 |
| Titel |
Water geochemistry to estimate reservoir temperature of Stabio springs,
Switzerland |
| VerfasserIn |
Sebastian Pera, Linda Soma |
| Konferenz |
EGU General Assembly 2017
|
| Medientyp |
Artikel
|
| Sprache |
en
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250151166
|
| Publikation (Nr.) |
 EGU/EGU2017-15723.pdf |
|
|
|
|
|
| Zusammenfassung |
| The Mendrisiotto region located in Southern Switzerland and close to the Italian border, is
characterized by the presence of a thick sequence of Mesozoic limestones and dolostones
above a volcanic rocks from Permian (Bernoulli, 1964). Within the carbonates, fractures and
dissolution processes increased limestone permeability and favored the widespread presence
of springs. The presence of few localized H2S and CH4 bearing springs is known from
historical times in Stabio. Its localization is related to the faulting affecting the area
(Balderer et Al., 2007). These waters were classified by Greber et Al. (1997) as
Na-(Ca)-(Mg)-HCO3-Cl-(SO4) type with having a total dissolved solid content in the range
of 0.8 and 1.2 gl−1. According with Balderer et Al. (2007) the stable isotopic composition
deviates from the global meteoric water line (IAEA, 1984) being the values of δ18O and δ2H
respectively 0.8 ‰ and 5‰ lower than the normal shallow groundwater of the area. The
values of δ13C of TDIC (-1.54‰ 1.44 ) indicate exchange with CO2 of thermo -
metamorphic or even Mantle origin. While 14C in TDIC (7.95, 26.0 pMC) and 3H
(1.1 ±0.7, 3.1±0.7 TU) indicates uprising of deep water along faults with some
mixing.
To estimate reservoir temperature, a new sampling was conducted in 2015 for chemical
and isotopic analysis. The sampling was carried out from the only source that allows getting
water directly from the dolostone in order to avoid mixing. Although some differences are
noticed respect to previous studies, the results show a substantial agreement for stable
isotopic composition of water, δ13C and 14C of TDIC. Reservoir temperature was calculated
by using several geothermometers. The results show a great variability ranging from 60 ˚ C
using Silica to more than 500 ˚ C using cationic ( Na – Ca) geothermometers; indicating that
besides mixing, exchange processes and chemical reactions along flow path affect
results.
This study was partially funded by Azienda Elettrica Ticinese
References
Balderer, W., Leuenberger, F., Frei, C., Surbeck, H., & Synal, H. A. (2007). Origin of the
Thermal Waters of Stabio (Switzerland) and Sirmione (Italy) based on Isotope and Chemical
Investigations. In Symposium on advances in isotope hydrology and its role in sustainable
water resources management; Vienna (Austria); 21-25 May 2007 (Vol. 39, pp. 631–641).
IAEA.
Bernoulli, D. (1964). Zur Geologie des Monte Generoso. Ein Beitrag zur Kenntnis der
südalpinen Sedimente. Beiträge zur Geologischen Karte der Schweiz Karte Schweiz. N.F.
118.
Greber, E., Leu, W., Schumacher, M. E., & Wyss, R. (1997). Hydrocarbon provinces in
the Swiss Southern Alps-a gas geochemistry and basin modelling study Fsl. Marine and
Petroleum Geology, 14(1), 3–25
IAEA. (1984). Isotopes Hydrology 1983. In Proc. Vienna Symposium 1984. Vienna:
IAEA |
|
|
|
|
|
|