Structure of the Crust and Mantle Down to 700 km Depth beneath the Longmenshan From <i>P</i> Receiver Functions

Qian, Hui; Mechie, J.; Li, Huan; Xue, Guangqi; Su, Hailin; Cui, Xiang

doi:10.1029/2017tc004726

Cited by 11 publications

(11 citation statements)

References 40 publications

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“…8) highlights a series of notable features that correspond to tectonic domains, with strong lateral variations across the major boundaries shaping the Tibetan plateau. These features are consistent with previous studies, including deep seismic soundings (Zeng et al 1995;Teng et al 2003) and passive seismic studies in the south (Acton et al 2011), northeast (Vergne et al 2002;Karplus et al 2011;Ye et al 2015), east (Zhang et al 2009;Qian et al 2018;Liu et al 2014) and southeast (Wang et al 2018a) of the plateau. For example, the thickest crust of 70-75 km is observed between the northern Lhasa Terrane and the Kunlun Fault (KF).…”

Section: Crustal Thicknesssupporting

confidence: 93%

Lithospheric structures of and tectonic implications for the central–east Tibetan plateau inferred from joint tomography of receiver functions and surface waves

Feng

Mechie

et al. 2020

Geophysical Journal International

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Summary We present an updated joint tomographic method to simultaneously invert receiver function waveforms and surface-wave dispersions for a 3-D S-wave velocity (Vs) model. By applying this method to observations from ∼900 seismic stations and with a priori Moho constraints from previous studies, we construct a 3-D lithospheric S-wave velocity model and crustal-thickness map for the central–east Tibetan plateau. Data misfit/fitting shows that the inverted model can fit the receiver functions and surface-wave dispersions reasonably well, and checkerboard tests show the model can retrieve major structural information. The results highlight several features. Within the plateau crustal thickness is > 60 km and outwith the plateau it is ∼40 km. Obvious Moho offsets and lateral variations of crustal velocities exist beneath the eastern (Longmen Shan Fault), northern (central-east Kunlun Fault) and northeastern (east Kunlun Fault) boundaries of the plateau, but with decreasing intensity. Segmented high upper-mantle velocities have varied occurrences and depth extents from south/southwest to north/northeast in the plateau. A Z-shaped upper-mantle low-velocity channel, which was taken as Tibetan lithospheric mantle, reflecting deformable material lies along the northern and eastern periphery of the Tibetan plateau, seemingly separating two large high-velocity mantle areas that respectively correspond to the Indian and Asian lithospheres. Other small high-velocity mantle segments overlain by the Z-shaped channel are possibly remnants of cold micro-plates/slabs associated with subductions/collisions prior to the Indian-Eurasian collision during the accretion of the Tibetan region. By integrating the Vs structures with known tectonic information, we derive that the Indian slab generally underlies the plateau south of the Bangong–Nujiang suture in central Tibet and the Jinsha River suture in eastern Tibet and west of the Lanchangjiang suture in southeastern Tibet. The eastern, northern, northeastern and southeastern boundaries of the Tibetan plateau have undergone deformation with decreasing intensity. The weakly resisting northeast and southeast margins, bounded by a wider softer channel of uppermost mantle material, are two potential regions for plateau expansion in the future.

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Section: Crustal Thicknesssupporting

confidence: 93%

Lithospheric structures of and tectonic implications for the central–east Tibetan plateau inferred from joint tomography of receiver functions and surface waves

Feng

Mechie

et al. 2020

Geophysical Journal International

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“…The thickening of the Tibetan crust and its southeastward flow mostly occurs along its SE margin (i.e., the crust in front of the Songpan‐Ganze terrane is thicker than that in surrounding areas). This interpretation is similar to the crustal thickening across the Longmenshan fault zone on the eastern Tibetan margin (e.g., Qian et al, 2018; Z. Zhang et al, 2009).…”

Section: Discussionsupporting

confidence: 78%

“…In contrast with sharp lateral variations in surface morphology and Moho depth across the Longmenshan fault zone on the eastern Tibetan margin, the southeastern (SE) Tibetan margin displays a relatively gentle variation in topography and diffuse pattern of surface deformation (e.g., Qian et al, 2018; Z. Zhang et al, 2009) (Figure 1a). Models proposed to account for the plateau's eastward growth include block extrusion guided by large‐scale strike‐slip faults (Molnar & Tapponnier, 1975; Tapponnier et al, 1982, 2001), continuous crustal shortening and thickening (England & Houseman, 1986; Yang & Liu, 2013), and lower crustal channel flow (Clark & Royden, 2000; Royden et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

