The IGAN Glacier in the Polar Urals: Isotopic Characteristics (18О, 2Н) of Ice

Abstract

Core drilling on the IGAN Glacier, one of the most studied glaciers of the Polar Urals, resulted in a 91-m-long ice core. This work has been done for the first time. The concentration, morphology, and composition of solid particles obtained by filtration, as well as the isotopic composition of the ice (δ¹⁸O, δ²H) were analyzed. Examination of the solid fraction on the filter surfaces made by means of scanning electron microscopy revealed the presence of porous aluminosilicate spherules with a diameter of 1–12 µm and a highcarbon substance in the form of flakes, scales and small porous fragments. On the whole, the morphology and composition of the spherules and carbonaceous particles corresponded to the ash and slag waste from thermal power plants, specifically fly ash, thus marking the development of the Vorkuta coal deposit and the associated infrastructure. The δ¹⁸O and δ²H values of the glacier ice change from −12.9 to −22.8‰ and from −90.8 to −167‰, respectively. Thus, the total variation range amounted 9.9‰ for δ¹⁸O and 157‰ for δ²H. The greatest variability of the isotopic composition was found within the upper 5 m of the core, where the density varies from 0.27 to 0.38 g/cm³, representing a snow–firn layer corresponding to one year of accumulation. At a depth of 4.8 m the density increases to 0.61 g/cm³, at 5.4 m — to 0.87 g/cm³, and below this depth varies between 0.83 and 0.93 g/cm³. With increasing density, δ¹⁸O and δ²H values increase toward average level with very small deviations, showing a very homogeneous distribution in depth. The δ18О and δ2Н isotopic relationship is approximated by the equation δ2Н = 7.32 δ18О + 2.97, R2 = 0.98, which is slightly different from the global meteoric water line. This difference may be related to specific features of the precipitation isotope formation in the Arctic sector of the East European Plain. The isotopic parameters of the ice suggest that the annual accumulation layer is primarily formed with the congelation ice from meltwater (including rainfall) at the end of the ablation season, with contributions of material from backwall areas of the cirque where snow and firn still remain.