We have developed a new concept on the formation of diverse geochemical types of salt lakes, in particular for those in the Transbaikal region. This concept explains the nature of their different chemical composition under the close landscape-climatic and geological-geochemical conditions. The extensive hydrogeochemical field data and thermodynamic calculations demonstrate that in addition to evaporation, interactions with rocks play a substantial role in the formation of the composition of these salt lakes. Such processes are most widespread in soda lakes, which is confirmed by the highest pH values (9.0-10.7). These lakes provide evidence of the interaction of the lake waters with aluminosilicates; their hydrolysis provides a pH increase and consequently a high concentration of carbonate ions.
