Teleseismic shear-wave splitting in SE Tibet: Insight into complex crust and upper-mantle deformation

Huang, Zhouchuan; Wang, Liangshu; Xu, Mingjie; Ding, Zhongli; Wu, Yanqiang; Wang, Pan; Mi, Ning; Yu, Dan; Hua, Li

doi:10.1016/j.epsl.2015.10.027

Cited by 49 publications

(53 citation statements)

References 49 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For other labelings, see Fig. 1 the pure-shear deformation in the lithosphere (e.g., Huang et al 2015a). Therefore, the model of lateral lithospheric extrusion (e.g., Tapponnier et al 1982Tapponnier et al , 2001 or thickening Asian crust (England and Houseman 1989) is potential model for the tectonics and dynamics in Yunnan SE to Tibet while ductile mid-lower crustal flow (e.g., Royden et al 1997Royden et al , 2008 does not exist to the south of 26°N in Yunnan.…”

Section: Discussionmentioning

confidence: 99%

“…9 Comparison between teleseismic shear-wave (e.g., SKS) splitting observations (orange and red bars) and the tensional axis (S h ; yellow bars) obtained in this study. The orange bars are the individual shear-wave splitting measurements in this region (e.g., Flesch et al 2005;Huang et al 2007Huang et al , 2011aHuang et al , 2015aLev et al 2006;Sol et al 2007;Wang et al 2008Wang et al , 2013 while the red bars are the smoothed averages in 2°9 2°areas surrounding the grid node…”

Section: Discussionmentioning

confidence: 99%

“…The mantle strain field is usually inferred from teleseismic shear-wave (e.g., SKS) splitting observations where the fast polarization directions of the fast S wave is parallel to the maximum strain axes (e.g., Mainprice 2007;Karato et al 2008). The average delay times of SKS splitting in Yunnan are of the order of 1.0-1.5 s (e.g., Flesch et al 2005;Lev et al 2006;Huang et al 2007Huang et al , 2011aHuang et al , 2015aSol et al 2007;Wang et al 2008Wang et al , 2013. Contribution of crustal anisotropy inferred from Pms splitting (Sun et al 2013) and surface wave inversion ) is generally \0.3 s in most Yunnan in spite of some larger delay time to the north of 26°N (Sun et al 2012).…”

Section: Discussionmentioning

confidence: 99%

“…The structures and dynamics in SE Tibet are essentially important for understanding the tectonic evolution of the plateau. However, there is ongoing debates on whether the crust and upper mantle are coupled or not beneath Yunnan SE to Tibet on the basis of the comparison between the crustal strain field inferred from GPS observations and the upper-mantle strain field inferred from teleseismic shear-wave (i.e., SKS, SKKS, and PKS) splitting analysis (e.g., Flesch et al 2005;Wang et al 2008;Huang et al 2015a).…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Crustal stress field in Yunnan: implication for crust-mantle coupling

Huang

Wang

et al. 2016

Earthq Sci

Self Cite

View full text Add to dashboard Cite

We applied the gCAP algorithm to determine 239 focal mechanism solutions 3:0 M W 6:0 ð Þwith records of dense ChinArray stations deployed in Yunnan, and then inverted 686 focal mechanisms (including 447 previous results) for the regional crustal stress field with a damped linear inversion. The results indicate dominantly strike-slip environment in Yunnan as both the maximum (r 1 ) and minimum (r 3 ) principal stress axes are sub-horizontal. We further calculated the horizontal stress orientations (i.e., maximum and minimum horizontal compressive stress axes: S H and S h , respectively) accordingly and found an abrupt change near *26°N. To the north, S H aligns NW-SE to nearly E-W while S h aligns nearly N-S. In contrast, to the south, both S H and S h rotate laterally and show dominantly fan-shaped patterns. The minimum horizontal stress (i.e., maximum strain axis) S h rotates from NW-SE to the west of Tengchong volcano gradually to nearly E-W in west Yunnan, and further to NE-SW in the South China block in the east. The crustal strain field is consistent with the upper mantle strain field indicated by shear-wave splitting observations in Yunnan but not in other regions. Therefore, the crust and upper mantle in Yunnan are coupled and suffering vertically coherent pure-shear deformation in the lithosphere.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Crustal stress field in Yunnan: implication for crust-mantle coupling

