Geology of the East Siberian Sea, Russian Arctic from seismic images

Status of project: 02.01.2006

 

Arctic Ocean
Source: BGR

The kinematics and history of the opening of the Arctic Ocean Basin, comprising the Eurasia and the geologically more complex Amerasia Basins, in Mesozoic and Early Tertiary times are first-order scientific problems awaiting solution in the Arctic. Present knowledge especially of the geologic framework of the Amerasia Basin and its continental margins is insufficient for solving the problems due to the polar ice pack which precludes the acquisition of the required geophysical data from conventional research vessels. However, an understanding of the geology of the wide shelves surrounding the Arctic Ocean Basin and an extrapolation of the geological features from the shelves could provide significant insight into the tectonic character of the Amerasia Basin, and would also facilitate a testing of the numerous competing circum-Arctic plate tectonic models.

 

 

 

 

 

 

 

 

 

 

 

 

Data acquisition under severe conditions
Source: BGR

East Siberian Sea
Source: BGR

The Federal Institute for Geosciences and Natural Resources (BGR) in co-operation with Sevmorneftegeofizika (SMNG) carried out a seismic survey on the shelf of the East Siberian Sea between longitudes 147° and 165°E in 1994 (cruise BGR94), using the research vessel MV AKADEMIK NEMCHINOV. The scientific objective was to reveal the structural style of that virtually unexplored East Siberian Shelf. Although adverse ice conditions often hampered the survey, about 2609 km of MCS data have been acquired on the East Siberian Shelf south of latitude 76°N. In addition, an about 496 km long seismic line was surveyed in 1994 along the Sannikov Strait that separates the New Siberian Islands in the north from the Lyakhov Islands in the south. This line provides a tie between our East Siberian data and our data set on the Laptev Shelf. Another MCS survey carried out by the BGR in 1997 off Siberia (cruise BGR97) added about 559 km of seismic data.Three seismic marker horizons were defined and mapped. Their ages were linked to main tectonic and regional events, and onshore findings.

 

 

 

 

Data example from Line BGR94-19
Source: BGR

Proposed evolution of the East Siberian Depocenter. Rotation model transform modified from Grantz et al. (1990) and onshore faults from Kos'ko & Trufanov (2002).
Source: BGR

The data reveal that there is no continuation of the large rift basins from the Laptev Shelf onto the East Siberian Shelf and there are no indications for the previously defined several hundred kilometers wide Blagoveshchensk Basin. The East Siberian Shelf is best described as an epicontinental platform that synsedimentarily subsided continuously since Late Cretaceous times with stronger subsidence to the northeast, resulting in the formation of a large depocenter. Some form of extensional/transtensional stresses affected the area and created relatively small ESE-WNW striking basins within this depocenter. These basins are filled with more than 6 km thick Late Cretaceous to Tertiary sediments. The general dip of the platform of the East Siberian Shelf towards the northeast may be explained by dip-slip movements along a major transform fault that is proposed by the rotation model for the opening of the Amerasia Basin.

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