High Vp/Vs ratio in the crust and uppermost mantle beneath volcanoes in the Central and Eastern Anatolia
High Vp/Vs ratio in the crust and uppermost mantle beneath volcanoes in the Central and Eastern Anatolia
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DOI：
10.1093/gji/ggy253
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发表时间：
2018-06
影响因子：
2.8
通讯作者：
Hejun Zhu
中科院分区：
文献类型：
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作者：
Hejun Zhu
本文在最近开发的欧洲大陆三维层析模型中分析了安纳托利亚地壳和上地幔的Vp、Vp和Vp/Vs比。在安纳托利亚中部和东部的火山场之下，地壳和上地幔中各向同性Vs明显减少，反映了研究区域与新近纪-第四纪岩浆活动相关的高温。这些慢波速度异常与模型中的高Vp/Vs比值有很好的对应关系。通过分析在VpandVsat不同深度的相对扰动，我观察到一个独特的模式与火山和非火山地区的网格点。与非火山网格点相比，火山网格点的线性回归结果具有较高的δlnVs/δ lnVp斜率。在火山区下方约50-60公里处观测到线性拟合斜率大于2.2的网格点。这些观测结果表明，在安纳托利亚中部和东部火山下的地壳和地幔上部存在部分熔融。地震观测与理论单相部分熔融计算之间的比较表明，在上地壳和下地壳中存在填充有几个体积百分比的熔体的裂缝。上地幔中可能存在长径比小于0.001的不完全熔融包裹体。
In this paper, I analyseVp,VsandVp/Vsratio for the crust and uppermost mantle of Anatolia in, a recently developed 3-D tomographic model for the European continent. Beneath volcanic fields in the Central and Eastern Anatolia, pronounced reductions in isotropicVsare observed in the crust and uppermost mantle, reflecting high temperature associated with Neogene–Quaternary magmatism in the study region. These slow wave speed anomalies correlate well with highVp/Vsratio in model. By analysing relative perturbations inVpandVsat different depths, I observe a distinct pattern for grid points associated with volcanic and non-volcanic regions. The linear regression results of volcanic grid points are characterized by high δlnVs/δlnVpslopes in comparison with non-volcanic grid points. Grid points with linear fitting slopes greater than 2.2 are observed around 50–60 km beneath volcanic provinces. These observations suggest the presence of partial melt in the crust and uppermost mantle beneath volcanoes in the Central and Eastern Anatolia. Comparisons between seismic observations with theoretical single phase partial melting calculations suggest the presence of cracks filled with a few volume per cent of melt in the upper and lower crust. Less thanmelt-filled inclusions with aspect ratio smaller than 0.001 might exist in the uppermost mantle.