Search results for "hydrothermal system"

Characterisation of the magmatic signature in gas emissions from Turrialba Volcano, Costa Rica

2014

The equilibrium composition of volcanic gases with their magma is often overprinted by interaction with a shallow hydrothermal system. Identifying the magmatic signature of volcanic gases is critical to relate their composition to properties of the magma (temperature, fO2, gas-melt segregation depth). We report measurements of the chemical composition and flux of the major gas species emitted from Turrialba Volcano during March 2013. Measurements were made of two vents in the summit region, one of which opened in 2010 and the other in 2012. We determined an average SO2 flux of 5.2 ± 1.9 kg s-1 using scanning ultraviolet spectroscopy, and molar proportions of H2O, CO2, SO2, HCl, CO and H2 ga…

Hydrothermal circulation on Ischia Island (Southern Italy), revealed by an integrated geochemical, geophysical and geological approach

2011

Volcano-hosted hydrothermal systems are complex geological objects, whose thorough characterisation requires extensive and interdisciplinary work. Indeed, even thought geological, geochemical and geophysical observations offer highly significant but independent information, only an integrated multidisciplinary approach can yield a comprehensive characterisation of the chemical/physical structure of hydrothermal systems. Notwithstanding the extensive application of geological, geochemical and geophysical techniques in geothermal research, there are only a few examples in the literature of concurrent use of the three techniques [Finizola et al., 2002; Zlotnicki et al., 2009]; these studies ov…

The Ischia Island hydrothermal system: an integrated multidisciplinary (geochemical, geophysical and geological) study

2011

Ischia Island is the emergent portion of a large volcanic complex on the Gulf of Naples (Southern Italy). Ischia volcano has undertaken a complex evolution since 150 ka b.p., with prolonged cycles of effusive and explosive eruptions alternated with quiescence periods (the most recent of which started after the 1302 A.D. Arso eruption). Currently, hot springs (with discharge temperature up to 90 C), fumarolic gas emissions with CO2 up to 97%, and diffuse soil degassing testify a persistent activity state of the Ischia volcano. Ischia Island is a very good example of an active volcano hosting a large hydrothermal system and, in particular, its south-western sector has long been known to be th…

The role of the aquifer in soil CO2 degassing in volcanic peripheral areas: A case study of Stromboli Island (Italy)

2017

Abstract The peripheral area of Stromboli Island, Italy, named “Scari”, was continuously studied between January 2009 and December 2010. Data on soil CO 2 flux and the partial pressure of CO 2 (pCO 2 ) in equilibrium with the thermal aquifer linked to the magmatic system are presented. Soil CO 2 fluxes range from 20 to 370 g m − 2  d − 1 and have been strongly affected by soil temperature variations. Soil CO 2 flux data were filtered with respect to the soil temperature and the calculated values, called “residuals”, were considered to detect changes induced by the magmatic system. The pCO 2 values change in a wide range from 0.03 to 0.6 (atm), showing rapid variations. The results of this s…

Hydrothermal pressure-temperature control on CO2 emissions and seismicity at Campi Flegrei (Italy)

2021

Fluids supplied by stored magma at depth are causal factors of volcanic unrest, as they can cause pressurization/heating of hydrothermal systems. However, evidence for links between hydrothermal pressurization, CO2 emission and volcano seismicity have remained elusive. Here, we use recent (2010−2020) observations at Campi Flegrei caldera (CFc) to show hydrothermal pressure, gas emission and seismicity at CFc share common source areas and well-matching temporal evolutions. We interpret the recent escalation in seismicity and surface gas emissions as caused by pressure-temperature increase at the top of a vertically elongated (0.3–2 km deep) gas front. Using mass (steam) balance consideration…

Chemical and isotopic characterization of Ischia hydrothermal system: an interpretative model of fluids circulation

2009

A roadmap for amphibious drilling at the Campi Flegrei caldera: insights from a MagellanPlus workshop

2019

Large calderas are among the Earth's major volcanic features. They are associated with large magma reservoirs and elevated geothermal gradients. Caldera-forming eruptions result from the withdrawal and collapse of the magma chambers and produce large-volume pyroclastic deposits and later-stage deformation related to post-caldera resurgence and volcanism. Unrest episodes are not always followed by an eruption; however, every eruption is preceded by unrest. The Campi Flegrei caldera (CFc), located along the eastern Tyrrhenian coastline in southern Italy, is close to the densely populated area of Naples. It is one of the most dangerous volcanoes on Earth and represents a key example of an acti…

Geochemistry of Zr, Hf and REE in extreme water environments: hyperacid, hyper saline and lake waters in hydrothermal systems

This PhD thesis concerns the geochemistry of Zr, Hf and REE in extreme water environments characterized by a wide spectrum of chemical physical-parameters and compositions. The investigations were carried out in hypersaline waters covering a wide range of Eh values along Dead Sea Fault (Israel), in hyperacid waters circulating in Nevado del Ruiz volcano-hydrothermal system (Colombia) and in CO2-rich waters belonging to the Pantelleria volcano-hydrothermal system (Italy), including the alkaline lake “Specchio di Venere” formed within a calderic depression. The wide spectrum of chemical-physical conditions and various water chemical compositions interacting with different solid phases allowed…

Quantitative models of hydrothermal fluid–mineral reaction: The Ischia case

2013

Abstract The intricate pathways of fluid–mineral reactions occurring underneath active hydrothermal systems are explored in this study by applying reaction path modelling to the Ischia case study. Ischia Island, in Southern Italy, hosts a well-developed and structurally complex hydrothermal system which, because of its heterogeneity in chemical and physical properties, is an ideal test sites for evaluating potentialities/limitations of quantitative geochemical models of hydrothermal reactions. We used the EQ3/6 software package, version 7.2b, to model reaction of infiltrating waters (mixtures of meteoric water and seawater in variable proportions) with Ischia’s reservoir rocks (the Mount Ep…

Reaction path models of magmatic gas scrubbing

2016

Gas-water-rock reactions taking place within volcano-hosted hydrothermal systems scrub reactive, water-soluble species (sulfur, halogens) from the magmatic gas phase, and as such play a major control on the composition of surface gas manifestations. A number of quantitative models of magmatic gas scrubbing have been proposed in the past, but no systematic comparison of model results with observations from natural systems has been carried out, to date. Here, we present the results of novel numerical simulations, in which we initialized models of hydrothermal gas-water-rock at conditions relevant to Icelandic volcanism. We focus on Iceland as an example of a "wet" volcanic region where scrubb…