Topography of the “410” and “660” km seismic discontinuities in the Izu‐Bonin Subduction Zone
Topography of the “410” and “660” km seismic discontinuities in the Izu‐Bonin Subduction Zone
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DOI：
10.1029/97gl01383
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发表时间：
1997-06
影响因子：
5.2
通讯作者：
J. D. Collier;G. Helffrich
中科院分区：
文献类型：
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作者：
J. D. Collier;G. Helffrich
利用从英国和美国西北部的垂直分量地震仪网络收集的数据，研究了俯冲岩石圈板片对伊豆-小笠原地区“410”和“660”km地幔地震不连续面的影响。通过检查俯冲板片中及其附近横向变化的温度的影响来测试这些不连续性的相变起源的后果。我们分析了从21个地震中收集的数据，深度在40和548公里之间。根据到达时间和慢度，我们确定反射和模式转换倾斜叠加映射的目的是“410”和“660”公里的不连续性。英国和美国的阵列数据的组合允许审问的不连续性属性的两侧和内部的板。结果表明，“410”最小深度为350公里，在板的内部和“660”最大深度为700公里。的相变起源的不连续性是一致的横向温度变化的影响与克拉珀龙斜率相反的迹象。在这里，我们看到“410”上的地形比“660”上的地形更多，这与热力学克拉珀龙斜率估计一致。“410”高程表明350 km深处的温度为600±75°C。我们看到一个更广泛的410板内部附近的弱证据，符合预期的热化学效应。
We study the effects of a subducting lithospheric slab on the “410” and “660” km mantle seismic discontinuities in the Izu‐Bonin region using data collected from networks of vertical component seismometers in the United Kingdom and northwestern United States. The consequences of a phase change origin for these discontinuities is tested by examining the effect of laterally changing temperature in and near the subducting slab. We analyse the data collected from 21 earthquakes with depths between 40 and 548 km. Based on arrival time and slowness we identify reflections and mode conversions in slant stacks with the aim of mapping the “410” and “660” km discontinuities. The combination of UK and US array data permits interrogation of the discontinuity properties on both sides of and also inside the slab. Results indicate a “410” minimum depth of 350 km in the interior of the slab and a “660” maximum depth of 700 km. A phase change origin for the discontinuities is consistent with the effects of lateral temperature changes on discontinuities with Clapeyron slopes of opposite signs. Here we see more topography on the “410” than the “660” consistent with thermodynamic Clapeyron slope estimates. “410” elevation suggests temperatures in the slab of 600±75°C at a depth of 350 km. We see weak evidence for a broader 410 near the slab interior, consistent with expected thermochemical effects.