ABSTRACT
ABSTRACT: Hydrogeological investigations consisting of structural, petrographical and geomorphological studies, geophysical and drilling operations and pumping tests, have demonstrated that the groundwater in the granite rocks in Sardinia may occur in fracture zones, weathered parts of the rock, and microgranite dikes. It has been confirmed that structural analysis is a valid method for determining the local fracture pattern in the rock. Tensional, shear, and overthrust fractures were produced by lateral stresses related to the different tectonic phases that have affected Sardinia during the Caledonian, Hercynian and Alpine orogeneses. The state of openness is strictly dependent upon the type of fracture, and is maximum along the tensile cracks and overthrust zones, and is strongly influenced by weathering and hydrothermal alteration. The dimensions of the aquifers may be limited by the presence of lamprophyre dikes, which act as flow barriers between contiguous granite sectors. In cases where these dikes are frequent, the granite aquifers may have good hydraulic conductivity but their storage capacity is poor. The aquifers in the granite rocks of Sardinia may contribute decisively to solving local water supply problems.
