Geophysical data obtained recently in the southwest part of the Barents Sea have disclosed much new information on the Lower Paleozoic section there. Part of this was from a profile of 1995-2000 along a traverse that extended from Super-Deep Well SG-3 in the north of the Kola Peninsula to Deep Stratigraphic Well Khays-1 in Franz Josef Land. These data supplement regional common depth point surveys made in recent years and other studies made in the southwest part of the Barents Sea. The totality of this material establishes the presence in the section of the southwest part of the Barents Shelf of a practically continuous stratigraphic succession from Riphean to Upper Mesozoic.
Characteristic of the sedimentary cover here is absence of sharp angular discordances and a gradual increase in density downward along the section. Individual units show considerable variation in thickness. In spite of this, subdivision of the section into individual litho-stratigraphic complexes and their correlation over distances is accomplished rather reliably.
Basement in this part of the Barents Shelf consists of granite and metamorphic rocks, the top of which is in the 12-15 km depth interval, rising to 10 km at the crest of the Central Barents high and almost to the surface near the coast of the Kola Peninsula.
The section of the sedimentary cover begins with Riphean rocks, which are bounded below and above by marker seismic horizons. The main part of the Riphean section consists of thick (9 km) uniform rocks with interface velocity of 5.2 to 5.3 kmps. These are correlated with the clastic Barents Sea Complex of Varanger Fjord. The overlying seismic complex correlates with the Rybachin Series of this same area. The presence of a strong relationship of velocity to depth indicates that these rocks are comparatively uniform in composition and have not lost their capacity for compaction. This is in good agreement with geological data that indicate a rather low degree of maturation of the organic matter. On a basis of the seismic data it is concluded that the Riphean here should be regarded as the lower part of the sedimentary cover.
Next in the section are two independent structural complexes, which have been studied in detail in various regions of the Barents Shelf by seismic surveys. These complexes are tied in to drill holes. The upper of these, at the top of the sedimentary cover, consists of clastics of the Upper Permian, Triassic, and Lower Cretaceous and is called the Upper Clastic Complex of the Barents Sea. The underlying complex includes Devonian clastics and possibly Upper Silurian and also carbonates of the Carboniferous and Lower Permian. Then the Lower Paleozoics are probably Cambrian, Ordovician, and possibly the lower part of the Silurian.
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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