The San Calogero thermal spring is located in the Island of Lipari (Aeolian volcanic arc) and was known (and used) since Greek and Roman times and thus represents an important archeological and cultural site. In this contribution we present new geochemical and isotopic data that could be useful for a better understanding of the observed thermal components. The waters have been sampled during a period of 2 years to evaluate the compositional variations. Temperature and pH range between 40-50°C and 7.0-7.6, respectively. The TDS varies between 2050 and 2170 mg/l, with very constant sulphate concentration. The isotopic ratios of oxygen and hydrogen (averages -6.4 and -24.1 for dellta-18O and delta-D, respectively) is displaced (on the left) from the meteoric water line, possibly suggesting the involvement of juvenile fluids. While 3He/4He ratios of gases dissolved into water are close to the atmospheric values, the dissolved CO2 appears nearly 100 times higher respect to that expected in water equilibrated with the atmosphere, with a carbon isotopic ratio approaching delta-13C of -10 ‰. The mentioned fluids appear to be extremely reactive, thus explains the pervasive alteration of the rhyolite rocks in the surroundings of the studied spring. Considering that the involvement of sea water is not observed, the next aim of this work is to define better the existence and extent of a mixing between meteoric water and volcanic fluids. The data thus contribute to define a hydro-archive that includes parameters important to detect the upraising of deep fluids. Results can also provide information that can be useful for the sustainable exploitation of the thermal spring.
Geochemical characterization of the San Calogero thermal spring (Lipari)
BIANCHINI, Gianluca;
2013
Abstract
The San Calogero thermal spring is located in the Island of Lipari (Aeolian volcanic arc) and was known (and used) since Greek and Roman times and thus represents an important archeological and cultural site. In this contribution we present new geochemical and isotopic data that could be useful for a better understanding of the observed thermal components. The waters have been sampled during a period of 2 years to evaluate the compositional variations. Temperature and pH range between 40-50°C and 7.0-7.6, respectively. The TDS varies between 2050 and 2170 mg/l, with very constant sulphate concentration. The isotopic ratios of oxygen and hydrogen (averages -6.4 and -24.1 for dellta-18O and delta-D, respectively) is displaced (on the left) from the meteoric water line, possibly suggesting the involvement of juvenile fluids. While 3He/4He ratios of gases dissolved into water are close to the atmospheric values, the dissolved CO2 appears nearly 100 times higher respect to that expected in water equilibrated with the atmosphere, with a carbon isotopic ratio approaching delta-13C of -10 ‰. The mentioned fluids appear to be extremely reactive, thus explains the pervasive alteration of the rhyolite rocks in the surroundings of the studied spring. Considering that the involvement of sea water is not observed, the next aim of this work is to define better the existence and extent of a mixing between meteoric water and volcanic fluids. The data thus contribute to define a hydro-archive that includes parameters important to detect the upraising of deep fluids. Results can also provide information that can be useful for the sustainable exploitation of the thermal spring.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
