Speleothems Reveal 500,000-Year History of Siberian Permafrost

Вакс, Антон; Gutareva, O. S.; Breitenbach, Sebastian F. M.; Erdenedalai, Avirmed; Mason, Andrew J.; Thomas, Alexander L.; Osinzev, Alexander V.; Kononov, A. M.; Henderson, Gideon M.

doi:10.1126/science.1228729

Cited by 119 publications

(102 citation statements)

References 29 publications

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“…Our results support the assertion that thaw of the $1.5 m of material overlying ice wedges occurred during the Holocene, as indicated by 14 C ages of <10 ka at depths of 1 m. Whether the shallow thawing developed in response to a warmer climate during the early Holocene or to repeated fire disturbance is uncertain. Nonetheless, our observed ( 234 U/ 238 U) values in deep yedoma cores suggest mean model ages up to $200 ka, consistent with other evidence of permafrost preservation for timescales on the order of $100 ka Vaks et al, 2013). Moreover, increasing DOC with depth in cores implies ongoing production of DOC from the surrounding organic matter over these timescales.…”

Section: Discussionsupporting

confidence: 85%

“…This is consistent with observations interpreted as long-term persistence of ground ice at the Palisades Bluff near Galena, Alaska (USA) and in the Yukon Territory (Canada) through the last large interglacial and highlights the potential resilience of yedoma (ice-and organic-rich loess permafrost) to climate change (Jorgenson et al, 2013b). In addition, recent work on speleothems suggests preservation of permafrost for >400 ka at similar latitudes in Siberia (Vaks et al, 2013). However, another 30-m-thick ice-rich loess permafrost deposit in northern Alaska dates only about 50 ka based on 14 C and thermo-luminescence dating (Kanevskiy et al, 2011).…”

Section: Age Model Applied To All Coressupporting

confidence: 80%

“…This possibility necessitates secondary geochronological evidence in support of dates obtained through 14 C analysis of solids, luminescence analysis of loess, and tephrachronology (Schirrmeister et al, 2002;Froese et al, 2008a;Jensen et al, 2008;Blinov et al, 2009). Given evidence for preservation of Pleistocene ice over timescales of 10 5 y Reyes et al, 2010a;Vaks et al, 2013), a direct measure of the age of ice in permafrost at timescales of 10 4 -10 6 y is needed.…”

Section: Introductionmentioning

confidence: 97%

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Uranium isotopes and dissolved organic carbon in loess permafrost: Modeling the age of ancient ice

Ewing

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O’Donnell

et al. 2015

Geochimica et Cosmochimica Acta

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The residence time of ice in permafrost is an indicator of past climate history, and of the resilience and vulnerability of high-latitude ecosystems to global change. Development of geochemical indicators of ground-ice residence times in permafrost will advance understanding of the circumstances and evidence of permafrost formation, preservation, and thaw in response to climate warming and other disturbance. We used uranium isotopes to evaluate the residence time of segregated ground ice from ice-rich loess permafrost cores in central Alaska. Activity ratios of 234 U vs. 238 U ( 234 U/ 238 U) in water from thawed core sections ranged between 1.163 and 1.904 due to contact of ice and associated liquid water with mineral surfaces over time. Measured ( 234 U/ 238 U) values in ground ice showed an overall increase with depth in a series of five neighboring cores up to 21 m deep. This is consistent with increasing residence time of ice with depth as a result of accumulation of loess over time, as well as characteristic ice morphologies, high segregated ice content, and wedge ice, all of which support an interpretation of syngenetic permafrost formation associated with loess deposition. At the same time, stratigraphic evidence indicates some past sediment redistribution and possibly shallow thaw among cores, with local mixing of aged thaw waters. Using measures of surface area and a leaching experiment to determine U distribution, a geometric model of ( 234 U/ 238 U) evolution suggests mean ages of up to $200 ky BP in the deepest core, with estimated uncertainties of up to an order of magnitude. Evidence of secondary coatings on loess grains with elevated ( 234 U/ 238 U) values and U concentrations suggests that refinement of the geometric model to account for weathering processes is needed to reduce uncertainty. We suggest that in this area of deep ice-rich loess permafrost, ice bodies have been preserved from the last glacial period (10-100 ky BP), despite subsequent fluctuations in climate, fire disturbance and vegetation. Radiocarbon ( 14 C) analysis of dissolved organic carbon (DOC) in thaw waters supports ages greater than $40 ky BP below 10 m. DOC concentrations in thaw waters increased with depth to maxima of >1000 ppm, despite little change in ice content or cryostructures. These relations suggest time-dependent produchttp://dx. ScienceDirectGeochimica et Cosmochimica Acta 152 (2015) 143-165 tion of old DOC that will be released upon permafrost thaw at a rate that is mediated by sediment transport, among other factors.

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Section: Discussionsupporting

confidence: 85%

Section: Age Model Applied To All Coressupporting

confidence: 80%

Section: Introductionmentioning

confidence: 97%

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Uranium isotopes and dissolved organic carbon in loess permafrost: Modeling the age of ancient ice

Ewing

Paces

O’Donnell

et al. 2015

Geochimica et Cosmochimica Acta

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“…5). Поскольку по климатическим сценариям в Арктике к концу XXI в. произойдёт повышение температуры воздуха на 7 ... 11 °C [34,35], следует ожидать значительного увеличения глубины оттаивания мерзлотных грунтов, что приведёт наряду с общим изменением водного баланса к резкому возрастанию солифлюкционных процессов.…”

Section: оползни и аномалии водной массыunclassified

Climatogenic Dynamics of Solifluction in the Permafrost Zone of Central Siberia

Харук¹,

Шушпанов²,

Im³

2015

J. Sib. Fed. Univ. Eng. technol.

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“…Увеличение глобальной температуры на 0.5-1 °C приведет к деградации ареалов прерывистой и островной мерзлоты в Сибири, а потепление на ~1.5 °C вызовет существенное оттаивание зоны сплошной мерзлоты выше 60 °с.ш. [4]. Таяние мерзлоты сопровождается интенсификацией солифлюкции и тер-мокарстовых процессов, что повлияет на инфраструктуру промышленных объектов Сибири, включая нефтегазовые комплексы.…”

Section: Introductionunclassified