Mantle Dynamics of the Eastern Mediterranean and Middle East: Constraints From P‐Wave Anisotropic Tomography
Mantle Dynamics of the Eastern Mediterranean and Middle East: Constraints From P‐Wave Anisotropic Tomography
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DOI：
10.1029/2019gc008512
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发表时间：
2019-10
期刊：
影响因子：
3.7
通讯作者：
Wei Wei-Wei;Dapeng Zhao;Feixiang Wei;Xiang Bai;Jiandong Xu
中科院分区：
文献类型：
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作者：
Wei Wei-Wei;Dapeng Zhao;Feixiang Wei;Xiang Bai;Jiandong Xu
东地中海和中东地区的高分辨率P波各向异性层析成像是通过反演大量高质量的P波到达时间来确定的。我们的研究结果清楚地显示了希腊俯冲带俯冲板块沿走向的变化。在北Hellenides的下方和后面至少有三个高速异常，它们与不同阶段的俯冲希腊板块有关，而在更南边的地区，则显示了一个俯冲至约1100公里深度的单一板块。塞浦路斯俯冲带的板块特征不明显，但在安纳托利亚中部下方显示出细尺度高速构造，这可能反映了分离的塞浦路斯板块。在希腊俯冲带的弧前地幔楔中出现了与海沟平行的快速度方向，这可能反映了板块曲率引起的地幔流动。在弧后爱琴海北部和安纳托利亚最西部，浅层地幔以NNE - SSW ~ N - S快速度方向为主，与当前地表形变的伸展方向吻合较好，表明岩石圈存在垂直相干变形。我们的研究结果表明，在阿拉伯西部存在大规模的地幔流动，这可能与扎格罗斯造山带和高加索造山带以及安纳托利亚岩石圈的西移有关。阿拉伯岩石圈板块在扎格罗斯板块之下比在美索不达米亚前深板块之下要薄，这表明在扎格罗斯造山带期间，有很大一部分地壳是从俯冲的阿拉伯岩石圈中剥离出来的。
High‐resolution images of P‐wave anisotropic tomography beneath the Eastern Mediterranean and Middle East are determined by inverting a large number of high‐quality P‐wave arrival times. Our results clearly show along‐strike variations of subducting slabs in the Hellenic subduction zone. At least three high‐velocity anomalies are imaged beneath and behind the north Hellenides, which are associated with the subducting Hellenic slab at different stages, while in regions further south, a single slab is revealed that has subducted down to a depth of ~1,100 km. The slab feature is not prominent in the Cyprus subduction zone, but a fine‐scale high‐velocity structure is revealed beneath the central Anatolia, which may reflect the detached Cyprus slab. Trench‐parallel fast‐velocity directions occur in the forearc mantle wedge of the Hellenic subduction zone, which may reflect mantle flow induced by slab curvature. In the backarc north Aegean and westernmost Anatolia, dominant NNE‐SSW to N‐S fast‐velocity directions exist in the shallow mantle, which accord well with the extensional direction of present deformation at the surface, suggesting a vertically coherent deformation in the lithosphere. Our results reveal a large‐scale mantle flow beneath western Arabia, which is possibly related to the Zagros and Caucasus orogens and westward motion of the Anatolia lithosphere. The Arabian lithospheric plate is thinner beneath the Zagros than that under the Mesopotamian Foredeep, suggesting that a large portion of the crust was scrapped off from the subducted Arabian lithosphere during the Zagros orogen.