Seismic observation of narrow plumes in the oceanic upper mantle

Li, X.; Kind, R.; Yuan, Xiaohui; Sobolev, S. V.; Hanka, W.; Ramesh, D. S.; Gu, Yu Jeffrey; Dziewoński, Adam M.

doi:10.1029/2002gl015411

Cited by 34 publications

(42 citation statements)

References 27 publications

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“…Although recently there has been success in providing seismological evidence for some plumelike structures with surface wave anisotropy tomography (Montagner and Guillot, 2000), finite-frequency body wave tomography (Montelli et al, 2004), and SS precursors and receiver functions (Li et al, 2003), new approaches for detecting plumes will help resolve the controversy. For example, seismic velocity anisotropy in the upper mantle can be detected by teleseismic shear wave splitting (Fig.…”

Section: Introductionmentioning

confidence: 99%

Shear wave splitting around hotspots: Evidence for upwelling-related mantle flow?

Walker

Bokelmann²,

Klemperer

et al. 2005

Plates, Plumes and Paradigms

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We review evidence for plumelike upwellings beneath the Eifel, Great Basin, Hawaii, Afar, and Iceland hotspots by using teleseismic shear wave splitting to resolve the anisotropy associated with mantle flow. An approximately parabolic pattern of fast polarization azimuths (φ) is consistent with splitting observations around the Eifel, Great Basin, and Hawaii hotspots, and this pattern may be explained by a model of upwelling material that is being horizontally deflected or sheared in the direction of absolute plate motion (parabolic asthenospheric flow, PAF). The source of splitting beneath Iceland and the Afar is not clear, but the data are not inconsistent with a plumelike upwelling. The success of the upwelling model in explaining the splitting data for the Eifel and the Great Basin, regions far from plate boundaries, suggests that a mantle anisotropy pattern exists for at least some hotspots driven by plumelike upwellings and that splitting can be a useful diagnostic to differentiate between plumelike and alternative sources (e.g., propagating cracks, leaky transform faults) for mantle hotspots. Furthermore, the PAF pattern provides two useful tectonic and geodynamic parameters: the direction of relative motion between the lithosphere and asthenosphere and the stagnation distance, which is proportional to the strength of the upwelling and the speed of the moving plate. When this pattern is used with other types of geophysical data such as seismic velocity tomographic images, one can estimate the plate speed, upwelling volumetric flow rate, buoyancy flux, asthenospheric thickness, excess temperature, and viscosity.

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Section: Introductionmentioning

confidence: 99%

Shear wave splitting around hotspots: Evidence for upwelling-related mantle flow?

Walker

Bokelmann²,

Klemperer

et al. 2005

Plates, Plumes and Paradigms

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show abstract

“…1), the topographies appear correlated and the apparent Clapeyron slope ratio γ 4 /γ 6 becomes positive, contrary to experimental expectations. This could be especially the case for up-going P waves converted into shear waves under seismological stations (P-to-S conversions) whose travel-times are strongly velocity-dependent (Li et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

Seismically deduced thermodynamics phase diagrams for the mantle transition zone

Tauzin

Ricard

2014

Earth and Planetary Science Letters

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Seismic discontinuities at 410 and 660 km depth are usually attributed to solid phase changes within the olivine component of the mantle. The Clapeyron slopes γ 410 and γ 660 , i.e. the thermal dependence of the depths of reactions, have been shown experimentally to be of opposite signs. Yet, their values are not well constrained by laboratory measurements. Seismological observations have not been more precise due to the difficulty to separate the competing effects of background wave-velocities and of temperature on the topography of discontinuities. In this study we use conversion imaging of interfaces under western US. We propose a new approach to derive a seismological estimate of the Clapeyron slopes with respect to γ 410 for the major and minor phase changes of the transition zone. We obtain γ 660 ≈ −3 MPa K −1 for γ 410 ≈ +3 MPaK −1 . We construct "seismic phase diagrams" of the transition zone that can be directly compared with experimental phase diagrams. We also apply a " Z -Γ " transform to better constrain the Clapeyron slopes γ of the minor phase changes. Although tenuous, signals in seismic phase diagrams suggest that minor phase transitions, both in the olivine and the non-olivine component of the mantle, have visible seismic expressions. They can tentatively be described as follows. The '410' is overlaid at low temperature by an interface corresponding to a decrease of velocity with depth and γ ≈ +3 MPaK −1 .The '660' widens at high temperature and is preceded at low temperature by an interface, the '620', with γ ≈ +7 MPaK −1 . A '520' is suggested with γ ≈ 2-3 MPa K −1 . These last two interfaces correspond to velocity increases with depth. At last, near 590 km depth, an interface may be associated with a velocity reduction showing a weak dependence on temperature (γ ∼ 0 MPa K −1 ).

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“…Утонение переходного слоя в целом подтверждается антикорреляцией его верхней и нижней границы [Shen et al, 1998;Li et al, 2000Li et al, , 2003Owens et al, 2000;Hooft et al, 2003], хотя в некоторых регионах (например, в западной части Северной Америки) границы 410 и 660 км антикоррелиру-ются друг с другом не всегда [Houser et al, 2008].…”

Section: подлитосферные расплавные аномалииunclassified

The latest geodynamics in Central Asia: primary and secondary mantle melting anomalies in the context of orogenesis, rifting, and lithospheric plate motions and interactions

Chuvashova¹,

Рассказов²,

Сунь³

2017

Geodin. tektonofiz.

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A comprehensive model for deep dynamics in Asia has been developed from the data on the evolution of melting anomalies in the context of lithospheric plate motions, interactions, orogeny, and rifting. The key components of our model are the primary (transition layer) and secondary (upper mantle) melting anomalies (Gobi, Baikal, and North Transbaikalia; and Hangay, Sayan, and Vitim, respectively). It is inferred that the primary melting anomalies originated at the beginning of the latest geodynamic stage (ca. 90 Ma) as a result of the transition layer distortion by lower mantle flows. Such primary anomalies were caused by avalanche collapses of the slab material that had been stagnated under the closed fragments of the Solonker, Ural-Mongolian paleooceans and the Mongol-Okhotsk Bay of Paleopacific. The secondary melting anomalies occurred due to the Early-Middle Miocene structural reorganization in the Pacific-Asian and Indo-Asian interaction zones. The primary melting anomalies governed the spatial distribution of forces and processes of the latest geodynamic stage. The secondary melting anomalies resulted from the lithospheric motions relative to the primary anomalies and provided for the development of orogeny and rifting. The BaikalMongolian corridor of asthenospheric flows was limited by the lateral zones of convergent interactions between India and Asia in the southwest, and North America and Asia in the northeast. In these lateral zones, Late Phanerozoic paleoslabs and ascending mantle fluxes were revealed in the transition layer, as well as in the upper mantle, without any destruction by the asthenospheric flows.

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Seismic observation of narrow plumes in the oceanic upper mantle

Cited by 34 publications

References 27 publications

Shear wave splitting around hotspots: Evidence for upwelling-related mantle flow?

Shear wave splitting around hotspots: Evidence for upwelling-related mantle flow?

Seismically deduced thermodynamics phase diagrams for the mantle transition zone

The latest geodynamics in Central Asia: primary and secondary mantle melting anomalies in the context of orogenesis, rifting, and lithospheric plate motions and interactions

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