Abstract
The object of this study is a recently (or in the Holocene) formed thick (up 2.7 m in height) buried massive ice body, exposed in 2 km South-East from the mouth of the river Akkani in the North-East of Chukotka in the vicinity of the settlement Lavrentiya. The structural-textural characteristics of ice and enclosing deposits are considered. It is shown that the overlying layers of sediments are loams with a slab structure and vertical-layer medium and thin-chill cryogenic structure and ice sockets. The ice of the body is very pure and transparent, visible to a depth of 0.5 m. There are some inclusions found in massive ice: sand and loams presented in forms of thin interlayers of particles or granules. The ice is full of bubbles. The main method of the research was the analysis of isotopes of oxygen and hydrogen within the stratified ice body, and also relationships between them as well as ratios between the deuterium excess and δ 2 Н. The thick and relatively contemporary massive ice layer buried under a layer of proluvial sediments had been found for the first time, and together with this, the isotope variations of the buried ice (δ 2 Н and δ 18 O) were determined. The mean values of δ 18 О and δ 2 H in the ice are rather stable and equal to −17.1 and −128.3‰, respectively. These isotope characteristics may be used for cryogenic reconstructions of massive ice formations widely distributed in the late Quaternary deposits in Eastern Chukotka.
Highlights
Изучен изотопный состав кислорода и водорода мощного современного ледяного пласта, погребённого под слоем пролювиальных отложений на побережье Чукотки вблизи посёлка Лаврентия
Аккани: 1 – горизонтальный отбор; 2 – вертикальный отбор; 3 – снежник; пунктирные линии – линейная аппроксимация значений, сплошная линия – глобальная линия метеорных вод Fig. 6. δ18O–δ2H relation for the samples of Akkani massive ground ice (а) and the snow pit near Anadyr' town (б): massive ice near Akkani: 1 – horizontal selection; 2 – vertical selection; 3 – snow pit near Anadyr'; the dotted lines show the linear approximation of the values, the solid line – Global Meteoric Water Line
Relation between δ2H and dexc from Akkani massive ground ice and snow pit near Anadyr': massive ice near Akkani: 1 – horizontal selec tion; 2 – vertical selection; 3 – snow pit near Anadyr'; the dotted lines show the linear approximation of the values
Summary
The object of this study is a recently (or in the Holocene) formed thick (up 2.7 m in height) buried massive ice body, exposed in 2 km South-East from the mouth of the river Akkani in the North-East of Chukotka in the vicinity of the settlement Lavrentiya. The mean values of δ18О and δ2H in the ice are rather stable and equal to −17.1 and −128.3‰, respectively These isotope characteristics may be used for cryogenic reconstructions of massive ice formations widely distributed in the late Quaternary deposits in Eastern Chukotka. Пластовые льды отно сятся к одному из самых интересных и сложных для правильной генетической идентификации криогенных объектов. Поэтому для выяснения генезиса той или иной пластовой ледяной залежи с мето дической точки зрения правильнее исследовать сочетание экзогенных и криогенных процессов (а иногда, но гораздо реже, и эндогенных). Для оценки природы пластовых ледяных за лежей важный критерий – приуроченность самых крупных массивов к территориям низмен ностей, которые в позднем плейстоцене испыты вали влияние морских трансгрессий. Подземные льды и наледи аналогов и изучение зависимостей δ18О–δ2H, а также δ2H–dexc, которые можно использовать для установления источника воды и условий образо вания сложных пластовых залежей
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