Siberian lake may yield best evidence so far of past climate change

December 22nd, 2008 - 11:23 am ICT by IANS  

University of MassachusettsWashington, Dec 22 (IANS) A team of scientists will drill deep into a frozen Siberian lake to retrieve core samples more than three million years old in a bid to answer questions about the earth’s past, especially evidence of temperature fluctuations.Almost impossibly remote, Lake El’gygytgyn (pronounced el’geegitgin), about 18 km in diameter, was formed 3.6 million years ago when a monster meteor, almost a kilometre across, slammed into the Earth between the Arctic Ocean and the Bering Sea, in the north of Russia’s Chukotka Autonomous Region.

Because this part of the Arctic was never covered by ice sheets or glaciers, it has received a steady drift of sediment - as much as 400 metres deep - since the impact.

Thus, beneath the crater lake that’s just over 180 metres deep, it offers a continuous deposit record unlike any other in the world, said Julie Brigham-Grette of the University of Massachusetts Amherst and colleagues.

The lake bed has been undisturbed by earthquakes, other underground shifting or drying for thousands of years. Pilot cores 16.7 metres long have already provided a snapshot of climate from 300,000 years ago.

Notably, the researchers hope they can learn more about the unexplained shift from a warm forest ecology to permafrost, some two million to three million years ago, said a Massachusetts University release.

Comparing cores from under Lake El’gygytgyn to those from lower latitudes will help the climate scientists with a high-resolution tool to study climatic change across northeast Asia “at millennial timescales,” Brigham-Grette said.

In addition to climate data, 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.

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