Lake Elgygytgyn is an impact crater that formed 3.6 million years ago in Chukotka, northeastern Siberia. The lake is bowl-shaped with a mean diameter of12 km and a maximum water depth of approximately 170 m. At present, the lake is ice-free only during the short summer period of approximately 3 months. Pilot cores retrieved in 1998 and 2003 showed that the lake sediments are highly susceptible to climate change. A seismic pre-site survey revealed approximately 330 m of lacustrine sediments on top of the suevite that was initially formed by the meteorite impact 3.6 million years ago. The lake sediments thus have the unique potential to unravel 3.6 million years of terrestrial Arctic climate history. Seismic profiles revealed that the upper approximately 150 m of the sediments are well-layered, but intercalated with debris flows and turbidites in the more proximal parts of the lake. The lower part of the sediments appears more massive to acoustically transparent in the seismic profiles. The sediment succession at the lake center is mostly undisturbed by mass transport deposits and forms an ideal place for deep drilling. The lake was drilled down into the impact bedrock in winter/spring 2010 within the framework of the ICDP. Three holes were drilled at one site in the lake center, reaching as far down as 517.3 m below lake floor with a total recovery of 75%. The cores penetrated 315 m of lacustrine sediments before they hit the suevite bedrock. Drilling was stopped 4 times to carry out downhole logging. Magnetic susceptibility of the cores was measured immediately after recovery at the drill camp laboratory. After the drilling campaign, all cores were shipped from Siberia to Germany, and core opening and sampling of the lacustrine sediments started in late 2009 at the University of Cologne, Germany. Density and p-wave velocities were measured during the sampling party and complete the on-site magnetic susceptibility measurement to a continuous record of physical properties.Here we present the physical properties measurements of the cores as well as downhole logging data along with the seismic record of the lake. Whole core magnetic susceptibility data show a high correlation between the cores of the different holes, and a perfect match with the downhole magnetic susceptibility data.
Helmholtz Research Programs > PACES I (2009-2013) > TOPIC 3: Lessons from the Past > WP 3.2: Tectonic, Climate and Biosphere Development from Greenhouse to Icehouse