Upper- and mid-crustal radial anisotropy beneath the central Himalaya and southern Tibet from seismic ambient noise tomography
Upper- and mid-crustal radial anisotropy beneath the central Himalaya and southern Tibet from seismic ambient noise tomography
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地震环境噪声层析成像显示喜马拉雅山中部和西藏南部的上地壳和中地壳径向各向异性
DOI：
10.1111/j.1365-246x.2012.05425.x
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发表时间：
2012-05
影响因子：
2.8
通讯作者：
Yao, Zhenxing
中科院分区：
文献类型：
--
作者：
Guo, Zhi;Gao, Xing;Wang, Wei;Yao, Zhenxing
通过对由地震环境噪声互相关恢复的瑞利波和乐夫波经验格林函数的分析，我们成像了藏南和喜马拉雅中部地区的径向各向异性和横波速度结构。喜马拉雅尼泊尔西藏地震实验项目部署的22个宽带地震台的密集射线路径覆盖为解决喜马拉雅中部和西藏南部地壳内的径向各向异性的空间分布提供了前所未有的机会。在浅层，主要与印度河-雅鲁山缝合带和喜马拉雅中部有关的负震级径向各向异性(Vsv&Gt；Vsh)明显，可能与青藏高原隆升过程中形成的古微裂隙或变质面理有关。随着深度的增加，径向各向异性的大小由负到正变化，并发现了一个具有显著正向各向异性(Vsv<；Vsh)的中地壳。中地壳各向异性层的顶部与我们先前研究中探测到的中地壳低速层的起始深度有很好的相关性。正的径向各向异性层和中地壳低速层的空间相关性可能表明，在喜马拉雅中部和西藏南部的中地壳内，由地壳侧向通道流动引起的矿物颗粒(最有可能是云母或角闪石)对齐。这一观测提供了独立的地震证据，支持热力学模型，该模型涉及青藏高原南侧集中的剥蚀效应驱动的低粘度中壳通道的南向挤压，以解释西藏喜马拉雅造山带的构造演化。
Through analysis of the Rayleigh wave and Love wave empirical Green's functions recovered from cross-correlation of seismic ambient noise, we image the radial anisotropy and shear wave velocity structure beneath southern Tibet and the central Himalaya. Dense ray path coverage from 22 broadband seismic stations deployed by the Himalayan Nepal Tibet Seismic Experiment project provides the unprecedented opportunity to resolve the spatial distribution of the radial anisotropy within the crust of the central Himalaya and southern Tibet. In the shallow subsurface, the obtained results indicate significant radial anisotropy with negative magnitude (VSV > VSH) mainly associated with the Indus Yarlung Suture and central Himalaya, possibly related to the fossil microcracks or metamorphic foliations formed during the uplifting of the Tibetan Plateau. With increasing depth, the magnitude of radial anisotropy varies from predominantly negative to predominantly positive, and a mid-crustal layer with prominent positive radial anisotropy (VSV < VSH) has been detected. The top of the mid-crustal anisotropic layer correlates nicely with the starting depth of the mid-crustal lower velocity layers detected in our previous study. The spatial correlation of the positive radial anisotropy layers and mid-crustal lower velocity layers might suggest lateral crustal channel flow induced alignment of mineral grains, most likely micas or amphiboles, within the mid-crust of the central Himalaya and southern Tibet. This observation provides independent seismic evidence to support the thermo-mechanical model, which involves the southward extrusion of a low viscosity mid-crustal channel driven by the denudation effect focused at the southern flank of the Tibetan Plateau to explain the tectonic evolution of the TibetanHimalayan orogen.
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影响因子：
64.8
作者：
M. Moschetti;M. Moschetti;M. Ritzwoller;F. Lin;Yingjie Yang
通讯作者：
M. Moschetti;M. Moschetti;M. Ritzwoller;F. Lin;Yingjie Yang
DOI：
10.1016/c2009-1-28330-4
发表时间：
2007
期刊：
--
影响因子：
--
作者：
G. Schubert
通讯作者：
G. Schubert
影响因子：
2.8
作者：
T. Yanovskaya;P. Ditmar
通讯作者：
T. Yanovskaya;P. Ditmar
影响因子：
1.6
作者：
T. Yanovskaya;E. S. Kizima;L. M. Antonova
通讯作者：
T. Yanovskaya;E. S. Kizima;L. M. Antonova
影响因子：
2.8
作者：
Bensen, G. D.;Ritzwoller, M. H.;Yang, Y.
通讯作者：
Yang, Y.