scholarly journals S wave Velocity Structure of the Crust and Upper Mantle Beneath Shanxi Rift, Central North China Craton and its Tectonic Implications

Tectonics ◽  
2021 ◽  
Vol 40 (4) ◽  
Author(s):  
Yan Cai ◽  
Jianping Wu ◽  
Andreas Rietbrock ◽  
Weilai Wang ◽  
Lihua Fang ◽  
...  
Keyword(s):  
Wave Velocity ◽  
Upper Mantle ◽  
North China Craton ◽  
North China ◽  
Velocity Structure ◽  
S Wave ◽  
Crust And Upper Mantle ◽  
Tectonic Implications ◽  
Shanxi Rift

Crust-mantle velocity structure in Shanxi rift, Central North China Craton

2020 ◽  
Author(s):  
Yan Cai ◽  
Jianping Wu
Keyword(s):  
Upper Mantle ◽  
High Velocity ◽  
North China Craton ◽  
Lower Crust ◽  
North China ◽  
Velocity Structure ◽  
Low Velocity ◽  
Crust And Upper Mantle ◽  
The North ◽  
Shanxi Rift

<p>North China Craton is the oldest craton in the world. It contains the eastern, central and western part. Shanxi rift and Taihang mountain contribute the central part. With strong tectonic deformation and intense seismic activity, its crust-mantle deformation and deep structure have always been highly concerned. In recent years, China Earthquake Administration has deployed a dense temporary seismic array in North China. With the permanent and temporary stations, we obtained the crust-mantle S-wave velocity structure in the central North China Craton by using the joint inversion of receiver function and surface wave dispersion. The results show that the crustal thickness is thick in the north of the Shanxi rift (42km) and thin in the south (35km). Datong basin, located in the north of the rift, exhibits large-scale low-velocity anomalies in the middle-lower crust and upper mantle; the Taiyuan basin and Linfen basin, located in the central part, have high velocities in the lower crust and upper mantle; the Yuncheng basin, in the southern part, has low velocities in the lower crust and upper mantle velocities, but has a high-velocity layer below 80 km. We speculate that an upwelling channel beneath the west of the Datong basin caused the low velocity anomalies there. In the central part of the Shanxi rift, magmatic bottom intrusion occurred before the tension rifting, so that the heated lithosphere has enough time to cool down to form high velocity. Its current lithosphere with high temperature may indicate the future deformation and damage. There may be a hot lithospheric uplift in the south of the Shanxi rift, heating the crust and the lithospheric mantle. The high-velocity layer in its upper mantle suggests that the bottom of the lithosphere after the intrusion of the magma began to cool down.</p>

Crust and Upper Mantle S-Wave Velocity Structure Across Northeastern Tibetan Plateau and Ordos Block

2005 ◽  
Vol 48 (2) ◽  
pp. 369-379 ◽  
Author(s):  
Jiu-Hui CHEN ◽  
Qi-Yuan LIU ◽  
Shun-Cheng LI ◽  
Biao GUO ◽  
Yuan-Gen LAI
Keyword(s):  
Tibetan Plateau ◽  
Wave Velocity ◽  
Upper Mantle ◽  
Velocity Structure ◽  
S Wave ◽  
Crust And Upper Mantle ◽  
Ordos Block ◽  
Northeastern Tibetan Plateau

scholarly journals Vestiges of underplating and assembly in the central North China Craton based on S-wave velocities

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Haoyu Tian ◽  
Chuansong He
Keyword(s):  
Group Velocity ◽  
Wave Velocity ◽  
Crustal Structure ◽  
North China Craton ◽  
Lower Crust ◽  
North China ◽  
Velocity Structure ◽  
S Wave ◽  
Middle Crust ◽  
Wave Velocities

AbstractThe destruction of the North China Craton (NCC) is a controversial topic among researchers. In particular, the crustal structure associated with the craton’s destruction remains unclear, even though a large number of seismic studies have been carried out in this area. To investigate the crustal structure and its dynamic implications, we perform noise tomography in the central part of the NCC. In this study, continuous vertical-component waveforms spanning one year from 112 broadband seismic stations are used to obtain the group velocity dispersion curves of Rayleigh waves at different periods, and surface wave tomography is employed to extract the Rayleigh wave group velocity distributions at 9–40 s. Finally, the S-wave velocity structure at depths of 0–60 km is determined by the inversion of pure-path dispersion data. The results show obvious differences in the crustal structure among the Western Block (WB), the Trans-North China Orogen (TNCO) and the Eastern Block (EB). The lower crust of the northern part of the EB exhibits a high-velocity S-wave anomaly, which may be related to magmatic underplating in the lower crust induced by an upwelling mantle plume. The S-wave velocity of the WB is lower than that of the TNCO in the upper and middle crust and is lower than that of both the TNCO and the EB in the lower crust. The crust of the TNCO shows higher S-wave velocities than the WB and EB in the upper and middle crust, and its overall S-wave velocity structure is clearly different from those of the WB and EB, implying that the crustal structure of the TNCO may contain vestiges of the Paleoproterozoic collision between the WB and EB and their subsequent assembly. This study marks the first time these findings are identified for the NCC.

Constraints on the composition of the crust and uppermost mantle in northwestern Canada: Vp/Vs variations along Lithoprobe's SNorCLE transect

2005 ◽  
Vol 42 (6) ◽  
pp. 1205-1222 ◽  
Author(s):  
Gabriela Fernández-Viejo ◽  
Ron M Clowes ◽  
J Kim Welford
Keyword(s):  
Wave Velocity ◽  
Upper Mantle ◽  
Laboratory Data ◽  
High Ratio ◽  
P Wave ◽  
S Wave ◽  
Uppermost Mantle ◽  
Crust And Upper Mantle ◽  
Slave Craton ◽  
Crustal Composition

Shear-wave seismic data recorded along four profiles during the SNoRE 97 (1997 Slave – Northern Cordillera Refraction Experiment) refraction – wide-angle reflection experiment in northwestern Canada are analyzed to provide S-wave velocity (Vs) models. These are combined with previous P-wave velocity (Vp) models to produce cross sections of the ratio Vp/Vs for the crust and upper mantle. The Vp/Vs values are related to rock types through comparisons with published laboratory data. The Slave craton has low Vp/Vs values of 1.68–1.72, indicating a predominantly silicic crustal composition. Higher values (1.78) for the Great Bear and eastern Hottah domains of the Wopmay orogen imply a more mafic than average crustal composition. In the western Hottah and Fort Simpson arc, values of Vp/Vs drop to ∼1.69. These low values continue westward for 700 km into the Foreland and Omineca belts of the Cordillera, providing support for the interpretation from coincident seismic reflection studies that much of the crust from east of the Cordilleran deformation front to the Stikinia terrane of the Intermontane Belt consists of quartzose metasedimentary rocks. Stikinia shows values of 1.78–1.73, consistent with its derivation as a volcanic arc terrane. Upper mantle velocity and ratio values beneath the Slave craton indicate an ultramafic peridotitic composition. In the Wopmay orogen, the presence of low Vp/Vs ratios beneath the Hottah – Fort Simpson transition indicates the presence of pyroxenite in the upper mantle. Across the northern Cordillera, low Vp values and a moderate-to-high ratio in the uppermost mantle are consistent with the region's high heat flow and the possible presence of partial melt.

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