The behaviour of antimony released from surface geothermal features in New Zealand

Journal of Volcanology and Geothermal Research

et al. 2017

This study focused on the geochemical and isotopic features of thermal fluids discharged from five zones located in the high altitude Puna plateau (Jujuy Province between S 22°20′-23°20′ and W 66°-67°), i.e. Granada, Vilama, Pairique, Coranzulí and Olaroz. Partially mature waters with a Na + -Cl − composition were recognized in all the investigated zones, suggesting that a deep hydrothermal reservoir hosted within the Paleozoic crystalline basement represents the main hydrothermal fluid source. The hydrothermal reservoirs are mainly recharged by meteoric water, although based on the δ 18 O-H 2 O and δD-H 2 O values, some contribution of andesitic water cannot be completely ruled out. Regional S-oriented faulting systems, which generated a horst and graben tectonics, and NE-, NW-and WE-oriented transverse structures, likely act as preferentially uprising pathways for the deep-originated fluids, as also supported by the Rc/Ra values (up to 1.39) indicating the occurrence of significant amounts of mantle He (up to 16%). Carbon dioxide, the most abundant compound in the gas phase associated with the thermal waters, mostly originated from a crustal source, although the occurrence of CO 2 from a mantle source, contaminated by organic-rich material due to the subduction process, is also possible. Relatively small and cold Na + -HCO 3 − -type aquifers were produced by the interaction between meteoric water and Cretaceous, Palaeogene to Miocene sediments. Dissolution of evaporitic surficial deposits strongly affected the chemistry of the thermal springs in the peripheral zones of the study area. Geothermometry in the Na-K-Ca-Mg system suggested equilibrium temperatures up to 200°C for the deep aquifer, whereas lower temperatures (from 105 to 155°C) were inferred by applying the H 2 geothermometer, likely due to re-equilibrium processes during the thermal fluid uprising within relatively shallow Na-HCO 3 aquifers. The great depth of the geothermal resource (possibly N 5000 m b.g.l.) is likely preventing further studies aimed to evaluate possible exploitation, although the occurrence of Liand Ba-rich deposits associated may attract financial investments, giving a pulse for the development of this remote region.

Section: Processes Controlling the Chemistry Of Waterssupporting

confidence: 77%

Fluid geochemistry of a deep-seated geothermal resource in the Puna plateau (Jujuy Province, Argentina)

Arnold

Cabassi

Journal of Volcanology and Geothermal Research

et al. 2017

“…Relatively high concentrations of As, Cs, Rb and Mn (Table 2), in the range of contents characterizing waters discharges in hydrothermal environment (e.g. Aiuppa et al, 2006;Kaasalainen and Stefánsson, 2012;Wilson et al, 2012;Göb et al, 2013), were also measured. Such high concentrations of Li, Rb and Cs (up to 7.6, 1.5 and 2.1 mg/L) are likely related to the high concentrations of these elements in rocks of rhyolitic and andesitic composition (Nicholson, 1993), which were recognized in the study area.…”

Section: Processes Controlling the Chemical And Isotopic Composition mentioning

confidence: 99%

Preliminary conceptual model of the Cerro Blanco caldera-hosted geothermal system (Southern Puna, Argentina): Inferences from geochemical investigations

Chiodi

Journal of South American Earth Sciences

Báez

et al. 2019

The Cerro Blanco Caldera (CBC) is the youngest collapse caldera system in the Southern Central Andes (Southern Puna, Argentina). The CBC is subsiding with at an average velocity of 0.87 cm/year and hosts an active geothermal system. A geochemical characterization of emitted fluids was carried out based on the chemical and isotopic compositions of fumaroles, and thermal and cold springs discharged in this volcanic area with the aim of constructing the first hydrogeochemical conceptual model and preliminary estimate the geothermal potential. The main hydrothermal reservoir, likely hosted within the pre-caldera basement rocks, has a Na +-Clˉ(HCO 3)c omposition with estimated temperatures ≥135°C. The unconsolidated, fine-grained Cerro Blanco ignimbrite likely acts as the cap-rock of the hydrothermal system. The presence of phreatic eruption breccias in the surrounding area of the geothermal fumaroles supports the effectiveness of the pyroclastic deposit as sealing rocks. The isotopic data of water (δ 18 O and δD) indicate a meteoric recharge of the hydrothermal reservoir, suggesting as recharge areas the sectors surrounding the CBC, mainly towards the W and NW where large outcrops of the pre-caldera basement exist. A fault-controlled hydraulic connection between the hot springs and the hydrothermal reservoir is proposed for the Los Hornitos area. The fumaroles show the typical compositional features of hydrothermal fluids, being dominated by water vapor with significant concentrations of H 2 S, CH 4 and H 2. Considering the high geothermal gradient of this area (∼104°C/km) and the relatively high fraction of mantle He (∼39%) calculated on the basis of the measured R/Ra values, the hydrothermal aquifer likely receives inputs of magmatic fluids from the degassing magma chamber. The preliminary geothermal potential at CBC was evaluated with the Volume Method, calculating up to E = 11.4*10 18 J. Both the scarce presence of superficial thermal manifestations and the occurrence of an efficient cap-rock likely contribute to minimize the loss of thermal energy from the reservoir. The results here presented constitute the necessary base of knowledge for further accurate assessment of the geothermal potential and ultimately the implementation of the geothermal resource as a viable energy alternative for small localities or mining facilities isolated from the National Interconnected System due to their remote localization.

“…They are indeed typically enriched in mineral and thermal waters (e.g. Hirner and Hippler, 2011 and references therein; Wilson et al, 2012), especially those related to volcanism and geothermal activity (e.g. Aiuppa et al, 2006) or to leaching processes of ore deposits hosting poly-metallic sulfides (e.g.…”

Section: Origin Of Watersmentioning

confidence: 99%

A combined geochemical and isotopic study of the fluids discharged from the Montecatini thermal system (NW Tuscany, Italy)

Capecchiacci

Vaselli

et al. 2015

Applied Geochemistry

a b s t r a c tThe thermo-mineral fluids discharges of Montecatini Terme (Northern Apennines, Tuscany, Italy) have been exploited since the Roman times and despite the fact that this thermal complex is one of the biggest in Europe, the most recent geochemical investigations were published almost 40 years ago. To fill this gap, in this paper a detailed geochemical and isotopic investigation on the main thermal springs and wells from the Montecatini thermal system (MTS) is presented.The chemical and isotopic features of the Montecatini waters suggested that they are mainly controlled by water-rock interaction processes between meteoric water, permeating at depth from the surrounding reliefs (up to 800 m a.s.l.), and the Triassic evaporites (Burano Formation) belonging to the Tuscan sedimentary series. The local stratigraphic and tectonic framework favors an efficient recharge of the hydrothermal reservoir by the meteoric precipitation from a large catchment area and this aspect plays a fundamental role for the longevity of the Montecatini thermal spas, notwithstanding the huge amount of thermal water exploited. The C-TDIC values were lower than those expected for a mantle/thermometamorphic CO 2 source. This can be explained by: (i) isotopic fractionation occurring during calcite precipitation and/or (ii) mixing with biogenically derived gases, occurring at relatively shallow depth.