Tomographic imaging of the underthrusting Indian slab and mantle upwelling beneath central Tibet

Zhang, Heng; Zhao, Dapeng; Zhao, Junmeng; Liu, Hongbing

doi:10.1016/j.gr.2014.02.012

Cited by 32 publications

(23 citation statements)

References 82 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As the most effective and practical geophysical methods, seismic imaging (Gao et al 2013;Karplus et al 2011;Kind et al 2002;Nabelek et al 2009;Nabelek and Nabelek 2014;Xu et al 2015a, b;Zhang et al 2011Zhang et al , 2013Zhao et al 2011Zhao et al , 2014aZhao and Nelson 1993) and magnetotelluric (MT) data modeling (Chen et al 1996;Le Pape et al 2012;Unsworth et al 2004Unsworth et al , 2005Wei et al 2001) have been widely applied to study the deep evolution and tectonic processes of the plateau over the past decades. Results of previous seismological studies have revealed some details for the extension Liang et al 2016;Tian et al 2015;Xu et al 2015a;Zhang et al 2015Zhang et al , 2016Zhang et al , 2011Zhao et al 2014b) and we believe that MT data can provide some indirect information to obtain a more comprehensive model. In this paper, we reprocessed previous MT data that were deployed in southern Tibet (Fig.…”

Section: Introductionmentioning

confidence: 75%

“…Seismic studies in western Tibet indicate that low-velocity zones exist widely in the middle crust and high velocity anomalies are imaged in the lower crust beneath southern Tibet and the hypothesis of radiogenic heating source appears to be unreasonable . Zhang et al (2015) suggest a LVZ above the northward underthrusting Indian slab beneath the YZS due to melts and/or fluids associated with the dehydration of the Indian plate. Unsworth et al (2005) discuss the crustal rheology beneath the Himalaya and southern Tibet by establishing a relationship between MT data and the partial melt fraction to obtain the effective viscosity.…”

Section: Discussionmentioning

confidence: 98%

See 1 more Smart Citation

Varying Indian crustal front in the southern Tibetan Plateau as revealed by magnetotelluric data

Xie

Jin

Wei

et al. 2017

Earth Planets Space

View full text Add to dashboard Cite

In the southern Tibetan plateau, which is considered to be the ongoing India-Eurasia continental collision zone, tracing of the Indian crustal front beneath Tibet is still controversial. We conducted deep subsurface electrical modeling in southern Tibet and discuss the geometry of the front of the Indian crust. Three areas along the Yarlung-Zangbo river zone for which previous magnetotelluric (MT) data are available were inverted independently using a three-dimensional MT inversion algorithm ModEM. Electrical horizontal slices at different depths and north-south oriented cross sections at different longitudes were obtained to provide a geoelectrical perspective for deep processes beneath the Tethyan Himalaya and Lhasa terrane. Horizontal slices at depths greater than − 15 km show that the upper crust is covered with resistive layers. Below a depth of − 20 km, discontinuous conductive distributions are primarily concentrated north of the Yarlung-Zangbo sutures (YZS) and could be imaged from mid-to lower crust. The results show that the maximum depth to which the resistive layers extend is over − 20 km, while the mid-to lower crustal conductive zones extend to depths greater than − 50 km. The results indicate that the conductive region in the mid-to lower crust can be imaged primarily from the YZS to south of the Bangong-Nujiang sutures in western Tibet and to ~ 31°N in eastern Tibet. The northern front of the conductive zones appears as an irregular barrier to the Indian crust from west to east. We suggest that a relatively less conductive subsurface in the northern portion of the barrier indicates a relatively cold and strong crust and that the front of the Indian crust might be halted in the south of the barrier. We suggest that the Indian crustal front varies from west to east and has at least reached: ~ 33.5°N at ~ 80°E, ~ 31°N at ~ 85°E, and ~ 30.5°N at ~ 87°E and ~ 92°E.

show abstract

Section: Introductionmentioning

confidence: 75%

Section: Discussionmentioning

confidence: 98%

Varying Indian crustal front in the southern Tibetan Plateau as revealed by magnetotelluric data

Xie

Jin

Wei

et al. 2017

Earth Planets Space

View full text Add to dashboard Cite

show abstract

“…The presence of substantial azimuthal anisotropy beneath Tibet is well established in studies using different techniques and data types, including surface-wave imaging (e.g., Griot et al 1998;Huang et al 2004;Su et al 2008;Yao et al 2010;Yi et al 2010;Yang et al 2010b;Ceylan et al 2012;Legendre et al 2015;Pandey et al 2015;Schaeffer et al 2016;Xie et al 2016;Chen et al 2016), shear-wave splitting analysis (e.g., McNamara et al 1994;Hirn et al 1995;Sandvol et al 1997;Sol et al 2007;Zhao et al 2010;Leon Soto et al 2012;Eken et al 2013;Chang et al 2015;Wu et al 2015a;Chen et al 2015;Liu et al 2016;Singh et al 2016;Ye et al 2016), receiver functions (e.g., Vergne et al 2003;Levin et al 2008;Shen et al 2015;Liu et al 2015;Kong et al 2016), attenuation studies (Bao et al 2012) and P-wave arrival times (e.g., Wei et al 2013;Huang et al 2014;Zhang et al 2016b;Wei et al 2016). Radial anisotropy (the difference between the vertically and horizontally polarized waves: V SV and V SH , respectively, in the case of S waves) is also well documented (e.g., Shapiro et al 2004;Huang et al 2010;Duret et al 2010;Guo et al 2012;Xie et al 2013;Li et al 2016).…”

