Mantle thermal structure and active upwelling during continental breakup in the North Atlantic

Holbrook, W. S.; Larsen, H. C.; Korenaga, Jun; Dahl‐Jensen, Trine; Reid, I.; Kelemen, P. B.; Hopper, John R.; Kent, G. M.; Lizarralde, D.; Bernstein, Stefan; Detrick, R. S.

doi:10.1016/s0012-821x(01)00392-2

Cited by 240 publications

(341 citation statements)

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“…The submarine Greenland-Iceland and Iceland-Faeroe ridges were studied with profiles hundreds of kilometres long. Long profiles were also shot on Iceland itself [Bott & Gunnarsson, 1980;Darbyshire et al, 1998;Holbrook et al, 2001]. The crust beneath these ridges was concluded to be ~ 30 km thick.…”

Section: The North Atlantic Igneous Provincementioning

confidence: 99%

Are ‘hot spots’ hot spots?

Foulger

2012

Journal of Geodynamics

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The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractThe term 'hot spot' emerged in the 1960's from speculations that Hawaii might have its origins in an unusually hot source region in the mantle. It subsequently become widely used to refer to volcanic regions considered to be anomalous in the then-new plate tectonic paradigm. It carried with it the implication that volcanism a) is emplaced by a single, spatially restricted, mongenetic melt-delivery system, assumed to be a mantle plume, and b) that the source is unusually hot. This model has tended to be assumed a priori to be correct. Nevertheless, there are many geological ways of testing it, and a great deal of work has recently been done to do so. Two fundamental problems challenge this work. First is the difficulty of deciding a 'normal' mantle temperature against which to compare estimates. This is usually taken to be the source temperature of midocean ridge basalts (MORB). However, Earth's surface conduction layer is ~ 200 km thick, and such a norm is not appropriate if the lavas under investigation formed deeper than the 40-50 km source depth of MORB. Second, methods for estimating temperature suffer from ambiguity of interpretation with composition and partial melt, controversy regarding how they should be applied, lack of repeatability between studies using the same data, and insufficient precision to detect the 200-300˚C temperature variations postulated. Available methods include multiple seismological and petrological approaches, modelling bathymetry and topography, and measuring heat flow. Investigations have been carried out in many areas postulated to represent either (hot) plume heads or (hotter) tails. These include sections of the mid-ocean spreading ridge postulated to include ridge-centred plumes, the North Atlantic Igneous Province, Iceland, Hawaii, oceanic plateaus, and high-standing continental areas such as the Hoggar swell. Most volcanic regions that may reasonably be considered anomalous in the simple plate-tectonic paradigm have been built by volcanism distributed throughout hundreds, even thousand of kilometres, and as yet no unequivocal evidence has been produced that any of them have high temperature anomalies compared with average mantle temperature for the same (usually unknown) depth elsewhere. Critical investigation of the genesis processes of 'anomalous' volcanic regions would be encouraged if use of the term 'hot spot' were discontinued in favor of one that does not assume a postulated origin, but is a description of unequivocal, observed char...

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Section: The North Atlantic Igneous Provincementioning

confidence: 99%

Are ‘hot spots’ hot spots?

Foulger

2012

Journal of Geodynamics

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“…[52] The establishment of the North Atlantic Igneous Province (NAIP) produced large amounts of young crust, increased the length of the midocean ridge and probably elevated the ocean floor [Roberts et al, 1984;White and McKenzie, 1989;Eldholm and Grue, 1994;Saunders et al, 1997;Holbrook et al, 2001] and may have contributed to sea level rise. The NAIP was not included in the recent reconstruction of ocean basin volume by Müller et al [2008], indicating that the estimated volume for this time interval could be too high, resulting in underestimates of sea level.…”

Section: Tectonic/volcanic Forcingmentioning

confidence: 99%

Eustatic variations during the Paleocene‐Eocene greenhouse world

et al. 2008

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[1] We reconstruct eustatic variations during the latest Paleocene and earliest Eocene ($58-52 Ma). Dinoflagellate cysts, grain size fractions, and organic biomarkers in marine sections at four sites from three continents indicate an increased distance to the coast during the Paleocene-Eocene thermal maximum (PETM). The same trend is recognized in published records from other sites around the world. Together, the data indicate a eustatic rise during the PETM, beginning 20 to 200 ka before the globally recorded negative carbon isotope excursion (CIE) at $55.5 Ma. Although correlations are tentative, we recognize other global transgressions during Chrons C25n and C24n. The latter may be associated with Eocene Thermal Maximum 2 ($53.5 Ma) or the ''X''-event ($52 Ma). These results suggest a link between global sea level and ''hyperthermal'' intervals, potentially because of the melting of small alpine ice sheets on Antarctica, thermal expansion of seawater, or both. However, the early onset of sea level rise relative to the CIE of the PETM suggests contributions from other mechanisms, perhaps decreasing ocean basin volume, on sea level rise.

