Isotopic composition of heterogeneous ice wedges in peatlands of the Pur‐Taz interfluve (northern West Siberia)

IF 3 3区地球科学 Q2 GEOGRAPHY, PHYSICAL

Permafrost and Periglacial Processes Pub Date : 2022-02-09 DOI:10.1002/ppp.2138

Ya. V. Tikhonravova, E. Slagoda, V. Butakov, E. Koroleva, G. Simonova, R. Sysolyatin

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引用次数: 3

Abstract

Heterogeneous ice wedges were studied within the peatland of the drained lake on the Pur‐Taz interfluve (67°20′14.8″, 078°55′47.1″, Northwest Siberia). The elements of the ice‐wedge structure were identified: young ice wedge, shoulders, selvages, closed‐cavity ices, and ice lenses in a peatland. Different genetic types of ice (ice vein, congelation ice, and segregated ice) were revealed by analyzing the elements of the ice‐wedge structure under polarized light and analyzing their chemical compositions. Genetic types of the ice indicate the different mechanisms of ice‐wedge formation. The ice vein forms due to fast bilateral freezing of primarily meltwater in a thermal contraction crack. The congelation ice forms due to the slow freezing of free water that has accumulated into a thermokarst cavity. The segregated ice forms due to pore water migration to the freezing zone. The elements of the ice‐wedge structure have variable stable isotope values (δ18O from −13.5‰ to −21.9‰ and δD from −87.7‰ to −154.6‰). The high range of deuterium excess values (13.8‰ to 32‰) indicates fractionation at condensation. The mean winter paleotemperature calculated using Vasil’chuk’s equations for the ice‐wedge pats formed by the ice veins varied in the range of −18 to −22°C, which is not very different from current values and is consistent with the isotopic data of ice wedges from nearby regions of Northwest Siberia. The paleotemperature average error can equal 4.5°C if we ignore the data on the ice petrographic analysis. The error depends on where and how the ice wedges are sampled, because of varying genetic types within the ground ice. This could lead to different palaeoclimatological interpretations.

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Pur‐Taz交错带泥炭地（西西伯利亚北部）异质冰楔的同位素组成

研究了Pur‐Taz交错带（67°20′14.8〃，078°55′47.1〃，西伯利亚西北部）排水湖泥炭地内的不均匀冰楔。确定了冰楔结构的元素：泥炭地中的年轻冰楔、肩部、边缘、闭腔冰和冰透镜体。通过在偏振光下分析冰楔结构的元素并分析其化学成分，揭示了冰的不同成因类型（冰脉、凝结冰和分离冰）。冰的成因类型表明了冰楔形成的不同机制。冰脉的形成是由于主要融水在热收缩裂缝中的快速双向冻结。凝结冰的形成是由于积聚在热岩溶洞穴中的自由水的缓慢冻结。分离的冰是由于孔隙水迁移到冻结区而形成的。冰楔结构的元素具有可变的稳定同位素值（δ18O从−13.5‰到−21.9‰，δD从−87.7‰到−154.6‰）。氘过量值的高范围（13.8‰到32‰）表明在冷凝时分馏。使用由冰脉形成的冰楔块的Vasil’chuk方程计算的冬季平均古温度在−18至−22°C的范围内变化，这与当前值没有太大差异，并且与西伯利亚西北部附近地区冰楔的同位素数据一致。如果忽略冰岩分析的数据，古温度平均误差可能等于4.5°C。误差取决于冰楔的采样地点和方式，因为地面冰中的遗传类型不同。这可能导致不同的古气候解释。

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来源期刊

Permafrost and Periglacial Processes 地学-地质学

CiteScore

9.70

自引率

8.00%

发文量

审稿时长

>12 weeks

期刊介绍： Permafrost and Periglacial Processes is an international journal dedicated to the rapid publication of scientific and technical papers concerned with earth surface cryogenic processes, landforms and sediments present in a variety of (Sub) Arctic, Antarctic and High Mountain environments. It provides an efficient vehicle of communication amongst those with an interest in the cold, non-glacial geosciences. The focus is on (1) original research based on geomorphological, hydrological, sedimentological, geotechnical and engineering aspects of these areas and (2) original research carried out upon relict features where the objective has been to reconstruct the nature of the processes and/or palaeoenvironments which gave rise to these features, as opposed to purely stratigraphical considerations. The journal also publishes short communications, reviews, discussions and book reviews. The high scientific standard, interdisciplinary character and worldwide representation of PPP are maintained by regional editorial support and a rigorous refereeing system.