Seismological evidence for the existence of serpentinized wedge mantle
Seismological evidence for the existence of serpentinized wedge mantle
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DOI：
10.1029/1999gl011080
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发表时间：
2000-03-15
影响因子：
5.2
通讯作者：
Kobayashi, Y
中科院分区：
文献类型：
--
作者：
Kamiya, S;Kobayashi, Y
通过绘制日本中部关东地区下方的泊松比图，可以在地震学上检测到蛇纹石化橄榄岩，因为蛇纹岩的泊松比高于地壳和上地幔中的其他岩石。我们使用走时断层扫描确定三维纵横波速度模型，然后构建三维泊松比图。模型显示板片上边界附近 20 至 70 公里深度范围内存在低速异常。在低速区，在20-45 km深度存在泊松比大于0.3的区域，我们将其归因于蛇纹化橄榄岩。低速区域的其余部分被解释为下降的洋壳，泊松比约为 0.25。高泊松比区域与低地震活动和弱板间耦合有关，这与蛇纹岩的延展性一致。
Serpentinized peridotite is detected seismologically by mapping Poisson's ratio beneath the Kanto district, central Japan, because serpentinite has a higher Poisson's ratio than other rocks in the crust and upper mantle. We determine three-dimensional P and S wave velocity models using travel time tomography and then construct a three-dimensional map of Poisson's ratio. The models show low velocity anomalies near the upper boundary of the slab in a depth range from 20 to 70 km. In the low velocity region, there is an area with Poisson's ratio greater than 0.3 at depths of 20-45 km, which we attribute to serpentinized peridotite. The rest of the low velocity region is interpreted as descending oceanic crust with a Poisson's ratio of about 0.25. The high Poisson's ratio area is associated with low seismicity and weak interplate coupling, which is consistent with the ductility of serpentinite.