It seemed obvious that the Scandinavian Caledonides extended on northward through the western part of the Barents Sea to Spitzbergen. Aeromagnetic surveys made almost simultaneously in the Norwegian and Russian sectors of the Barents Sea, however, showed no such continuation of structure.
In spite of extensive seismic surveys that elucidated the upper part of the sedimentary section of the region, the so-called "Upper Clastic Complex" of Permian-Mesozoic age, the Lower Paleozoic "Caledonide Complex" had until recently received little study. The sedimentary rocks of the Lower Paleozoic and their structures, although known on practically all the islands and borders of the Barents Sea, either are represented by litho-facies that are difficult to correlate or occur in different tectonic environments.
Classic overthrust structures of Caledonian age are described in Scandinavia. They involve Riphean-Lower Paleozoic rocks, which have total thickness on the order of 20 km. At the base of this section is the clastic Riphean Baltic Sea Complex 8-9 k thick. In the middle are Upper Cambrian volcano-clastic rocks 2 km thick, then various clastics and volcanics of Ordovician age, and at the top are calcareous rocks and graywacke. This section has practically no analog either in structure or litho-facies in other parts of the region.
The structure of all the coastal area of West Spitzbergen has been determined largely not by Caledonian but by Cenocoic deformation. Also, the pre-Alpine structure of this zone exhibits no large structural discordance either at the top or at the base of the Lower Paleozoic section in those sectors where reconstructions are reliable. The character of the deformation of the youngest and oldest rocks of the sedimentary cover is practically the same. There is no doubt as to good correspondence along the entire section from the Upper Riphean-Lower Paleozoic to the Paleogene.
The Spitzbergen region of occurrence of Lower Paleozoic rocks thus cannot be interpreted as a continuation or analog of Caledonide collision structures of Scandinavia neither with respect to composition of the section nor character of deformation, nor style of post-orogenic development. Such a correlation falls short also structurally: The thrusts young toward the west in West Spitzbergen, whereas the picture is just the opposite in Scandinavia.
The composition and structure of the Lower Paleozoic rocks in the various regions peripheral to the Barents Sea are so diverse that without data directly from an offshore area any comparison will remain a problem. Some features of their thickness have led to a tendency to trace buried continuations of Caledonian structure through the entire Barents Shelf in the form of a continuous belt. However, not one of the intrpretations based on such a concept has been confirmed by marine geophysical data. Devonian and Late Paleozoic rifting accompanied by horizontal shifting of large crustal blocks must be taken into account.
Taken from Verba and Ivanova, 2000; digested in Petroleum
Geology, vol. 36, no. 2, in preparation, two maps, one cross section.
Copyright 2002 James Clarke. You are encouraged to print out this
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