西宁药水滩地热田水化学特征及热水起源初探

Hydrochemistry and Origin of the Yaoshuitan Geothermal Field, Xining, Qinghai

西宁药水滩地热田热水的出露温度为18.1～40℃,TDS含量为1041～1707mg/L;冷泉水出露温度为3.5～6.5℃,TDS含量为210～403mg/L。水化学类型全部为HCO3型水,表明地下水经过相对浅的循环溢出地表。但热水比冷泉水有相对高的B表明热水比冷水有相对深的循环,样品的水化学特征是大气水与岩石相互作用处于早期的典型表现。SiO2地质温度计估算的热储温度为44～66℃。D和18O的测试结果表明:热田的水源于大气降水补给。氚含量和14C定年结果表明:热泉水的年龄为47.605±2.86ka,而冷泉水均来自1950年以后的大气降水补给。

Thermal and cold spring waters from the Yaoshuitan geothermal field have outlet temperatures of 18.4 to 40℃ and 3.5～6.5℃, respectively, and TDS of 1041～1707 mg/L and 210 to 403 mg/L, respectively. Bicarbonate waters for all samples suggest relative shallow circulation, however, high of B in the thermal waters suggest that thermal waters have a relatively deeper circulation than cold spring waters. Chemical characteristics of all samples are typical of the earliest stages of interaction between meteoric waters and rocks. Quartz geothermometer for the thermal water suggest that reservoir temperatures varies between 44～66℃. δD and δ^18O values indicate a meteoric origin for the waters from the geothermal field. Tritium content and carbon-14 dating show an age is 47.605±2.86 ka BP for thermal waters, and cold spring waters were recharge after 1950.