In extensional tectonic settings, vertical movements of the earth's
surface are largely controlled
by rates of strain. Extensional strain rates within the Larderello geothermal
area,
located in inner parts of the
Northern Apennines, have been evaluated together with uplift rates and
40Ar/39Ar cooling ages. Results indicate
that extensional strain rates have been relatively low
(5.8×10−17 s−1), since the middle
Pliocene.
Differential uplift rates are estimated to have been high (c.
0.2 mm/year).
Strain and uplift rates within the
Larderello region are consistent with the regional tectonic framework.
The low strain rate, rapid uplifting
and high heat flow within southern Tuscany can be explained by an
eastward dipping lithospheric shear
maintained since at least middle Pliocene times.