Seeking Earth's Past by Drilling in Remote Arctic
Source Newsroom: University of Massachusetts Amherst
Newswise — Drilling by an international team of paleoclimatologists to retrieve sediment and meteorite-impact rocks began in mid-March under a frozen Siberian lake, with a goal to retrieve the longest continuous climate data ever collected for the Arctic, over 3.6 million years. Within a few days of the drill hitting sediment, scientists at Lake El'gygytgyn, 62 miles north of the Arctic Circle, had reached down more than 65 meters, according to University of Massachusetts Amherst geoscientist Julie Brigham-Grette, lead scientist. She said, "We are just passing 1.0 million years in the record, with 100 percent recovery."
Almost impossibly remote, "Lake E," was formed 3.6 million years ago when a monster meteor, more than a half-mile across, slammed into the Earth between the Arctic Ocean and the Bering Sea. Because the area was never covered by ice sheets or glaciers, it has received a steady drift of sediment " as much as a quarter mile (1,312 feet or 400 meters) deep " since impact. Brigham-Grette and colleagues including Martin Melles of the University of Cologne, Germany, designed the study to burrow back in time for core samples that offer a continuous depositional record unlike any other in the world, under the lake that's over 560 feet deep, equal to the height of the Washington Monument.
El'gygytgyn offers a truly unprecedented opportunity, Brigham-Grette notes, for piecing together a clearer picture of the hemisphere's prehistoric climate and the dynamic processes of global climate change since the meteor's impact. Notably, the researchers hope they can learn more about the unexplained shift from warm forest ecology to permafrost, some 2 million to 3 million years ago.
Scientists from institutes in Germany, Russia and Austria as well as UMass Amherst have been flying in by helicopter for focused tests over the past 10 years, drilling pilot cores and taking other samples and measurements. The site has passed every test, showing, for example, the lake bed has been undisturbed by earthquakes, other underground shifting or drying for thousands of years.
Comparing cores from under Lake El'gygytgyn to those from lower latitudes will give the climate scientists a high-resolution tool for studying climatic change across northeast Asia "at millennial timescales," Brigham-Grette says. In addition, cores may offer the researchers an opportunity to study the 3.6-million-year-old "impact breccia," that is, how Earth's bedrock responded to the meteor's impact.
The researchers started out last December by building a 250-mile ice road to the lake in order to use the windswept ice as a drilling platform. Drills were specially designed to withstand the area's extreme weather conditions. Work will continue until May 2009, as part of the International Continental Scientific Drilling Program (ICDP).
Workers and scientists will live in a protected personnel carrier that will also transport cores from the rig on the lake ice to the science camp on the shore. Sediment cores will be processed for shipment and stored at the lake in a temperature-controlled container until they can be flown to St. Petersburg and later trucked to the University of Cologne, Germany, for study by the international team. An "archive half" of each core will also be stored at the University of Minnesota.
The international collaboration is funded by the U.S. National Science Foundation, the German Federal Ministry for Education and Research, the Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, and GeoForschungsZentrum, Potsdam. In addition to UMass Amherst, investigators from the Russian Academy of Sciences' Far East Geological Institute, Vladivostok, the Northeast Interdisciplinary Scientific Research Institute, Magadan, and Roshydromet's Arctic and Antarctic Research Institute, St. Petersburg, are taking part.
Several high-resolution diagrams and photographs are available with this story at www.umass.edu/newsoffice.