Abstract:The formation age of potash deposits in Central Asia Basin was constrained roughly from Late Jurassic to Early Cretaceous. The formation age of salt minerals could be determined if they have not been altered since deposition. Otherwise, the isotopic dating results could only indicate their postdepositional process. To obtain the formation age of the Central Asia Basin potash deposits and/or understand the post-depositional alterations of salt minerals, the authors performed rubidium-strontium (Rb-Sr) isotopic dating on these salt minerals. The result shows that there is no reliable Rb-Sr isochron, indicating that these salt minerals have not kept closed after their formation. The Rb-Sr model ages of the potash minerals and rock salts range from approximately 9 to 4 Ma and 190 to 170 Ma, respectively. This result seems to have been caused by dissolution and recrystallization by extraneous or decomposition of carnallite fluids. The potash salts accumulated more radiogenic 87Sr than the rock salts, because the potash salts contained more Rb than the rock salts. The dissolution and recrystallization of the potash and rock salts resulted in decreasing of 87Sr/86Sr ratios in the potash salts, but increasing of 87Sr/86Sr ratios in the rock salts. Although dating of salt minerals in other potash deposits of the world indicates that salt minerals are not suitable for dating the formation age of potash deposits, radiogenic isotopes of salt minerals can be used to constrain the metamorphic and hydrologic history of potash basins.