Geochemical features of major and rare-earth element behavior in the Paratunka and Bol’shebannyi hydrothermal systems of Kamchatka

This paper presents original data on the content and distribution of major and rare-earth elements in the modern hydrothermal systems of the Paratunka and Bol’shebannyi thermal water deposits. In spite of the similar geochemical type of the waters, the individual sites of the hydrothermal systems differ in the major component composition, which is caused by the time of water–rock interaction, temperature control, and the possible influence of seawater intrusions. The REE concentrations in the studied thermal waters are extremely low (a few tenths of ppb). A distinctive feature of these thermal waters is the presence of a positive Eu anomaly. The possible reasons for its appearance are discussed. Calculation of REE speciation shows that the main parameters controlling the formation of the REE complexes in the Paratunka and Bol’shebannyi hydrothermal systems are their individual chemical properties, as well as pH, Eh, and temperature of the aqueous solution.