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Helium and carbon isotopes in the dissolved gases of Friuli Region (NE Italy): Geochemical evidence of CO2 production and degassing over a seismically active area
Author(s)
Language
English
Obiettivo Specifico
3.2. Tettonica attiva
Status
Published
JCR Journal
JCR Journal
Peer review journal
Yes
Title of the book
Issue/vol(year)
1-2/266 (2009)
Publisher
Elsevier
Pages (printed)
76–85
Issued date
August 2009
Keywords
Abstract
The first geochemical data showing the existence of an active degassing activity over a large seismically
active sector of the Southern Alps (Friuli Region, NE Italy) are presented. The dissolved gases, helium and
carbon isotopic systematics of 46 water samples taken from 13 sites running along E–W and NE–SW faults
besides the natural degassing of a 5000 km2 wide area are investigated. The chemical composition of the
dissolved gases revealed that a CO2-rich gas phase feeds the local groundwaters. 3He/4He ratios (R)
normalized to the atmospheric 3He/4He ratio (Ra=1.39×10−6) and corrected for the atmospheric
contamination (R/Rac), range from 0.29 to 1 as a result of a two component (radiogenic and atmospheric)
mixing. The δ13C values of total dissolved inorganic carbon (TDIC) ranging from −15.28 to −0.75‰ vs. PDB,
show the occurrence of multiple gas–water interactions. The mixing between the atmospheric air and a
crustal source and the gas–water interactions occurring at various extents appears to be the main control on
the observed He–C systematics. The natural CO2 degassing was evaluated by a soil gas survey carried out by a
grid of about 100 measuring sites located over the area that generated destructive seismic sequences (e.g. the
Gemona sequence of 1976; main shocks M6.4 of 6th May and M6.1 of 11th and 15th September). The results
obtained show that a significant amount of crustal-originated gases are released over the continental area of
Eastern Southern Alps. The evidence that carbon dioxide is associated with radiogenic-type helium denotes
the lack of the mantle as primary energy and degassing source, highlighting the possibility that CO2 is
produced by thermo-mechanical processes occurring at seismogenic depth. The information provided here
may be used to start up a long-term geochemical monitoring of this seismically active area and could be able
to detect the modifications occurring to the circulating fluids to gain a better insight on the relationships
between the fluids' geochemistry and the activity of the local seismogenic faults.
active sector of the Southern Alps (Friuli Region, NE Italy) are presented. The dissolved gases, helium and
carbon isotopic systematics of 46 water samples taken from 13 sites running along E–W and NE–SW faults
besides the natural degassing of a 5000 km2 wide area are investigated. The chemical composition of the
dissolved gases revealed that a CO2-rich gas phase feeds the local groundwaters. 3He/4He ratios (R)
normalized to the atmospheric 3He/4He ratio (Ra=1.39×10−6) and corrected for the atmospheric
contamination (R/Rac), range from 0.29 to 1 as a result of a two component (radiogenic and atmospheric)
mixing. The δ13C values of total dissolved inorganic carbon (TDIC) ranging from −15.28 to −0.75‰ vs. PDB,
show the occurrence of multiple gas–water interactions. The mixing between the atmospheric air and a
crustal source and the gas–water interactions occurring at various extents appears to be the main control on
the observed He–C systematics. The natural CO2 degassing was evaluated by a soil gas survey carried out by a
grid of about 100 measuring sites located over the area that generated destructive seismic sequences (e.g. the
Gemona sequence of 1976; main shocks M6.4 of 6th May and M6.1 of 11th and 15th September). The results
obtained show that a significant amount of crustal-originated gases are released over the continental area of
Eastern Southern Alps. The evidence that carbon dioxide is associated with radiogenic-type helium denotes
the lack of the mantle as primary energy and degassing source, highlighting the possibility that CO2 is
produced by thermo-mechanical processes occurring at seismogenic depth. The information provided here
may be used to start up a long-term geochemical monitoring of this seismically active area and could be able
to detect the modifications occurring to the circulating fluids to gain a better insight on the relationships
between the fluids' geochemistry and the activity of the local seismogenic faults.
