Publication Date:
2017-04-04
Description:
We describe the results of a detailed hydrogeochemical campaign on the groundwater circulating in two
regional aquifers located in the area of the Abruzzo 2009 earthquakes. The influx of deeply derived CO2 rich
gases into the two aquifers is highlighted by the 13C isotopic composition of dissolved carbon species. The
source of the gas is roughly localised beneath the epicentral area of the earthquakes where the presence of
sources of fluids under high pressure is suggested by seismological investigations. The carbon isotopic-mass
balance of the aquifers indicates that the amount of the deep CO2 dissolved and transported by the
groundwaters is ~530 t/day. The chemical and isotopic composition of the gas entering the aquifers, named
Abruzzo gas, has been derived by comparing the data measured in the springs with the results of a gas–water–
rock reaction model, that simulates the evolution of the chemical and isotopic composition of groundwater
affected by the input of a deeply-derived CO2 rich gas phase. The composition of Abruzzo gas is compared to
that of 40 large gas emissions located in central Italy. The gas becomes progressively richer in radiogenic
elements (4He and 40Ar) and in N2, from the volcanic complexes in the west to the Apennines in the east. The
Abruzzo gas, in agreement with its location, well matches the composition of the gases emitted in the pre-
Apennine region. These geochemical features, consistent with the structural setting of the region, indicate
increasing residence times of the gas in the crust moving from west to east. In particular we suggest that the
strong increase in radiogenic crustal gases reflects the occurrence of deep traps where the gas is stored at high
pressures for a long time and that such high pressure gas pockets play a major role in the generation of
Apennine earthquakes.
Description:
Published
Description:
389–398
Description:
2.4. TTC - Laboratori di geochimica dei fluidi
Description:
4.5. Studi sul degassamento naturale e sui gas petroliferi
Description:
JCR Journal
Description:
reserved
Keywords:
carbon dioxide
;
Abruzzo earthquakes
;
carbon isotopes
;
helium isotopes
;
04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry
;
04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
;
04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
;
04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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