Estimation of the similarity of isotope diagrams from two synchronous adjacent ice wedges of the Batagay yedoma

The detailed isotopic plots based on δ18O and δ2 H values were analyzed for two parallel and synchronous syngenetic ice wedges (IW-17 and IW-20), exposed in the upper 20 meters of the outcrop in the Batagay Yedoma (Upper Ice Complex), Northern Yakutia. Based on the new 14C accelerator mass spectrometry (AMS) datings of organic matter extracted from the ice, the ice wedge formation began no later than 42 ka BP, slowed significantly around 26 ka BP, and ceased around 11 ka BP. Very low values of the isotopic composition were observed in the studied ice wedges. The mean δ18O values ranged from −31 to −36.2‰, while the mean δ2 H values ranged from −232 to −283‰. Comparison of the detailed isotopic curves for the two adjacent ice wedges allowed to identify sections at the same depth with similar isotopic values, as well as sections with isotope data that differed by 1−2‰ for δ18O and more than 10‰ for δ2 H. Different isotopic signal from adjacent ice wedges at the same depth may be explained by different frequencies of frost cracking during the present stage of their growth. This is associated with reaching an optimal width, at which cracking occurs more intensively. The lower δ18O and δ2 H values for IW-20 compared to IW-17 at a specific depth probably suggest that these ice wedges belong to different polygonal systems. The primary generation ice wedge (IW-17) was more likely to crack, while the secondary generation ice wedge (IW-20) located within a primary polygonal network cracked during severe winters only. It was found that between 42 and 26 ka BP, ice wedges in the Batagay Yedoma were formed under severe winter conditions of the Late Pleistocene. The mean January air temperature during the ice wedge growth period ranged from −47 to −53°C. During the initial stages of each ice wedge growth cycle, frost cracking and their growth mainly occurred during colder winters.