Dynamics of mantle flow and melting at a ridge-centered hotspot: Iceland and the Mid-Atlantic Ridge

Ito, Garrett; Lin, Jian; Gable, Carl W.

doi:10.1016/0012-821x(96)00151-3

Cited by 149 publications

(164 citation statements)

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“…Strong upwelling mantle flow is expected within the plume conduit as demonstrated in numerical models [29][30][31]. This flow tends to align olivine a-axes in a vertical direction, which results in a weak azimuthal anisotropy and a strong radial anisotropy with a vertical symmetry axis.…”

Section: Origin Of the Fast Anomalymentioning

confidence: 78%

“…Because melt generated in the plume conduit migrates upward, the residual mantle left behind becomes more depleted and Mg-rich, and will be associated with a higher velocity [32][33][34]. The fast anomaly we imaged is centered at ~135 km depth, while the initial depth of melting beneath Iceland is estimated at ~110 km depth from geochemistry data [35], which is adopted in geodynamical modeling [29][30][31]. However, the mantle beneath Iceland probably contains more water and eclogite [36][37][38][39], which will allow melting to start at greater depths.…”

Section: Origin Of the Fast Anomalymentioning

confidence: 98%

“…Numerical models of both types are able to predict the crustal variations in Iceland and the V-shaped gravity anomalies at the Reykjanes Ridge [29][30][31][32][33]40]. Since olivine a-axes tend to align in mantle flow directions, seismic anisotropy can be used to constrain mantle flows.…”

Section: Channeling Of Flow Along Ridge Axesmentioning

confidence: 99%

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Seismic structure of Iceland from Rayleigh wave inversions and geodynamic implications

Detrick

2006

Earth and Planetary Science Letters

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Section: Origin Of the Fast Anomalymentioning

confidence: 78%

Section: Origin Of the Fast Anomalymentioning

confidence: 98%

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Seismic structure of Iceland from Rayleigh wave inversions and geodynamic implications

Detrick

2006

Earth and Planetary Science Letters

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“…6), with the exception for melting in the spinel stability field (applying the K D values determined by McDade et al (2003a), see also Stracke et al (2006)). Beneath Iceland's rift zones both active and passive mantle upwelling influence the mantle flow regime (Olson et al, 1993;Ribe et al, 1995;Ito et al, 1996;Maclennan et al, 2001;Shorttle et al, 2011). High mantle temperatures near the plume axis result in fast buoyancy-driven mantle upwelling, whereas further away, at lower mantle temperature, the upwelling is slower.…”

Section: Regional Variability In the Mantle Upwellingmentioning

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

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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.

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“…The second category [e.g., Buck and Su, 1989;Scott and Stevenson, 1989;Su and Buck, 1993;Cordery and Phipps Morgan, 1993;Barnouin-Jha and Parmentier, 1997] investigated melt migration beneath mid-ocean ridges while neglecting the compaction of the solid matrix due to melt extraction and ignoring the transient behavior of melt migration within the upper mantle. Ito et al [1996] and Barnouin-Jha and Parmentier [1997] considered a steady state melt migration in their models of the mid-ocean ridges. Steady state melt migration within an upwelling plume is possible only if melt is extracted or solidified in the top portion of the JOURNAL OF GEOPHYSICAL RESEARCH, VOL.…”

Section: Introductionmentioning

confidence: 99%

Effects of melt migration on the dynamics and melt generation of diapirs ascending through asthenosphere

Ghods

Arkani‐Hamed

2002

J. Geophys. Res.

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[1] Melting of a plume head can affect its dynamics by creating melt retention buoyancy. Melt migration controls the distribution of the melt retention buoyancy and affects the dynamics of the plume. We investigate in detail the effects of melt migration on the dynamics and partial melting of a 20-km radius mantle diapir, using axisymmetric two-phase flow models. We first study melt migration in a diapir with a 10% initial melt where no further melting is allowed. The diapir dynamics are modeled for permeable and impermeable cases. In the permeable model, melt migrates within the diapir, whereas no relative motion is allowed between melt and solid matrix in the impermeable model. The permeable model shows a progressive increase of melt fraction in the top portion and decrease in the bottom part of the diapir. This results in a melt buoyancy polarization that elongates the diapir and increases its upwelling velocity. We then model the dynamics of the permeable and impermeable diapirs allowing melting to occur. The velocity of the permeable diapir and its melt generation are significantly larger than that of the impermeable diapir. In general, the permeable diapirs lack the mushroom shape observed for the impermeable ones. Because of intensive computational demand of the two-phase flow modeling, our detailed studies are limited to small diapirs. However, we also investigate a 200-km-diameter mantle plume and show that melt migration produces a nibble of higher melt fraction at the top of the plume that ascends much faster than the bulk of the plume.

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Dynamics of mantle flow and melting at a ridge-centered hotspot: Iceland and the Mid-Atlantic Ridge

Cited by 149 publications

References 45 publications

Seismic structure of Iceland from Rayleigh wave inversions and geodynamic implications

Seismic structure of Iceland from Rayleigh wave inversions and geodynamic implications

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

Effects of melt migration on the dynamics and melt generation of diapirs ascending through asthenosphere

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