Eastern Turkey is an ideal location to study continental collision, which is manifested here by the presence of extensive volcanism and rapid tectonic uplift. To better understand the relationship between these surface phenomena and underground structures, we collect continuous waveform data from 121 seismic stations in the region to investigate the S wave velocity structure of the crust and upper mantle using ambient noise tomography. We obtain Rayleigh wave dispersion curves for periods between 5 and 100 s based on frequency-Bessel (F-J) transform dispersion analysis. We then perform quasi-Newton inversion to calculate the S wave velocity structure between 0 and 200 km. The results indicate the presence of two high-velocity anomalies: one in the southern Black Sea that may represent stable and cold lithospheric mantle and another near Lake Van that may represent the subduction remnant of the southern branch of the Neo-Tethys Ocean. In addition, the results demonstrate that the overall velocity in the study area is lower than the global average and reveal extensive upper mantle low-velocity zones (UMLVZs) which represent asthenospheric materials, and mid-crustal low-velocity zones (MCLVZs). In this study, we propose two possible formation mechanisms of the MCLVZs: one is partial melting, and the other is the formation of low-velocity compositional layering due to complex refining and differentiation processes and subsequent continent reworking. Considering that the spatial distribution of the MCLVZs and UMLVZs is well correlated with regional volcanic activity, the MCLVZs and UMLVZs may provide the driving force and are the material sources for volcanism in the area. Furthermore, the extremely thin and weak lithospheric mantle lid and the exceedingly shallow lithosphere asthenosphere boundary (LAB) indicate that the lower part of the lithosphere has delaminated and that the asthenosphere intrudes into a very shallow location, which then supports regional tectonic uplift.

中文翻译：

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基于环境噪声层析成像的土耳其东部地壳和上地幔S波速度结构

土耳其东部是研究大陆碰撞的理想地点，这里存在广泛的火山活动和快速的构造隆起。为了更好地了解这些地表现象与地下结构之间的关系，我们收集了该地区121个地震台的连续波形数据，利用环境噪声层析成像研究地壳和上地幔的S波速度结构。我们基于频率贝塞尔 (FJ) 变换色散分析获得了 5 至 100 s 周期的瑞利波色散曲线。然后我们进行拟牛顿反演来计算0到200 km之间的S波速度结构。结果表明存在两个高速异常：一个位于黑海南部，可能代表稳定而寒冷的岩石圈地幔，另一个位于凡湖附近，可能代表新特提斯洋南支的俯冲遗迹。此外，研究结果表明，研究区的总体速度低于全球平均水平，并揭示了广泛的代表软流圈物质的上地幔低速区（UMLVZ）和中地壳低速区（MCLVZ）。在这项研究中，我们提出了MCLVZ的两种可能的形成机制：一种是部分熔融，另一种是由于复杂的精炼和分化过程以及随后的大陆改造而形成低速成分层。考虑到MCLVZ和UMLVZ的空间分布与区域火山活动具有良好的相关性，MCLVZ和UMLVZ可能为该地区的火山活动提供驱动力和物质来源。此外，极薄而弱的岩石圈地幔盖和极浅的岩石圈软流圈边界（LAB）表明岩石圈下部已经分层，软流圈侵入到很浅的位置，从而支撑了区域构造隆起。