Geological, hydrogeological and geochemical surveys were carried out in
the Piedilago area (Ossola-Simplon region) in order to investigate the
geothermal resources present in this area. Following these surface
exploration efforts an exploratory geothermal well of 248 m was drilled
in 1991. It discharges a thermal water with temperatures up to 43
degrees C and calcium (sodium) sulphate composition with a TDS close to
1350 mg/l. Chemical geothermometers suggest a reservoir temperature
close to 45 degrees C indicating that the well virtually produces the
pure uncooled thermal water. The Piedilago ex-ample is here considered
as the departure point to establish both general criteria for further
geothermal investigations in young mountains chains and taking into
consideration all the available data on geology and fluid geochemistry
of thermal systems in the Ossola-Simplon region, to constrain a
geothermal model for the Lower Pennine Zone.