The relationship between shear wave velocity, temperature, attenuation and viscosity in the shallow part of the mantle

Priestley, Keith; McKenzie, Dan

doi:10.1016/j.epsl.2013.08.022

Cited by 250 publications

(376 citation statements)

References 47 publications

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“…These slow wave speeds give way to fast wave speeds away from the ridges over a few hundred kilometres as the plate forms (Parsons & Sclater 1977). The upper mantle beneath the East Pacific Rise shows as a broad, strong slow wave speed feature in the 100 km depth map with a transition from slow to fast wave speeds toward the older portion of the Pacific Plate, similar to what has been observed in Rayleigh wave models of the Pacific Plate (Forsyth 1977;Zhang & Tanimoto 1991;Ritzwoller et al 2004;Priestley & McKenzie 2006;Maggi et al 2006;Priestley & McKenzie 2013). By ∼200 km depth the low wave speeds associated with the MidAtlantic Ocean, Indian Ocean and southern Pacific Ocean spreading ridges largely disappear but the low wave speeds associated with the East Pacific Rise persist to as much as 250 km depth.…”

Section: The Regionalizationsupporting

confidence: 49%

“…The exceptions are the South Indian shield and the North China craton, neither of which has a deep, high wave-speed β h (z) root. The cratonic roots extend somewhat deeper in the CAM2016SH models than they do in the comparable β v (z) models (Debayle & Ricard 2012;Priestley & McKenzie 2013). Gung et al (2003) suggest that roots of continental shields appear deeper in β h (z) models than they do in β v (z) models due to radial anisotropy arising from present-day asthenospheric flow aligning the mineral fabric leading to the strong fast β h (z) signature.…”

Section: The Regionalizationmentioning

confidence: 79%

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A global horizontal shear velocity model of the upper mantle from multimode Love wave measurements

Ho¹,

Priestley²,

Debayle

2016

Geophys. J. Int.

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S U M M A R YSurface wave studies in the 1960s provided the first indication that the upper mantle was radially anisotropic. Resolving the anisotropic structure is important because it may yield information on deformation and flow patterns in the upper mantle. The existing radially anisotropic models are in poor agreement. Rayleigh waves have been studied extensively and recent models show general agreement. Less work has focused on Love waves and the models that do exist are less well-constrained than are Rayleigh wave models, suggesting it is the Love wave models that are responsible for the poor agreement in the radially anisotropic structure of the upper mantle. We have adapted the waveform inversion procedure of Debayle & Ricard to extract propagation information for the fundamental mode and up to the fifth overtone from Love waveforms in the 50-250 s period range. We have tomographically inverted these results for a mantle horizontal shear wave-speed model (β h (z)) to transition zone depths. We include azimuthal anisotropy (2θ and 4θ terms) in the tomography, but in this paper we discuss only the isotropic β h (z) structure. The data set is significantly larger, almost 500 000 Love waveforms, than previously published Love wave data sets and provides ∼17 000 000 constraints on the upper-mantle β h (z) structure. Sensitivity and resolution tests show that the horizontal resolution of the model is on the order of 800-1000 km to transition zone depths. The high wave-speed roots beneath the oldest parts of the continents appear to extend deeper for β h (z) than for β v (z) as in previous β h (z) models, but the resolution tests indicate that at least parts of these features could be artefacts. The low wave speeds beneath the mid-ocean ridges fade by ∼150 km depth except for the upper mantle beneath the East Pacific Rise which remains slow to ∼250 km depth. The resolution tests suggest that the low wave speeds at deeper depths beneath the East Pacific Rise are not solely due to vertical smearing of shallow, low wave speeds. Four prominent, low wave-speed features occur at transition zone depths-one aligned along the East African Rift, one centred south of the Indian peninsula, one located south of New Zealand and one in the south Pacific Ocean coinciding with the location of the South Pacific Superswell. The low wave-speed features south of New Zealand and south of the Indian peninsula correspond spatially with the two largest negative geoid lows on Earth.

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Section: The Regionalizationsupporting

confidence: 49%

Section: The Regionalizationmentioning

confidence: 79%

A global horizontal shear velocity model of the upper mantle from multimode Love wave measurements

Ho¹,

Priestley²,

Debayle

2016

Geophys. J. Int.

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“…9A) reveals that depth to the LAB varies from 77 to 127 km for the GDH1, while the LAB depths derived from the PSM model are systematically deeper by 15 -20 km than GDH1. We observed that the modelled LAB geometry for the PSM matches well with the LAB values retrieved from the global grid of upper mantle structure PM_v2_2012 (Priestley and McKenzie, 2013) except for the difference in lateral placement of their deepening. On the other hand, the modeled LAB values from the GDH1 agree well with the estimates of LAB based on the available seismological data in the BOB (Singh, 1990;Mitra et al, 2011;Bhattacharya et al, 2013).…”

Section: Lithospheric Structuresupporting

confidence: 62%

Lithosphere structure and upper mantle characteristics below the Bay of Bengal

et al. 2016

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SUMMARY:The oceanic lithosphere in the Bay of Bengal (BOB) formed 80 -120 Ma following the breakup of eastern Gondwanaland. Since its formation, it has been affected by the emplacement of two long N-S trending linear aseismic ridges (85 o E and Ninetyeast) and by the loading of ca.20-km of sediments of the Bengal Fan. Here, we present the results of a combined spatial and spectral domain analysis of residual geoid, bathymetry and gravity data constrained by seismic reflection and refraction data. Self-consistent geoid and gravity modeling defined by temperature-dependent mantle densities along a N-S transect in the BOB region revealed that the depth to the Lithosphere-Asthenosphere boundary (LAB) deepens steeply from 77 km in the south to 127 km in north, with the greater thickness being anomalously thick compared to the lithosphere of similar-age beneath the Pacific Ocean. The Geoid-Topography Ratio (GTR) analysis of the 85°E and Ninetyeast ridges indicate that they are compensated at shallow depths.

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“…They are principally controlled by V sv , the velocity of vertically polarised shear waves, which in turn is more sensitive to temperature than to composition (Jordan 1979, Qiu et al 1996, Lee 2003, Schutt and Lesher 2006, Priestley and M c Kenzie 2006. A number of models of V s have now been published (Lekić and Romanowicz 2011, Ritsema et al 2011, Priestley and M c Kenzie 2013. All show that, as expected, the shear wave velocity is high beneath cratons, owing to the low temperature in their roots.…”

Section: Craton Formationmentioning

confidence: 84%

“…Fig. 2b shows a map of the lithosphere thickness beneath southern Asia, determined from V sv (Priestley and M c Kenzie 2013). The spatial resolution of the surface wave tomography is sufficient to show that not only Tibet, but the Tien Shan, Hindu Kush and Zagros mountain ranges are also underlain by thick lithosphere.…”

Section: Craton Formationmentioning

confidence: 99%