不同地质背景地热系统水-岩作用下温泉水的地球化学特征--以重庆市温塘峡背斜温泉、滇东小江断裂带温泉为例

Hydrogeochemical features of hot spring under water-rock processes of different geologic conditions——A case in the Wentangxia hot spring of Chongqing and the hot spring at Xiaojiang fault zone of the East Yunnan

本文以重庆市温塘峡背斜和滇东小江断裂带出露温泉为例,探讨了其水文地球化学特征的差异。研究发现,由于地质背景条件基本相同,温塘峡背斜出露的温泉水文地球化学特征比较接近,水化学类型为SO4-Ca（Mg）型,而小江断裂带温泉水文地球化学特征差异较大,泉水水化学类型主要有HCO3-Na型（YN1）、HCO3-Ca型（YN2）、SO4-Ca（Mg）型（YN3和YN5）和SO4-HCO3-Ca-Na型（YN4）,这与各泉点所处地质背景条件不同有很大关系。此外,通过对Na-K-Mg和Na-K-Mg-Ca图解模型的解读得出,所有样品均未达到水-岩平衡,仅有YN1泉点样品接近完全平衡线,表明YN1接近水-岩作用平衡状态,并由上述图解模型估算得到YN1点热储温度大概为100~120℃,与运用SiO2温标计算的热储温度（133~139℃）相差不大。此外,水化学特征和Na-K-Mg-Ca图解分析也表明,YN2与温塘峡背斜温泉水-岩作用过程比较相似。

Taking the Wentangxia hot springs in Chongqing and the hot springs at Xiaojiang fault zone in the East Yunnan as the research object,the hydrogeochemic features are studied in the paper.It is found that the hydrogeochemic features of the hot springs outcrop from Wentangxia anticline are similar because of the same geologic backgrounds,and their hydrochemistry types are SO4-Ca（Mg）;but that the hydrochemic features of the thermal water outcrop from Xiaojiang fault zone are quiet different for their difference of geologic conditions,their hydrochemistry types are HCO3-Na（YN1）,HCO3-Ca（YN2）,SO4-Ca（YN3 and YN5）and SO4-HCO3-Ca-Na（YN4）.In addition,the Na-K-Mg diagram model and the Na-K-Mg-Ca diagram model evidently shows that all of the water samples have not reached equilibrium between water and rock,and only YN1 is closest to the complete equilibrium line to be close to equilibrium state.Moreover,the temperatures calculated with the silica geothermometer indicates a geothermal reservoir at 133~139 ℃,which is similar to the geothermal reservoir temperatures of YN1 showed by Na-K-Mg diagram and Na-K-Mg-Ca diagram（100~120 ℃）.The analysis on hydrochemistry and Na-K-Mg-Ca diagram shows the water-rock process of YN2 is similar to the hot springs outcrop from Wentangxia anticline.