Evidence for mechanically coupled lithosphere in central Asia and resulting implications

Wang, Chun-Yong; Flesch, L. M.; Silver, Paul G.; Chang, Ling; Chan, W. W.

doi:10.1130/g24450a.1

Cited by 226 publications

(285 citation statements)

References 35 publications

(51 reference statements)

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“…In the case of lithospheric deformation, the mantle can deform by simple shear, either right-or left-lateral pure shear, or intermediate cases. As discussed by Wang et al (2008), it is nevertheless possible to address this problem if it can be assumed that the mantle deforms by either simple shear or pure shear (excluding intermediate cases), in which case the instantaneous maximum shear directions are invariant for simple shear, and the instantaneous maximum extension direction is invariant for pure shear. It is possible to distinguish between simple shear (right or left lateral) and pure shear by utilizing the rotational component of the velocity gradient tensor, after a correction has been made for rigid-body rotation (Wang et al 2008) using the line-rotation method (e.g., Holt and Haines 1993).…”

Section: Continental Regionsmentioning

confidence: 99%

“…McNamara et al 1994;Huang et al 2000;Flesch et al 2005;Lev et al 2006;Sol et al 2007;Wang et al 2008) and a wealth of data is now available to carry out the type of hypothesis testing described above. The two end-member models of asthenospheric flow and vertically coherent deformation were evaluated by Wang et al (2008), making use of nearly 200 splitting observations and 2000 GPS observations in a joint analysis. It was found that the vertically coherent deformation model provided an excellent fit to the data (Fig.…”

Section: Tibetan Plateau and Surrounding Regionsmentioning

confidence: 99%

“…This result suggests that (1) the mantle lithosphere dominates the anisotropic signal in Tibet, and (2) that the crust and mantle deform coherently during the building of the Tibetan Plateau. Given the importance of gravitational relaxation in driving deformation it can be further inferred that the crust and mantle are mechanically coupled (Wang et al 2008). This places a first-order constraint on deformation style for Tibet and points to the importance of this joint splitting and crustal deformation analysis in studying continental dynamics.…”

Section: Tibetan Plateau and Surrounding Regionsmentioning

confidence: 99%

See 2 more Smart Citations

Shear Wave Splitting and Mantle Anisotropy: Measurements, Interpretations, and New Directions

2009

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Measurements of the splitting or birefringence of seismic shear waves that have passed through the Earth's mantle yield constraints on the strength and geometry of elastic anisotropy in various regions, including the upper mantle, the transition zone, and the D 00 layer. In turn, information about the occurrence and character of seismic anisotropy allows us to make inferences about the style and geometry of mantle flow because anisotropy is a direct consequence of deformational processes. While shear wave splitting is an unambiguous indicator of anisotropy, the fact that it is typically a near-vertical path-integrated measurement means that splitting measurements generally lack depth resolution. Because shear wave splitting yields some of the most direct constraints we have on mantle flow, however, understanding how to make and interpret splitting measurements correctly and how to relate them properly to mantle flow is of paramount importance to the study of mantle dynamics. In this paper, we review the state of the art and recent developments in the measurement and interpretation of shear wave splitting-including new measurement methodologies and forward and inverse modeling techniques,-provide an overview of data sets from different tectonic settings, show how they help us relate mantle flow to surface tectonics, and discuss new directions that should help to advance the shear wave splitting field.

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Section: Continental Regionsmentioning

confidence: 99%

Section: Tibetan Plateau and Surrounding Regionsmentioning

confidence: 99%

Section: Tibetan Plateau and Surrounding Regionsmentioning

confidence: 99%

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Shear Wave Splitting and Mantle Anisotropy: Measurements, Interpretations, and New Directions

2009

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“…GPS displacement vectors (Gan et al, 2007) and SKS anisotropy measurements (Wang et al, 2008) indicate that the Tibetan crust (and possibly also the lithosphere and asthenosphere) is escaping eastwards, and that the main portion of the flow is being redirected towards the south east after it encounters the Sichuan Basin ( Figure 1). As part of the Yangtze craton, the Sichuan Basin is an old, intact block that remained undeformed during the orogenic events that formed the Tibetan plateau.…”

Section: Introductionmentioning

confidence: 99%

Seismic signature of the collision between the east Tibetan escape flow and the Sichuan Basin

Zhang

Yuan

Chen

et al. 2010

Earth and Planetary Science Letters

208

137

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GPS displacement vectors show that the crust in east Tibet is being squeezed in an easterly direction by the northward motion of the Indian plate, and the Sichuan Basin is resisting this stream and redirecting it mainly towards Indochina. The Longmen Shan, containing the steepest rise to the high plateau anywhere in Tibet, results from the strong interaction between the east Tibetan escape flow and the rigid Yangtze block (Sichuan Basin), but the kinematics and dynamics of this interaction are still the subject of some debates. We herein present results from a dense passive-source seismic profile from the Sichuan Basin into eastern Tibet in order to study the deep structure of this collision zone. Using P and S receiver function

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“…Surface waves can provide better depth-dependent azimuthal anisotropy Lin and Ritzwoller 2011) than shear wave splitting measurements in the crust and upper mantle (Savage 1999;Wang et al 2008). Therefore, it may provide more reliable constraints on crust and upper mantle deformation patterns by examining radial variations of azimuthal anisotropy.…”

Section: Discussionmentioning

confidence: 99%

A method for inversion of layered shear wavespeed azimuthal anisotropy from Rayleigh wave dispersion using the Neighborhood Algorithm

Yao

2015

Earthq Sci

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Seismic anisotropy provides important constraints on deformation patterns of Earth's material. Rayleigh wave dispersion data with azimuthal anisotropy can be used to invert for depth-dependent shear wavespeed azimuthal anisotropy, therefore reflecting depth-varying deformation patterns in the crust and upper mantle. In this study, we propose a two-step method that uses the Neighborhood Algorithm (NA) for the point-wise inversion of depth-dependent shear wavespeeds and azimuthal anisotropy from Rayleigh wave azimuthally anisotropic dispersion data. The first step employs the NA to estimate depthdependent V SV (or the elastic parameter L) as well as their uncertainties from the isotropic part Rayleigh wave dispersion data. In the second step, we first adopt a difference scheme to compute approximate Rayleigh-wave phase velocity sensitivity kernels to azimuthally anisotropic parameters with respect to the velocity model obtained in the first step. Then we perform the NA to estimate the azimuthally anisotropic parameters G c /L and G s /L at depths separately from the corresponding cosine and sine terms of the azimuthally anisotropic dispersion data. Finally, we compute the depth-dependent magnitude and fast polarization azimuth of shear wavespeed azimuthal anisotropy. The use of the global search NA and Bayesian analysis allows for more reliable estimates of depth-dependent shear wavespeeds and azimuthal anisotropy as well as their uncertainties.We illustrate the inversion method using the azimuthally anisotropic dispersion data in SE Tibet, where we find apparent changes of fast axes of shear wavespeed azimuthal anisotropy between the crust and uppermost mantle.

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Evidence for mechanically coupled lithosphere in central Asia and resulting implications

Cited by 226 publications

References 35 publications

Shear Wave Splitting and Mantle Anisotropy: Measurements, Interpretations, and New Directions

Shear Wave Splitting and Mantle Anisotropy: Measurements, Interpretations, and New Directions

Seismic signature of the collision between the east Tibetan escape flow and the Sichuan Basin

A method for inversion of layered shear wavespeed azimuthal anisotropy from Rayleigh wave dispersion using the Neighborhood Algorithm

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