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Valery Kaminsky, VNIIOkeangeologia (Russian Federation)
Georgy Avetisov, VNIIOkeangeologia (Russian Federation)
Victor Poselov, VNIIOkeangeologia (Russian Federation)
Vasily Palamarchuk, VNIIOkeangeologia (Russian Federation)
Vladimir Glebovsky, VNIIOkeangeologia (Russian Federation)
Andrey Chernyh, VNIIOkeangeologia (Russian Federation)
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An integrated geological and geophysical field program was carried out along the geotransect ¡°Arctic 2007¡±in May-June 2007. The study area is situated to the north of Kotel¡¯ny Island (in the New Siberian Islands Archipelago) in the transition zone between the Lomonosov Ridge and the adjacent Siberian Shelf. This area with coordinates 140.85-138.80¢ªE, 77.29- 84.31¢ªN and 144.96-147.88¢ªE, 77.29-84.25¢ªN is encompassed by a swath that is 600 km long and 100 km wide, with a submeridional orientation. Transcending the scientific study of the geological structure and tectonic evolution of the area, a primary goal of this field work was the validation of outer limits of Russian continental shelf in accordance with article 76 of the UN Convention of the Law of the Sea. The suite of investigations included: simultaneous aeromagnetic and aerogravity surveys within the study area at a flight line spacing of 10 km; seismic observations accompanied by on-ice gravity measurements; and geological sampling along the central axis of the study area. Deep seismic sounding (DSS) with explosives was the main method of seismic observations. Distances between receivers and shot points were equal to 2.5-5 km and 50 km, respectively. Seismic refraction and seismic reflection observations were carried out in addition to DSS. A pre-existing potential field database compiled in VNIIOkeangeologia was significantly supplemented and improved with new high-quality aeromagnetic and gravity information. This updated database was used for 2D and 3D modeling of the main deep surfaces in the earth¡¯s crust (basement and Moho), and for determining the tectonic structure within the study area. Analysis of new seismic information presented in the preliminary seismic section allows several conclusions: (1) three key horizons (basement - upper crust, lower crust and Moho) are traced from the shelf area to the Lomonosov Ridge; (2) thickness of crust in the northern shelf varies in the limits of 25-26 km while within the transition zone and the Lomonosov Ridge it decreases slightly to 20-22 km; (3) the thickness of the upper crust ranges from 3 to 5 km. Features of the geological structure of the study region and possible mechanisms of its development are discussed.
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