Chemical transport in geothermal systems in Iceland

Franzson, Hjalti; Zierenberg, Robert A.; Schiffman, P.

doi:10.1016/j.jvolgeores.2008.01.027

Cited by 72 publications

(54 citation statements)

References 19 publications

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“…The complete dissolution of primary basalt at high temperatures, reported in the literature (e.g., Franzson et al 2008), seems to be supported by this modeling, at least when volcanic gases are involved. For albite being usually stable at high temperatures, it is difficult to evaluate which part comes from the protolith, and which part is secondary.…”

Section: Discussionsupporting

confidence: 82%

“…To a wider extent, numerous modeling studies of the mineralogical evolution of basaltic systems have been done (Griffith and Shock 1997;Franzson et al 2008;Navarre-Sitchler et al 2011;Gysi and Stefansson 2011;Pham et al 2011;Aradottir et al 2012;Aradottir et al 2013;Catalano 2013;Hellevang et al 2013), but none of those reported the porosity evolution during reactive transport and water-rock interaction. The evolution of porosity has potentially important implications for basalt alteration.…”

Section: The Need For Modelingmentioning

confidence: 99%

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Differential alteration of basaltic lava flows and hyaloclastites in Icelandic hydrothermal systems

2015

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Geological field observations evidence that active and fossil Icelandic hydrothermal systems are typically embedded into an intercalation of almost completely altered and nearly unaltered volcanic rock layers. We investigated the reasons for this finding with help of geochemical reaction path calculations, by studying the mineralogical evolution of contrasting lithofacies-basalt flows and hyaloclastites at various temperatures and pressures, different recharge water composition, and gas content. From this study, we conclude that the initial porosity of protoliths and volume changes due to their transformation into secondary minerals are sufficient to explain the different extents of alteration as observed in field studies. In addition, we present a generalized kinetic model to estimate the alteration time of glassy fragments in hyaloclastite as a function of grain size, surface roughness, and temperature. This time was found to be rather short, ranging from a few hours to a few years.

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Section: Discussionsupporting

confidence: 82%

Section: The Need For Modelingmentioning

confidence: 99%

Differential alteration of basaltic lava flows and hyaloclastites in Icelandic hydrothermal systems

2015

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“…In the Vista Alegre region, the most intense alteration is related to amethyst or copper mineralization (Duarte et al 2009, Hartmann 2008, Pinto et al 2011. Hydrothermal alteration in basaltic rocks may have significantly modified the concentrations of oxides such as Al 2 O 3 , Fe 2 O 3 (t) and K 2 O, and some mobile trace elements such as Rb, Ba, Sr and Cu (Frantzon et al 2008). On the other hand, TiO 2 , REE and HFSE have high valencies and electronegativities, small radii and strong chemical bonds, so they are nearly immobile during hydrothermal alteration (e.g.…”

Section: Effects Of Alterationmentioning

confidence: 99%

Flow-by-flow chemical stratigraphy and evolution of thirteen Serra Geral Group basalt flows from Vista Alegre, southernmost Brazil

Pinto

Hartmann

2011

An. Acad. Bras. Ciênc.

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“…In order to gauge the direction of elemental changes (gains or losses), we normalized samples to Zr (Figure ), which is generally immobile even during high degrees of hydrothermal alteration [ Humphris and Thompson , ; Floyd and Winchester , ; Zierenberg et al ., ; Barrett and MacLean , ; Franzson et al ., ]. Aside from low susceptibility for mobilization by hydrothermal processes, Zr is a particularly good alteration monitor because it is present at fairly high concentrations relative to other trace elements.…”

Section: Resultsmentioning

confidence: 99%

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

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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.

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Chemical transport in geothermal systems in Iceland

Cited by 72 publications

References 19 publications

Differential alteration of basaltic lava flows and hyaloclastites in Icelandic hydrothermal systems

Differential alteration of basaltic lava flows and hyaloclastites in Icelandic hydrothermal systems

Flow-by-flow chemical stratigraphy and evolution of thirteen Serra Geral Group basalt flows from Vista Alegre, southernmost Brazil

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

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