Historic magmatism on the Reykjanes Peninsula, Iceland: a snap-shot of melt generation at a ridge segment

Peate, David W.; Baker, Joel A.; Jakobsson, Sveinn P.; Waight, Tod E.; Kent, Adam J.R.; Grassineau, Nathalie; Skovgaard, Anna Cecile

doi:10.1007/s00410-008-0339-4

Cited by 77 publications

(83 citation statements)

References 93 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Similar small-volume picritic lava shields exist in the Reykjanes Peninsula (Jakobsson et al 1978;Gee et al 1998;Saemundsson et al 2010) and Northern Volcanic Zone (e.g., Maclennan et al 2002). Isotopic data on picrites in Iceland require a relatively unradiogenic mantle source (e.g., Elliot et al 1991;Chauvel and Hémond 2000;Momme et al 2003;Brandon et al 2007;Peate et al 2008), and there has been considerable debate about whether this depleted source is regional ambient MORB mantle or an intrinsic component of the upwelling plume (e.g., Kerr et al 1995;Fitton et al 1997Fitton et al , 2003Chauvel and Hémond 2000;Kempton et al 2000;Stracke et al 2003;Thirlwall et al 2004;Kokfelt et al 2006;Peate et al 2008;Koorneef et al 2012). Although few have been dated, each of these units appears to be among the oldest postglacial units in its immediate vicinity and most are thought to be early postglacial in age.…”

Section: Postglacial Icelandic Picritesmentioning

confidence: 98%

Effects of deglaciation on the petrology and eruptive history of the Western Volcanic Zone, Iceland

2015

View full text Add to dashboard Cite

New observations and geochemical analyses of volcanic features in the 170-km-long Western Volcanic Zone (WVZ) of Iceland constrain spatial and temporal variations in volcanic production and composition associated with the last major deglaciation. Subglacial eruptions represent a significant portion of the late Quaternary volcanic budget in Iceland. Individual features can have volumes up to ∼48 km 3 and appear to be monogenetic. Subaqueous to subaerial transition zones provide minimum estimates of ice sheet thickness at the time of eruption, although water-magma interactions and fluctuating lake levels during eruption can lead to complex lithological sequences. New major and trace element data for 36 glacial and postglacial eruptive units, combined with observations of lava surface quality, passage zone heights, and 3 He exposure ages of some glacial units, indicate a maximum in volcanic production in the WVZ during the last major ice retreat. Anomalously high volcanic production rates continue into the early postglacial period and coincide with significant incompatible element depletions and slightly higher CaO and SiO 2 and lower FeO content at a given MgO. Subglacial units with strong incompatible element depletions also have lava surfaces that lack evidence of subsequent glaciation. These units likely formed after the onset of deglaciation, when rapidly melting ice sheets increased decompression rates in the underlying mantle, leading to anomalously high melting rates in the depleted upper mantle. This process also can explain the eruption of extremely depleted picritic lavas during the early postglacial period. These new observations indicate that the increased volcanic activity associated with glacial unloading peaked earlier than previously thought, before Iceland was completely ice free.

show abstract

Section: Postglacial Icelandic Picritesmentioning

confidence: 98%

Effects of deglaciation on the petrology and eruptive history of the Western Volcanic Zone, Iceland

2015

View full text Add to dashboard Cite

show abstract

“…3. Note that the accuracy of the age-corrected data is limited by the precision of the available age estimates for each lava flow (Peate et al, 2009;Sinton et al, 2005 (Chen et al, 1986), rendering the ( 234 U/ 238 U) ratios in oceanic basalts susceptible to disturbance by seawater-rock interaction. All RP, WV and NV samples have ( 234 U/ 238 U) within error of secular equilibrium, demonstrating they were not affected by post-eruptive seawater alteration.…”

Section: Sample Preparation and Analytical Techniquesmentioning

confidence: 99%

The influence of source heterogeneity on the U–Th–Pa–Ra disequilibria in post-glacial tholeiites from Iceland

