Structural controls on the hydrogeochemistry of Azarshahr travertine springs, NW Iran

Travertine deposits in Azarshahr, NW Iran, are one of the most extensive travertine deposits in the world. The process of travertine deposit is currently active in the several springs. It was used a multidisciplinary approach to determine the source of fluids and structural characteristics of travertine springs. Results of in-situ measurements and type of travertine deposits, demonstrate that the springs are of thermogenic type with hydrothermal sources. Hydrogeochemical diagrams and ionic ratios represent that the type of spring waters are calcium carbonate, with increased sodium and chloride ions levels due to mixing with brine waters. Geophysical studies showed that these brines originated from the Urmia Lake or related brines, which are intruded through fracture systems to relay zones of faults and mixed with hydrothermal bicarbonate-saturated fluids. This phenomenon shows that hydrochemistry of travertine springs are affected by Urmia Lake or related brines.