East-west crustal structure and “down-bowing” Moho under the northern Tibet revealed by wide-angle seismic profile

Zhang, Zhongjie; Li, Yingkang; Wang, Guangjie; Teng, Jun; Klemperer, S. L.; Li, Jingwei; Fan, Jinyi; Chen, Yun

doi:10.1360/02yd9057

Cited by 26 publications

(14 citation statements)

References 13 publications

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“…al.2005;KIND et al, 2002) have shown that the depth of Moho beneath the LSA station ranges between 73 and 78 km. Summarizing our results from receiver functions and the artificial sounding profile (ZHANG et al, 2001(ZHANG et al, , 2002, we believe that about 70 km of the depth of the Moho in this Vol. 165, 2008 Structure and Significance of S-wave Velocity and Poisson's Ratio area is more reliable.…”

Section: S-wave Velocity Structure In the Crust And Upper Mantlesupporting

confidence: 57%

“…Many studies (WU et. al., 2005;ZHANG et al, 2001;MITRA et al, 2005) conclude that a wide layer of low velocities exists in this area. Especially there exist two obvious interfaces beneath the LSA station at approximately a depths of 70 km and 90 km.…”

Section: S-wave Velocity Structure In the Crust And Upper Mantlementioning

confidence: 91%

“…The tectonics is closely related to the collision and squeezing of the Indian and Eurasian plates since 45 Ma, which generates the complex geological structure in the areas. Many studies (ZENG et al, 1992;ZHANG Z. et al, 2002;2001;2005a,b) indicate that the collision between the two huge plates caused severe crust deformation in the Sichuan-Yunnan areas and formed many structural units of fold systems and fault belts. The Sichuan-Yunnan areas are located at the southern end of the south-north Seismic Belt in China.…”

Section: Introductionmentioning

confidence: 99%

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Structure and Significance of S-wave Velocity and Poisson’s Ratio in the Crust beneath the Eastern Side of the Qinghai-Tibet Plateau

Yang

Zhang

2008

Pure appl. geophys.

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The receiver functions of body waves of distant earthquakes obtained for the regions beneath 41 digital stations (Lhasa and GANZ in Tibet, Mandalay and Rangoon in Myanmar, SHIO in India, CHTO in Thailand, and station network in Sichuan and Yunnan) were used to invert for S-wave structure in the crust and upper mantle in Sichuan, Yunnan, and their surrounding areas. Meanwhile the distribution characteristics of the Poisson's ration and the crustal thickness in Sichuan and Yunnan areas were also obtained. Results indicate that the depth of Moho beneath the eastern side of Qinghai-Tibetan plateau varies strikingly. It is obvious that the greatest changes in crustal thickness occur in a north-south direction. The crustal thickness decreases from north to south, being as thick as 70 km in eastern Tibet, the northern portion of our area of interest, and less than 30 km in Chaing Mai and Rangoon, the southern portion of our area. There are, however, exceptions regarding the trend. The thickness exhibits an east-west variation trend in the area from Ma'erkong-Kongding in Sichuan to Lijiang in Yunnan. In general the Jinpingshan-Longmenshan fault and Anninghe fault can be taken as the boundaries of this exception area. The thickness in Kongding in the west is 68 km, while it is only 39 km in Yongchuan in the east. Moreover the Poisson's ratio values in the blocks of central Sichuan and SichuanYunnan Diamond are high, and a low velocity layer in the crust of this area can be obviously detected. The distribution characteristics of the high Poisson's ratio and the low velocity of the crust in this block correspond to the tectonic structure, being in contrast with the surrounding areas. Combining with the distribution features of the modern tectonic stress field, it is deduced that the Sichuan-Yunnan area is probably the channel through which the materials of the lithosphere flow eastward.

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Section: S-wave Velocity Structure In the Crust And Upper Mantlesupporting

confidence: 57%

Section: S-wave Velocity Structure In the Crust And Upper Mantlementioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

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Structure and Significance of S-wave Velocity and Poisson’s Ratio in the Crust beneath the Eastern Side of the Qinghai-Tibet Plateau

Yang

Zhang

2008

Pure appl. geophys.

