Lake El'gygytgyn is located in Chukotka, Northeast Siberia. The lake originates from a meteorite impact that occurred some 3.6 million years ago. The impact crater has a diameter of 18 km, and the lake inside the crater is some 12 km in diameter with a water depth of 170 m. At present, the lake is only ice-free during 3 summer months, and ice-covered by up to 1.5 m of ice during winter. Tundra vegetation surrounds the lake, and the tree line is located some 100 km further south.
In 2000 and 2003, we did two expeditions to Lake El'gygytgyn to acquire seismic reflection data. We could identify up to 320 m of sediments inside the lake. Our colleagues of the University of Cologne, Germany, and of UMass, Amherst, USA took sediment cores during both expeditions and also earlier on in 1998. They discovered that the upper 16 m of sediment contain about 300.000 years of paleoclimate history in high resolution unprecedented in the Arctic realm. With the age of the impact crater being 3.6 million years we assumed that the lake's sediments would contain the paleoclimate history of this entire time span. That would be 1 million prior to the onset of the glaciation of the Northern Hemisphere!
Using our seismic data we could show that the sediments were never glacially overprinted, i.e. there was no erosion during the entire time span.
After 10 years of intense pre-site surveys and preparations we finally were able to drill two boreholes within the framework of the International Continental Scientific Drilling Program (ICDP). In autumn 2008, a permafrost borehole was drilled next to the western shore of the lake, and in spring 2009, we drilled from the frozen lake into the sediment column and further into the underlying bedrock (see article). During the drilling campaign, the ice cover of the lake was thickened to hold the drill rig, and we drilled in absolute darkness (polar night) at temperatures of down to -45°C.
The sediment cores retrieved during the deep drilling campaign revealed that the lake's sediment in fact hold a complete archive of paleoclimate history since it's formation. We could show that the glaciation of this part of the Northern Hemisphere started some 2.7 million years ago in a stepwise manner (see article). The sediments also revealed some super-warm interglacials that were ca. 4-5°C warmer than today (see article).