DOI: 10.1016/j.tecto.2021.228932
论文题名: Pn tomography and anisotropic study of the Indian shield and the adjacent regions
作者: Illa B. ; Reshma K.S. ; Kumar P. ; Srinagesh D. ; Haldar C. ; Kumar S. ; Mandal P.
刊名: Tectonophysics
ISSN: 00401951
出版年: 2021
卷: 813 语种: 英语
中文关键词: Asia
; Indian Shield
; Pn wave
; Seismic anisotropy
; Tomography
; Uppermost mantle
英文关键词: Gravitation
; Seismic waves
; Structural geology
; Tectonics
; Tomography
; Velocity
; Wave propagation
; Absolute plate motions
; Body-wave tomographies
; Complex pattern
; Distance ranges
; Surrounding regions
; Tectonic deformations
; Tibetan Plateau
; Uppermost mantle
; Anisotropy
; collision zone
; gravity wave
; mantle source
; P-wave
; seismic anisotropy
; tectonic evolution
; tomography
; upper mantle
; Indian Shield
英文摘要: High-resolution P-wave velocity and anisotropy structure of the hitherto elusive uppermost mantle beneath the Indian shield and its surrounding regions are presented to unravel the tectonic imprints in the lithosphere. We inverted high quality 19,500 regional Pn phases from 172 seismological stations for 4780 earthquakes at a distance range of 2° to 15° with a mean apparent Pn velocity of 8.22 km/s. The results suggest that the Pn velocity anomalies with fast anisotropic directions are consistent with the collision environments in the Himalaya, Tibetan Plateau, Tarim Basin, and Burmese arc regions. The higher Pn anomalies along the Himalayan arc explicate the subducting cold Indian lithosphere. The cratonic upper mantle of the Indian shield is characterized by Pn velocity of 8.12–8.42 km/s, while the large part of the central Indian shield has higher mantle-lid velocity of ~8.42 km/s with dominant anisotropic value of 0.2–0.3 km/s (~7.5%) suggesting the presence of mafic ‘lava pillow’ related to the Deccan volcanism. The impressions of the rifts and the mobile belts are conspicuous in the velocity anomaly image indicating their deep seated origin. The Pn anisotropy in the Indian shield exhibits a complex pattern and deviates from the absolute plate motion directions derived from the SKS study, demonstrating the presence of frozen anisotropy in the Indian lithospheric uppermost mantle, due to the large scale tectonic deformation after its breakup from the Gondwanaland. Whereas, Pn and SKS anisotropic observations are well consistent in Tarim basin, Tibetan regions, eastern Himalayan syntaxis and the Burmese arc. The modeled anisotropic Pn clearly manifests a lower velocity anomaly bounded by 85°E and 90°E ridges in the southern Bay of Bengal. Further, 85°E ridge spatially separates the BoB lithosphere into faster and slower regions consistent with the body wave tomography and free-air gravity observation. © 2021 Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/170823
Appears in Collections: 气候变化与战略
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作者单位: CSIR- National Geophysical Research Institute, Uppal Road, Hyderabad, India
Recommended Citation:
Illa B.,Reshma K.S.,Kumar P.,et al. Pn tomography and anisotropic study of the Indian shield and the adjacent regions[J]. Tectonophysics,2021-01-01,813