Rare earth element contents in high pCO ₂ groundwaters of Sakhalin Island (the Far East of Russia)

摘要

The geochemistry of rare earth elements in cold, high pCO_(2)mineral waters was studied through the sampling of springs and boreholes of Sakhalin Island (the Russian Far East). The main common features of studied waters are the Na-Cl-HCO_(3)hydrochemical type, high TDS (6–20 g/L), alkaline pH (6.2–7.4), and reducing environment (-195 to +62 mV). The North American Shale Composite-normalized patterns of groundwaters exhibited a heavy REEs enrichment with high positive Eu anomalies. Both, positive and negative Ce anomalies were detected in CO_(2)-rich mineral waters. The distinct positive Eu/Eu~(*)in waters indicates water-rock interaction processes and positive Ce/Ce~(*)corresponds to reducing conditions. The various processes responsible for negative Ce anomaly in reducing environment are described.