Publication Date:
2017-04-03
Description:
Several types of natural gas emissions (soil gas, low temperature
fumaroles, gas bubbling in mud pools) were collected monthly on Mt. Etna
volcano between July 2000 and July 2003 both from its summit and its
flanks. Samples were analysed for the determination of the concentrations
of CO2, CH4, He, H2, CO as well as the isotopic ratios of 13 14 C/ C of CO2
(δ13C) and He (R/Ra). The analysed gases were chemically divided into two
groups: air-contaminated (from sites closer to the summit vents of Mt. Etna)
and CO2 - rich. Among the latter, samples from the lower SW flank of the
volcano showed high contents of biogenic thermogenic and/or microbial
CH4. Isotopic shift in the δ13C values is caused by input of organic CO2
and/or by interaction between magmatic CO2 and shallow ground water
as a function of water temperature and CO2 flux from depth. Based on a
graphic method applied to δ13
TDIC C of some ground water, the inferred
isotopic composition of the pristine magmatic gas at Mt. Etna is
characterised by δ13C values ranging from -2 to -1 0
00 .
During the period July 2000 - July 2003 significant variations were
observed in many of the investigated parameters almost at all monitored
sites. Seasonal influences were generally found to be negligible, with only a
limited effect of air temperature changes on soil CO2 and ground temperature
in only two of the air-contaminated sites. The largest chemical anomalies
were observed in the air-contaminated sites, probably because of the
strong buffering power of local ground water on gases released through the
most peripheral areas where the CO2-rich sites are located. The anomalous
changes observed during the study period can be explained in terms of progressive gas release from separate batches of magma that ascend towards
the surface in a step-wise manner. Data relevant to the period following
the 2002-03 eruption suggest that magma kept accumulating beneath
the volcano, thus increasing the probability of a new large eruption
at Mt. Etna.
Description:
Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Palermo
Description:
Published
Description:
805-841
Description:
open
Keywords:
Mt. Etna
;
Geochemistry
;
Gases
;
Eruptive activity
;
04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
Format:
67393 bytes
Format:
text/plain
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