Secondary processes determining the pH of alkaline waters in crystalline rock systems

Asta, María P.; Gimeno, M. Concepción; Auqué, Luis F.; Gómez, J.; Acero, Patricia; Mercadal, María Pilar Lapuente

doi:10.1016/j.chemgeo.2010.05.019

Cited by 16 publications

(5 citation statements)

References 37 publications

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“…To our knowledge, both this depth and deep-fluid temperature are the highest inferred from spring analyses at any active orogenic geothermal system worldwide. Hot springs elsewhere in similar structural and topographic settings with normal background geotherms (<30 °C/km) typically reveal min-T eq < 150 °C and hence lower penetration depths, such as in the Canadian Rocky Mountains (Grasby and Hutcheon, 2001), the Qilian Mountains in China (Stober et al, 2016), the Pyrenees in Spain (Asta et al, 2010), and other locations in the Swiss Alps (Sonney and Vuataz, 2009). In comparison, more active orogens with high geothermal gradients yield higher min-T eq values, such as the 200 °C temperature inferred from springs on the Alpine fault in New Zealand (Reyes et al, 2010).…”

Section: Implications For Deep Meteoric Water Infiltrationmentioning

confidence: 99%

Penetration depth of meteoric water in orogenic geothermal systems

Diamond

Wanner

Waber

2018

Geology

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Warm springs emanating from deep-reaching faults in orogenic belts with high topography and orographic precipitation attest to circulation of meteoric water through crystalline bedrock. The depth to which this circulation occurs is unclear, yet it is important for the cooling history of exhuming orogens, for the exploitation potential of orogenic geothermal systems, and for the seismicity of regional faults. The orogenic geothermal system at Grimsel Pass, Swiss Alps, is manifested by warm springs with a clear isotopic fingerprint of high-altitude meteoric recharge. Their water composition and their occurrence within a 3 Ma fossil upflow zone render them particularly favorable for estimating the temperature along the deep flow path via geochemical modeling. Because the background geotherm has remained stable at 25 °C/km and other heat sources are unavailable, the penetration depth can be derived from the deep-water temperature. We thus estimated the base of the Grimsel system to be at 230-250 °C and 9-10 km depth. We propose that deep temperatures in such systems, particularly those with normal background geotherms (<30 °C/km), have been systematically underestimated. Consequently, far more enthalpy may be accessible for geothermal energy exploitation around the upflow zones than previously thought. Further, the prevalence of recent earthquake foci at ≤10 km beneath Grimsel suggests that meteoric water is involved in the seismicity of the host faults. Our results therefore call for reappraisal of the heat budget and the role of meteoric water in seismogenesis in uplifting orogens.

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Section: Implications For Deep Meteoric Water Infiltrationmentioning

confidence: 99%

Penetration depth of meteoric water in orogenic geothermal systems

Diamond

Wanner

Waber

2018

Geology

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“…Na-K, K-Mg) has been proven very useful to estimate the reservoir temperature in high temperature systems (> 180 ºC), in which the equilibrium between the water and the minerals in the reservoir is generally reached. However, their use in intermediate to low temperature systems or in carbonate-evaporitic reservoirs, as the case studied here, is usually considered inappropriate due to the range of their calibration temperatures, the chemical features of the water used for the calibration and/or the mineral phases involved in the equilibrium situations (Auqué, 1993;Chiodini et al, 1995;D'Amore and Arnórsson, 2000;Asta et al, 2010). Despite these limitations, the K-Mg and silica geothermometers and some of their calibrations have been use here as they have provided good results in similar cases (Fernández et al, 1988;Michard and Bastide, 1988;Pastorelli et al, 1999;Wang et al 2015).…”