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“…Rayleigh and Love waves at periods longer than 30 and 40 s, respectively, make clear that the Plateau is mainly characterized by low velocities due to the presence of a thick crust (ZHANG et al, 2002(ZHANG et al, , 2004. The low velocity distribution at increasing periods indicates lateral heterogeneity of the upper mantle and the extrusion of deep materials (YIN and HARRISON, 2000;ZHANG and KLEMPERER, 2005).…”

Section: Discussionmentioning

confidence: 97%

Love and Rayleigh Wave Tomography of the Qinghai-Tibet Plateau and Surrounding Areas

Chen

Badal

2009

Pure Appl. Geophys.

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Surface wave data were initially collected from events of magnitude Ms C 5.0 and shallow or moderate focal depth occurred between 1980 and 2002: 713 of them generated Rayleigh waves and 660 Love waves, which were recorded by 13 broadband digital stations in Eurasia and India. Up to 1,525 source-station Rayleigh waveforms and 1,464 Love wave trains have been processed by frequency-time analysis to obtain group velocities. After inverting the path-averaged group times by means of a damped least-squares approach, we have retrieved location-dependent group velocities on a 2°9 2°-sized grid and constructed Rayleighand Love-wave group velocity maps at periods 10.4-105.0 s. Resolution and covariance matrices and the rms group velocity misfit have been computed in order to check the quality of the results. Afterwards, depth-dependent SV-and SH-wave velocity models of the crust and upper mantle are obtained by inversion of local Rayleigh-and Love-wave group velocities using a differential damped least-squares method. The results provide: (a) Rayleighand Love-wave group velocities at various periods; (b) SV-and SH-wave differential velocity maps at different depths; (c) sharp images of the subducted lithosphere by velocity cross sections along prefixed profiles; (d) regionalized dispersion curves and velocity-depth models related to the main geological formations. The lithospheric root presents a depth that can be substantiated at *140 km (Qiangtang Block) and exceptionally at *180 km in some places (Lhasa Block), and which exhibits laterally varying fast velocity very close to that of some shields that even reaches *4.8 km/s under the northern Lhasa Block and the Qiangtang Block. Slow-velocity anomalies of 7-10% or more beneath southern Tibet and the eastern edge of the Plateau support the idea of a mechanically weak middle-to-lower crust and the existence of crustal flow in Tibet.

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“…Hirn et al (1984) estimated that the average depth beneath the Lhasa terrane is ~55 km, while the average value of 70 km was suggested by Wu et al (1995). Zhang et al (2001) estimated the Moho depths in northern Tibet to be at least 80 km. Teleseismic receiver function analysis of seismograms recorded on a ~700 km long profile of 17 broadband seismographs traversing the north-west Himalayas conducted by Rai et al (2006) revealed a progressive northward Moho deepening from ~40 km beneath Delhi south of the Himalayan fore deep to ~75 km beneath Taksha at the Karakoram fault.…”

Section: Introductionmentioning

confidence: 99%

Moho Interface Modeling Beneath the Himalayas, Tibet and Central Siberia Using GOCO02S and DTM2006.0

Tenzer¹,

Bagherbandi²,

Hwang³

et al. 2013

Terr. Atmos. Ocean. Sci.

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We apply a newly developed method to estimate the Moho depths and density contrast beneath the Himalayas, Tibet and Central Siberia. This method utilizes the combined least-squares approach based on solving the inverse problem of isostasy and using the constraining information from the seismic global crustal model (CRUST2.0). The gravimetric forward modeling is applied to compute the isostatic gravity anomalies using the global geopotential model (GOCO02S)

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East-west crustal structure and “down-bowing” Moho under the northern Tibet revealed by wide-angle seismic profile

Cited by 26 publications

References 13 publications

Structure and Significance of S-wave Velocity and Poisson’s Ratio in the Crust beneath the Eastern Side of the Qinghai-Tibet Plateau

Structure and Significance of S-wave Velocity and Poisson’s Ratio in the Crust beneath the Eastern Side of the Qinghai-Tibet Plateau

Love and Rayleigh Wave Tomography of the Qinghai-Tibet Plateau and Surrounding Areas

Moho Interface Modeling Beneath the Himalayas, Tibet and Central Siberia Using GOCO02S and DTM2006.0

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