Huang

Wang

et al. 2016

Earthq Sci

Self Cite

View full text Add to dashboard Cite

show abstract

“…[] suggested that the delamination of a thickened lithospheric root could occur beneath the eastern Tibet and be responsible for the growth of the eastern Tibetan margin. In the southeastern margin of the Tibetan Plateau, seismic anisotropy from shear wave splitting reveals a conspicuous change in the fast direction, implying the existence of complex mantle deformation [ Lev et al ., ; Huang et al ., ].…”

Section: Introductionmentioning

confidence: 99%

Lithospheric structure of the southeastern margin of the Tibetan Plateau from Rayleigh wave tomography

Gao

et al. 2017

JGR Solid Earth

View full text Add to dashboard Cite

Lithospheric shear wave velocity beneath the southeastern margin of the Tibetan Plateau is obtained from Rayleigh wave tomography using earthquake data recorded by the temporary ChinArray and permanent China Digital Seismic Array. Fundamental mode Rayleigh wave phase velocities at periods of 20–100 s are determined and used to construct the 3‐D shear wave velocity model. Low‐velocity anomalies appear along or close to the major faults in the middle crust and become a broad zone in the lower crust, suggesting block extrusion in the shallow crust and diffuse deformation in the lower crust, both of which play important roles in accommodating the collision between the Indian and Eurasian plates. A vertical low‐velocity column beneath the Tengchong Volcano is observed, which could be caused by upwelling of warm mantle due to the lithosphere extension in the Thailand rift basin to the south or by fluid‐induced partial melting due to the subduction of the Burma slab. The western Yangtze Craton is characterized by low velocity in the crust and uppermost mantle above the fast mantle lithosphere, indicating possible thermal erosion at the western craton edge resulted from the extrusion of the Tibetan Plateau. A low‐velocity zone is imaged at the depths of 70–150 km beneath the eastern part of the Yangtze Craton, which could be caused by small‐scale mantle convection associated with the subduction of the Burma microplate and/or the opening of the South China Sea.

show abstract

Fault Slip and GPS Velocities Across the Shan Plateau Define a Curved Southwestward Crustal Motion Around the Eastern Himalayan Syntaxis

et al. 2018

View full text Add to dashboard Cite

Characterizing the 700 km wide system of active faults on the Shan Plateau, southeast of the eastern Himalayan syntaxis, is critical to understanding the geodynamics and seismic hazard of the large region that straddles neighboring China, Myanmar, Thailand, Laos, and Vietnam. Here we evaluate the fault styles and slip rates over multi‐timescales, reanalyze previously published short‐term Global Positioning System (GPS) velocities, and evaluate slip‐rate gradients to interpret the regional kinematics and geodynamics that drive the crustal motion. Relative to the Sunda plate, GPS velocities across the Shan Plateau define a broad arcuate tongue‐like crustal motion with a progressively northwestward increase in sinistral shear over a distance of ~700 km followed by a decrease over the final ~100 km to the syntaxis. The cumulative GPS slip rate across the entire sinistral‐slip fault system on the Shan Plateau is ~12 mm/year. Our observations of the fault geometry, slip rates, and arcuate southwesterly directed tongue‐like patterns of GPS velocities across the region suggest that the fault kinematics is characterized by a regional southwestward distributed shear across the Shan Plateau, compared to more block‐like rotation and indentation north of the Red River fault. The fault geometry, kinematics, and regional GPS velocities are difficult to reconcile with regional bookshelf faulting between the Red River and Sagaing faults or localized lower crustal channel flows beneath this region. The crustal motion and fault kinematics can be driven by a combination of basal traction of a clockwise, southwestward asthenospheric flow around the eastern Himalayan syntaxis and gravitation or shear‐driven indentation from north of the Shan Plateau.

show abstract

Teleseismic shear-wave splitting in SE Tibet: Insight into complex crust and upper-mantle deformation

Cited by 49 publications

References 49 publications

Crustal stress field in Yunnan: implication for crust-mantle coupling

Crustal stress field in Yunnan: implication for crust-mantle coupling

Lithospheric structure of the southeastern margin of the Tibetan Plateau from Rayleigh wave tomography

Fault Slip and GPS Velocities Across the Shan Plateau Define a Curved Southwestward Crustal Motion Around the Eastern Himalayan Syntaxis

Contact Info

Product

Resources

About