Tianjin Institute of Geothermal Exploration and Development Design, Tianjin 300250, China

TDS of Ordovician geothermal fluid around Tianjin changes greatly with differences between east and west, and there is a high anomaly of TDS and F^- in southwestwith a maximum of TDS is 418 mg/L. Through the analysis ofδD-δ18O and fluid dynamic field, the authors consider that the Ordovician geothermal fluid p recip i2 tation came from northern Yanshan area, and drained to south and west. The high abnormal areas of TDS are coin2 cident with the geopotential abnormal areas of reservoir fluid level inWumishan Formation of Jixian System, and the geopotential ofWumishan reservoir fluid level is 23.21��26.96 m higher than Ordovicianps, which indicates recharging dynamical conditions from Wumishan geothermal to Ordovician top. The Liqizhuang fracture which traverses the anomaly area is the recharging passage fromWumishan to Ordovician. The pyrites with 1% concentration at Ordovician strata can enhance the concentration of SO₄^2-  under oxidative decompositionaction, which led to the TDS and F^- anomalies in the western area.