Stable water isotope data of ice wedges at the Batagay megaslump and the Adycha River, including other Siberian ice-wedge sites for regional comparison

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 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 that 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.

针对北半球大陆性最强的区域——雅库特内陆亚纳高地的冰楔（ice wedge）开展研究，旨在阐明中更新世以来冬季气候与大陆性的演化特征。巴塔盖巨型滑塌（Batagay megaslump）出露冰楔与复合楔体，研究人员从3个冰地层单元（cryostratigraphic unit）中采集了样品：可能形成于海洋同位素阶段（Marine Isotope Stage，MIS）6之前的下冰复杂岩，以及上冰复杂岩（耶多玛冻土，Yedoma）和上砂层（二者均形成于MIS 3至2时期）。附近的阿迪恰河（Adycha River）阶地保存有全新世晚期（MIS 1）的冰楔，可作为现代解译参考标准。巴塔盖地区MIS 3期上冰复杂岩中的冰楔稳定同位素组成（平均δ¹⁸O约为-35‰），较雅库特沿海与中部地区的其他17处冰楔研究点位更为贫化。这一观测结果表明，MIS 3时期亚纳高地的冬季气温更低，大陆性更强。同样，与雅库特其他点位相比，全新世楔状冰的同位素值也更为贫化（平均δ¹⁸O约为-29‰）。下冰复杂岩（平均δ¹⁸O约为-33‰）与MIS 3~2期上砂层（平均δ¹⁸O介于-33‰至-30‰之间）的冰楔同位素特征，区域性辨识度相对较低。该砂层单元保留了快速堆积砂席中成楔速度较快的痕迹，以及沉积后发生同位素分馏的相关证据。