Summary Karst water is the most important source of water supply for Shanxi province,northern China. The Shentou springs are representative of the 19 major karst springs at Shanxi.The total area of the Shentou karst water system is 5316 km2, the Middle Ordovician limestonebeing its major karst aquifer. In this study, data about the strontium isotope geochemistry andmajor ion hydrochemistry were analyzed to understand the flow patterns and hydrogeochemicalprocesses of karst water at Shentou. The contour map of TDS value of karst water and that of Srconcentration are similar, showing the general tendency of increase from the northern, westernand southern boundary to the discharge area. The average values of 87Sr/86Sr ratios of karstwater decrease from recharge (0.7107) to discharge area (0.7102), evolving towards those oflimestone hostrocks. Comparison of 87Sr/86Sr ratios with Sr content suggests that isotopic compositionsof some karst water samples from the recharge and flow through area should be theresult of interaction between aquifer limestone matrix and strontium-poor recharge waters ofmeteoric origin. However, for samples from the discharge area that are plotted above the mixingline, mixing with groundwater in the Quaternary aquifers with high 87Sr/86Sr ratios may beanother factor controlling Sr isotope chemistry. Two major groundwater flow paths were discernedfrom hydrogeological and geochemical data. Along both flow paths, the 87Sr/86Sr ratiosof karst water show a general tendency of decrease. Geochemical modeling of the major iongeochemistry of karst water using PHREEQC also indicates that the chemistry of springs shouldbe affected by the incorporation of groundwater in Quaternary aquifer. The effect of the mixingaction on the spring hydrochemistry in flow path 1 is more remarkable than that in flow path 2,according to different mixing ratios in both paths (30% in flow path 1 and 5% in flow path 2).a 2006 Elsevier B.V. All rights reserved.