Koornneef

Stracke

Bourdon

2012

Geochimica et Cosmochimica Acta

View full text Add to dashboard Cite

We investigate the relative influence of mantle upwelling velocity and source heterogeneity on the melting rates recorded by 230 230 Th excesses and distance from the inferred plume centre is consistent with a model of decreasing mantle upwelling velocity with increasing distance from the plume axis. However, the model is not substantiated by the ( 231 Pa/ 235 U) data as the correlation with distance from the plume centre is weak. On the scale of individual eruption centres, the observed U-series are influenced by variations in melt transport time, source porosity, and local variations in mantle upwelling velocity. Broad correlations between ( 230 Th/ 238 U) and ( 231 Pa/ 235 U) and highly incompatible trace element ratios for samples from the Western Volcanic Zone provide, however, evidence for a significant underlying effect of source heterogeneity on the U-series data. Low 230 Th and 231 Pa excesses in enriched samples from the Western Volcanic Zone with high U/Th, Nb/U and Nb/La indicate that partial melts from an enriched source component, characterised by high melt productivity but low bulk D U /D Th , influence the U-series systematics of the erupted melts. These results re-affirm the presence of comparatively larger abundances of enriched material in the mantle source beneath the South Western Rift of Iceland, which has been suggested based on relationships between highly incompatible element and Pb isotope ratios in Icelandic basalts. Overall, our results highlight the importance of lithological heterogeneity on the melting behaviour of the upper mantle and the composition of oceanic basalts.

show abstract

“…Tholeiitic basalts make up the preponderance of exposed lavas. Compared to the "picritic basalts, the tholeiitic basalts are more evolved (MgO generally <8%), have high trace element concentrations, have Nb/Zr ratios >0.7, and are referred to as 'trace element enriched (TEE)' (Gee et al, 1998;Kokfelt et al, 2006;Peate et al, 2009). …”

Section: Geology Of the Reykjanes Peninsulamentioning

confidence: 99%

“…Highly variable proportions of cumulate phases (olivine, spinel and plagioclase) in the picritic basalts suggest the parental liquid was primitive basalt as opposed to a true picrite (Gee et al, 1998;Revillon et al, 1999). "Picritic" basalts in the Reykjanes volcanic system are defined by high MgO, low trace element concentrations, Nb/Zr ratios <0.7, and are referred to as "trace element depleted (TED)" (Gee et al, 1998;Peate et al, 2009). Tholeiitic basalts make up the preponderance of exposed lavas.…”

Section: Geology Of the Reykjanes Peninsulamentioning

confidence: 99%

Geochemical bias in drill cutting samples versus drill core samples returned from the Reykjanes Geothermal System, Iceland

Fowler

Zierenberg

2016

Geothermics

View full text Add to dashboard Cite

a b s t r a c tThe wholerock major and trace element composition of drill cutting samples are compared to drill core samples from adjacent depths in the seawater recharged Reykjanes geothermal system in Iceland. The first appearance of alteration minerals and lithologies in drill cutting samples is a useful tool for interpreting broad subsurface characteristics. However, use of drill cutting samples for determining igneous affinity and elemental exchanges during hydrothermal alteration is problematic. Samples recovered from immediately above and below the cored intervals in wells RN-17B and RN-30 demonstrate that drillcutting samples are biased towards preservation of least altered primary igneous minerals and more resistant alteration minerals, including albite, quartz, and epidote, with preferential loss of finer-grained and less resistant minerals including chlorite and actinolite. This selective recovery obscures elemental exchanges resulting from hydrothermal alteration processes. For some elements, compositional variations (enrichments and depletions) measured from 9.5 m of core exceeds that observed in ∼3000 m of cutting analyses. Concentration ratios of hydrothermally immobile elements including Zr, Nb, V, Y, HREE, Hf, Ta and Th in deep (>2245 m) spot drill core samples record bimodal, trace element-enriched and trace element-depleted precursor compositions similar to subaerial Reykjanes Peninsula basalts. The same elements in nearly 3000 m of drill cutting samples from well RN-17 overwhelmingly reflect the more common trace element-enriched igneous precursor, demonstrating that mixing of drill cutting samples obscures details of their igneous affinity. A new and different drill rig was used to deepen well RN-17 below 2266 m in a sidetrack hole (RN-17ST), which resulted in a change in drilling conditions, accompanied with an increased well deviation angle from ∼0• to ∼4• . Wholerock geochemical results for drill cutting samples from RN-17ST are homogenous for virtually every element; suggesting the change in drilling conditions resulted in extreme mixing of the drill cuttings. Anomalously high concentrations of Cu, Ni, Cr and Ta in some drill cutting samples likely reflects contamination of drill cutting samples by metal alloys used in drill bits and drill collars or more resistant spinel and sulfide phases.

show abstract

Historic magmatism on the Reykjanes Peninsula, Iceland: a snap-shot of melt generation at a ridge segment

Cited by 77 publications

References 93 publications

Effects of deglaciation on the petrology and eruptive history of the Western Volcanic Zone, Iceland

Effects of deglaciation on the petrology and eruptive history of the Western Volcanic Zone, Iceland

The influence of source heterogeneity on the U–Th–Pa–Ra disequilibria in post-glacial tholeiites from Iceland

Geochemical bias in drill cutting samples versus drill core samples returned from the Reykjanes Geothermal System, Iceland

Contact Info

Product

Resources

About