References
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model coupled to an atmospheric general circulation model. J. Geophys. Res. 100
(D2), 2817–2831.
Capasso, G., Inguaggiato, S., 1998. A simple method for the determination of dissolved
gases in naturalwaters. An application to thermalwaters from Vulcano island. Appl.
Geochem. 13, 631–642. doi:10.1016/S0883-2927(97) 00109-1.
Carapezza, M.L., Granieri, D., 2004. CO2 soil flux at Vulcano (Italy): comparison between
active and passive methods. Appl. Geochem. 19, 73–88. doi:10.1016/S0883-2927
(03) 00111-2.
Carulli, G.B., Ponton, M., 1992. Interpretazione strutturale profonda del settore centrale
carnico-friulano. Studi Geol. Camerti 2, 275–284 (CROP 1-1°).
Carulli, G.B., Feruglio, G., Longo, Salvador, G., Stolfa, D., 1972. Risultati preliminari di una
ricerca geomineraria nelle Alpi Carniche (Val D'Aupa e Val Pesarina). 2nd
symposium on the Mineral Deposits in the Alps, Ljubljana, pp. 393–403.
Castello, B., Selvaggi, G., Chiarabba, C., Amato, A., 2006. CSI, Catalogo della sismicità
italiana 1981–2002, versione 1.1, INGV-CNT Roma. http://www.ingv.it/CSI/2006.
Cataldi, R., Mongelli, F., Squarci, P., Taffi, L., Zito, G., Calore, C., 1995. Geothermal ranking
of Italian territory. Geothermics 24, 115–129. doi:10.1016/0375-6505(94) 00026-9.
Cheloni, D., Mantenuto, S., D'Agostino, N., Hunstad, I., Selvaggi, G., 2004. Cinematica
e deformazione attiva della regione padano - adriatica. 23° GNGTS conference,
pp. 32–35.
Chiodini, G., Frondini, F., Kerrik, D.M., Rogie, J., Parello, P.F., Peruzzi, L., Zanzari, A.R.,1999.
Quantification of deep CO2 fluxes from central Italy. Examples of carbon balance for
regional aquifers and of soil diffuse degassing. Chem. Geol. 159, 205–222.
Chiodini, G., Frondini, F., Cardellini, C., Parello, F., Peruzzi, L., 2000. Rate of diffuse carbon
dioxide earth degassing estimated from carbon balance of regional aquifers: the
case of Central Apennine (Italy). J. Geophys. Res. 105 (B4), 8423–8434.
D'Agostino, N., Avallone, A., Cheloni, D., D'Anastasio, E., Mantenuto, S., Selvaggi, G.,
2008. Active tectonics of the Adriatic region from GPS and earthquake slip vectors.
J. Geophys. Res. 113. doi:10.1029/2008JB005860.
Deines, P., Langmuir, D., Russell, S., 1974. Stable carbon isotope ratios and the existence
of a gas phase in the evolution of carbonate groundwaters. Geochim. Cosmochim.
Acta 38, 1147–1164.
Faure, G., 1986. Principles of isotope geology 2nd ed. Wiley, New York. 589 pp.
Favara, R., Grassa, F., Inguaggiato, S., Pecoraino, G., Capasso, G., 2002. A simple method to
determine the δ13C content of total dissolved inorganic carbon. Geofís. Int. 41 (3),
313–320.
Galadini, F., Poli, M.E., Zanferrari, A., 2005. Seismogenic sources potentially responsible
for earthquakes with M > 6 in the Eastern Southern Alps (Thiene-Udine sector,
NE Italy). Geophys. J. Int. 161, 739–762. doi:10.1111/j.1365-246X.2005.02571.x.
Gianelli, G., 1985. On the origin of geothermal CO2 by metamorphic processes. Boll. Soc.
Geol. Ital. 104, 575–584.
