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Fluid Geochemistry of Tacaná Volcano-Hydrothermal System
Author(s)
Language
English
Obiettivo Specifico
4V. Dinamica dei processi pre-eruttivi
Status
Published
Pages Number
139-154
Refereed
Yes
Title of the book
Issued date
April 2015
ISBN
978-3-642-36833-2
Abstract
Tacaná hosts an active volcano-hydrothermal system, characterized by boiling
temperature fumaroles, near the summit (3,600–3,800 m asl), and bubbling degassing
thermal springs near its base (1,000–2,000 m asl). The magmatic signature of gases
rising to the surface is attested by their high CO2 contents (δ13CCO2 = −3.6 ± 1.3 ‰),
and relatively high 3He/4He ratios (6.0 ± 0.9 RA), with a CO2/3He ratio typical for the
Central American Arc (2.3 × 1010–6.9 × 1011). Such magmatic signature is
practically identical for the near-summit fumaroles, and the bubbling gases at the
base of Tacaná edifice. Besides the HCO3-enrichment in thermal spring waters, the
springs (pH 5.8–6.7) show a SO4-and minor Cl-enrichment: a CO2 and H2S + SO2-
rich magmatic steam condenses into a deeper geothermal aquifer, and the resulting
hydrothermal fluid mixes with meteoric waters near the surface. The recharge area
for the thermal springs is located at higher elevations (>400 m higher than spring
outlet elevation), as inferred from the δD-δ18O data for rivers, thermal and cold
springs. These general insights of the Tacaná volcano-hydrothermal system serve as
the baseline for future volcanic surveillance, and geothermal prospection. The main
locus of hydrothermal activity is located inside the Tacaná horseshoe-shaped crater in
the northwestern sector of the volcanic edifice. In terms of volcanic hazard, this
sector can be considered the most probable site for future phreatic activity.
temperature fumaroles, near the summit (3,600–3,800 m asl), and bubbling degassing
thermal springs near its base (1,000–2,000 m asl). The magmatic signature of gases
rising to the surface is attested by their high CO2 contents (δ13CCO2 = −3.6 ± 1.3 ‰),
and relatively high 3He/4He ratios (6.0 ± 0.9 RA), with a CO2/3He ratio typical for the
Central American Arc (2.3 × 1010–6.9 × 1011). Such magmatic signature is
practically identical for the near-summit fumaroles, and the bubbling gases at the
base of Tacaná edifice. Besides the HCO3-enrichment in thermal spring waters, the
springs (pH 5.8–6.7) show a SO4-and minor Cl-enrichment: a CO2 and H2S + SO2-
rich magmatic steam condenses into a deeper geothermal aquifer, and the resulting
hydrothermal fluid mixes with meteoric waters near the surface. The recharge area
for the thermal springs is located at higher elevations (>400 m higher than spring
outlet elevation), as inferred from the δD-δ18O data for rivers, thermal and cold
springs. These general insights of the Tacaná volcano-hydrothermal system serve as
the baseline for future volcanic surveillance, and geothermal prospection. The main
locus of hydrothermal activity is located inside the Tacaná horseshoe-shaped crater in
the northwestern sector of the volcanic edifice. In terms of volcanic hazard, this
sector can be considered the most probable site for future phreatic activity.
Type
book chapter
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Rouwet Tacana AVotW 2015.pdf
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1.04 MB
Format
Adobe PDF
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