REY geochemistry in groundwater from Paratunka geothermal area (Kamchatka peninsula, Far East of Russia)

摘要

New data on geochemistry of the Paratunka deposit of mineral waters-Russian biggest geothermal system is presented in this paper. Studied waters are thermal (T = 45-80 A degrees C), alkaline (ph = 7.9-8.7), belong to Ca-Na Cl-SO4 type with reducing environment (Eh = - 150 to - 180 mV) leading to Ce- (+ 0.31) and Eu- (+ 0.8) anomalies. Evolution of chemical type of thermal water from Na-SO4 to Ca-Cl is discussed from the point of water-rock interaction and marine water intrusion as well. REY concentrations are extremely low due to alkaline pH (a(REY) = 25-165 ppt). First reliable data on REY concentration in alkaline thermal water, surrounding river water and suspended matter of these waters gave an opportunity to discuss cerium, europium and yttrium anomalies in terms of sorption/desorption processes and pH/Eh dependencies, confirmed by thermodynamic calculations of the REE migration forms.