Oxygen and Hydrogen Isotope Compositions of Lithalsa Frozen Core: A Case Study from the Sentsa River Valley, East Sayan

This is the first detailed study of permafrost in the area based on analysis of cryostructures and distribution of stable isotopes in lithalsa intrusive-segregation ice. The lithalsas predominantly have reticulate or lenticular cryostructures and ice contents over 50-60 %.

The lateral and vertical δ¹⁸O and δ²H patterns suggest cascade growth with the large lithalsa formed before the small one. Lithalsas can nucleate and grow during progressive lake shallowing. They feed mainly from ground water during freezing of wet frost-susceptible finegrained soil, or less often, from meteoric or lake water.