SUCCESSFUL DEEP DRILLING 2009 AT LAKE EL'GYGYTGYN, NE RUSSIA: TOWARDS A CONTINUOUS 3.6 MYR ARCTIC PALEOCLIMATE RECORD

Lake El’gygytgyn, located 100 km north of the Arctic Circle (67°30' N, 172°05' E), was created 3.6 Ma by a meteorite impact. Throughout Spring 2009, scientific drilling operations recovered 512 m of lake sediment and impact breccia that will provide new insights into the climate evolution of the Arctic and late Cenozoic formation of the crater. The temporal length and geologic significance of the climate record is absolutely unprecedented in the entire Arctic region, and more than 30 times longer than temporal records from the Greenland Ice Sheet.

Nearly 355 m of sediment were cored with outstanding recovery from three adjacent holes. Replicate cores to ~100 m below lake floor (mblf) from each site date back to ~2.0 Ma. In addition, a single core extending to the time of impact at 3.6 Ma was collected to a depth of 315 mblf, albeit with lower recovery in places due to surprising sequences of coarse sand and gravel interbedded with lacustrine mud. These coarser units suggest unexpected glacial influences that imply different moisture sources and snowline depression for the earliest Northern Hemisphere glaciations. Roughly 40 m of basal sediments record the earliest history of the lake in the warm middle Pliocene. This interval is especially valuable as a possible analog for future climate due to CO2 forcing. Beneath lake sediments, we successfully recovered 157 m of impact breccias and suevites over a depth interval of 207 m.

Field measurements were restricted to whole core magnetic susceptibility and a range of other properties using down-hole logging instruments. Yet warm and cold cycles, similar to those seen in pilot cores extending to 300 ka ago (16 mblf), can be seen in the new cores extending to more than 100 mblf. This record suggests the cores will produce new information on the style and onset of Northern Hemisphere glacial cycles for the first time seen with such clarity in an arctic terrestrial setting.