鄂尔多斯白垩系盆地地下水的形成与演化：来自Cl及其同位素36Cl的证据

鄂尔多斯自垩系地下水盆地地处中国西部干旱-半干旱地区,其南部和北部分别被黄土和沙漠覆盖,地下水水化学组成在区域上差异显著,北部以淡水为主,南部以微咸-半咸水为主.在沙漠区和黄土区的深层含水层中(埋深大于400 m)分别采集了5组和3组水化学同位素样品.T和14C的分析结果表明,地下水的滞留时间在20343 a内,并且未...

The Formation and Evolution of Groundwater in the Ordos Cretaceous Basin: Evidences From Cl and its Isotope in Groundwater

The Ordos Cretaceous Basin is located at western area, a arid-semiarid area. Its south section and north section is covered by loess and desert, respectively. Chemical compositions of groundwater are prominently different regionally. In the north, freshwater dominates the groundwater, but in the south, brackish water does. 8 groups of hydrochemical and isotopic samples were collected from deep groundwater (more than 400 m depth) in this basin. Results of T and 14C show that groundwater residence times are within 20343 years, and are not polluted by human being. Based on Cl concentrations and 36Cl of groundwater, influences of evaporation on the recharge of precipitation and the Cl concentrations of groundwater were discussed. This study shows that all of the evaporation and the dissolution of stratum Cl have magnitude effects on the Cl concentrations of groundwater. The groundwater in the desert section was evaporated by 29.9-63.0 times in comparison with precipitation during its recharge, which provided more than 21.3-45.3 mg/L of Cl to the groundwater. In the loess section, the groundwater was evaporated by 266.0-523.7 times, with 191.5-377.0 mg/L of Cl derived from evaporation.