Geology of the Severnaya Zemlya Archipelago and the North Kara Terrane in the Russian high Arctic |
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Authors: | Henning Lorenz Peep Männik David Gee Vasilij Proskurnin |
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Institution: | 1.Department of Earth Sciences,Uppsala University,Uppsala,Sweden;2.Institute of Geology,Tallinn University of Technology,Tallinn,Estonia;3.VSEGEI,St. Petersburg,Russia |
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Abstract: | The Severnaya Zemlya Archipelago is located at 80°N near the continental shelf break, between the Kara and Laptev seas. Sedimentary
successions of Neoproterozoic and Palaeozoic age dominate the bedrock geology. Together with Northern Tajmyr, Severnaya Zemlya
constitutes the main land areas of the North Kara Terrane (NKT), which is inferred here to have been a part of the Timanide
margin of Baltica, i.e. an integral part of Baltica at least since the Vendian. Vendian turbidites derived from the Timanide
Orogen are inferred to have been deposited on Neoproterozoic greenschist facies, granite-intruded basement. Shallow-water
siliclastic deposition in the Early to Mid-Cambrian was followed by highly organic-rich shales in the Late Cambrian and influx
of more turbidites. An episode of folding, the Kan’on River deformation, separates these formations from the overlying Tremadocian
conglomerates and sandstones. In the Early Ordovician, rift-related magmatic rocks accompanied the deposition of variegated
marls, sandstones, carbonates and evaporites. Dark shales and gypsiferous limestones characterise the Mid-Ordovician. Late
Ordovician quartz-sandstones mark a hiatus, followed by carbonate rocks that extend up into and through most of the Silurian.
The latter give way upwards into Old Red Sandstones, which are inferred to have been deposited in a Caledonian foreland basin.
Deformation, reaching the area in the latest Devonian or earliest Carboniferous and referred to as the Severnaya Zemlya episode,
is thought to be Caledonian-related. The dominating E-vergent structure was controlled by décollement zones in Ordovician
evaporite-bearing strata; detachment folds and thrusts developed in the west and were apparently impeded by a barrier of Ordovician
igneous rocks in the east. Below the décollement zones, the Neoproterozoic to Early Ordovician succession was deformed into
open to close folds. The exposed strata in the lower structural level have been juxtaposed with those in the upper structural
level along the major N-trending Fiordovoe Lake Fault Zone, which involved several kilometres of dextral strike-slip movement
and downthrow to the west. A major Early Carboniferous unconformity separates the folded Mid-Palaeozoic and older rocks from
overlying Carboniferous formations, as on Franz Joseph Land and Svalbard. Subsequent latest Palaeozoic to Early Mesozoic orogeny,
as on Taimyr, apparently had little influence on the Severnaya Zemlya successions. |
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Keywords: | Geology Tectonics Caledonian Severnaya Zemlya Baltica |
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