Past climate and continentality inferred from ice wedges at Batagay megaslump in the Northern Hemisphere's most continental region, Yana Highlands, interior Yakutia

Abstract

Abstract. Ice wedges in the Yana Highlands of interior Yakutia – the most continental region of the Northern Hemisphere – were investigated to elucidate changes in winter climate and continentality that have taken place since the Middle Pleistocene. The Batagay megaslump exposes ice wedges and composite wedges that were sampled from three cryostratigraphic units: the lower ice complex of likely pre-Marine Isotope Stage (MIS) 6 age, the upper ice complex (Yedoma) and the upper sand unit (both MIS 3 to 2). A terrace of the nearby Adycha River provides a Late Holocene (MIS 1) ice wedge that serves as a modern reference for interpretation. The stable-isotope composition of ice wedges in the MIS 3 upper ice complex at Batagay is more depleted (mean δ18O about −35 ‰) than those from 17 other ice-wedge study sites across coastal and central Yakutia. This observation points to lower winter temperatures and therefore higher continentality in the Yana Highlands during MIS 3. Likewise, more depleted isotope values are found in Holocene wedge ice (mean δ18O about −29 ‰) compared to other sites in Yakutia. Ice-wedge isotopic signatures of the lower ice complex (mean δ18O about −33 ‰) and of the MIS 3–2 upper sand unit (mean δ18O from about −33 ‰ to −30 ‰) are less distinctive regionally. The latter unit preserves traces of fast formation in rapidly accumulating sand sheets and of post-depositional isotopic fractionation.

A spatial reconstruction of Siberian Last Glacial Maximum climate from pollen data

“…Stable isotope analyses and macrofossils indicate regionally homogeneous colder winter temperatures (e.g. Meyer et al, 2002;Kienast et al, 2005;Andreev et al, 2011;Wetterich et al, 2011;Opel et al, 2019). In contrast, inconsistent results are reported for summer temperature.…”

“…In high-latitude Central Siberia and along the Arctic Ocean coastline, dryer conditions than today are reconstructed from a variety of proxies (e.g. Sher et al, 2005;Pitul'Ko et al, 2007;Andreev et al, 2011;Ashastina et al, 2018;Opel et al, 2019). Stable isotope analyses and macrofossils indicate regionally homogeneous colder winter temperatures (e.g.…”

Sub-surface Carbon Stocks in Northern Taiga Landscapes Exposed in the Batagay Megaslump, Yana Upland, Yakutia

“…Based on current cryolithological research and various dating approaches the permafrost exposed in the Batagay megaslump differentiates into the following seven units [1,5,6] starting from the slump bottom: (1) diamicton above slate bedrock, (2) lower ice complex, (3) lower sand unit, (4) prominent lenses of woody debris, (5) upper ice complex, (6) upper sand unit, and (7) a near-surface layer. The chronological sequence is not continuous, but contains hiatuses and traces of thermo-erosional degradation, especially during multiple interglacials during mid-and late Pleistocene [6][7][8].…”

“…The analysis of stable water isotope (δ18O, δD) composition of the ice wedges from the upper ice complex revealed low winter temperatures during MIS 3 under enhanced continentality of the Yana Upland [5,10]. Ice wedges of both sand units retain traces of rapid sand formations [5].…”

“…The analysis of stable water isotope (δ18O, δD) composition of the ice wedges from the upper ice complex revealed low winter temperatures during MIS 3 under enhanced continentality of the Yana Upland [5,10]. Ice wedges of both sand units retain traces of rapid sand formations [5]. It was further shown that the wedge ice of multiple generations of the Batagay megalump has a hydrogencarbonate-calcium dominated composition and a homogenous content of micro-and macroelements [11] pointing to stable moisture sources, i.e.…”