Isotopic and palynological compositions of a massive ice in the Mordyyakha River, Central Yamal Peninsula

Vasil’chuk, Y.K.; Vasil’chuk, A.C.; Budantseva, N.A.

Авторы: Vasil’chuk Yu K., Vasil’chuk A.C., Budantseva N.A.
Журнал: Doklady Earth Sciences
Том: 446
Номер: 1
Год издания: 2012
Издательство: Maik Nauka/Interperiodica Publishing
Местоположение издательства: Russian Federation
Первая страница: 1105
Последняя страница: 1109
DOI: 10.1134/S1028334X12090164
Аннотация: The investigation objective is to study a new massive ice in the Mordyyakha River valley (the Central Yamal Region), to determine the contents of stable oxygen and hydrogen isotopes in the ice, and to study pollen spectrum remains. A new ice outcrop studied in August 2011 is located in the central part of the Yamal Region in the upper Mordyyakha River (68о11′18′′ N and 68°51′39′′ E) at absolute of 66–70 m a.s.l. The body of over 4 m in thickness with a normal horizontal bedding laterally passes into vertically bedded ice crossed by syngenetic ice wedge of 4–5 m in thickness. The relatively narrow range and specific distribution of the δ18O (from –20 to –23.2‰) and δD (–156.8 to –172.9‰) values indicate that the studied beds originated from soil in the upper Mordyyakha River. The isotopic compositions of ice and obliquely oriented ice soil occurring in the left part of the outcrop demonstrate insignificant isotopic variations (from –22.4 to –23.3‰ δ18O) and, thus, ice segregation formation under open system conditions. The pollen spectrum is characterized by high contents of pollen and spores of moisture resistant plants,tion is confirmed by typical tundra features of the pollen spectra: dwarf birch pollen (8–28%), alder pollen (6–11%), pollen of gramineous plants (11–50%), ling pollen (42%), heather pollen (29–39%), green moss spores (1–38%), horsetail spores (26%), pollen of water resistant plants such as Thalictrum (7%), and a significant content of pre-Pleistocene palynomorphs (3–24%). The distinguished taxons are either absent in ice and snow cover of glaciers as, for instance, redeposited pre-Quaternary forms, or are rare in occurrence as, for instance, heather pollen, green moss, and horsetail spores. The Late Pleistocene cryochron was favorable for the burial of freshwater lake ice overlying the saline lake sediments. Syngenetic ice wedge forming paragenesis of bedded and ice wedge ices could develop in the peripheries of the lakes. When water unexpectedly discharged from the salt lakes, ice mounds could appear due to formation of closed thaw zones at the boundary between the cover lake ice and cryolitic salt deposits. Outflow of the indicated ice mounds could result in formation of vertically bedded injection ice. This is one possible scenario of the formation of the Mordyyakha paragenetic complex composed of horizontally and vertically bedded sweet water ice and crossing syngenetic ice wedge. The whole complex is located on highly salted, most likely, lake sediments. As for the horizontally massive ice, it can be of both congelation and segregation types.
Добавил в систему: Васильчук Юрий Кириллович

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Isotopic and palynological compositions of a massive ice in the Mordyyakha River, Central Yamal Peninsulaстатья

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