Gurrieri, S., Valenza, M., 1988. Gas transport in natural porous mediums: a method for
measuring CO2 flows from the ground in volcanic and geothermal areas. Rend. Soc.
Ital. Mineral. Petrol. 43, 1151–1158.
Heinicke, J., Braun, T., Burgassi, P., Italiano, F., Martinelli, G., 2006. Gas flux anomalies in
seismogenic zones in the Upper Tiber Valley, Central Italy. Geophys. J. Int. 167,
794–806. doi:10.1111/j.1365-246X.2006.03134.x.
Hernández Perez, P., Notsu, K., Tsurumi, M., Mori, T., Ohno, M., Shimoike, Y., Salazar, J.,
Pérez, N., 2003. Carbon dioxide emissions from soils at Hakkoda, north Japan.
J. Geophys. Res. 108 (B4), 2210. doi:10.1029/2002JB001847.
Hickman, S., Sibson, R., Bruhn, R., 1995. Introduction to special section: mechanical
involvement of fluids in faulting. J. Geophys. Res. 100 (B7), 12831–12840.
Italiano, F., Martinelli, G., Nuccio, P.M., 2001. Anomalies of mantle-derived helium
during the 1997–1998 seismic swarm of Umbria-Marche, Italy. Geophys. Res. Lett.
28 (No. 5), 839–842.
Italiano, F., Martinelli, G., Rizzo, A., 2004. Geochemical evidence of seismogenic-induced
anomalies in the dissolved gases of thermal waters: a case study of Umbria (Central
Apennines, Italy) both during and after the 1997–1998 seismic swarm. G-Cubed 5,
11. doi:10.1029/2004GC000720.
Italiano, F., Martinelli, G., Plescia, P., 2008. CO2 degassing over seismic areas: the role of
mechanochemical production at the study case of Central Apennines. Pageoph 165
(1), 75–94. doi:10.1007/s00024-007-0291-7.
Javoy, M., Pineau, F., Delorme, H., 1986. Carbon and nitrogen isotopes in the mantle.
Chem. Geol. 57 (1–2), 41–62. doi:10.1016/0009-2541(86) 90093-8.
Kissin, I.G., Pakhomov, S.I., 1967. The possibility of carbon dioxide generation at depth at
moderately low temperature. Dokl. Akad. Nauk SSSR 174, 451–454.
Kissin, I.G., Pakhomov, S.I., 1969. Geochemistry of Carbon Dioxide in Deep Zones of the
Underground Hydrosphere. Geokhimiya, 1969, no. 4, pp. 460–471.
Kissin, I.G., Pakhomov, S.I., 1975. Some features of the geochemistry of thermal water in
platform areas from experimental data. Proceedings of the Grenoble Symposium,
August 1975: IAHS publ., vol. 119, pp. 7–15.
Lan, T.F., Yang, T.F., Lee, H., Chen, Y.G., Chen, C.H., Song, S.R., Tsao, S., 2007. Compositions
and flux of soil gas in Liu-Huang-Ku hydrothermal area, northern Taiwan.
J. Volcanol. Geotherm. Res. 165 (1–2), 32–45.
Merlini, S., Doglioni, C., Fantoni, R., Ponton, M., 2002. Analisi strutturale lungo un profilo
geologico tra la linea Fella-Sava e l'avampaese adriatico (Friuli Venezia Giulia-
Italia). Mem. Soc. Geol. It. 57, 293–300.
Mook, W.G., Bommerson, J.C., Staverman, W.H., 1974. Carbon isotope fractionation
between bicarbonate and gaseous carbon dioxide. Earth Planet. Sci. Lett. 22,
169–176. doi:10.1016/0012-821X(74) 90078-8.
Morner, N.A., Etiope, G., 2002. Carbon degassing from the lithosphere. Global Planet.
Change 33 (1–2), 185–203. doi:10.1016/S0921-8181(02) 00070-X.
