by Staff Writers
Munich, Germany (SPX) Jun 22, 2012
During the past 2.8 million years extreme warm periods occurred in the Arctic at irregular intervals. Analytical results from the longest sediment core that has ever been drilled in the terrestrial areas of the Arctic have shown temperatures that were previously considered impossible for the Arctic Circle. In addition, a notable correlation of the warm periods in the Arctic with large melting events in Antarctica points to previously unknown interactions between the Polar Regions.
These are the findings of an international research team led by Professor Martin Melles of the University of Cologne in the latest issue of the journal "Science".
The results come from a sediment core that was drilled in 2009 from the lake El'gygytgyn in the extreme northeastern of Siberia as part of an elaborate winter expedition. The lake was formed 3.6 million years ago when a meteorite impact created a crater 18 kilometers in diameter.
Since then it is continuously collecting sediment, year by year. In addition, of all places the meteorite crashed into one of the few regions in the Arctic, which were not reached by glaciation during the ice ages. As a consequence, the sedimentary sequence is gapless and almost completely undisturbed.
"The uniqueness of the climate archive becomes clear when you keep in mind that with these core samples we advanced about 30 times further into Earth's history, as it is the case with the longest ice cores off the Greenland ice cap," says Martin Melles.
To do so, the age of each sediment layer of Lake El'gygytgyn had to be determined precisely. This was the task of the participating scientists from the GFZ German Research Centre for Geosciences (Helmholtz Association).
The researcher Eeva Haltia-Hovi (GFZ, now University of Lund, Sweden) used the magnetic properties of the minerals in the sediments: the Earth's magnetic field has reversed many times in the past million years, these reversals are reflected in the sediments.
The prerequisite for precise age determination is the detection of the color spectrum, millimeter by millimeter, and the magnetic susceptibility of the drilled sediments across the entire length of the core profile of 318 m. For this, GFZ scientist Norbert Nowaczyk especially developed a core scanner.
He also designed a software package that allows the processing of the extensive data records of all the partners. The diverse sedimentological, geochemical, magneto-and biostratigraphic records could thus be correlated with the known climate cycles of the last 3.6 million years in high resolution. Overall, the resulting age model created for the sediments from Lake El'gygytgyn includes more than 600 nodes.
The "El'gygytgyn Drilling Project" was part of the International Continental Scientific Drilling Program ICDP, the coordination of which is held at the GFZ.
The GFZ's Operational Support Group of the ICDP provided valuable data on various in-situ parameters (temperature, natural gamma radiation, etc.) via geophysical measurements in two wells.
The comparison of downhole measurements with measurements carried out on site on the drill cores allowed the correlation of depths and the filling of gaps in the core, an important prerequisite for further investigations.
Helmholtz Association of German Research Centres
Beyond the Ice Age
Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.
New deglaciation data opens door for earlier First Americans migration
Corvallis, OR (SPX) Jun 22, 2012
A new study of lake sediment cores from Sanak Island in the western Gulf of Alaska suggests that deglaciation there from the last Ice Age took place as much as 1,500 to 2,000 years earlier than previously thought, opening the door for earlier coastal migration models for the Americas. The Sanak Island Biocomplexity Project, funded by the National Science Foundation, also concluded that the ... read more
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2012 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement|