Lithospheric structure beneath the central and western North China Craton and the adjacent Qilian orogenic belt from Rayleigh wave dispersion analysis

Wei, Zigen; Chen, Ling; Jiang, Mingming; Ling, Yuan Yuan

doi:10.1016/j.tecto.2015.02.008

Cited by 24 publications

(9 citation statements)

References 61 publications

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“…The average velocity model of the craton is complicated, due to the two relatively low velocity layers observed at 100–140 km and 185–210 km depths. The shallow one may be within the lithospheric mantle and the deep one related to the lithosphere‐asthenosphere boundary, as suggested by S wave receiver functions [ Chen et al , ] and Rayleigh wave analysis in the Ordos Block [ Jiang et al , ; Wei et al , ].…”

Section: Tomography Resultsmentioning

confidence: 99%

“…Due to the expected great variations in lithospheric structure from Northeastern Tibet to the craton region [ Li and van der Hilst , ; L. Zhao et al , ; H. Li et al , ; Chen et al , ; Jiang et al , ; Wei et al , , ], we divided the region into two subareas according to the tectonic boundaries: the craton and Tibet. The nodes within different subareas used different model settings in shear wave velocity inversions.…”

Section: Methodsmentioning

confidence: 99%

“…In between the blocks is the Khondalite Belt, along which the Yinshan and Ordos Blocks collided in the Paleoproterozoic [ Zhao et al , ; G. Zhao et al , ]. Geophysical and geological studies show that the lithosphere of the Ordos Block is light, thick, and refractory, with high seismic wave velocities and low seismicity [ Li and Yang , ; L. Zhao et al , ; Zhu et al , ; Jiang et al , ; Chen et al , ; Wei et al , ]. These observations suggest that the Ordos Block is stable and generally intact [ Zhu et al , ], although it is surrounded by two Cenozoic rifts (Figure ), namely, the Shanxi‐Shaanxi Rift and the Yinchuan‐Hetao Rift [ Zhang et al , ].…”

Section: Geological Settingmentioning

confidence: 99%

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Limited southward underthrusting of the Asian lithosphere and material extrusion beneath the northeastern margin of Tibet, inferred from teleseismic Rayleigh wave tomography

et al. 2017

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The northeastern margin of Tibet is of key importance in understanding the uplift and expansion of Tibetan Plateau. In this research, we perform Rayleigh wave tomography from 20 s to 167 s using the data recorded by China Digital Seismic Network and several portable seismic arrays in Northeastern Tibet and adjacent areas. Our resultant 3‐D shear wave velocity model exhibits strong lateral variations in the lithosphere. High shear wave velocities are observed in the mantle of the cratonic Ordos and Yangtze Blocks, as well as the East Qinling Orogen. The Qilian Orogen is underlain by a ∼120 km thick lithosphere of intermediate velocities and a low‐velocity layer of asthenospheric mantle below the depth of 120 km. Low velocities are characteristic in the middle‐to‐lower crust of the Songpan‐Ganzi Terrane and the West Qinling Orogen, possibly representing the crustal flow penetrating the Kunlun Fault. An uppermost mantle low‐velocity zone is found in the same location, indicating either the asthenosphere upwelling or the transitional crust‐mantle boundary layer. Our observations have two tectonic implications. First, the large‐scale eastward Tibetan material extrusion into Eastern China through the East Qinling Orogen is unlikely to be an ongoing process above 200 km depth; second, the southward subduction of the North China Craton toward Northeastern Tibet may not have fully developed in this region. Furthermore, we propose that the difference in the lithospheric strength between the Qaidam Block and the West Qinling Orogen is a critical element to control the tectonics in the northeastern margin of Tibet.

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Section: Tomography Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

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Limited southward underthrusting of the Asian lithosphere and material extrusion beneath the northeastern margin of Tibet, inferred from teleseismic Rayleigh wave tomography

et al. 2017

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“…The depositional thickness decreases southeastward in the Ordos block (Figure ), suggesting that the extensional effect caused by the mantle convection decreased southeastward [ Zhang et al ., ]. The relatively low velocity in the upper mantle beneath the northern Ordos block (Figures g–h) may represent upwelling of asthenospheric material and may indicate that the northern Ordos block experienced lithospheric modification during the Cenozoic [e.g., Bao et al ., ; Wei et al ., ]. Thus, the modification of the lithosphere beneath the Ordos block may also be associated with the mantle flow.…”

Section: Discussionmentioning

confidence: 99%

Three‐dimensional lithospheric S wave velocity model of the NE Tibetan Plateau and western North China Craton

Xingchen

Ding

et al. 2017

JGR Solid Earth

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We present a new 3‐D lithospheric Vs model for the NE Tibetan Plateau (NETP) and the western North China Craton (NCC). First, high‐frequency receiver functions (RFs) were inverted using the neighborhood algorithm to estimate the sedimentary structure beneath each station. Then a 3D Vs model with unprecedented resolution was constructed by jointly inverting RFs and Rayleigh wave dispersions. A low‐velocity sedimentary layer with thicknesses varying from 2 to 10 km is present in the Yinchuan‐Hetao graben, Ordos block, and western Alxa block. Velocities from the middle‐lower crust to the uppermost mantle are generally high in the Ordos block and low in the Alxa block, indicating that the Alxa block is not part of the NCC. The thickened crust in southwestern Ordos block and western Alxa block suggests that they have been modified. Two crustal low‐velocity zones (LVZs) were detected beneath the Kunlun Fault (KF) zone and western Qilian Terrane (QLT). The origin of the LVZ beneath the KF zone may be the combined effect of shear heating, localized asthenosphere upwelling, and crustal radioactivity. The LVZ in the western QLT, representing an early stage of the LVZ that has developed in the KF zone, acts as a decollement to decouple the deformation between the upper and lower crust and plays a key role in seismogenesis. We propose that the crustal deformation beneath the NETP is accommodated by a combination of shear motion, thickening of the upper‐middle crust, and removal of lower crust.

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“…The heat flow is moderate (about 60 mW/m 2 ) in these areas [ Hu et al , ; Wang , ; Tao and Shen , ], and the temperature in the lower crust (40 km depth) is estimated to be ~700–800° revealed by a 3‐D thermal structure study [ Sun et al , ], both of which indicate that the temperature may not be high enough to result in partial melting in the lower crust. However, prominent low‐ V anomalies exist in the upper mantle beneath the Qilian Orogenic Belt and Western Qinling, reflecting hot materials in the upper mantle there [e.g., Tian et al , ; Li et al , ; Pandey et al , ; Wei et al , ], which result in the moderate heat flow in these areas and heat the lower crust to a certain extent.…”

Section: Interpretation and Discussionmentioning

confidence: 99%

Seismic tomography and anisotropy of the Helan‐Liupan tectonic belt: Insight into lower crustal flow and seismotectonics

et al. 2016

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We determined detailed 3‐D P and S wave velocities (Vp and Vs) and Poisson's ratio (σ) images as well as P wave azimuthal anisotropy in the crust and uppermost mantle beneath the Helan‐Liupan tectonic belt (HLTB) and adjacent regions. The data set used in this study consists of 38,880 P wave and 35,117 S wave arrival times from 5028 local earthquakes recorded by 66 seismic stations in the study area during 1980 to 2014. Obvious low‐Vp and low‐σ anomalies are revealed in the lower crust beneath the Qilian Orogenic Belt and Western Qinling, which we interpret as a weakened zone mainly caused by water and capable of ductile flow on a geological timescale. Our P wave anisotropy results suggest that the flow direction in the lower crust is nearly parallel to the direction of the geodetic crustal motion and that of the upper mantle flow beneath the study region. Most of the 26 large historical earthquakes (1125–1954) in the study region occurred in the boundary zones where Vp, Vs, and σ change drastically over a short distance. Beneath the source areas of the large historical earthquakes, fluid‐related low‐velocity zones exist widely in the lower crust. The fluids result from dehydration of hydrous minerals in the deeper crust and uppermost mantle beneath the northeastern Tibetan Plateau. When the fluids migrate upward to the active faults, the fault zone friction is reduced and so large crustal earthquakes can be triggered. Our present results shed new light on the seismogenesis and geodynamics of the northeastern Tibetan Plateau and adjacent areas.

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Lithospheric structure beneath the central and western North China Craton and the adjacent Qilian orogenic belt from Rayleigh wave dispersion analysis

Cited by 24 publications

References 61 publications

Limited southward underthrusting of the Asian lithosphere and material extrusion beneath the northeastern margin of Tibet, inferred from teleseismic Rayleigh wave tomography

Limited southward underthrusting of the Asian lithosphere and material extrusion beneath the northeastern margin of Tibet, inferred from teleseismic Rayleigh wave tomography

Three‐dimensional lithospheric S wave velocity model of the NE Tibetan Plateau and western North China Craton

Seismic tomography and anisotropy of the Helan‐Liupan tectonic belt: Insight into lower crustal flow and seismotectonics

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