摘要
运用水化学和同位素示踪的原理追溯地热水的水岩相互作用和起源,得出武山和天水地热水为pH较高(7.94～9.06)的低TDS(226～255 mg/L)HCO3型水,通渭和清水地热水为pH较低(7.1～8.07)的较高TDS(915～1 793 mg/L)SO4型水,地热水的水化学特征主要受不同的围岩及与围岩相互作用的程度所控制。地热水的δD和δ18O值说明地热水起源于大气降水,且未受水-岩同位素交换明显影响。综合应用各种地热温标,估算地热水的热储温度为70～111℃,属于中低温地热资源。对年均降雨量约500 mm的天水及其南北地区,应采取采、停交替的地热水利用方式。
A geochemical study of geothermal water has been carried out in the Tianshui and its northern-southern area.Geothermal water of Wushan and Tianshui is bicarbonate water of low salinity characterized by pH in 7.94-9.06 and low total dissolved solids（TDS）（226-255 mg/L）,which were probably formed by water-rock interaction between meteoric rain,biotite plagioclase gneiss rock and carbonate sediment in reservior.While geothermal water of Tongwei and Qingshui is sulfate water with characteristics of pH in 7.1-8.07 and high total dissolved solids（TDS）（915-1 793 mg/L）,which may arised from water-rock interaction between meteoric rain,variscan granite and sinian amphogneiss.The isotopic data show that the origin of thermal water is meteoric water and not severely affected by water-rock isotope exchange.Assessments of various chemical geothermometer applied on the geothermal waters suggested the probable existence of a deep geothermal reservoir of middle-low enthalpy（70-111°C） in the Tianshui and its northern-southern area.The sustainable utilization of the thermal water will be maintained if the total withdrawal rate is relatively small,and an alternative pumping and non-pumping pattern is used in Tianshui and its northern-southern area with mean yearly rainfall of near 500 mm.
出处
《地理科学》
CSCD
北大核心
2011年第6期668-673,共6页
Scientia Geographica Sinica
基金
国家自然科学基金项目(50879033)资助
关键词
天水及南北地区
水化学
同位素
地热温标
Tianshui and northern-southern area
hydrochemistry
isotope
geothemometry
