Evolution of low-18O Icelandic crust

Pope, E. C.; Bird, Dennis K.; Arnórsson, Stefán

doi:10.1016/j.epsl.2013.04.043

Cited by 38 publications

(21 citation statements)

References 95 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…6 and supplementary material), are unlikely to be produced by melting hydrothermally altered material (all elements are strongly incompatible, but have variable mobilities in hot fluids). Moreover, δ 18 O of dacites from Heiðarsporður measured in previous studies (Nicholson et al, 1991;Jónasson, 2005;Pope et al, 2013) are neither particularly low nor scattered for Icelandic magmas, hence not consistent with partial melting of hydrothermally altered material (Fig. 9).…”

Section: Melting Of Hydrothermally Altered Crust?mentioning

confidence: 48%

“…Fractionation has been already suggested by Pope et al (2013), andJónasson (2005), although only for the rock suite from basalts to icelandites. Pope et al (2013) base their interpretation mainly on the homogeneity of the δ 18 O data (Fig. 9) and the major elements composition.…”

Section: Crystal Fractionation and Magma Mixingmentioning

confidence: 92%

“…Non-differentiated basalts means thatNicholson et al (1991) do not make any distinction between Olivine-basalts and Fe-Ti basalts. Data fromNicholson et al (1991).,Jónasson (2005), andPope et al (2013). Symbols and colors as inFig.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Origin of the compositional diversity in the basalt-to-dacite series erupted along the Heiðarsporður ridge, NE Iceland

Mancini

Mattsson

2015

Journal of Volcanology and Geothermal Research

View full text Add to dashboard Cite

Section: Melting Of Hydrothermally Altered Crust?mentioning

confidence: 48%

Section: Crystal Fractionation and Magma Mixingmentioning

confidence: 92%

See 1 more Smart Citation

Origin of the compositional diversity in the basalt-to-dacite series erupted along the Heiðarsporður ridge, NE Iceland

Mancini

Mattsson

2015

Journal of Volcanology and Geothermal Research

View full text Add to dashboard Cite

“…; Pope et al . ) and from altered subsurface basalts collected from drill cuttings (open diamonds — Sveinbjörnsdóttir et al . ; hatched diamonds — Hattori & Muehlenbachs ).…”

Section: Resultsmentioning

confidence: 99%

“…; Pope et al . ) and altered bulk rock samples from drill cuttings in several Krafla wells (−10.5 to −3.4‰, Hattori & Muehlenbachs ; Sveinbjörnsdóttir et al . ).…”

Section: Resultsmentioning

confidence: 99%

Hydrogeology of the Krafla geothermal system, northeast Iceland

et al. 2015

View full text Add to dashboard Cite

The Krafla geothermal system is located in Iceland's northeastern neovolcanic zone, within the Krafla central volcanic complex. Geothermal fluids are superheated steam closest to the magma heat source, two‐phase at higher depths, and sub‐boiling at the shallowest depths. Hydrogen isotope ratios of geothermal fluids range from −87‰, equivalent to local meteoric water, to −94‰. These fluids are enriched in 18O relative to the global meteoric line by +0.5–3.2‰. Calculated vapor fractions of the fluids are 0.0–0.5 wt% (~0–16% by volume) in the northwestern portion of the geothermal system and increase towards the southeast, up to 5.4 wt% (~57% by volume). Hydrothermal epidote sampled from 900 to 2500 m depth has δD values from −127 to −108‰, and δ18O from −13.0 to −9.6‰. Fluids in equilibrium with epidote have isotope compositions similar to those calculated for the vapor phase of two‐phase aquifer fluids. We interpret the large range in δDEPIDOTE and δ18OEPIDOTE across the system and within individual wells (up to 7‰ and 3.3‰, respectively) to result from variable mixing of shallow sub‐boiling groundwater with condensates of vapor rising from a deeper two‐phase reservoir. The data suggest that meteoric waters derived from a single source in the northwest are separated into the shallow sub‐boiling reservoir, and deeper two‐phase reservoir. Interaction between these reservoirs occurs by channelized vertical flow of vapor along fractures, and input of magmatic volatiles further alters fluid chemistry in some wells. Isotopic compositions of hydrothermal epidote reflect local equilibrium with fluids formed by mixtures of shallow water, deep vapor condensates, and magmatic volatiles, whose ionic strength is subsequently derived from dissolution of basalt host rock. This study illustrates the benefits of combining phase segregation effects in two‐phase systems during analysis of wellhead fluid data with stable isotope values of hydrous alteration minerals when evaluating the complex hydrogeology of volcano‐hosted geothermal systems.

show abstract