Lithogeochemical signatures of high-sulfur therapeutic mud from Nuhu-Nur Lake (Irkutsk region): comparison with the therapeutic mud of the world

IIn therapeutic mud (peloids) of Lake Nuhu Nur, major oxides, trace elements, and mineral phases are determined from sedimentary columns taken in the central and near-coastal parts of the lake. In the center of the lake, layers with high and low contents of total sulfur (Stot) and S2− alternate. Sulfur is part of sulfates: gypsum, tenardite, and hexahydrite. The distribution of S is generally correlated with Na2O, CaO, Sr, and U with a strong negative correlation with other major oxides and trace elements. In near-coastal parts of the lake, there are layers enriched and depleted with CaO, which strongly correlates with Sr. Lithogeochemical signatures of peloids show concentration of therapeutic components in the bottom sediments of the lake due to processes similar to weathering of rocks of silicic composition in arid climate. In terms of major oxides and trace elements, peloids from Lake Nuhu Nur are generally comparable to those from Wudalianchi (Northeast China), coastal regions of Brazil, as well as Georgia and Spain, but are closest to therapeutic high-sulfur sulfate mud of Kopahue in Argentina.