Hydrogeochemical and isotope geochemical study of northwestern Algerian thermal waters

Mohamed Belhai, Yasuhiro Fujimitsu, Fatima Zohra Bouchareb-Haouchine, Tatsuto Iwanaga, Masami Noto, Jun Nishijima

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4 Citations (Scopus)

Abstract

Northwestern Algeria is characterized by a large number of thermal waters and volcanic eruptions and belongs to the Alpine-Magrebide belt. The geothermal reservoirs that feed these reservoirs are mainly hosted by a fractured Jurassic limestone and dolomite sequence. Seven samples were collected from thermal springs of near-neutral pH (6.2 to 7.56) with discharge temperatures between 42.9 and 66.1 °C. Hydrogeochemical analyses of the thermal waters reveal four types (Na+-Ca2+-Cl, Na+-Ca2+-Cl-HCO3 , Na+-Ca2+-Cl-SO4 2−, and Na+-HCO3 -Cl) and show high total dissolved solids up to 4002 mg/L. Stable isotopic results (δ18 O and δ D) indicate that the thermal waters are of meteoric origin deeply infiltrated and heated by advective heat anomalies and raised up to the surface through deep-seated faults acting as hydrothermal conduits. The estimated reservoir temperatures using silica geothermometers and fluid-mineral equilibria overlap between 66 and 125 °C, while Na/K and K/Mg geothermometers give much higher and lower results, respectively, and are mainly influenced by mixing with cooler Mg groundwaters as indicated by the Na-K-Mg plot in the immature water field and in silica and chloride mixing models. Thermal waters deeply circulated and heated at a depth of 2 km were supplied by the higher geothermal gradients, which can reach 42.8 °C km−1 due to the complex geological setting.

Original languageEnglish
Article number169
Pages (from-to)1-17
Number of pages17
JournalArabian Journal of Geosciences
Volume9
Issue number3
DOIs
Publication statusPublished - Mar 1 2016

All Science Journal Classification (ASJC) codes

  • Environmental Science(all)
  • Earth and Planetary Sciences(all)

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