The San Calogero thermal spring located in the Island of Lipari (Aeolian volcanic arc) has been monitored and studied since the nineteen century due its importance for the local population. In this contribution we present new geochemical and isotopic data that could be useful for a better understanding of the observed thermal components. In particular, the thermal waters have been sampled during a 2 years period (August 2012 - April 2013) 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 2200 mg/l, with constant sulphate/chloride ratio. The oxygen-hydrogen isotopic fingerprint of samples taken in the proximal point of emission of the spring (averages -6.05 ‰ and -26.1‰ for delta 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 delta13C -10 ‰. We hypothesize that these geochemical and isotopic features are inherited by a deep juvenile component variously mixed with meteoric water. The upraising fluids appear to be extremely reactive, thus explains the pervasive alteration of the volcanic rocks in the surroundings of the studied spring. The data thus contribute to define a hydro-archive and 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): indications of active juvenile contributions
BIANCHINI, Gianluca;MARCHINA, Chiara;COLOMBANI, Nicolo';TASSINARI, Renzo
2013
Abstract
The San Calogero thermal spring located in the Island of Lipari (Aeolian volcanic arc) has been monitored and studied since the nineteen century due its importance for the local population. In this contribution we present new geochemical and isotopic data that could be useful for a better understanding of the observed thermal components. In particular, the thermal waters have been sampled during a 2 years period (August 2012 - April 2013) 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 2200 mg/l, with constant sulphate/chloride ratio. The oxygen-hydrogen isotopic fingerprint of samples taken in the proximal point of emission of the spring (averages -6.05 ‰ and -26.1‰ for delta 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 delta13C -10 ‰. We hypothesize that these geochemical and isotopic features are inherited by a deep juvenile component variously mixed with meteoric water. The upraising fluids appear to be extremely reactive, thus explains the pervasive alteration of the volcanic rocks in the surroundings of the studied spring. The data thus contribute to define a hydro-archive and 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.
