Determination of the main factors controlling chemistry of Bibitalkhone karst spring, Southwest Iran

• Autores: N. Kalantari, H. R. Mohammadi-Behzad, A. Charchi, A. Nadri
• Localización: Carbonates and Evaporites, ISSN 0891-2556, Vol. 31, Nº. 4, 2016, págs. 449-460
• Idioma: inglés
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• Resumen

  • Bibitalkhone spring with an average annual discharge of 2 m3/s is one of the important karstic springs in the Southwest of Iran which has a special hydrochemical behavior different from the other karstic springs. This study shows that the dominant water types of the spring are Cl–Na and HCO3–Ca for dry (approximately 8 months of year) and rainy (about 4 months of year) periods, respectively. While the host rock of the spring is composed of limestone and dolomite, the dominant type of the spring water doesn’t match the lithology of the host aquifer. The monthly physico-chemical parameters and major ions of the spring measured for 24 months (from October 2012 to September 2014) and the results analyzed using factor analysis and hydrochemical diagrams (including the composition, dissolution domains and Piper diagrams) to understand the odd behavior of this spring and also the factors which control the spring hydrochemistry. The oxygen-18 and deuterium contents of the spring water measured in four periods at February (rainy period), June (after the rainy period), October (before the next rainy period) and December (the next rainy period) of 2013. The results indicate that the water chemistry of the Bibitalkhone spring is controlled by various factors. One of the most important factors is the input of exotic waters from the neighboring karstic catchment which has circulated within a lithology of high limestone purity. Although these waters contribute to recharge of the Bibitalkhone spring throughout the year, their effect is more obvious during the rainy period. The other important factor is the dissolution of salty/gypsum layers (mostly salt). These layers are in direct contact with the southern limb of the host aquifer and their effects on the chemistry of spring water are more evident in the dry period. However, the available structural evidences suggest that the tectonic factor plays an important role in the chemistry of the spring water, since the main faults in the region somehow control the two previous factors.