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Victor Poselov, VNIIOkeangeologia (Russian Federation)
Lidia Poselova, VNIIOkeangeologia (Russian Federation)
Valery Kaminsky, VNIIOkeangeologia (Russian Federation)
Ekaterina Astafurova, VNIIOkeangeologia (Russian Federation)
Victor Butsenko, VNIIOkeangeologia (Russian Federation)
Vladimir Glebovsky, VNIIOkeangeologia (Russian Federation)
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During the "Arctic-2005" expedition, VNIIOkeangeologia carried out integrated geological and geophysical investigations within the Mendeleev Ridge (MR) and its transition to the shelves of the East-Siberian and Chukchi seas. These investigations included: deep seismic sounding (DSS) along a 600-km profile, seismic refraction and seismic reflection observations, gravity field measurements from drifting ice, aerogeophysical surveys over a 600x100 km swath, and geological sampling.
Several conclusions can be drawn from the processing and joint interpretation of all available geological and geophysical data collected in the study area:
1. Based on new bathymetry information it is established that in terms of geomorphology the MR may be subdivided according to a system of steps with different absolute depth marks - 1400-1700, 1700-2000, 2000-2500, 2500-3000 m that become deeper northward.
2. From a tectonic perspective, the geotransect intersects two main geological structures: the southern part of the MR and the northern flank of the Northern Chukchi Depression (NCD).
3. Sedimentary cover along the profile consists of three structural units and two upper units are divided by the regional Late Oligocene unconformity. Signatures of Aptian-Albian trap magmatism are established in the lower sedimentary unit. These signatures are reflected in the structure of the magnetic anomaly field.
4. Total thickness of the earth's crust along the geotransect varies from 28.5 km in the northern flank of the NCD up to 36.5 km in the MR. The crust in the NCD includes about 12 km of sedimentary units, while in the MR the most significant part of the crust (about 20-24 km) consists of lower crust and crust-mantle formations. The thicknesses of the upper crust and sedimentary units in the MR are 5-7.5 and 5-6 km, respectively.
5. It is established that the Mendeleev Ridge, similar to the Chukchi Borderland and Northwind Ridge, is a submerged block of continental crust. This block is presented by ancient platform with Pre-Cambrian - Caledonian basement. It was developed until Late Mesozoic time. The most considerable transformations of the block took place in Aptian-Albian and Late Cretaceous period of continental rift genesis and volcanism.
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