Predictions and Observations for the Oceanic Lithosphere From S-to-P Receiver Functions and SS Precursors.
Predictions and Observations for the Oceanic Lithosphere From S-to-P Receiver Functions and SS Precursors.
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DOI：
10.1029/2018gl077675
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发表时间：
2018-06-16
影响因子：
5.2
通讯作者：
Harmon N
中科院分区：
文献类型：
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作者：
Rychert CA;Harmon N
海洋岩石圈通常用热半空间冷却（HSC）或板块模型来描述，两者都以逐渐过渡到下面的软流圈为特征。散射波在海洋下方发现了尖锐的地震不连续性，可能来自板块底部。主动源研究表明，从熔体通道尖锐的不连续性。我们计算合成S-到-P接收器功能和SS前体的HSC和板块模型，也为渠道。我们发现，HSC和板块模型的速度梯度太平缓，从板的基础上创建可解释的散射波。预测微妙阶段将遵循与观测相似的趋势，在较老的年龄变平。因此，地震不连续性可能是由一个热控制的过程，也可以解释他们的振幅，如熔化。熔体可能在通道中聚结，尽管通道>10 km厚应该可以通过散射波成像来分辨。根据半空间和板块模型预测了弱散射相位，深度随年龄增加，并平坦化至50-80 km。与观察到的散射波深度匹配，但不匹配振幅，表明热控制过程，例如，熔融定义板Telesephone散射相应该解决LAB熔融通道成像的主动源研究，这表明更大的复杂性
The ocean lithosphere is classically described by the thermal half‐space cooling (HSC) or the plate models, both characterized by a gradual transition to the asthenosphere beneath. Scattered waves find sharp seismic discontinuities beneath the oceans, possibly from the base of the plate. Active source studies suggest sharp discontinuities from a melt channel. We calculate synthetic S‐to‐P receiver functions and SS precursors for the HSC and plate models and also for channels. We find that the HSC and plate model velocity gradients are too gradual to create interpretable scattered waves from the base of the plate. Subtle phases are predicted to follow a similar trend as observations, flattening at older ages. Therefore, the seismic discontinuities are probably caused by a thermally controlled process that can also explain their amplitude, such as melting. Melt may coalesce in channels, although channels >10 km thick should be resolvable by scattered wave imaging. Weak scattered phases are predicted from half‐space and plate models, increasing in depth with age, and flattening to 50–80 km A match with observed scattered wave depths, but not amplitudes, suggests a thermally controlled process, e.g., melt defines the plate Teleseismic scattered phases should resolve an LAB melt channel imaged by active source studies, suggesting greater complexity