Fractionation processes affecting the stable carbon isotope signature of thermal waters from hydrothermal/volcanic systems: The examples of Campi Flegrei and Vulcano Island (southern Italy)

Venturi, Stefanía; Tassi, Franco; Bicocchi, Gabriele; Cabassi, Jacopo; Capecchiacci, Francesco; Capasso, Giorgio; Vaselli, Orlando; Ricci, Andrea; Grassa, Fausto

doi:10.1016/j.jvolgeores.2017.08.001

Cited by 40 publications

(21 citation statements)

References 76 publications

(101 reference statements)

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“…They suggest that hot gases condense near the surface and generate a water table which in the Agnano plain forms lake Agnano. Troiano et al. (2019) identify a highly resistive (vapor‐rich) anomaly corresponding to the southeastern edge of the Astroni crater, while the Agnano plain is characterized by a mainly conductive anomaly. Water from the Agnano well has high

P_{C O_{2}}

values, less negative carbon isotope signatures than meteoric water and high HCO

_{3}^{- 2}

concentrations, indicating a contribution of heat and hydrothermal fluids from a magmatic system (Venturi et al., 2017). …”

Section: Discussionmentioning

confidence: 99%

Gravimetric Constraints on the Hydrothermal System of the Campi Flegrei Caldera

2020

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The Campi Flegrei caldera (Italy) has been undergoing unrest over the past five decades including episodes of rapid ground deformation, seismicity, and variations in gas emissions. Hydrothermal fluids and gases are released most vigorously in the central sector of the caldera at the fumarolic fields of Solfatara volcano and Pisciarelli. We conducted a high-precision gravity survey coupled with inverse modeling to image the shallow (<2-km depth) structure of the hydrothermal feeder system. Results indicate the presence of three low density bodies beneath Pozzuoli, Astroni volcano and the Solfatara/Pisciarelli fumarolic fields. The first two are inferred to be sealed hydrothermal systems trapped beneath impermeable cap rock, while the latter depicts a plume-like geothermal feeder system reaching the surface via a combination of Solfatara's maar-diatreme structure and the intersection of NW-SE and NE-SW trending regional faults. The density contrasts of the reservoirs from background values are best explained by a multiphase mixture of caldera fill containing a secondary and interconnected void volume fraction of between 0.2 and 0.3 that hosts a vapor volume fraction ψ v of between 0.38 and 1 and a liquid volume fraction ψ l fraction of between 0 and 0.62. This work highlights the control of volcano-tectonic structures on fluid movement in the shallow crust of hydrothermally active volcanic systems undergoing sustained or periodic unrest.

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P_{C O_{2}}

values, less negative carbon isotope signatures than meteoric water and high HCO

_{3}^{- 2}

concentrations, indicating a contribution of heat and hydrothermal fluids from a magmatic system (Venturi et al., 2017). …”

Section: Discussionmentioning

confidence: 99%

Gravimetric Constraints on the Hydrothermal System of the Campi Flegrei Caldera

2020

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“…The caldera shows strong hydrothermal activity, consisting of thermal springs, steam-heated pools, and fumaroles (e.g. Caliro et al, 2007;Chiodini et al, 2001;Passaro et al, 2016;Todesco et al, 2003;Stanzione, 2003, 2004;Vaselli et al, 2011;Venturi et al, 2017). The Solfatara crater hosts one of the largest fumarolic discharges worldwide, mostly located in the NE and SE portions of the crater, with a related thermal energy flux of~100 MW (Chiodini et al, 2001) and is characterized by a widespread soil diffuse degassing emitting about 79 × 10 6 g CO 2 /day and 1.04 × 10 3 g CH 4 /day from the hydrothermalized bottom area (Tassi et al, 2013).…”

Section: Solfatara Cratermentioning

confidence: 99%

Carbon isotopic signature of interstitial soil gases reveals the potential role of ecosystems in mitigating geogenic greenhouse gas emissions: Case studies from hydrothermal systems in Italy

Venturi

Tassi

Magi

et al. 2019

Science of The Total Environment

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“…In order to elucidate the processes controlling the δ 13 C-CO 2 values of the lakes waters, the isotope mass balance and the measured δ 13 C-TDIC values were used to compute the δ 13 C values of CO 2(aq) resulting from CO 2(g) dissolution (δ 13 C-CO 2(aq)_dis ), as explained in detail in Venturi et al (2017), as follows:…”

Section: Processes Governing the Chemical And Isotopic Composition Ofmentioning

confidence: 99%

Water and dissolved gas geochemistry at Coatepeque, Ilopango and Chanmico volcanic lakes (El Salvador, Central America)

Cabassi

Capecchiacci

Magi

et al. 2019

Journal of Volcanology and Geothermal Research

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Coatepeque (on the E slope of Santa Ana Volcano), Ilopango (inside Ilopango Caldera) and Chanmico (associated with San Salvador Volcano) are volcanic lakes in El Salvador, showing a thermocline at a relatively shallow depth (from 30 to 40 m, from 20 to 40 m and from 5 to 15 m depth, respectively) and anoxic conditions below 33, 24 and 4 m depth, respectively. The Na +-Cl − composition of the Coatepeque and Ilopango lakes, displaying TDS values up to 1226 and 1216 mg/L, respectively, is likely due to hydrothermal fluids that feed these two lakes, as also confirmed by Cl − /Br − molar ratios ≤ 650, high As, B, Li and Si contents and Cl − /SO 4 2− ratio N 1. The Mg 2 +-HCO 3 − water composition of Lake Chanmico, whose TDS values were between 566 and 856 mg/L, suggests water-rock interaction processes with mafic/ultramafic rocks variably affected by serpentinization processes, which produced high Mg 2+ , Si and B concentrations. Waters at depth were characterized by the presence of CO 2 from an extra-lacustrine source, as suggested by δ 13 C-CO 2 values significantly less negative than those typically related to biogenic processes, albeit this gas was found in smaller quantities when compared to those recorded in other meromictic lakes hosted in quiescent volcanic systems (e.g. Lake Kivu in DRC, Monticchio, Albano and Averno lakes in Italy, Hule and Rio Cuarto lakes in Costa Rica, Lake Pavin in France). The occurrence of CH 4 , whose concentrations in Lake Chanmico were up to two orders of magnitude higher than those recorded in Coatepeque and Ilopango lakes, suggests bacterial methanogenesis.

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Fractionation processes affecting the stable carbon isotope signature of thermal waters from hydrothermal/volcanic systems: The examples of Campi Flegrei and Vulcano Island (southern Italy)

Cited by 40 publications

References 76 publications

Gravimetric Constraints on the Hydrothermal System of the Campi Flegrei Caldera

Gravimetric Constraints on the Hydrothermal System of the Campi Flegrei Caldera

Carbon isotopic signature of interstitial soil gases reveals the potential role of ecosystems in mitigating geogenic greenhouse gas emissions: Case studies from hydrothermal systems in Italy

Water and dissolved gas geochemistry at Coatepeque, Ilopango and Chanmico volcanic lakes (El Salvador, Central America)

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