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Sharp Lateral Moho Variations Across the SE Tibetan Margin and Their Implications for Plateau Growth

Huang

Wang

et al. 2020

JGR Solid Earth

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The tectonic uplift of the Tibetan Plateau is a focus in the geosciences. Middle‐lower crustal flow is a popular model to interpret the geodynamic mechanism on the margin of the Tibetan Plateau. The model predicts different surface and Moho topographies across the plateau boundary due to the different strengths of the surrounding blocks, that is, sharp boundaries on the eastern plateau boundary and gentle variations in the southeastern plateau boundary. Here, we employ receiver function and common conversion point stacking analysis with the seismic waveforms recorded by the dense ChinArray and other local seismic stations to accurately define the Moho topography in southeastern (SE) Tibet. We find that the Moho under the Tibetan Plateau is much deeper than that under the surrounding Yangtze Craton and Indochina block; abrupt Moho changes are found across the southeastern plateau margin, similar to that under the eastern plateau margin. We interpret these sharp Moho variations across the plateau margin to have developed when the Tibetan Plateau was extruded southeastward in the late Miocene. Subsequent gravity collapse resulted in crustal extension and gentle topographic variation, while the sharp Moho slope was preserved.

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“…7), CRUST2.0, (Fig. 8) and other recent studies (Qian et al, 2018;Xu et al, 2016;Wang et al, 2015). All these models indicate that crustal thickness is deeper to the west of the Longmen Mountains than to the east of the Longmen Mountains, which all showed an approximately 45 km thick crust below the Sichuan basin, thickening beneath the Longmen Mountains and the high Tibetan Plateau to about 60-80 km.…”

Section: Discussionsupporting

confidence: 69%

Inverting Rayleigh surface wave velocities for crustal thickness in eastern Tibet and the western Yangtze craton based on deep learning neural networks

Cheng

Liu

et al. 2019

Nonlin. Processes Geophys.

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Abstract. Crustal thickness is an important factor affecting lithospheric structure and deep geodynamics. In this paper, a deep learning neural network based on a stacked sparse auto-encoder is proposed for the inversion of crustal thickness in eastern Tibet and the western Yangtze craton. First, with the phase velocity of the Rayleigh surface wave as input and the theoretical crustal thickness as output, 12 deep-sSAE neural networks are constructed, which are trained by 380 000 and tested by 120 000 theoretical models. We then invert the observed phase velocities through these 12 neural networks. According to the test error and misfit of other crustal thickness models, the optimal crustal thickness model is selected as the crustal thickness of the study area. Compared with other ways to detect crustal thickness such as seismic wave reflection and receiver function, we adopt a new way for inversion of earth model parameters, and realize that a deep learning neural network based on data driven with the highly non-linear mapping ability can be widely used by geophysicists, and our result has good agreement with high-resolution crustal thickness models. Compared with other methods, our experimental results based on a deep learning neural network and a new Rayleigh wave phase velocity model reveal some details: there is a northward-dipping Moho gradient zone in the Qiangtang block and a relatively shallow north-west–south-east oriented crust at the Songpan–Ganzi block. Crustal thickness around Xi'an and the Ordos basin is shallow, about 35 km. The change in crustal thickness in the Sichuan–Yunnan block is sharp, where crustal thickness is 60 km north-west and 35 km south-east. We conclude that the deep learning neural network is a promising, efficient, and believable geophysical inversion tool.

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Structure of the Crust and Mantle Down to 700 km Depth beneath the Longmenshan From P Receiver Functions

Cited by 11 publications

References 40 publications

Lithospheric structures of and tectonic implications for the central–east Tibetan plateau inferred from joint tomography of receiver functions and surface waves

Lithospheric structures of and tectonic implications for the central–east Tibetan plateau inferred from joint tomography of receiver functions and surface waves

Sharp Lateral Moho Variations Across the SE Tibetan Margin and Their Implications for Plateau Growth

Inverting Rayleigh surface wave velocities for crustal thickness in eastern Tibet and the western Yangtze craton based on deep learning neural networks

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