Synchronous Isotopic Curves in Ice Wedges of the Batagay Yedoma: Precision Matching and Similarity Scoring

Abstract

ABSTRACTThe purpose of the study is to compare the results of the stable isotope analysis (δ18O, δ2H, and deuterium excess values) of parallel and synchronous ice wedges exposed in one outcrop in the upper part of the Batagay Yedoma (67.58° N, 134.77° E) and to estimate their precision, that is, a measure of similarity of independent isotope results of two ice wedges. Detailed sampling of two syngenetic ice wedges (IW‐17 and IW‐20) for isotope analysis was carried out in the exposure of the thermo‐erosional ravine in the southeastern part of the Batagay megaslump. In total, results of 105 measurements for IW‐17 and 59 measurements for IW‐20 were obtained. According to 14C AMS ages of organic microinclusions in the ice‐wedge ice, the studied ice wedges began to form no later than 42 cal ka BP. The termination of their growth was dated to about 11.7 cal ka BP. For both ice wedges, generally low isotope values were obtained. For the IW‐17, the mean values are −34.38‰ for δ18O, −264.82‰ for δ2H, and 10.2‰ for dexc. For IW‐20, the mean isotope values are −34.09‰ for δ18O, −262.91‰ for δ2H, and 9.84‰ for dexc. Statistical tests showed significant correlations between the isotope data in the upper parts of ice wedges that may be explained by similar conditions during their growth at this stage. Our results allow us to refine the solutions to the two main issues studied of the Late Pleistocene Yedoma: the age of the ice wedges, the accuracy of the isotope profiles, and the paleotemperature interpretation of the isotope records.