Poli, M.E., 1996. Analisi strutturale del Monte di Medea (Friuli): tettonica polifasica
nell'avampaese sudalpino orientale. Atti Ticin. Sci. Terra (Serie Speciale) 4, 103–113.
Sano, Y., Marty, B., 1995. Origin of carbon in fumarolic gas from island arc. Chem. Geol.
119, 265–274. doi:10.1016/0009-2541(94) 00097-R.
Sano, Y., Wakita, H., 1988. Precise measurement of helium isotopes in terrestrial gases.
Bull. Chem. Soc. Jpn. 61, 1153–1157. doi:10.1246/bcsj.61.1153.
Slejko, F., Petrini, R., Carulli, G.B., Italiano, F., Ditta, M., 2007. Preliminary geochemicaland isotopic data on springs along the Fella-Sava fault zone (NE Italy). Boll. Geofis.Teor. Appl. 48 (4), 423–434.
Sugisaki, R., Taki, K., 1987. Simplified analysis of He, Ne and Ar dissolved in natural
waters. Geochem. J. 21, 21–23.
Talamo, R., Pampaloni, M., e Grassi, S., 1978. Risultati delle misure di livellazione di alta
precisione eseguite dall'Istituto Geografico Militare nelle zone del Friuli interessate
dalle recenti attività sismiche. Boll. Geod. Sci. Affini 37, 61–75.
Thomas, D., 1988. Geochemical precursors to seismic activity. Pure Appl. Geophys. 126
(2–4), 241–266.
Toutain, J.P., Baubron, J.C., 1999. Gas geochemistry and seismotectonics: a review.
Tectonophysics 304 (1–2), 1–27. doi:10.1016/S0040-1951(98) 00295-9.
Venturini, C., 1990. Cinematica neogenico-quaternaria del Sudalpino orientale (settore
friulano). Studi Geol. Camerti 2 (CROP 1-1A), 109–116.
Zanferrari, A., Poli, M.E., Rogledi, S., 2003. The external thrust-belt of the Eastern
Southern Alps in Friuli (NE Italy). Mem. Soc. Geol. Ital. 54, 159–162.
model coupled to an atmospheric general circulation model. J. Geophys. Res. 100
(D2), 2817–2831.
Capasso, G., Inguaggiato, S., 1998. A simple method for the determination of dissolved
gases in naturalwaters. An application to thermalwaters from Vulcano island. Appl.
Geochem. 13, 631–642. doi:10.1016/S0883-2927(97) 00109-1.
Carapezza, M.L., Granieri, D., 2004. CO2 soil flux at Vulcano (Italy): comparison between
active and passive methods. Appl. Geochem. 19, 73–88. doi:10.1016/S0883-2927
(03) 00111-2.
Carulli, G.B., Ponton, M., 1992. Interpretazione strutturale profonda del settore centrale
carnico-friulano. Studi Geol. Camerti 2, 275–284 (CROP 1-1°).
Carulli, G.B., Feruglio, G., Longo, Salvador, G., Stolfa, D., 1972. Risultati preliminari di una
ricerca geomineraria nelle Alpi Carniche (Val D'Aupa e Val Pesarina). 2nd
symposium on the Mineral Deposits in the Alps, Ljubljana, pp. 393–403.
Castello, B., Selvaggi, G., Chiarabba, C., Amato, A., 2006. CSI, Catalogo della sismicità
italiana 1981–2002, versione 1.1, INGV-CNT Roma. http://www.ingv.it/CSI/2006.
Cataldi, R., Mongelli, F., Squarci, P., Taffi, L., Zito, G., Calore, C., 1995. Geothermal ranking
of Italian territory. Geothermics 24, 115–129. doi:10.1016/0375-6505(94) 00026-9.
Cheloni, D., Mantenuto, S., D'Agostino, N., Hunstad, I., Selvaggi, G., 2004. Cinematica
e deformazione attiva della regione padano - adriatica. 23° GNGTS conference,
pp. 32–35.
