The mantle flow below the Alps from isolated mantle anisotropy based on differential Ps – XKS Splitting
The mantle flow below the Alps from isolated mantle anisotropy based on differential Ps – XKS Splitting
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基于微分 Ps 的孤立地幔各向异性的阿尔卑斯山下方的地幔流 – XKS 分裂
DOI：
10.5194/egusphere-egu2020-2810
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
G. Rümpker
中科院分区：
文献类型：
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作者：
F. Link;G. Rümpker
<p>SKS分裂测量在欧洲阿尔卑斯山显示各向异性快轴平行/亚平行相对于山区带。这表明，地幔流与旋转分量根据orthodox的假设下，快轴直接反映流动方向。由于地壳各向异性的可能贡献，这可能会产生误导。因此，我们隔离地壳各向异性使用改进的接收函数方法，占各向异性和结构特性。</p><p>地壳各向异性的分析基于Kaviani & R mpker（2015）提出的叠加方法ü。我们修改他们的方法，通过引入一个时间选择性分裂分析的地壳Ps和PpPs阶段。根据模型参数H、地壳厚度、纵横波速度比α、各向异性百分比和快轴方位，对各向异性效应校正后的相位进行叠加。</p><p>阿尔卑斯山由于其山根和复杂的构造历史而显示出相当大的莫霍地形。这可以显著地偏转地壳相位，从而在接收器功能中引入主导外观。因此，我们分析了倾斜界面（不考虑各向异性），然后在我们的分析中使用改进的模型来推断地壳的各向异性。</p><p>了解地壳各向异性的贡献，我们纠正这种影响的XKS波形隔离地幔的各向异性。剩余的分裂表明，在软流圈的流动模式的近似改进，而复杂性可能仍然意味着岩石圈地幔的影响。</p><p>我们将我们的方法应用于AlpArray网络的站点，从而在欧洲阿尔卑斯山的地壳各向异性的详细分布，并显示第一个结果，从校正的XKS波形和接收器功能分析的地壳各向异性的孤立地幔各向异性。</p>
<p>SKS-splitting measurements in the European Alps show an anisotropic fast axes parallel/subparallel relative to the mountain-belt. This indicates a mantle flow with a rotational component according to the orogeny under the assumption that the fast axes directly reflect the flow direction. This might be misleading due to a possible crustal contribution of anisotropy. Therefore, we isolate the crustal anisotropy using an improved receiver function method that accounts for anisotropic and structural properties.</p><p>The analysis for the crustal anisotropy is based on the stacking method proposed by Kaviani & Rümpker (2015). We modify their approach by introducing a time-selective splitting analysis of the crustal Ps- and PpPs-phases. The stacking is performed to the phases after correction of the anisotropic effect according to the model parameters H, the crustal thickness,  κ, the P-to S-wave velocity ratio, a, the percentage of anisotropy and φ, the fast axis orientation.</p><p>The Alps show a considerable Moho-topography due to its mountain root and its complex tectonic history. This can significantly deflect the crustal phases introducing a dominating appearance in the receiver functions. We therefore analyse for a dipping interface (not accounting for anisotropy) and then use an improved model in our analysis to infer the anisotropic properties of the crust.</p><p>Knowing the crustal anisotropic contribution we correct for this effect on the XKS-waveforms to isolate the anisotropy of the mantle. The remaining splitting shows an improved approximation of the flow patterns in the asthenosphere, while complexities might still imply an effect of the lithospheric mantle.</p><p>We apply our approach to stations of the AlpArray network resulting in a detailed distribution of the crustal anisotropy in the European Alps and show first results for the isolated mantle anisotropy from the corrected XKS-waveforms and the crustal anisotropy from the receiver-function analysis.</p>