Seismic attenuation beneath Europe and the North Atlantic: Implications for water in the mantle

Zhu, Hejun; Bozdag, E.; Duffy, Thomas S.; Tromp, Jeroen

doi:10.1016/j.epsl.2013.08.030

Cited by 67 publications

(49 citation statements)

References 66 publications

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“…The high‐density anomaly is right above the upper mantle low‐ V s zone (−4.6% with respect to PREM), which also follows the TESZ from the Black Sea to southern Sweden (Zuilhuis & Nolet, ). The V s anomaly, although not imaged in more recent regional tomographic models (Lebedev et al, ; Legendre et al, ; Zhu et al, ) was explained as the image of a highly hydrated subducting slab associated with closure of the Tornquist Ocean and collisional tectonics along the edge of the East European craton (Nolet & Zuilhuis, ). If this interpretation is correct, the high‐density body imaged in our model may be the shallow part of the oceanic slab, which is not resolved in seismic tomography due to the counter play of composition and low temperature, on one side, and high water content, on the other side.…”

Section: Density Of Subcontinental Lithosphere Mantle (Sclm)mentioning

confidence: 97%

“…However, a comparison of different continental regions calculated by different groups is challenging, in part due to fundamentally different assumptions on thermal structure of the upper mantle and on the depth range to which mantle gravity anomalies are confined. In particular, one may use thermal models constrained by surface heat flux and xenolith geothermobarometry and resolved on a 1° × 1° spatial grid (Artemieva et al, ; Artemieva & Mooney, ) or may constrain mantle temperatures from seismic tomography (Goes et al, , ; Kaban et al, ), despite that geophysical studies indicate the presence of a strong nonthermal (compositional, melt, water, and grain size) component in seismic velocity variations (Afonso & Schutt, ; Artemieva, ; Faul & Jackson, ; Godey et al, ; Lee, ; Zhu et al, ), and lateral resolution of these models is significantly less than 1° × 1° (Foulger et al, ).…”

Section: Introductionmentioning

confidence: 99%

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Thermochemical Heterogeneity and Density of Continental and Oceanic Upper Mantle in the European‐North Atlantic Region

Shulgin

Artemieva

2019

JGR Solid Earth

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We present a new model, EUNA‐rho, for the density structure of the continental and oceanic upper mantle based on 3‐D tesseroid gravity modeling. On continent, there is no clear difference in lithospheric mantle (LM) density between the cratonic and Phanerozoic Europe, yet an ~300‐km‐wide zone of a high‐density LM along the Trans‐European Suture Zone may image a paleosubduction. Kimberlite provinces of the Baltica and Greenland cratons have a low‐density (3.32 g/cm3) mantle where all non‐damondiferous kimberlites tend to a higher‐density (3.34 g/cm3) anomalies. LM density correlates with the depth of sedimentary basins implying that mantle densification plays an important role in basin subsidence. A very dense (3.40–3.45 g/cm3) mantle beneath the superdeep platform basins and the East Barents shelf requires the presence of 10–20% of eclogite, while the West Barents Basin has LM density of 3.35 g/cm3 similar to the Variscan massifs of western Europe. In the North Atlantics, south of the Charlie Gibbs fracture zone (CGFZ) mantle density follows half‐space cooling model with significant deviations at volcanic provinces. North of the CGFZ, the entire North Atlantics is anomalous. Strong low‐density LM anomalies (< −3%) beneath the Azores and north of the CGFZ correlate with geochemical anomalies and indicate the presence of continental fragments and heterogeneous melting sources. Thermal anomalies in the upper mantle averaged down to the transition zone are 100–150 °C at the Azores and can be detected seismically, while a <50 °C anomaly around Iceland is at the limit of seismic resolution.