Chiodini, G., Frondini, F., Kerrik, D.M., Rogie, J., Parello, P.F., Peruzzi, L., Zanzari, A.R.,1999.
Quantification of deep CO2 fluxes from central Italy. Examples of carbon balance for
regional aquifers and of soil diffuse degassing. Chem. Geol. 159, 205–222.
Chiodini, G., Frondini, F., Cardellini, C., Parello, F., Peruzzi, L., 2000. Rate of diffuse carbon
dioxide earth degassing estimated from carbon balance of regional aquifers: the
case of Central Apennine (Italy). J. Geophys. Res. 105 (B4), 8423–8434.
D'Agostino, N., Avallone, A., Cheloni, D., D'Anastasio, E., Mantenuto, S., Selvaggi, G.,
2008. Active tectonics of the Adriatic region from GPS and earthquake slip vectors.
J. Geophys. Res. 113. doi:10.1029/2008JB005860.
Deines, P., Langmuir, D., Russell, S., 1974. Stable carbon isotope ratios and the existence
of a gas phase in the evolution of carbonate groundwaters. Geochim. Cosmochim.
Acta 38, 1147–1164.
Faure, G., 1986. Principles of isotope geology 2nd ed. Wiley, New York. 589 pp.
Favara, R., Grassa, F., Inguaggiato, S., Pecoraino, G., Capasso, G., 2002. A simple method to
determine the δ13C content of total dissolved inorganic carbon. Geofís. Int. 41 (3),
313–320.
Galadini, F., Poli, M.E., Zanferrari, A., 2005. Seismogenic sources potentially responsible
for earthquakes with M > 6 in the Eastern Southern Alps (Thiene-Udine sector,
NE Italy). Geophys. J. Int. 161, 739–762. doi:10.1111/j.1365-246X.2005.02571.x.
Gianelli, G., 1985. On the origin of geothermal CO2 by metamorphic processes. Boll. Soc.
Geol. Ital. 104, 575–584.
Gurrieri, S., Valenza, M., 1988. Gas transport in natural porous mediums: a method for
measuring CO2 flows from the ground in volcanic and geothermal areas. Rend. Soc.
Ital. Mineral. Petrol. 43, 1151–1158.
Heinicke, J., Braun, T., Burgassi, P., Italiano, F., Martinelli, G., 2006. Gas flux anomalies in
seismogenic zones in the Upper Tiber Valley, Central Italy. Geophys. J. Int. 167,
794–806. doi:10.1111/j.1365-246X.2006.03134.x.
Hernández Perez, P., Notsu, K., Tsurumi, M., Mori, T., Ohno, M., Shimoike, Y., Salazar, J.,
Pérez, N., 2003. Carbon dioxide emissions from soils at Hakkoda, north Japan.
J. Geophys. Res. 108 (B4), 2210. doi:10.1029/2002JB001847.
Hickman, S., Sibson, R., Bruhn, R., 1995. Introduction to special section: mechanical
involvement of fluids in faulting. J. Geophys. Res. 100 (B7), 12831–12840.
Italiano, F., Martinelli, G., Nuccio, P.M., 2001. Anomalies of mantle-derived helium
during the 1997–1998 seismic swarm of Umbria-Marche, Italy. Geophys. Res. Lett.
28 (No. 5), 839–842.
Italiano, F., Martinelli, G., Rizzo, A., 2004. Geochemical evidence of seismogenic-induced
anomalies in the dissolved gases of thermal waters: a case study of Umbria (Central
Apennines, Italy) both during and after the 1997–1998 seismic swarm. G-Cubed 5,
11. doi:10.1029/2004GC000720.
Italiano, F., Martinelli, G., Plescia, P., 2008. CO2 degassing over seismic areas: the role of
mechanochemical production at the study case of Central Apennines. Pageoph 165
(1), 75–94. doi:10.1007/s00024-007-0291-7.
Javoy, M., Pineau, F., Delorme, H., 1986. Carbon and nitrogen isotopes in the mantle.
