A top to bottom lithospheric study of Africa and Arabia
A top to bottom lithospheric study of Africa and Arabia
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DOI：
10.1016/j.tecto.2007.07.008
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发表时间：
2006-10
期刊：
影响因子：
2.9
通讯作者：
M. Pasyanos;A. Nyblade
中科院分区：
文献类型：
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作者：
M. Pasyanos;A. Nyblade
我们研究了非洲，阿拉伯半岛和邻近的海洋地区的岩石圈结构与基模表面波在一个广泛的周期范围。包括周期短于35秒的群速度，使我们能够检查比整个大陆以前的研究更浅的功能。在此过程中，我们绘制了非洲地壳厚度图。主要特征包括西非、刚果和卡拉哈里沙漠下地壳厚度增加。我们发现地壳变薄下中生代和新生代裂谷，包括贝努埃海槽，红海，东非，中非和西非裂谷系统，沿着与地壳厚度变化不太突然的被动大陆边缘。我们还发现，在北非的地壳厚度差异之间的西非东撒哈拉盾。地壳剪切波速度一般在大洋区和陆壳区较快，而在较新的地壳和活动及残余造山区较慢。更深的结构，与岩石圈的厚度和现代裂谷作用有关，与以前的工作基本一致。在俯冲带下，我们发现岩石圈较厚，上地幔速度较快，而在裂谷带下，我们发现岩石圈较薄，上地幔速度较慢。然而，我们也发现，在刚果大陆的中部，缺乏一个厚的龙骨。在被列为热点的地区没有一致的影响，这表明这些特征似乎有许多起源。最后，非洲的超级井似乎造成了非洲大部分地区的高海拔和隆起，产生了明显不同的影响（如温度，影响时间等特征所示）。在北方和南方。这与浅层的幕式活动是一致的，这在今天的非洲东北部和阿拉伯半岛得到了很好的表达。
We study the lithospheric structure of Africa, Arabia and adjacent oceanic regions with fundamental-mode surface waves over a broad period range. Including group velocities with periods shorter than 35 s allows us to examine shallower features than previous studies of the whole continent. In the process, we have developed a crustal thickness map of Africa. Main features include crustal thickness increases under the West African, Congo, and Kalahari cratons. We find crustal thinning under Mesozoic and Cenozoic rifts, including the Benue Trough, Red Sea, and East, Central, and West African rift systems, along with less abrupt crustal thickness changes at passive continental margins. We also find crustal thickness differences in North Africa between the West African Craton and East Saharan Shield. Crustal shear wave velocities are generally faster in oceanic regions and cratons, and slower in more recent crust and in active and remnant orogenic regions. Deeper structure, related to the thickness of cratons and modern rifting, is generally consistent with previous work. Under cratons we find thick lithosphere and fast upper mantle velocities, while under rifts we find thinned lithosphere and slower upper mantle velocities. However, we also find the lack of a thick cratonic keel beneath the central portion of the Congo Craton. There are no consistent effects in areas classified as hotspots, indicating that there seem to be numerous origins for these features. Finally, it appears that the African Superswell, which is responsible for high elevation and uplift over large portions of Africa, has had a significantly different impact (as indicated by features such as temperature, time of influence, etc.) in the north and the south. This is consistent with episodic activity at shallow depths, which is well-expressed in northeastern Africa and Arabia today.