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Crustal structure beneath the Ethiopian Plateau and adjacent areas from receiver functions: Implications for partial melting and magmatic underplating
Tectonophysics ( IF 2.7 ) Pub Date : 2021-03-31 , DOI: 10.1016/j.tecto.2021.228857
Tuo Wang , Stephen S. Gao , Qiuyue Yang , Kelly H. Liu

Receiver function measurements of crustal thickness (H) and Vp/Vs provide important information on the formation and evolution of continental plateaus and rift zones such as the Ethiopian Plateau, the Afar and Main Ethiopian Rifts in northeastern Africa. Unfortunately, the presence of a low-velocity sedimentary layer atop most of the Cenozoic rift basins may lead to strong reverberations that can mask the P-to-S conversions from the Moho, resulting in unreliable H and Vp/Vs measurements. Here we estimate H and Vp/Vs beneath the Afar Depression (AD), Ethiopian Plateau (EP), and the Main Ethiopian Rift (MER) by stacking receiver functions. Reliable H and Vp/Vs measurements are obtained at a total of 69 stations, among which 18 stations are pre-processed by applying the reverberation removal technique. In comparison to the MER and EP, the AD is characterized by a thinner crust and higher Vp/Vs, and the thinnest crust and highest Vp/Vs are found in the Red Sea Rift (RSR) in central AD. Gradual variations of H and Vp/Vs between the previous and present axes of the RSR support a gradual rather than jumpy migration model of the axis. The overall high Vp/Vs values in the study area can be interpreted as a combined result of continental flood basalts at the surface, magmatic intrusion, and crustal partial melting. The relatively low amplitude of the P-to-S converted phases from the Moho observed in the southern part of the western Ethiopian Plateau and the AD with the exception of the RSR may be attributed to magmatic underplating.



中文翻译:

埃塞俄比亚高原下方的地壳结构和接收器功能的邻近区域:对部分熔融和岩浆底层的影响

地壳厚度(H)和Vp / Vs的接收函数测量提供了有关非洲大陆高原和裂谷区(如埃塞俄比亚高原,阿法尔和主要埃塞俄比亚裂谷)的形成和演化的重要信息。不幸的是,在大多数新生代裂谷盆地的顶部存在低速沉积层,可能导致强烈的混响,从而掩盖了莫霍面从P到S的转换,从而导致H和Vp / Vs测量值不可靠。在这里,我们通过叠加接收器函数来估算阿法尔低压(AD),埃塞俄比亚高原(EP)和埃塞俄比亚主要裂谷(MER)以下的H和Vp / Vs。在总共69个站中获得了可靠的H和Vp / Vs测量值,其中通过应用混响去除技术对18个站进行了预处理。与MER和EP相比,AD的特征是地壳较薄,Vp / Vs较高,而地壳最薄且Vp / Vs最高的是AD中部的红海裂谷(RSR)。RSR的先前轴和当前轴之间的H和Vp / Vs的逐渐变化支持该轴的渐进而不是跳跃的迁移模型。研究区域中总体较高的Vp / Vs值可以解释为地表大陆性洪水玄武岩,岩浆侵入和地壳部分融化的综合结果。在埃塞俄比亚高原西部和AD的南部,从Moho到P-S转换相的振幅相对较低,除了RSR异常外,这可能归因于岩浆的欠镀作用。RSR的先前轴和当前轴之间的H和Vp / Vs的逐渐变化支持该轴的渐进而不是跳跃的迁移模型。研究区域中总体较高的Vp / Vs值可以解释为地表大陆性洪水玄武岩,岩浆侵入和地壳部分融化的综合结果。在埃塞俄比亚高原西部和AD的南部,从Moho到P-S转换相的振幅相对较低,除了RSR异常外,这可能归因于岩浆的欠镀作用。RSR的先前轴和当前轴之间的H和Vp / Vs的逐渐变化支持该轴的渐进而不是跳跃的迁移模型。研究区的总体高Vp / Vs值可以解释为表层大陆洪水玄武岩,岩浆侵入和地壳部分融化的综合结果。在埃塞俄比亚高原西部和AD的南部,从Moho到P-S转换相的振幅相对较低,除了RSR异常外,这可能归因于岩浆的欠镀作用。和地壳部分融化。在埃塞俄比亚高原西部和AD的南部,从Moho到P-S转换相的振幅相对较低,除了RSR异常外,这可能归因于岩浆的欠镀作用。和地壳部分融化。在埃塞俄比亚高原西部和AD的南部,从Moho到P-S转换相的振幅相对较低,除了RSR异常外,这可能归因于岩浆的欠镀作用。

更新日期:2021-04-08
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