Chem. Geol. 57 (1–2), 41–62. doi:10.1016/0009-2541(86) 90093-8.
Kissin, I.G., Pakhomov, S.I., 1967. The possibility of carbon dioxide generation at depth at
moderately low temperature. Dokl. Akad. Nauk SSSR 174, 451–454.
Kissin, I.G., Pakhomov, S.I., 1969. Geochemistry of Carbon Dioxide in Deep Zones of the
Underground Hydrosphere. Geokhimiya, 1969, no. 4, pp. 460–471.
Kissin, I.G., Pakhomov, S.I., 1975. Some features of the geochemistry of thermal water in
platform areas from experimental data. Proceedings of the Grenoble Symposium,
August 1975: IAHS publ., vol. 119, pp. 7–15.
Lan, T.F., Yang, T.F., Lee, H., Chen, Y.G., Chen, C.H., Song, S.R., Tsao, S., 2007. Compositions
and flux of soil gas in Liu-Huang-Ku hydrothermal area, northern Taiwan.
J. Volcanol. Geotherm. Res. 165 (1–2), 32–45.
Merlini, S., Doglioni, C., Fantoni, R., Ponton, M., 2002. Analisi strutturale lungo un profilo
geologico tra la linea Fella-Sava e l'avampaese adriatico (Friuli Venezia Giulia-
Italia). Mem. Soc. Geol. It. 57, 293–300.
Mook, W.G., Bommerson, J.C., Staverman, W.H., 1974. Carbon isotope fractionation
between bicarbonate and gaseous carbon dioxide. Earth Planet. Sci. Lett. 22,
169–176. doi:10.1016/0012-821X(74) 90078-8.
Morner, N.A., Etiope, G., 2002. Carbon degassing from the lithosphere. Global Planet.
Change 33 (1–2), 185–203. doi:10.1016/S0921-8181(02) 00070-X.
Poli, M.E., 1996. Analisi strutturale del Monte di Medea (Friuli): tettonica polifasica
nell'avampaese sudalpino orientale. Atti Ticin. Sci. Terra (Serie Speciale) 4, 103–113.
Sano, Y., Marty, B., 1995. Origin of carbon in fumarolic gas from island arc. Chem. Geol.
119, 265–274. doi:10.1016/0009-2541(94) 00097-R.
Sano, Y., Wakita, H., 1988. Precise measurement of helium isotopes in terrestrial gases.
Bull. Chem. Soc. Jpn. 61, 1153–1157. doi:10.1246/bcsj.61.1153.
Slejko, F., Petrini, R., Carulli, G.B., Italiano, F., Ditta, M., 2007. Preliminary geochemicaland isotopic data on springs along the Fella-Sava fault zone (NE Italy). Boll. Geofis.Teor. Appl. 48 (4), 423–434.
Sugisaki, R., Taki, K., 1987. Simplified analysis of He, Ne and Ar dissolved in natural
waters. Geochem. J. 21, 21–23.
Talamo, R., Pampaloni, M., e Grassi, S., 1978. Risultati delle misure di livellazione di alta
precisione eseguite dall'Istituto Geografico Militare nelle zone del Friuli interessate
dalle recenti attività sismiche. Boll. Geod. Sci. Affini 37, 61–75.
Thomas, D., 1988. Geochemical precursors to seismic activity. Pure Appl. Geophys. 126
(2–4), 241–266.
Toutain, J.P., Baubron, J.C., 1999. Gas geochemistry and seismotectonics: a review.
Tectonophysics 304 (1–2), 1–27. doi:10.1016/S0040-1951(98) 00295-9.
Venturini, C., 1990. Cinematica neogenico-quaternaria del Sudalpino orientale (settore
friulano). Studi Geol. Camerti 2 (CROP 1-1A), 109–116.
Zanferrari, A., Poli, M.E., Rogledi, S., 2003. The external thrust-belt of the Eastern
Southern Alps in Friuli (NE Italy). Mem. Soc. Geol. Ital. 54, 159–162.
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