Section: Azimuthal and Radial Anisotropy Beneath Tibet: A Brief Synthmentioning

confidence: 99%

Complex, multilayered azimuthal anisotropy beneath Tibet: evidence for co-existing channel flow and pure-shear crustal thickening

Agius

Lebedev²

2017

Geophysical Journal International

View full text Add to dashboard Cite

SUMMARYOf the two debated, end-member models for the late-Cenozoic thickening of Tibetan crust, one invokes "channel flow" (rapid viscous flow of the mid-lower crust, driven by topography-induced pressure gradients and transporting crustal rocks eastward) and the other-"pure shear" (faulting and folding in the upper crust, with viscous shortening in the mid-lower crust). Deep-crustal deformation implied by each model is different and would produce different anisotropic rock fabric. Observations of seismic anisotropy can thus offer a discriminant. We use broadband phase-velocity curves-each a robust average of tens to hundreds of measurements-to determine azimuthal anisotropy in the entire lithosphere-asthenosphere depth range and constrain its amplitude. Inversions of the differential dispersion from path pairs, region-average inversions and phase-velocity tomography yield mutually consistent results, defining two highly anisotropic layers with different fast-propagation directions within each: the middle crust and the asthenosphere.In the asthenosphere beneath central and eastern Tibet, anisotropy is 2-4 per cent and has a NNE-SSW fast-propagation azimuth, indicating flow probably driven by the NNEward, shallow-angle subduction of India. The distribution and complexity of published shear-wave splitting measurements can be accounted for by the different anisotropy in the mid-lower crust and asthenosphere. The estimated splitting times that would be ac-2 M.R. Agius and S. Lebedev cumulated in the crust alone are 0.25-0.8 s; in the upper mantle-0.5-1.2 s, depending on location. In the middle crust (20-45 km depth) beneath southern and central Tibet, azimuthal anisotropy is 3-5 and 4-6 per cent, respectively, and its E-W fast-propagation directions are parallel to the current extension at the surface. The rate of the extension is relatively low, however, whereas the large radial anisotropy observed in the middle crust requires strong alignment of mica crystals, implying large finite strain and consistent with high-rate horizontal flow. Together, radial and azimuthal anisotropy suggest eastward mid-crustal channel flow in central Tibet, along the regional topography gradient.In NE high Tibet, mid-crustal azimuthal anisotropy is 4-8 per cent and has WNW-ESE and NW-SE fast-propagation directions, parallel to the net extension at the surface. These fast directions are inconsistent with channel flow following the SW-NE regional topography gradient. Instead, they suggest similar net deformation in the (decoupled) shallow and deep crust. In the brittle upper crust, it is accommodated by strike-slip faulting; in the ductile mid-lower crust-by shear oriented at ∼45 • to the faults. Although mid-crustal flow beneath NE Tibet may transport some material towards the plateau periphery at a low region-average rate, the dominant mid-crust deformation pattern is shear parallel to the plateau boundary. This implies that channel flow from central Tibet is not the main cause of the on-going crustal thickening farther northeast.

show abstract

“…The subducting Indian plate is clearly imaged as a high-V zone beneath western, central and eastern parts of Tibet by teleseismic tomography using data recorded by portable seismic stations so far deployed along several profiles in the Tibetan Plateau (e.g., Zhang et al , 2014Zhao et al 2014). A typical example is the Indian lithosphere that is descending beneath the Eurasian plate, resulting in the Tibetan Plateau.…”

Section: Continental Plate Subductionsmentioning

confidence: 99%

Multiscale Seismic Tomography

Zhao

2015

Self Cite

100

View full text Add to dashboard Cite

Tomographic imaging of the underthrusting Indian slab and mantle upwelling beneath central Tibet

Cited by 32 publications

References 82 publications

Varying Indian crustal front in the southern Tibetan Plateau as revealed by magnetotelluric data

Varying Indian crustal front in the southern Tibetan Plateau as revealed by magnetotelluric data

Complex, multilayered azimuthal anisotropy beneath Tibet: evidence for co-existing channel flow and pure-shear crustal thickening

Multiscale Seismic Tomography

Contact Info

Product

Resources

About