Diffuse surface emanations as indicator of structural permeability in fault-controlled geothermal systems

Jolie, Egbert; Klinkmueller, M.; Moeck, Inga

doi:10.1016/j.jvolgeores.2014.11.003

Cited by 24 publications

(23 citation statements)

References 45 publications

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“…Current efforts focus on the development of improved filter techniques to enable a distinction between different sources. The study area is an excellent test site to illustrate both surface and subsurface effects, and to distinguish between geogenic (e.g., geology, geothermal fault) and anthropogenic (e.g., infrastructure) effects based on a statistical data set separation (Jolie et al, 2015b). The approach presented here can be applied using parameters other than the ones we used; in other geological environments, gases and surface emanations not originating from magmatic processes may become more interesting (e.g., from biogenic processes).…”

Section: Discussionmentioning

confidence: 99%

“…A moderate to very strong correlation was determined among CO 2 , H 2 S, 222 Rn, and 222 Rn/ 220 Rn. The very weak correlation between LDR and the other parameters results from an anthropogenic effect on the LDR along Interstate Highway 80 in the northwestern sector (Jolie et al, 2015b). Structural permeability is not correlated to fault zones with either high slip or high dilation tendencies, but rather to a combination of both ( Fig.…”

Section: Surface Signal Versus Fault Traces-2-d Horizontal Modelmentioning

confidence: 94%

“…Along the Brady's fault zone, abundant geothermal surface activity is observed, such as fumaroles, alteration zones, and warm ground. The area was explored by measuring diffuse degassing rates and emanations at the surface to assess relative fracture permeability (Table 1; Jolie et al, 2015b). The measurements along a predefined grid (50 × 50 m for CO 2 and H 2 S; 50 × 100 m for radon) revealed the internal setup (e.g., structural segmentation) of the investigated area at high resolution, and added decisive information about the orientation of open fracture segments, complementary to existing information (Faulds et al, 2012).…”

Section: Study Area and Methodsmentioning

confidence: 99%

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Linking gas fluxes at Earth’s surface with fracture zones in an active geothermal field

Jolie

Klinkmueller

Moeck

et al. 2016

Geology

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The percolation of fluids is of utmost relevance for the utilization of underground resources; however, the location and occurrence of fractures are not always known, and important characteristics of faults, such as stress state and permeability, are commonly uncertain. Using a case study at the Brady’s geothermal field in Nevada (USA), we demonstrate how permeable fractures can be identified and assessed by combining fault stress models with measurements of diffuse degassing and emanations at Earth’s surface. Areas of maximum gas emissions and emanations correspond to fault segments with increased slip and dilation tendency, and represent a fingerprint of the geothermal system at depth. Thus, linking gas fluxes with fault stress models serves as a measure of the connectivity between surface and subsurface.

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Section: Discussionmentioning

confidence: 99%

Section: Surface Signal Versus Fault Traces-2-d Horizontal Modelmentioning

confidence: 94%

Section: Study Area and Methodsmentioning

confidence: 99%

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Linking gas fluxes at Earth’s surface with fracture zones in an active geothermal field

Jolie

Klinkmueller

Moeck

et al. 2016

Geology

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“…For a successful exploration strategy in these environments, information on the system's current activity and fault permeability (e.g., upflows and outflows) is required at a high spatial resolution. The best geochemical approach for obtaining such high spatial resolution observations are soil gas surveys (e.g., CO 2 , 222 Rn, and 220 Rn), which help to identify the most permeable structures with highest hydrothermal fluid flow (Jolie, Klinkmueller, et al, ; Neri et al, ). In this paper we prove the suitability of these techniques for geothermal exploration projects.…”

Section: Introductionmentioning

confidence: 99%

“…Fault segments with strong gas emissions are characterized by increased slip and dilation tendencies (Jolie, Moeck, et al, ; Jolie et al, ). Analyses of a variety of soil gases have proven their suitability for assessing the tectonic and volcanic controls on geothermal systems (Hunt et al, ; Jolie, Klinkmueller, et al, ; Jolie et al, ; Lee et al, ). These gases provide vital information for the exploration of geothermal fields and help in targeting wells in the most permeable structures with the greatest flow rates of high‐temperature hydrothermal fluids.…”

Section: Introductionmentioning

confidence: 99%

Pinpointing Deep Geothermal Upflow in Zones of Complex Tectono‐Volcanic Degassing: New Insights from Aluto Volcano, Main Ethiopian Rift

Jolie

Hutchison

Driba

et al. 2019

Geochem Geophys Geosyst

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Active rifts release large amounts of gases from deep sources to the atmosphere by advection and diffusion processes along permeable fracture zones. The objective of this study is to develop geothermal exploration concepts for areas with little or no hydrothermal surface expressions suitable for fluid sampling and analyses (e.g., hot springs, geysers, and fumaroles). In such areas, soil gas surveys can complement established geophysical and geochemical exploration. We report CO2, 222Rn (radon), and 220Rn (thoron) emission data and ground temperatures from the Aluto volcanic complex in the Main Ethiopian Rift to improve understanding of tectonic and volcanic controls on the existing geothermal system. This suite of gas emission measurements allows us to identify major, deep‐rooted permeable structures with active fluid circulation and identify suitable drilling targets for geothermal production wells on Aluto. We show that significant differences in gas signatures (i.e., efflux and spatial pattern) can be used to identify predominantly volcanically and/or tectonically influenced compartments. Major gas emissions indicate significant fluid circulation at depth, which is typical for magmatic systems. Such high gas emissions have been observed in areas affected by major tectonic structures interacting with magmatic bodies at depth (tectono‐volcanic). Predominantly fault‐controlled sectors also show hydrothermal fluid circulation, but to a lower extent compared to tectono‐volcanic sectors. Within the Aluto volcanic complex, geothermal production wells mainly target such fault‐controlled domains, whereas results of the study indicate strongest fluid circulation in tectono‐volcanic sectors. This result should be considered for the future exploration and development strategy of the site.

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The measurement of soil gases and shallow temperature for determination of active faults in a geothermal area: a case study from Ömer–Gecek, Afyonkarahisar (West Anatolia)

et al. 2018

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Diffuse surface emanations as indicator of structural permeability in fault-controlled geothermal systems

Cited by 24 publications

References 45 publications

Linking gas fluxes at Earth’s surface with fracture zones in an active geothermal field

Linking gas fluxes at Earth’s surface with fracture zones in an active geothermal field

Pinpointing Deep Geothermal Upflow in Zones of Complex Tectono‐Volcanic Degassing: New Insights from Aluto Volcano, Main Ethiopian Rift

The measurement of soil gases and shallow temperature for determination of active faults in a geothermal area: a case study from Ömer–Gecek, Afyonkarahisar (West Anatolia)

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