Abstract:

Multi-layers and a large amount of gypsum and lithofacies paleogeographic data from predecessors indicate that Jurassic marine layers of Qiangtang basin have good saline condition. There is a series of Ca-chloride springs in Jurassic layers of Dogai Coring area. For this study 30 salt springs water samples were collected from field. Then, chemical composition, δ¹⁸O and δD of water samples were determined in laboratory. Geochemical analysis demonstates that salt springs have high concentration of Na⁺,Cl^-,Ca²⁺,K⁺, Li, Rb and poor concentration of Br, B. In addition, geochemical coefficients of water samples have obvious anomaly of potash mineral. δ¹⁸O and δD of salt springs reveal that springs water came from atmospheric precitation. When meteoric water entered into stratum and became groundwater, saline minerals of stratum were dissolved and  lixiviation brine have been generated as groundwater. This is consistent with the result of coefficients of geochemistry analysis. In sum, potash perspective of south bank of Dogai Coring Lake is the best one of four sampling locations, whose salt springs have high salinity and concentration of K⁺ and might lixiviate potash-halite and potash stratum. Northwest side of Wananhu, Yuanquanhe and Dongwenquan take a second place of potash perspective. They have relatively lower salinity and anomaly of potash mineral.

Key words: Qiangtang basin, Dogai Coring, salt spring, potash, lixiviation brine