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“…The surface is held motionless to allow the plume to rise from the base to the top of the model, and for it to begin spreading like a "pancake" beneath the lithosphere. Once the pancake expands to a diameter of ∼2400 km-the approximate extent of influence along the Greenland continental margin (Holbrook et al, 2001)-continental rifting and the seafloor spreading sequence initiates.…”

Section: Model Setupmentioning

confidence: 99%

“…For example, oceanic crustal thickness was ∼8 km along the early AR (Breivik et al, 2006), as thick or thicker along much of the RR, and significantly thicker (>30 km) along the Iceland-Greenland and IcelandFaeroe volcanic ridges (e.g. Holbrook et al, 2001;Smallwood et al, 1999). Shortly after continental breakup, the relative location of the hotspot center was likely near the margin of east Greenland (Fig.…”

Section: Introductionmentioning

confidence: 98%

“…White and McKenzie, 1989). Seismic studies document igneous crustal thicknesses of up to ∼35 km along both continental margins near the center of the Iceland hotspot track, and thicknesses 15 km extending 1000 km along the margins to the north and south (Breivik et al, 2006;Holbrook et al, 2001;Mjelde et al, 2008;Voss et al, 2009). Shortly after breakup (∼54-52 Ma), oceanic crust began forming along three main spreading centers, the RR, AR, and Mohns Ridge (MR) (Fig.…”

Section: Introductionmentioning

confidence: 98%

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The origin of the asymmetry in the Iceland hotspot along the Mid-Atlantic Ridge from continental breakup to present-day

Howell

Ito

Breivik

et al. 2014

Earth and Planetary Science Letters

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The Iceland hotspot has profoundly influenced the creation of oceanic crust throughout the North Atlantic basin. Enigmatically, the geographic extent of the hotspot influence along the Mid-Atlantic Ridge has been asymmetric for most of the spreading history. This asymmetry is evident in crustal thickness along the present-day ridge system and anomalously shallow seafloor of ages ∼49-25 Ma created at the Reykjanes Ridge (RR), SSW of the hotspot center, compared to deeper seafloor created by the nowextinct Aegir Ridge (AR) the same distance NE of the hotspot center. The cause of this asymmetry is explored with 3-D numerical models that simulate a mantle plume interacting with the ridge system using realistic ridge geometries and spreading rates that evolve from continental breakup to present-day. The models predict plume-influence to be symmetric at continental breakup, then to rapidly contract along the ridges, resulting in widely influenced margins next to uninfluenced oceanic crust. After this initial stage, varying degrees of asymmetry along the mature ridge segments are predicted. Models in which the lithosphere is created by the stiffening of the mantle due to the extraction of water near the base of the melting zone predict a moderate amount of asymmetry; the plume expands NE along the AR ∼70-80% as far as it expands SSW along the RR. Without dehydration stiffening, the lithosphere corresponds to the near-surface, cool, thermal boundary layer; in these cases, the plume is predicted to be even more asymmetric, expanding only 40-50% as far along the AR as it does along the RR. Estimates of asymmetry and seismically measured crustal thicknesses are best explained by model predictions of an Iceland plume volume flux of ∼100-200 m 3 /s, and a lithosphere controlled by a rheology in which dehydration stiffens the mantle, but to a lesser degree than simulated here. The asymmetry of influence along the present-day ridge system is predicted to be a transient configuration in which plume influence along the Reykjanes Ridge is steady, but is still widening along the Kolbeinsey Ridge, as it has been since this ridge formed at ∼25 Ma.

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Mantle thermal structure and active upwelling during continental breakup in the North Atlantic

Cited by 240 publications

References 55 publications

Are ‘hot spots’ hot spots?

Are ‘hot spots’ hot spots?

Eustatic variations during the Paleocene‐Eocene greenhouse world

The origin of the asymmetry in the Iceland hotspot along the Mid-Atlantic Ridge from continental breakup to present-day

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