Shear wave anisotropy beneath the Aegean inferred from SKS splitting observations
Shear wave anisotropy beneath the Aegean inferred from SKS splitting observations
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DOI：
10.1029/2010jb007884
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发表时间：
2011-04
影响因子：
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通讯作者：
C. Evangelidis;W. Liang;N. Melis;K. Konstantinou
中科院分区：
文献类型：
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作者：
C. Evangelidis;W. Liang;N. Melis;K. Konstantinou
[1] SKS分裂参数是在爱琴海地区使用爱琴海南部密集的临时网络和运行的永久网络记录的事件来测量的，特别是在希腊弧的弧后和近海沟区域。一般来说，快各向异性方向在弧后区域是与沟槽垂直的，在沟槽附近是与沟槽平行的。火山弧附近的各向异性测量标志着这两个区域之间的过渡。在后弧中，从南到北观察到延迟时间逐渐增加，主要是NE-SW方向。在基克拉泽斯群岛，这种模式与 GPS 速度和变质核复合体的伸展线状相关。我们首选的弧后区域各向异性来源是由后退的下降板片引起的地幔楔流。海沟的最西端终端显示出与凯法利尼亚转换断层平行且垂直于汇聚边界的方向。在伯罗奔尼撒半岛下方，海沟平行流可能位于浅倾板块下方，尽管分散的测量也可能反映了过去海沟西北-东南走向的化石各向异性。在克里特岛西部，可能正在进入大陆碰撞阶段，各向异性模式变为与海沟垂直，可能存在底板源。克里特岛中东部的良好零点表明各向异性起源向东发生变化。在海沟的最东侧，快速方向与海沟平行。这反映了类似的底板流，可能会在土耳其西部下方的板片边缘周围变成环形。这也可能在地幔楔内产生海沟平行流。
[1] SKS splitting parameters are measured in the Aegean region using events recorded at a dense temporary network in the south Aegean and the operating permanent networks, especially focusing in the back‐arc and the near‐trench areas of the Hellenic arc. In general, fast anisotropy directions are trench perpendicular in the back‐arc area and trench parallel near the trench. Anisotropy measurements near the volcanic arc mark the transition between these two regions. In the back arc, a gradual increase is observed in delay times from south to north, with a prevailing NE‐SW direction. In Cyclades, this pattern is correlated with GPS velocities and stretching lineations of metamorphic core complexes. Our preferred source of anisotropy in the back‐arc region is the mantle wedge flow, induced by the retreating descending slab. The westernmost termination of the trench reveals directions parallel with the Kefalonia Transform Fault and perpendicular to the convergence boundary. Beneath Peloponnese, the trench‐parallel flow is probably located beneath the shallow‐dipping slab, although scattered measurements may also reflect fossil anisotropy from a past NW‐SE strike of the trench. In western Crete, which may be entering a stage of continental collision, the anisotropy pattern changes to trench perpendicular, with a possible subslab source. Good nulls in central east Crete indicate a change in the anisotropy origin toward the east. At the easternmost side of the trench, fast directions are trench parallel. This reflects a similar subslab flow that may become toroidal around the slab edge beneath western Turkey. This may also produce a trench‐parallel flow within the mantle wedge.