Section: Chemical and Isotopic Geothermometersmentioning

confidence: 99%

Geochemistry, geothermometry and influence of the concentration of mobile elements in the chemical characteristics of carbonate-evaporitic thermal systems. The case of the Tiermas geothermal system (Spain)

et al. 2017

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The Tiermas low temperature geothermal system, hosted in the Paleocene-Eocene carbonates of the Jaca-Pamplona basin, has been studied to evaluate the geochemistry and the temperature of the waters in the deep reservoir. These waters are of chloridesodium type and emerge with a temperature of about 37 ºC. Two hydrogeochemical groups of waters have been distinguished: one with lower sulphate concentration and lower TDS (about 7,500 ppm) and the other with higher sulphate content and TDS values (close to 11,000 ppm). There are also slight differences in the reservoir temperature estimated for each group. These temperatures have been determined by in the vicinity of the injection well due to desiccation of the waters and, 2) carbonate dissolution and sulphate precipitation in the long term.

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“…In exhumed fossil systems, δ 18 O and δ 2 H analyses of hydrothermal minerals and fluid inclusions combined with petrological calculations and structural arguments suggest infiltration depths in the range of 5–23 km (Barker et al, ; Butler et al, ; Cartwright & Buick, ; Craw, ; Jenkin et al, ; McCaig et al, ; Menzies et al, ; Mulch et al, ; Nesbitt et al, ; Sharp et al, ; Upton et al, ; Wickham et al, ), implying deep reservoir temperatures up to 400–600 °C (Mulch et al, ; Upton et al, ). In contrast, classical solute geothermometry applied to analyses of hot springs in orogenic belts usually reveal reservoir temperatures below 150 °C, such as in the Canadian Rocky Mountains (Grasby et al, ), the Qilian Mountains in China (Stober et al, ), the Pyrenees in Spain (Asta et al, ), and the Swiss Alps (Sonney & Vuataz, ). Higher reservoir temperatures are found where extreme uplift rates elevate local geothermal gradients (e.g., Alpine Fault, New Zealand, Reyes et al, ; Sutherland et al, ) or where deep‐sourced, nonmeteoric fluids advect heat upon ascent (e.g., Newell et al, ).…”

Section: Introductionmentioning

confidence: 99%

Quantification of 3‐D Thermal Anomalies From Surface Observations of an Orogenic Geothermal System (Grimsel Pass, Swiss Alps)

2019

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Geothermal systems in amagmatic orogens involve topography-driven infiltration of meteoric water up to 10 km deep into regional-scale faults and exfiltration of the heated water in surface springs. The thermal anomalies along the upflow zones have not been quantified, yet they are key to estimating the geothermal exploitation potential of such systems. Here we quantify the three-dimensional heat anomaly below the orogenic geothermal system at Grimsel Pass, Swiss Alps, where warm springs emanate from an exhumed, fossil hydrothermal zone. We use discharge rates and temperatures of the springs, temperature measurements along a shallow tunnel, and the formation temperature and depth of the fossil system to constrain coupled thermal-hydraulic numerical simulations of the upflow zone. The simulations reveal that upflow rates act as a first-order control on the temperature distribution and that the site is underlain by an ellipsoidal thermal plume enclosing 10 2 -10 3 PJ of anomalous heat per km depth. When the fossil system was active (3.3 Ma), the thermal plume was double its present size, corresponding to a theoretical petrothermal power output of 30-220 MW, with the 120°C threshold for geothermal electricity production situated at less than 2-km depth. We conclude that mountainous orogenic belts without igneous activity and even with only low background geothermal gradients typical of waning orogens are surprisingly promising plays for petrothermal power production. Our study implies exploration should focus on major valley floors because there the hydraulic head gradients and thus upflow rates and heat anomalies reach maximum values.

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Secondary processes determining the pH of alkaline waters in crystalline rock systems

Cited by 16 publications

References 37 publications

Penetration depth of meteoric water in orogenic geothermal systems

Penetration depth of meteoric water in orogenic geothermal systems

Geochemistry, geothermometry and influence of the concentration of mobile elements in the chemical characteristics of carbonate-evaporitic thermal systems. The case of the Tiermas geothermal system (Spain)

Quantification of 3‐D Thermal Anomalies From Surface Observations of an Orogenic Geothermal System (Grimsel Pass, Swiss Alps)

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