The use of hydrogeochemical analyses and multivariate statistics for the characterization of thermal

• 作者: Riad Kouadra Abdeslam Demdoum Nabil Chabour Rebiha Benchikh
• 学科: 地球科学
• 关键词: Hydrogeochemistry Thermal waters Multivariate statistical analysis Silica geothermometers Mixing models Cold groundwaters
• 年，卷（期）: 2022,（2）
• 页码范围: 292-306
• 页数: 14页
• 语种: 英文
• DOI: 10.1007/s11631-018-0298-z

摘要

This paper deals with the results of a hydrogeochemistry study on the thermal waters of the Constantine area, Northeastern Algeria, using geochemical and statistical tools. The samples were collected in December 2016 from twelve hot springs and were analyzed for physicochemical parameters (electric conductivity, pH, total dissolved solids, temperature, Ca, Mg, Na, K, HCO3, Cl, SO4, and SiO2). The waters of the thermal springs have temperatures varying from 28 to 51℃ and electric conductivity values ranging from 853 to 5630 μS/cm. Q-mode Cluster analysis resulted in the determination of two major water types: a Ca–HCO3–SO4 type with a moderate salinity and a Na–K–Cl type with high salinity. The plot of the major ions versus the saturation indices suggested that the hydrogeochemistry of thermal groundwater is mainly controlled by dissolution/precipitation of carbonate minerals, dissolution of evaporite minerals (halite and gypsum), and ion exchange of Ca (and/or Mg) by Na. The Gibbs diagram shows that evaporation is another factor playing a minor role. Principal Component Analysis produced three significant factors which have 88.2% of total variance that illustrate the main processes controlling the chemistry of groundwaters, which are respectively: the dissolution of evaporite minerals (halite and gypsum), ion exchange, and dissolution/precipitation of carbonate minerals. The subsurface reservoir temperatures were calculated using different cation and silica geothermometers and gave temperatures ranging between 17 and 279℃. The Na–K and Na–K-Ca geothermometers provided high temperatures (up to 279℃), whereas, estimated geotemperatures from K/Mg geothermometers were the lowest (17-53℃). Silica geothermometers gave the most reasonable temperature estimate of the subsurface waters overlap between 20 and 58℃, which indicate possible mixing with cooler Mg groundwaters indicated by the Na–K–Mg plot in the immature water field and in silica and chloride mixing models. The