THE ORIGIN OF ICE MOUNDS NEAR THE ERKATA-YAKHA RIVER, YAMAL PENINSULA, FROM THE RELATIONSHIP BETWEEN δD AND δ18О ISOTOPE RATIOS

Ice mounds are widespread cryogenic landforms that occur during freezing of water-saturated sediments and in ice segregation or ice injection with the formation of ice cores. Complex mechanisms of occurrence of these landforms have their own characteristics depending on the type of enclosing sediments, water and gas saturation, freezing rate, and other factors. Ice formation processes are often accompanied by explosions of the central part with the occurrence of negative landforms. In response to the widespread occurrence of perennially frozen gas-saturated rocks, these processes are accompanied by gas emissions, gas inflammation. and other, less intense gas shows. It is quite difficult in these conditions to determine the causes of the catastrophic phenomenon, to reconstruct the dynamics of the process, and to understand the role of gas-saturated fluids. In this paper, an attempt has been made to determine the ice formation conditions using isotopic techniques. The isotopic composition of ice can reflect the conditions of ice formation at the time of occurrence of ice mounds and its related possibility of participation of gas-saturated fluids from deep-lying gas-bearing horizons [Buddo et al., 2023, 2024]. The composition of stable isotopes δD and δ 18 O was determined for three ice mounds in the south of the Yamal Peninsula, where there were catastrophic explosions of ice mounds with the formation of large craters. The results of the study made it possible to reconstruct the conditions of ice mound occurrence and to determine different ice formation modes.