Geothermal systems in Iceland: Structure and conceptual models—I. High-temperature areas

Arnórsson, Stefán

doi:10.1016/0375-6505(95)00025-9

Cited by 174 publications

(161 citation statements)

References 91 publications

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“…The volcanic system is hosted in an oblique extensional tectonic setting, resulting in episodic fissure eruptions (Clifton and Kattenhorn, 2006). Tectonic extension-controlled structures and active volcanism have resulted in significant geothermal activity along the Reykjanes Peninsula, notably in the Reykjanes and Svartsengi geothermal systems (Jakobsson et al, 1978;Arnórsson, 1995). The Reykjanes geothermal system is located on the western tip of the Reykjanes Peninsula, approximately 50 km southwest of Reykjavík (Fig.…”

Section: Geological Settingmentioning

confidence: 99%

“…The Reykjanes geothermal fluid is seawater, chemically modified due to boiling and fluid/rock interaction (Tómasson and Kristmannsdóttir, 1972;Arnórsson, 1978;Ólafsson and Riley, 1978;Arnórsson, 1995;Bird and Spieler, 2004;Friðleifsson and Elders, 2005;. Compared to seawater, hydrothermal fluids in the Reykjanes geothermal system have similar concentrations of Na and Cl; increased concentrations of K, Ca, SiO 2 , Fe, and Al; and decreased concentrations of SO 4 and Mg indicating that mineral precipitation, and significant water rock interaction have occurred (Lonker et al, 1993;Arnórsson, 1995;Pope et al, 2009).…”

Section: Geological Settingmentioning

confidence: 99%

“…Compared to seawater, hydrothermal fluids in the Reykjanes geothermal system have similar concentrations of Na and Cl; increased concentrations of K, Ca, SiO 2 , Fe, and Al; and decreased concentrations of SO 4 and Mg indicating that mineral precipitation, and significant water rock interaction have occurred (Lonker et al, 1993;Arnórsson, 1995;Pope et al, 2009).…”

Section: Geological Settingmentioning

confidence: 99%

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Evolution of fluid–rock interaction in the Reykjanes geothermal system, Iceland: Evidence from Iceland Deep Drilling Project core RN-17B

Fowler

Zierenberg

Schiffman

et al. 2015

Journal of Volcanology and Geothermal Research

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We describe the lithology and present spatially resolved geochemical analyses of samples from the hydrothermally altered Iceland Deep Drilling Project (IDDP) drill core RN-17B. The 9.3 m long RN-17B core was collected from the seawater-dominated Reykjanes geothermal system, located on the Reykjanes Peninsula, Iceland. The nature of fluids and the location of the Reykjanes geothermal system make it a useful analog for seafloor hydrothermal processes, although there are important differences. The recovery of drill core from the Reykjanes geothermal system, as opposed to drill cuttings, has provided the opportunity to investigate evolving geothermal conditions by utilizing in-situ geochemical techniques in the context of observed paragenetic and spatial relationships of alteration minerals. The RN-17B core was returned from a vertical depth of~2560 m and an in-situ temperature of~345°C. The primary lithologies are basaltic in composition and include hyaloclastite breccia, fine-grained volcanic sandstone, lithic breccia, and crystalline basalt. Primary igneous phases have been entirely pseudomorphed by calcic plagioclase + magnesium hornblende + chlorite + titanite + albitized plagioclase + vein epidote and sulfides. Despite the extensive hydrothermal metasomatism, original textures including hyaloclastite glass shards, lithic clasts, chilled margins, and shell-fragment molds are superbly preserved. Multi-collector LA-ICP-MS strontium isotope ratio ( 87 Sr/ 86 Sr) measurements of vein epidote from the core are consistent with seawater as the dominant recharge fluid. Epidote-hosted fluid inclusion homogenization temperature and freezing point depression measurements suggest that the RN-17B core records cooling through the two-phase boundary for seawater over time to current in-situ measured temperatures. Electron microprobe analyses of hydrothermal hornblende and hydrothermal plagioclase confirm that while alteration is of amphibolite-grade, it is in disequilibrium and the extent of alteration is dependent upon protolith type and water/rock ratio. Alteration in the RN-17B core bares many similarities to that of Type II basalts observed in Mid-Atlantic Ridge samples.

