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Scientists learn how to date back objects found in Arctic's underground ice

June 07, 19:37 UTC+3 MOSCOW

Underground ice not only keeps the organics but also offers data on the ancient climate

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MOSCOW, June 7. /TASS/. Scientists of the Moscow State University offer new methods to date back more accurately than previously the objects frozen into underground ice in the Arctic. The University's Professor Yuri Vasilchuk told TASS the new methods would be helpful for archeologists, specialists in permafrost construction and paleo biologists, who study DNA's evolution.

"Since the underground ice and layers form gradually, one layer may keep frozen organic samples of the time difference of 5-10 thousand years. In order to learn how to calculate most precisely the radio-carbon date, we have offered the following method: we compared all the organic samples - branches, bones, grass, moss - inside one permafrost layer. In the thick layer, which had formed for 25,000 years, we found samples with the ages of 20, 30, 40 thousand years. Our suggestion was that most close to the truth would be the youngest date, so we had them compared at various depths, and they fit rather well in the chronology order," the professor said.

"In order to check the method" the scientists had to "split every organic sample into micro samples - seeds of one color, branches only with bark and only without bark, only grass, - and calculated their ages," he continued.

Usually, specialists fear to give a younger age to the samples - if any parts of modern organics get into the sample, the age becomes much less. This is also what happens with the underground ice - the organics also gets mixed there, though within thousands of years, and this complicates the task to quote the age.

More precise dating of the organics, frozen in the Arctic ice, would be helpful for many sciences, the professor said. "The improved methods would be useful for archeologists, studying sites of ancient people in the North, for paleo biologists to research DNA's evolution, and for those who build houses in permafrost - in order to forecast more accurately spread of the ice," he said.

Underground storage of climate data

Underground ice not only keeps the organics - it also offers data on the ancient climate, the professor said.

"Oxygen isotopes in the ancient iced channels remain stable for hundreds thousand years. I have managed to see a dependence between the air temperature and oxygen isotopes in the ice channels. The number of heavy isotopes equaled the average winter temperature in the region," the scientist said. "In order to check the supposition, I travelled the North and was searching insistently for traces of the channels - this became almost a kind of sports for me."

Ice channels emerge from cracks in the soil because of low temperatures, and they may go down developing to the width of 3-4 meters. Many-layered channels in frozen soils may be as high as 50 meters, he continued. Geography of the biggest channels is vast - Duvannyi Yar and Zelenyi Mys in Yakutia, Seyakha on Yamal, the valley of the Main River in Chukotka.

The common features of most layers filled with the channels is the same time frame of their formation.

"The layers of mighty ice with channels, like the ones in Yamal, and like those on the Gydanskyi Peninsula (Krasnoyarsk Territory and the Yamal-Nenets Autonomous District - TASS), in Taimyr (Krasnoyarsk Territory - TASS), in the northern and central regions of Yakutia, in the Magadan region and in Chukotka, formed over 40 to 10 thousand years," the scientist said. "This is a common feature for all those regions."

The research results are published in the GeoResJ international magazine.

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