Hydrogeochemical study of an ophiolitic aquifer: a case study of Lago (Southern Italy, Calabria)

摘要

A hydrogeochemical survey was carried out in the area of Lago (Calabria region, Southern Italy) and outcropping geological units were classified from the hydrogeological point of view, to explain the evolution of local groundwaters. In addition, reaction path modeling was performed to simulate the evolution of groundwaters upon interaction with local metabasalts, phyllites, and serpentinites, by means of the EQ3/6 software package, version 8.0. Simulations were carried at constant temperature of 14.1 degrees C, which reproduces the average temperature of local groundwaters. Three different simulations have been performed for the average metabasalt fixing the fugacity of CO2 at either 10(-2.4) bar (mean value), 10(-2.0) bar (mean value + 1 sigma), or 10(-2.9) bar (mean value - 1 sigma). The simulation for the average serpentinite and phyllite was carried out at the mean value of the fugacity of CO2 (10(-2.4) bar). All evidences acquired in this study, namely the hydrogeological framework, the chemical analysis of local groundwaters and the results of reaction path modeling, consistently point out that groundwater circulation under ordinary hydraulic gradient, primarily occurs in the ophiolitic sub-complex and that dissolution of metabasalts and serpentinites controls the chemical characteristics of the groundwaters from the study area.