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Formation of Rifts in Central Tibet: Insight From P Wave Radial Anisotropy
Ist Teil von
Journal of geophysical research. Solid earth, 2018-10, Vol.123 (10), p.8827-8841
Ort / Verlag
Washington: Blackwell Publishing Ltd
Erscheinungsjahr
2018
Link zum Volltext
Quelle
Wiley Online Library
Beschreibungen/Notizen
The strikes of rifts in western Tibet show NNW‐SSE trending, whereas the rifts in eastern Tibet strike in the NNE‐SSW direction. The difference in the rift strike orientation suggests that the formation mechanisms of these rifts are different in southern Tibet, which can be most reliably inferred from seismic structure beneath these rifts. In this work we study 3‐D P wave velocity structure and radial anisotropy using a large number of travel time data recorded by the ANTILOPE and Hi‐CLIMB portable seismic arrays deployed in central Tibet. Our results show that to the west of the Pumuqu Xianza rift, a low‐velocity zone with a positive radial anisotropy exists beneath the Lopu Kangri rift (~85°E), which may reflect melt‐filled cracks. A high‐velocity zone with a negative radial anisotropy is revealed beneath the Pumuqu Xianza rift (~88°E), which reflects lithospheric downwelling. The different upper mantle structures may result in the patterns of rift strike orientation in central Tibet.
Key Points
Different formations of rifts are revealed in central Tibet
The regular strike orientations of rifts are related to different upper mantle structures
Lithospheric downwelling caused the Pumuqu Xianza rift