Imaging Poisson's Ratio of the Uppermost Mantle beneath China

Shi, Pengfei; Sun, Ying; Mn, Toksoz; John), Chen Yj (Chen Yongshun; Gao, Xin; Wang, Z; Jm, Zhao; Liu, Hb

doi:10.1785/0120090024

Cited by 8 publications

(6 citation statements)

References 33 publications

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“…Rather few V p / V s ratios for the uppermost mantle beneath China are reported. Though Pei et al [] imaged the Poisson's ratio of the uppermost mantle beneath China by inverting the travel time differences between Pn and Sn, assuming that P waves have the same raypaths as S waves.…”

Section: Discussionsupporting

confidence: 81%

Uppermost mantle structure beneath eastern China and its surroundings from Pn and Sn tomography

Sun

2016

Geophysical Research Letters

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The Pn and Sn residuals from regional events provide strong constraints on the structure and lithological characteristics of the uppermost mantle beneath eastern China and its surroundings. With the dense Chinese Digital Seismic Network in eastern China, separate Pn and Sn tomographic inversions have been exploited to obtain P and S velocities at a resolution of 2° × 2° or better. The patterns of P velocities are quite consistent with the S velocities at depth of 50 and 60 km, but the amplitude of P wave speed anomalies are a little larger than those of S wave speed. The low P wave speed, high S wave speed, and low Vp/Vs ratio beneath the northern part of Ordos Basin are related to upwelling hot material. Abrupt changes in material properties are indicated from the rapid variations in the Vp/Vs ratio.

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Section: Discussionsupporting

confidence: 81%

Uppermost mantle structure beneath eastern China and its surroundings from Pn and Sn tomography

Sun

2016

Geophysical Research Letters

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“…In eastern Tibet, a high Poisson's ratio anomaly was revealed in the crust [ Xu et al , 2007; Pei et al , 2011b], which suggests that the crust is deformable, and a lower S‐wave velocity indicates that the temperature of the crust is high [ Zhao et al , 2010]. Although the pervasive low‐V anomalies at shallower depths (Figures 4a and 4b) may suggest the existence of crustal flow in the study region, it is not clear whether the flow is continuous or not, even if it exists.…”

Section: Discussionmentioning

confidence: 99%

Convergence of the Indian and Eurasian plates under eastern Tibet revealed by seismic tomography

Zhang¹,

Zhao²,

Zhao³

et al. 2012

Geochem Geophys Geosyst

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[1] A three-dimensional P wave velocity model of the crust and upper mantle down to 400-km depth beneath eastern Tibet is obtained using many temporary seismic stations of the ASCENT project and the Namche Barwa Broadband Seismic Network. We collected 16,508 arrival times of P, Pn and Pg phases from 573 local and regional earthquakes and 7,450 P wave arrivals from seismograms of 435 teleseismic events. Our high-quality data set enables us to reconstruct the 3-D velocity structure under eastern Tibet in more detail than the previous studies. In the shallow depth, our results show that the low velocity zones are not interconnected well (no wide-spread low velocity zones), which may reflect the complex pattern of material flowing in the study region. Below the Moho, we find that the Indian lithospheric mantle underthrusts sub-horizontally under eastern Tibet, and the extent of the northward advancing Indian lithosphere decreases from west to east. In the north, the Asian lithospheric mantle is detected under the vicinity of the Qaidam Basin. Between the Indian and Asian lithospheric mantles, there is an obvious low-velocity anomaly which may reflect an upwelling mantle diapir.Components: 5400 words, 6 figures.

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“…The Pn velocities beneath northern Arabia and the Caspian region are faster than average [ Al‐Lazki et al , 2004; Ritzwoller et al , 2002; Angus et al , 2006]. The lower Pn and Sn velocities were observed in central Tibet than around blocks such as Tarim, Qaidam, Sichuan basin and Indian plate [ Barazangi and Ni , 1982; McNamara et al , 1997; Hearn et al , 2004; Liang et al , 2004; Phillips et al , 2005; Liang and Song , 2006; Sun and Toksoz , 2006; Sun et al , 2008; Pei et al , 2007, 2011]. This high degree of variability suggests that the earth structure may be extremely complicated in collision regions.…”

Section: Introductionmentioning

confidence: 99%

Tomographic Pn and Sn velocity beneath the continental collision zone from Alps to Himalaya

2011

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[1] We have obtained Vp and Vs velocity images of the uppermost mantle beneath the continental collision zone from the Alps to the Himalaya by performing tomographic inversion using both Pn and Sn travel times. 654,999 Pn arrivals and 121,838 Sn arrivals were selected from the joint database including ISC/EHB, Iran bulletin and the Annual Bulletin of Chinese Earthquakes. Average Pn and Sn velocities are 8.04 km/s and 4.60 km/s, respectively, and maximum velocity perturbations are about 6%. Pn velocity correlates well with topography. In general, mountains, with high elevations, show low velocity, while the seas, basins and plains with low elevations show high velocity because the mountains are collision zones with strong tectonic activity and the low elevation areas are stable plates. The large tectonic lines are boundaries between high and low Pn velocity, such as plate boundaries, sutures and faults between plates and orogens. Sn velocity shows a very similar pattern to Pn velocity. A geodynamic cartoon is proposed to show the relationship between velocity and tectonics, indicating that the sutures are boundaries with high dip angles and the plate boundaries are low angle reverse faults in the region.

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Imaging Poisson's Ratio of the Uppermost Mantle beneath China

Cited by 8 publications

References 33 publications

Uppermost mantle structure beneath eastern China and its surroundings from Pn and Sn tomography

Uppermost mantle structure beneath eastern China and its surroundings from Pn and Sn tomography

Convergence of the Indian and Eurasian plates under eastern Tibet revealed by seismic tomography

Tomographic Pn and Sn velocity beneath the continental collision zone from Alps to Himalaya

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