Geochemical Characterization of East Siberian Ice Wedges: Implications for Paleoenvironmental Conditions and Provenance

ABSTRACT Ice wedges in permafrost have recently gained attention as valuable archives for reconstructing paleoclimate and paleoenvironmental conditions. Yet, the abundant solutes and solids embedded within them remain largely unexplored despite their significant potential as unique paleoenvironmental proxies. This study investigated the properties of ice wedges, focusing on the mineralogical and geochemical characteristics of their meltwaters and embedded solid particles, to examine the origins of the ice and solid particles, as well as the paleoweathering conditions during their formation. This research analyzed ice wedge samples from the Cyuie, Churapcha, and Zyryanka sites in East Siberia. The analysis of ice wedge characteristics included measurements of pH, electrical conductivity, alkalinity, solid content, and dissolved cation concentrations in bulk ice samples after controlled melting. The solid particles were also analyzed for elemental compositions, particle morphology, and Fe/Mn solid phases. We found that the dissolved concentrations of cations such as Ca, Mg, Na, K, and Si and their relative abundances in ice wedges resembled those in common soil porewater, suggesting that the chemical compositions of the ice wedges were substantially influenced by surrounding soil or soil porewater. In particular, the geochemical characteristics of the solid particles indicate a more mafic origin for samples from Zyryanka compared with those from Cyuie and Churapcha, reflecting regional differences in geological origins. Poor sorting and angular shape of the solid particles suggest that they likely originated from nearby soils or cold, dry environments, rather than from distant sources via atmospheric transport. Further analysis of trace elements (Th, Sc, and Zr), linear combination fitting (LCF) for Fe/Mn phase analysis, and clay particle contents showed higher degrees of weathering in the particles from Zyryanka samples compared with those from the other two sites, likely reflecting not only differences in source rocks but also the regional paleoenvironmental conditions. This also highlights that the ice wedges and their source materials provide opportunities for local paleoenvironmental reconstructions and soil provenance studies. Our findings encourage further research on the regional context of the origins of ice wedge, solid particle sources, and the potential for postformational interactions between solid particles and water chemistry.