Isotopic constraints on ice age fluids in active geothermal systems: Reykjanes, Iceland

Pope, E. C.; Bird, Dennis K.; Arnórsson, Stefán; Fridriksson, Thráinn; Elders, W. A.; Friðleifsson, G. Ó.

doi:10.1016/j.gca.2009.03.033

Cited by 49 publications

(35 citation statements)

References 59 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…References: Hekla gas, and summit precipitation (this study); Hekla cold springs Holm et al, 2010); Hekla low altitude precipitation (Á rnason, 1976);Theistareykir, Krafla, Námafjall (Arnó rsson and Barnes, 1983;Sveinbjornsdottir et al, 1986;Darling and Á rmannsson, 1989);Hveragerdi, Leirá (Arnó rsson and Barnes, 1983); Reykjanes (Ó lafsson and Riley, 1978;Arnó rsson and Barnes, 1983;Pope et al, 2009); GMWL (Craig, 1961). modelled and magmatic gas H 2 O/CO 2 compositions, with residual gases being typically less hydrous (H 2 O/CO 2 range from 0.01 to 5.3). At the under-boiling conditions explored here, CO 2 is the favourite gas species reaching the surface following scrubbing.…”

mentioning

confidence: 88%

See 1 more Smart Citation

Degassing regime of Hekla volcano 2012–2013

Ilyinskaya

Aiuppa

Bergsson

et al. 2015

Geochimica et Cosmochimica Acta

Self Cite

View full text Add to dashboard Cite

Hekla is a frequently active volcano with an infamously short pre-eruptive warning period. Our project contributes to the ongoing work on improving Hekla's monitoring and early warning systems. In 2012 we began monitoring gas release at Hekla. The dataset comprises semi-permanent near-real time measurements with a MultiGAS system, quantification of diffuse gas flux, and direct samples analysed for composition and isotopes (d 13 C, dD and d 18 O). In addition, we used reaction path modelling to derive information on the origin and reaction pathways of the gas emissions.Hekla's quiescent gas composition was CO 2 -dominated (0.8 mol fraction) and the d À1 are sourced from a small area at the volcano's summit. There was no detectable gas flux at other craters, even though some of them had higher ground temperatures and had erupted more recently.Our measurements are consistent with a magma reservoir at depth coupled with a shallow dike beneath the summit. In the current quiescent state, the composition of the exsolved gas is substantially modified along its pathway to the surface through cooling and interaction with wall-rock and groundwater. The modification involves both significant H 2 O condensation and scrubbing of S-bearing species, leading to a CO 2 -dominated gas emitted at the summit. We conclude that a compositional shift towards more S-and H 2 O-rich gas compositions if measured in the future by the permanent MultiGAS station should be viewed as sign of imminent volcanic unrest on Hekla.

show abstract

mentioning

confidence: 88%

“…Fig. 10 also shows isotopic composition of water from volcanic systems with active geothermal systems (Darling and Á rmannsson, 1989;Pope et al, 2009). Deep geothermal fluid tends to plot to the right of GMWL being less d…”

Section: The Water Isotopes (Dd and Dmentioning

confidence: 99%

Degassing regime of Hekla volcano 2012–2013

Ilyinskaya

Aiuppa

Bergsson

et al. 2015

Geochimica et Cosmochimica Acta

Self Cite

View full text Add to dashboard Cite

show abstract

“…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%

“…The salinity of fluid inclusions in quartz, plagioclase, and calcite in wells RN-9 and RN-10 (Franzson et al, 2002), along with deuterium and oxygen isotope studies of fluids and alteration minerals, have been used to suggest an evolution of hydrothermal fluids from meteoric to seawater (Ólafsson and Riley, 1978;Sveinbjörnsdóttir et al, 1986;Lonker et al, 1993;Pope et al, 2009;. The postulated evolving temperature conditions and fluid compositions in the Reykjanes geothermal system have been attributed to the presence of a substantial ice sheet overlying the Reykjanes Peninsula during the Pleistocene, providing a mechanism for fresh water recharge and increased pressure, which raised the boiling point curve and resulted in the formation of anomalously shallow, high-temperature alteration minerals (Sveinbjörnsdóttir et al, 1986;.…”

Section: Geological Settingmentioning

confidence: 99%

“…Important differences between Reykjanes and seafloor systems include evidence for a period of meteoric fluid recharge during the Pleistocene, when a substantial icesheet was present (Sveinbjörnsdóttir et al, 1986;Franzson et al, 2002;Pope et al, 2009;. The Reykjanes geothermal system also lacks the hydrostatic pressure of overlying cold seawater; therefore much greater depths must be reached before the venting temperatures observed in seafloor hydrothermal systems are achieved.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

View full text Add to dashboard Cite

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.

show abstract

Elemental changes and alteration recorded by basaltic drill core samples recovered from in situ temperatures up to 345°C in the active, seawater‐recharged Reykjanes geothermal system, Iceland

Fowler

Zierenberg

2016

Geochem Geophys Geosyst

View full text Add to dashboard Cite

Hydrothermal activity results in element exchanges between seawater and oceanic crust that contribute to many aspects of ocean chemistry; therefore, improving knowledge of the associated chemical processes is of global significance. Hydrothermally altered basaltic drill core samples from the seawater‐recharged Reykjanes geothermal system in Iceland record elemental gains and losses similar to those observed in samples of hydrothermally altered oceanic crust. At Reykjanes, rocks originally emplaced on the seafloor were buried by continued volcanism and subsided to the current depths (>2250 m below surface). These rocks integrate temperature‐dependent elemental gains and losses from multiple stages of hydrothermal alteration that correspond to chemical exchanges observed in rocks from different crustal levels of submarine hydrothermal systems. Specifically, these lithologies have gained U, Mg, Zn, and Pb and have lost K, Rb, Ba, Cu, and light rare earth elements (La through Eu). Alteration and elemental gains and losses in lithologies emplaced on the seafloor can only be explained by a complex multistage hydrothermal alteration history. Reykjanes dolerite intrusions record alteration similar to that reported for the sheeted dike section of several examples of oceanic crust. Specifically, Reykjanes dolerites have lost K, Rb, Ba, and Pb, and gained Cu. The Reykjanes drill core samples provide a unique analog for seawater‐oceanic crust reactions actively occurring at high temperatures (275–345°C) beneath a seafloor hydrothermal system.

show abstract

Isotopic constraints on ice age fluids in active geothermal systems: Reykjanes, Iceland

Cited by 49 publications

References 59 publications

Degassing regime of Hekla volcano 2012–2013

Degassing regime of Hekla volcano 2012–2013

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

Elemental changes and alteration recorded by basaltic drill core samples recovered from in situ temperatures up to 345°C in the active, seawater‐recharged Reykjanes geothermal system, Iceland

Contact Info

Product

Resources

About