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Section: Density Of Subcontinental Lithosphere Mantle (Sclm)mentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Thermochemical Heterogeneity and Density of Continental and Oceanic Upper Mantle in the European‐North Atlantic Region

Shulgin

Artemieva

2019

JGR Solid Earth

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“…The answer remains controversial because only one natural sample of hydrous ringwoodite with ~1 wt % of water has been discovered [ Pearson et al , ]. Although a few geophysical observations suggest the MTZ next to subducted slabs is hydrated by the slab dehydration [e.g., Zhu et al , ], others claim that no water is brought below 400 km depth by subduction [e.g., Green et al , ]. A related debate concerns global MTZ water content, as geophysical evidence for high water content (on the order of 0.1 wt %) has been found in the Pacific MTZ [ Huang et al , ], although Houser [] suggests a dry MTZ globally with only a few hydrous regions with ~0.6 wt % of water.…”

Section: Introductionmentioning

confidence: 99%

A sporadic low‐velocity layer atop the 410 km discontinuity beneath the Pacific Ocean

Wei

Shearer

2017

JGR Solid Earth

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Waveforms of SS precursors recorded by global stations are analyzed to investigate lateral heterogeneities of upper mantle discontinuities on a global scale. A sporadic low‐velocity layer immediately above the 410 km discontinuity (LVL‐410) is observed worldwide, including East Asia, western North America, eastern South America, the Pacific Ocean, and possibly the Indian Ocean. Our best data coverage is for the Pacific Ocean, where the LVL‐410 covers 33–50% of the resolved region. Lateral variations of our LVL‐410 observations show no geographical correlation with 410 km discontinuity topography or tomographic models of seismic velocity, suggesting that the LVL‐410 is not caused by regional thermal anomalies. We interpret the LVL‐410 as partial melting due to dehydration of ascending mantle across the 410 km discontinuity, which is predicted by the transition zone water filter hypothesis. Given the low vertical resolution of SS precursors, it is possible that the regions without a clear LVL‐410 detection also have a thin layer. Therefore, the strong lateral heterogeneity of the LVL‐410 in our observations suggests partial melting with varying intensities across the Pacific and further provides indirect evidence of a hydrous mantle transition zone with laterally varying water content.

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“…Even though general agreement exists on the transport of water via subduction to shallow mantle depths of < 250 km, the abundance of hydrous phases in deep subducted slabs still remains a disputed issue [ Abers , ; Hacker et al ., ; Hirschmann , ]. Indirect evidences for the transport of water via subduction into deeper mantle regions are provided by seismic anomalies in the vicinity of deep slabs, including seismic velocity attenuations [ Lawrence and Wysession , ; Zhu et al ., ], reduced seismic bulk velocities [ Chen and Brudzinski , ], seismic shear wave anisotropies [ Chen and Brudzinski , ; Di Leo et al ., ], deviations from the globally observed depth and thicknesses of the major mantle seismic discontinuities [ Deuss et al ., ], and from observed elevated electrical conductivities [ Guo and Yoshino , ; Ichiki et al ., ]. Additional evidence for the continuous transport of hydrous phases into deep mantle regions are provided by the presence of low‐velocity layers recently detected above subducted slabs in Tonga and Japan [ Savage , ; Tonegawa et al ., ].…”

Section: Introductionmentioning

confidence: 99%

Single‐crystal equation of state of phase D to lower mantle pressures and the effect of hydration on the buoyancy of deep subducted slabs

et al. 2013

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[1] An understanding of the physical properties of the hydrous magnesium silicate phase D is important for the interpretation of the seismic anomalies observed in subducted slabs and to evaluate the effect of hydration on slab dynamics. Here we report the equation of state of phase D (Mg 1.1 Si 1.8 H 2.5 O 6 ) up to 65 GPa obtained from high-precision single-crystal X-ray diffraction. A single-crystal of phase D was loaded in a diamond anvil cell using helium as pressure transmitting medium to ensure quasi-hydrostatic conditions during the entire data collection. The volume of phase D decreases smoothly over the entire pressure range, without the anomalies in the compressibility reported at 40 GPa in previous powder diffraction studies. If existing in phase D, a hydrogen bond symmetrization transition as predicted by first-principles calculation is therefore not associated with anomalies in the volume compression behavior. The isothermal bulk modulus K T and its pressure derivative K′ T obtained from the fitting of the unit cell volumes using a third-order Birch

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Seismic attenuation beneath Europe and the North Atlantic: Implications for water in the mantle

Cited by 67 publications

References 66 publications

Thermochemical Heterogeneity and Density of Continental and Oceanic Upper Mantle in the European‐North Atlantic Region

Thermochemical Heterogeneity and Density of Continental and Oceanic Upper Mantle in the European‐North Atlantic Region

A sporadic low‐velocity layer atop the 410 km discontinuity beneath the Pacific Ocean

Single‐crystal equation of state of phase D to lower mantle pressures and the effect of hydration on the buoyancy of deep subducted slabs

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