 |
| Titel |
Advective heat transport associated to regional Earth degassing in central Apennine (Italy) |
| VerfasserIn |
Carlo Cardellini, Giovanni Chiodini, Stefano Caliro, Claudio Chiarabba, Francesco Frondini |
| Konferenz |
EGU General Assembly 2013
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250074897
|
|
|
|
|
|
| Zusammenfassung |
| The main springs of central Italy Apennines were investigated, in order to compute the
amount of heat transported by groundwaters and to compute the fraction of heat due to the
geothermal heat flux. The 46 investigated springs represent a significant portion of the
permeable structures of the Apennine being characterised by a cumulative flow rate of 130
m3/s, i.e. ~ 50% of the water discharged in this sector of the Apennines. The groundwaters
are characterised by relatively low temperatures, but the occurrence of an heat anomaly is
evident when the differences between the temperatures of springs and recharge waters are
compared with the corresponding altitude difference. A total amount of heat of ~ 2.1
à 109 J/s has been estimated to be transported by these groundwaters. Most of
this heat (57%) is given by geothermal warming while the remaining 43% is due
to gravitational potential energy dissipation. The computed geothermal warming
implies very high heat flux, with values higher than 300 mW/m2, in a large sector of
the Apennines which was considered to date be characterised by normal to low
conductive heat flux. The same area is affected by high fluxes of CO2 from a deep
source and the strict correlation between the geothermal warming and the input
of deep CO2-rich fluids is testified by the fact that all the thermally anomalous
groundwaters are also affected by the input of deeply derived CO2 contrary to those
not thermally anomalous which display any input of deeply derived CO2. This
correspondence reasonably suggest the geothermal heat is transported from depth
by CO2 rich fluids, which enter the aquifers and mix with infiltrating waters. The
amount of geothermal heat transported by central Apennine cold groundwaters is
in absolute very high. It results the double than the hydrothermal heat discharge
of the US Cascade Range (~1Ã103 MW) and is about the half of the total heat
discharged at Yellowstone, one of the largest hydrothermal system of the world (5-6
à 103 MW). The large heat flux anomaly highlighted by this study opens a new
vision of the Apennines belt and requires the existence of a thermal source such
as a large magmatic intrusion at depth. Recent tomographic images of the area
confirm the presence of such intrusion visible as a broad negative velocity of seismic
waves. In addition, our results indicate that the thermal regime of tectonically active
areas of the Earth, where meteoric waters infiltrate and deeply circulate, should
be revised on the base of mass and energy balances of the groundwater systems. |
|
|
|
|
|
|