The thermal structure of the lithosphere from shear wave velocities

Priestley, Keith; McKenzie, Dan

doi:10.1016/j.epsl.2006.01.008

Cited by 424 publications

(445 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%

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%

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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“…However, there is little evidence that significant stretching has occurred in the Tarim since the Paleozoic. A low extension rate is also suggested by the presence of N 150 km thick lithosphere beneath this basin (Lei and Zhao, 2007;Priestley and McKenzie, 2006;Xu et al, 2002). Lithospheric extension therefore cannot be the principal trigger of melting of the mantle in Tarim.…”

Section: Evidence For Plume Involvementmentioning

confidence: 99%

“…In fact, the relatively long time span of magmatism, pre-volcanic crustal uplift and intrusion of alkalic magmas of the Tarim LIP are more consistent with a plume incubation model , in which the lithosphere contributed both directly and indirectly to the formation and evolution of the province. It is likely that the relatively thick lithosphere (N150 km) presently beneath Tarim (Lei and Zhao, 2007;Priestley and McKenzie, 2006;Xu et al, 2002) may have existed in the Permian and prevented the convecting asthenosphere/plume from decompression melting. As proposed for the Parana-Etendeka and Karoo LIPs, the generation of the first two episodes of magmatism in the Tarim LIP can be accounted for by a plume heating model, in which melting of enriched components in the lithospheric mantle is due to conductive and advection heating by upwelling mantle plume (Gibson et al, 2006).…”

Section: Evidence For Lithospheric Involvementmentioning

confidence: 99%

“…Priestley and McKenzie (2006) converted seismic shear wave velocities into temperature profiles and then fitted a geotherm to the resulting temperature estimates to construct global/regional lithospheric variation maps. From this study it is clear that the present-day lithosphere beneath Tarim is relatively thick, ranging from 150 to 200 km.…”

Section: Geological Settingmentioning

confidence: 99%

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The Early Permian Tarim Large Igneous Province: Main characteristics and a plume incubation model

Wei

Luo

et al. 2014

Lithos

250

160

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“…Normal faults do not necessarily relate to crustal thinning or 'orogenic collapse' (Dewey 1988), as material was constantly being replaced by underthrusting from the south. Recent surface-wave tomography studies imply a highvelocity lithospheric mantle beneath the whole plateau (except the far north under the Kun Lun) to a depth of 225-250 km (Priestley & McKenzie 2006;Priestley et al 2008), arguing strongly against any lithospheric delamination beneath Tibet. Thin viscous sheet models also ignore depth-dependent behaviour and do not allow for lateral shear or detachments between upper and lower crust or between lower crust and mantle (Royden et al 1997).…”

Section: Continuum Modelsmentioning

confidence: 99%

Crustal–lithospheric structure and continental extrusion of Tibet

Searle

Elliott

Phillips

et al. 2011

JGS

240

154

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Crustal shortening and thickening to c. 70-85 km in the Tibetan Plateau occurred both before and mainly after the c. 50 Ma India-Asia collision. Potassic-ultrapotassic shoshonitic and adakitic lavas erupted across the Qiangtang (c. 50-29 Ma) and Lhasa blocks (c. 30-10 Ma) indicate a hot mantle, thick crust and eclogitic root during that period. The progressive northward underthrusting of cold, Indian mantle lithosphere since collision shut off the source in the Lhasa block at c. 10 Ma. Late Miocene-Pleistocene shoshonitic volcanic rocks in northern Tibet require hot mantle. We review the major tectonic processes proposed for Tibet including 'rigid-block', continuum and crustal flow as well as the geological history of the major strikeslip faults. We examine controversies concerning the cumulative geological offsets and the discrepancies between geological, Quaternary and geodetic slip rates. Low present-day slip rates measured from global positioning system and InSAR along the Karakoram and Altyn Tagh Faults in addition to slow long-term geological rates can only account for limited eastward extrusion of Tibet since Mid-Miocene time. We conclude that despite being prominent geomorphological features sometimes with wide mylonite zones, the faults cut earlier formed metamorphic and igneous rocks and show limited offsets. Concentrated strain at the surface is dissipated deeper into wide ductile shear zones.

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The thermal structure of the lithosphere from shear wave velocities

Cited by 424 publications

References 47 publications

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

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

The Early Permian Tarim Large Igneous Province: Main characteristics and a plume incubation model

Crustal–lithospheric structure and continental extrusion of Tibet

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