Chemical and isotopic signature of groundwater in the Santa Ninfa karst system and possible inferences on neotectonics
Main Article Content
Abstract
The Santa Ninfa karst system is an area strongly controlled by tectonics, whose intense fracturing gave rise to the formation of a large number of cavities that foster the drainage of water. The hydrogeochemical characters of groundwater circulating in this aquifer, together with its isotopic signature, were investigated in detail. The chemistry of groundwater reflects the nature of the rocks hosting the aquifers, constituted by primary and diagenetic selenitic gypsum, salts, and gypsum- arenite, whose dissolution is responsible of the geochemical fingerprint of the quasi-totality of the samples. A single site (CAM) is characterised by a different chemical composition, indicating a mixing between Ca-sulphate, Ca-bicarbonate and a NaCl-rich water. From the chemical point of view, no evidence of interaction between shallow groundwater and deep fluids has been detected. Conversely, isotopic fluctuations highlight mixing processes between surficial (evaporated) runoff and groundwater. Different mixing proportion among these endmembers can be reflected in variations of the chemical character of the sampled springs. Changes in mixing proportions can be the effect of differential permeability variations, in turn produced by local stress field changes during seismogenic processes. In this scenario the geochemical monitoring of the Santa Ninfa karst aquifer could be of relevant interest in the study of seismogenic processes in this area, with particular reference to the relationship between seismic and geochemical transients.
Article Details
Open-Access License
No Permission Required
Istituto Nazionale di Geofisica e Vulcanologia applies the Creative Commons Attribution License (CCAL) to all works we publish.
Under the CCAL, authors retain ownership of the copyright for their article, but authors allow anyone to download, reuse, reprint, modify, distribute, so long as the original authors and source are cited. No permission is required from the authors or the publishers.