International Geologiical Congress - Oslo 2008

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AAA-01 Paleogeographic evolution of the Arctic region during the Phanerozoic - Part 1

 

The Arctic tectonic puzzles

 

Victor Khain, Geological Institute, Russian Academy Sci. (Russian Federation)
Nadezhda Filatova, Geological Institute, Russian Academy Sci. (Russian Federation)
 

 

Though the latest investigations have considerably advanced our knowledge on the tectonics and geodynamics of the Arctic region, problems still remain. Problematic is the reconstruction of the Grenville, Baikalian, and Caledonian orogenic belts and their continuation into eastern Arctic regions (here and after the modern coordinates are used). The presence of the Grenville belt in the Arctic region is confirmed by Riphean ophiolites and collisional granitoids (850 Ma) of the Taimyr Peninsula. Grenville structures are presumed in the Hyperborean craton from NE Spitsbergen up to the New Siberian, De Long, and Canadian Arctic archipelagoes. The Baikalian orogenic belt was formed at the Vendian--Cambrian boundary as a result of closing the ocean, which was originated at the time of splitting the Epigrenville Rodinia supercontinent into several continents, namely, Baltica, Siberia, Hyperborea, Laurentia. The Baikalian belt, formed by collision of those continents, extends within the Timan--Pechora plate, from the Polar Urals, Taimyr Peninsula, and the shelves of the Barents, Kara and Laptev seas. The eastern continuation of the Baikalian foldbelt was revealed on the Wrangel Island, Chukotka, Seward Peninsula, and Brooks Range, where mafic-ultramafic complexes, 700 Ma in age, were discovered, and syncollisional granitoids and metamorphic rocks of the amphibolite and greenschist facies from 750 to 547 Ma years. The Caledonian Iapetus Ocean originated in the Cambrian between the Laurentia and Baltica continents. Farther east it extended between Hyperborea and the Siberian craton, embracing the Kara Sea, Taimyr Peninsula, shelves of the East-Siberian and Chukchi seas, which were found to contain volcanic-terrigenous deposits analogous to the Franklin complex of Alaska and ophiolites of the Innuitian system. The presence of Cambrian and Ordovician ophiolites in the suture of the Kolyma loop indicates the continuation of its eastern branch to the east of the Siberian Craton. One more problem is the reconstruction of the primary position of the South Anyuy--Angayucham Ocean. As the South Anyuy suture has been shifted to the southwest along a dextral strike slip fault, this ocean might have initially been located much farther to the southeast representing a branch of the Pacific. Another problem in the Arctic region refers to the time of the final opening the Amerasian Basin. The information on this problem was supplemented by data on the Aptian--Albian alkaline plume magmatism discovered on the continental framing of the Basin and indicating the commencement of extensional regime in its western part.
This work is supported by the RAS (program no. 14) and the RFBR (project no. 08-05-00748).

 

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