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Section: Geological Settingmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

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Evolution of fluid–rock interaction in the Reykjanes geothermal system, Iceland: Evidence from Iceland Deep Drilling Project core RN-17B

Fowler

Zierenberg

Schiffman

et al. 2015

Journal of Volcanology and Geothermal Research

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“…Recently, the Hellisheiði geothermal field in the south of the volcano was started to be exploited. Due to the meteoric origin of the geothermal fluid in the Hengill area (Arnórsson, 1995), the salinity in Hellisheiði is very low with a concentration of total dissolved solids of approx. 1500 ppm (Franzson et al, 2005).…”

Section: Hellisheiði Geothermal Fieldmentioning

confidence: 99%

“…Beside temperature, the ingression of hydrogen is an important aspect that has to be considered using optical fibres in harsh environments. Within the geothermal fluid of high temperature geothermal wells in Iceland, hydrogen is often present (Arnórsson, 1995). In the presence of hydrogen, however, optical properties of fibres degrade rapidly due to hydrogen ingression and hydroxyl formation (Smithpeter et al, 1999;Williams et al, 2000;Normann et al, 2001).…”

mentioning

confidence: 99%

Thermal, mechanical and chemical influences on the performance of optical fibres for distributed temperature sensing in a hot geothermal well

Reinsch

Henninges

Ásmundsson³

2013

Environ Earth Sci

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Structural wellbore integrity is an important issue for a sustainable provision of geothermal energy. Raman scattering based fiber optic distributed temperature sensing (DTS) can help to monitor the status of a well and therefore help to optimize expensive work-over activities. This study reports on the installation of a fibre optic cable in the cemented annulus behind the anchor casing in the high temperature geothermal well HE-53, Hellisheiði geothermal field, SW Iceland. Although the cable has been damaged during the installation, temperature data could be acquired during the entire length of installation down to 261.3 m. Temperature measurements were performed during the installation in spring 2009, during the onset of a flow test in summer 2009 and after a 8.5 month shut-in period in summer 2010. During the flow test, maximum temperatures of 230• C were measured after two weeks fluid production. Using optical time domain reflectometry (OTDR), attenuation measurements at 850 and 1300 nm enabled to identify mechanical, thermal, and chemical degradation along the optical fibre. The observed degradation led to erroneous temperature readings and limits, due to the optical budget of the DTS system, the accessible length of the fibre. The characteristics and the influence of the different degradation mechanisms on the accuracy of the DTS measurements are discussed and recommendations for an optimized installation are given.

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Geothermal control on flow patterns in the Last Glacial Maximum ice sheet of Iceland

Bourgeois

Dauteuil

Vliët-Lanoé

2000

Earth Surf. Process. Landforms

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Because it is located both on the Mid-Atlantic Ridge and on a mantle plume, Iceland is a region of intense tectonics and volcanism. During the last glaciation, the island was covered by an ice sheet approximately 1000 m thick. A reconstruction of the ice flow lines, based on glacial directional features, shows that the ice sheet was partly drained through fast-flowing streams. Fast flow of the ice streams has been recorded in megascale lineations and flutes visible on the currently deglaciated bedrock, and is confirmed by simple mass balance considerations. Locations of the major drainage routes correlate with locations of geothermal anomalies, suggesting that ice stream activity was favoured by lubrication of the bed by meltwater produced in regions of high geothermal heat flux. Similar control of ice flow by geothermal activity is expected in ice sheets currently covering tectonically and volcanically active area such as the West Antarctic ice sheet.

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Geothermal systems in Iceland: Structure and conceptual models—I. High-temperature areas

Cited by 174 publications

References 91 publications

Evolution of fluid–rock interaction in the Reykjanes geothermal system, Iceland: Evidence from Iceland Deep Drilling Project core RN-17B

Evolution of fluid–rock interaction in the Reykjanes geothermal system, Iceland: Evidence from Iceland Deep Drilling Project core RN-17B

Thermal, mechanical and chemical influences on the performance of optical fibres for distributed temperature sensing in a hot geothermal well

Geothermal control on flow patterns in the Last Glacial Maximum ice sheet of Iceland

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