Oxygen Isotope and Deuterium Indication of the Origin and 14C Age of the Massive Ice, Bovanenkovo, Central Yamal Peninsula

Vasil’chuk, Y.K.; Vasil’chuk, A.C.; Budantseva, N.A.; Chizhova, J.N.; Papesch, W.; Podborny, Y.Y.; Sulerzhitsky, L.D.

Авторы: Vasil’chuk Yu K., Vasil’chuk A.C., Budantseva N.A., Chizhova Ju N., Papesch W., Podborny Ye Ye, Sulerzhitsky L.D.
Журнал: Doklady Earth Sciences
Том: 429
Номер: 8
Год издания: 2009
Издательство: Maik Nauka/Interperiodica Publishing
Местоположение издательства: Russian Federation
Первая страница: 1326
Последняя страница: 1332
DOI: 10.1134/S1028334X09080194
Аннотация: The conditions and forming time of massive ice were specified (Bovanenkovo gas condensate field, Central Yamal). Here, massive ice lies as stratums, laccoliths, stocks, and lenses. Three thousand bore¬holes 10—100 m in depth were analyzed. In 260 of them massive ice was broached. The ice foot is situated from 1 to 57 m deep. The maximal thickness of ice broached with boreholes came to 28.5 m; on average, it was about 8 m. The extension of massive ice is sometimes more than 2000 m, and its area is quite often more than 10 km2. According to the radiocarbon method, loams of the third terrace, containing and overlapping ice deposits, were formed from 25 000 to 20 000 years ago or somewhat later. These strongly peat loams con¬taining massive ice formed either in shallow sea conditions or during periodical draining conditions of beaches or low laida, where organic matter appeared due to erosion and deposition and accumulated during draining and overgrowing of drains. In more inclement conditions than at present, loam deposits were frozen immediately, forming massive ice, which occupied the barely water-saturated layers. The oxygen isotope composition (δ18O) of massive ice samples varied from —12.49‰ (here and further, relative to SMOW) to —22.95‰. The deuterium concentration (δD) varied from —91.7 to —177.1‰. Deuterium kurtosis (dexc) varied from 3.4 to 10.6‰. In one seam outcrop, the content of stable isotopes varied significantly. Here, at a depth of 0.2-0.8 m, the δ18O content varied by more than 10‰ (from -12.49 to -22.75), and the δD con¬tent, from —91.7 to —171.9‰. Such variations testify about ice extraction upon freezing of water-saturated grounds in a closed system. According to palynological analysis of ice stratums, numerous remains of unicellular green algae and diatoms were revealed. It is possible that this is evidence of the existence of a fresh well, which was a source of water, feeding the layer. Most probably these were near-bottom silt waters of a large lake or desalted bay, which were frozen syngenetically. This accentuates the new type of massive ice, syncri-ogenic segregative ice, which probably formed 25 000—20 000 yr BP.
Добавил в систему: Васильчук Юрий Кириллович

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Oxygen Isotope and Deuterium Indication of the Origin and 14C Age of the Massive Ice, Bovanenkovo, Central Yamal Peninsulaстатья

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