Cryogeochemical features of Holocene and Late Pleistocene syngenetic ice wedges at the mouth of the Seyakha (Zelenaya) River, East Yamal Peninsula

Abstract

The purpose of the paper is to establish the range of variability of mineralization and ionic composition of water-soluble salts in ice wedges of different ages near the Seyakha village (Eastern Yamal Peninsula) in outcrops of the river floodplain, Holocene peat bog and yedoma, as well as to establish the contribution of atmospheric nutrition of ice wedge and structure-forming ice. In the ice wedge of the yedoma the total mineralization is very variable from 17 to 309 mg/l, which indicates the participation of Ob Bay waters in addition to atmospheric waters. Sometimes there is a noticeable presence of sea salts in the sediments of the floodplain at the mouth of the river, associated with the influx of Ob Bay waters during surge surges of the bay level in the mouth of the river. It has been revealed a noticeable change of the mineralization of structure-forming ice in the Holocene peat, its regular gradual decrease from bottom to top is from 576 to 18 mg/l. This indicates that the reason of the lacustrine-marsh basin (or rather, several small basins) formation was the thawing of large masses of highly mineralized segregated and pore ice contained in the upper part of the lagoon-marine terrace. As the peat bog accumulated, the role of atmospheric precipitation increased, and in the final phase of ice formation in the upper part of the peat, atmospheric precipitation completely dominated.