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

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.

Quaternary sodic and potassic intraplate volcanism in northeast China controlled by the underlying heterogeneous lithospheric structures

Geology ◽  
2021 ◽  
Author(s):  
Xingli Fan ◽  
Qi-Fu Chen ◽  
Yinshuang Ai ◽  
Ling Chen ◽  
Mingming Jiang ◽  
...  
Keyword(s):  
Upper Mantle ◽  
Lithospheric Mantle ◽  
Northeast China ◽  
Velocity Structure ◽  
Seismic Velocity ◽  
Subcontinental Lithospheric Mantle ◽  
Seismic Velocities ◽  
S Wave ◽  
Crust And Upper Mantle ◽  
Potassic Volcanism

The origin and mantle dynamics of the Quaternary intraplate sodic and potassic volcanism in northeast China have long been intensely debated. We present a high-resolution, three-dimensional (3-D) crust and upper-mantle S-wave velocity (Vs) model of northeast China by combining ambient noise and earthquake two-plane wave tomography based on unprecedented regional dense seismic arrays. Our seismic images highlight a strong correlation between the basalt geochemistry and upper-mantle seismic velocity structure: Sodic volcanoes are all characterized by prominent low seismic velocities in the uppermost mantle, while potassic volcanoes still possess a normal but thin upper-mantle “lid” depicted by high seismic velocities. Combined with previous petrological and geochemical research findings, we propose that the rarely erupted Quaternary potassic volcanism in northeast China results from the interaction between asthenospheric low-degree melts and the overlying subcontinental lithospheric mantle. In contrast, the more widespread Quaternary sodic volcanism in this region is predominantly sourced from the upwelling asthenosphere without significant overprinting from the subcontinental lithospheric mantle.

scholarly journals Upper Mantle P and S Wave Velocity Structure of the Kalahari Craton and Surrounding Proterozoic Terranes, Southern Africa

2019 ◽  
Vol 46 (16) ◽  
pp. 9509-9518 ◽  
Author(s):  
Kameron Ortiz ◽  
Andrew Nyblade ◽  
Mark Meijde ◽  
Hanneke Paulssen ◽  
Motsamai Kwadiba ◽  
...  
Keyword(s):  
Wave Velocity ◽  
Southern Africa ◽  
Upper Mantle ◽  
Velocity Structure ◽  
S Wave ◽  
Kalahari Craton
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