TY - JOUR
T1 - A synoptic view of the distribution and connectivity of the mid-crustal low velocity zone beneath Tibet
AU - Yang, Yingjie
AU - Ritzwoller, Michael H.
AU - Zheng, Yong
AU - Shen, Weisen
AU - Levshin, Anatoli L.
AU - Xie, Zujun
N1 - Copyright 2012 by the American Geophysical Union. Originally published as Yang, Y., M. H. Ritzwoller, Y. Zheng, W. Shen, A. L. Levshin, and Z. Xie (2012), A synoptic view of the distribution and connectivity of the mid-crustal low velocity zone beneath Tibet, J. Geophys. Res., 117, B04303. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.
PY - 2012/4/1
Y1 - 2012/4/1
N2 - Based on 1-2 years of continuous observations of seismic ambient noise data obtained at more than 600 stations in and around Tibet, Rayleigh wave phase velocity maps are constructed from 10 s to 60 s period. A 3-D Vsv model of the crust and uppermost mantle is derived from these maps. The 3-D model exhibits significant apparently inter-connected low shear velocity features across most of the Tibetan middle crust at depths between 20 and 40 km. These low velocity zones (LVZs) do not conform to surface faults and, significantly, are most prominent near the periphery of Tibet. The observations support the internal deformation model in which strain is dispersed in the deeper crust into broad ductile shear zones, rather than being localized horizontally near the edges of rigid blocks. The prominent LVZs are coincident with strong mid-crustal radial anisotropy in western and central Tibet and probably result at least partially from anisotropic minerals aligned by deformation, which mitigates the need to invoke partial melt to explain the observations. Irrespective of their cause in partial melt or mineral alignment, mid-crustal LVZs reflect deformation and their amplification near the periphery of Tibet provides new information about the mode of deformation across Tibet.
AB - Based on 1-2 years of continuous observations of seismic ambient noise data obtained at more than 600 stations in and around Tibet, Rayleigh wave phase velocity maps are constructed from 10 s to 60 s period. A 3-D Vsv model of the crust and uppermost mantle is derived from these maps. The 3-D model exhibits significant apparently inter-connected low shear velocity features across most of the Tibetan middle crust at depths between 20 and 40 km. These low velocity zones (LVZs) do not conform to surface faults and, significantly, are most prominent near the periphery of Tibet. The observations support the internal deformation model in which strain is dispersed in the deeper crust into broad ductile shear zones, rather than being localized horizontally near the edges of rigid blocks. The prominent LVZs are coincident with strong mid-crustal radial anisotropy in western and central Tibet and probably result at least partially from anisotropic minerals aligned by deformation, which mitigates the need to invoke partial melt to explain the observations. Irrespective of their cause in partial melt or mineral alignment, mid-crustal LVZs reflect deformation and their amplification near the periphery of Tibet provides new information about the mode of deformation across Tibet.
UR - http://www.scopus.com/inward/record.url?scp=84859731353&partnerID=8YFLogxK
U2 - 10.1029/2011JB008810
DO - 10.1029/2011JB008810
M3 - Article
AN - SCOPUS:84859731353
SN - 0148-0227
VL - 117
SP - 1
EP - 20
JO - Journal of Geophysical Research
JF - Journal of Geophysical Research
IS - 4
M1 - B04303
ER -