R. Masoumi; A. A. Calagari; K. Siahcheshm; S. Porkhial
Abstract
The geothermal field at the south of Mount Sabalan is a part of the geothermal system of the Sabalan volcano region wherein manifestations of young volcanic activities including hot springs and surficial steams are observable. The surficial hydrothermal fluids in this area show maximum temperature of ...
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The geothermal field at the south of Mount Sabalan is a part of the geothermal system of the Sabalan volcano region wherein manifestations of young volcanic activities including hot springs and surficial steams are observable. The surficial hydrothermal fluids in this area show maximum temperature of 77°C, pH range of 6.4-7.4, and maximum TDS values of 7006 mg/l. Generally, these waters are divided compositionally into two groups. The first are mainly Na-Cl waters while the second are chiefly Ca-Na-HCO3 waters. The rare and heavy elements in these fluids are principally boron, lithium, rubidium, cesium, arsenic, and mercury whose maximum abundances are 33511, 14265, 3418, 10366, and 5 ppb, respectively. Considering the lithologic units in the area, vast hydrothermal fluid activities, and wide-spread alteration zones, boron-bearing minerals were regarded to be as the major sources of this element, which was leached and transported by geothermal fluids. Boron concentration in these fluids is controlled in part by fixation in clay minerals. Further considerations in geochemical behavior of the rare and heavy elements in this geothermal field demonstrated that lithium and rubidium were absorbed by quartz and clay minerals, respectively at temperatures <300°C, and also Cl- ion played a main role for transportation of mercury. Although the concentration values of B, Hg, As, and Li in the geothermal fluids of the studied area are not high enough to warrant the potential economic mineralization for these elements, the presence of these elements in these hot waters was recognized to be very consequential from two environmental respects; firstly because these geothermal waters are being directly used for swimming and bathing in the area, and secondly they may act as hazardous pollutant sources when mixed with the underground and drinking waters.
