The El’gygytgyn crater in northeast Russia was created 3.6 million years ago by the impact of a large meteorite, about one kilometre in diameter. A lake, Lake El’gygytgyn, was formed within the crater of about 15 km in diameter and a depth of 175 m.
Scientists were interested in the crater for two reasons: First, to study the impact and shock effects on acid volcanic rocks as well as to determine the composition of the meteorite that formed the crater. Second, the about 300 m thick deposit of lake sediments below the lake bottom constitutes a unique climate archive of a largely unknown Arctic climate history.
Russian scientists discovered this lake about 20 years ago as a unique place to study climate changes in the Arctic. Ten years ago a group of international scientists from USA, Germany, Russia and Austria was formed to investigate the crater centre and the sediments which were accumulated at the lake bottom by obtaining cores samples. This can only be done by drilling either from a floating platform during the short Siberian summer season or from the ice surface in the winter months. The scientists opted for the latter alternative. A stable ice platform, properly designed and monitored, provides a safer and more reliable base for a drill rig. At this stage of the planning (in 2007), EBA was asked by DOSECC, a drilling company specialized in deep-hole core drilling, to advise the project team on ice engineering related matters.
For over a period of about one year EBA participated in the project planning which consisted of attending several workshops in Washington, DC, Cologne, Potsdam and Moscow, weekly conference calls, many telephone discussions and several hundred email exchanges. The challenge was to coordinate the interests/demands of several international groups and still operate within the given budget.
The project consisted basically of an onshore camp located at the west side of the lake, two ice platforms to support the drill rig and an on-ice road linking the camp with the ice platforms. Design calculations indicated that the naturally grown ice needed to be thickened in order to support the drilling platform by the end of January. No flooding (thickening) of the ice was required along the ice road.
After sorting out lengthy visa and permit issues and finalizing travel plans within Russia, and covering 20 time zones between Vancouver and Pevek (port in Siberia), the EBA team finally arrived at Lake El’gygytgyn at the end of January-without our equipment which was still being held at customs in Moscow. However, we managed to organize pumps for flooding from a Canadian goldmine nearby and started ice thickening on February 3. The routing of the on-ice road had to be changed due to the presence of an active pressure ridge.
High winds, snow storms and densely packed snow presented a challenge and hampered the on-ice work. The weight of the snow depressed the ice to such an extent, that almost the entire lake ice would be flooded if holes or cracks would extend through the ice (negative free board).
The first 1,000 m² large ice platform was cleared from snow with a dozer by pushing snow towards the platform edge. Thickening of the platform was accomplished by flooding the ice in layers of about 10 cm/day over a period of 10 days and hence doubling the thickness of the naturally grown ice. With an average thickness of 1.95 m the platform was completed by mid February and ready for the installation of the drill rig.
Both, ice road and ice pad were monitored continuously by EBA to ensure safe on-ice operations until May, when equipment and personnel were taken off the ice.
The results of this expedition are about 500 m worth of sediment and impact rock cores which were retrieved from a frozen lake surface under sometimes rather challenging conditions. The drill cores have been considered by international scientists as extremely valuable because of their uniqueness. The analysis of the cores will take several years.
Volker Neth - Ice Scientist
This page was last updated on: 7/8/2009 2:16:00 PM
