains the Alpha Cordillera, probably a dormant mid-ocean ridge from an older period of sea-floor spreading. The Canada basin is rimmed on the south by a discontinuously exposed system of Paleozoic fold belts, elements of which seem to extend into the Lomonosov Ridge at both of its ends. In contrast to the Eurasian basin, the Canada basin does not have a good geographic fit of its continental margins. Paleozoic orogenic events around the rim of the Canada basin may reflect a period of sea-floor spreading against its continental margins in the manner postulated for the present Pacific Ocean. The close similarity in the geology of Alaska and Siberia indicates that North America and Eurasia were connected since the Paleozoic and probably since the Precambrian, and that a proto-Arctic Ocean basin, structurally separate from the Pacific and the Atlantic, can be identified as a center of Paleozoic marine sedimentation that served as an avenue for polar migration of faunas. A series of models showing the evolution of the Arctic Ocean basin that take into account the development of the above features can be postulated. End_of_Article - Last_Page 2474------------