Crustal structure of the Gulf of Aden southern margin: Evidence from receiver functions on Socotra Island (Yemen)
Crustal structure of the Gulf of Aden southern margin: Evidence from receiver functions on Socotra Island (Yemen)
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DOI：
10.1016/j.tecto.2014.10.014
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发表时间：
2014-12-10
期刊：
影响因子：
2.9
通讯作者：
Obrebski, Mathias
中科院分区：
文献类型：
--
作者：
Ahmed, Abdulhakim;Leroy, Sylvie;Obrebski, Mathias
在缺乏岩浆的环境中，大陆的分裂主要是由于断层作用和板块减薄而发生的。这些过程的时空变化可能受到裂谷前基底结构以及裂谷早期同裂谷分段的影响。为了更好地了解地壳变形和断裂前的结构对断裂的影响，我们使用接收函数从索科特拉岛，这是陆上渐新世-中新世时代的亚丁湾南缘的一部分，记录。我们确定的地壳厚度和弹性性质的变化，从我们解释的程度相关的减薄和地壳成分的延伸。我们计算的接收器函数显示，索科特拉岛中部的平均地壳厚度近似为28 km，沿边缘向西沿着减小到平均近似为21 km。此外，地壳变薄，接近大陆-海洋过渡到类似的16公里的西北部。假设初始裂谷前地壳厚度为35公里（未变形的阿拉伯板块），我们估计索科特拉岛下的拉伸系数在2.1-2.4之间。我们的研究结果表明，相当大的差异之间的地壳结构的索科特拉岛的东部和西部两侧的Hadibo传输带的两侧，东部显示出一个明确的壳内转换阶段和厚地壳相比，西部。索科特拉岛的大多数测量结果显示Vp/V-s比值在1.70和1.77之间，与地表暴露的花岗岩和碳酸盐岩类型的Vp/Vs值大致一致。我们的研究结果强烈表明，侵入的镁铁质岩是不存在或最小的，提供的证据表明，机械减薄容纳了大部分的地壳伸展。从我们的观察，我们解释，索科特拉岛的西部对应于一个经典的岩浆贫大陆边缘的颈缩区，而东部对应于近端域。(C)© 2014 Elsevier B. V.保留所有权利。
Breakup of continents in magma-poor setting occurs primarily by faulting and plate thinning. Spatial and temporal variations in these processes can be influenced by the pre-rift basement structure as well as by early syn-rift segmentation of the rift. In order to better understand crustal deformation and influence of pre-rift architecture on breakup we use receiver functions from teleseismic recordings from Socotra which is part of the subaerial Oligo-Miocene age southern margin of the Gulf of Aden. We determine variations in crustal thickness and elastic properties, from which we interpret the degree of extension related thinning and crustal composition. Our computed receiver functions show an average crustal thickness of similar to 28 km for central Socotra, which decreases westward along the margin to an average of similar to 21 km. In addition, the crust thins with proximity to the continent-ocean transition to similar to 16 km in the northwest. Assuming an initial pre-rift crustal thickness of 35 km (undeformed Arabian plate), we estimate a stretching factor in the range of similar to 2.1-2.4 beneath Socotra. Our results show considerable differences between the crustal structure of Socotra's eastern and western sides on either side of the Hadibo transfer zone; the east displays a clear intracrustal conversion phase and thick crust when compared with the western part. The majority of measurements across Socotra show V-p/V-s ratios of between 1.70 and 1.77 and are broadly consistent with the Vp/Vs values expected from the granitic and carbonate rock type exposed at the surface. Our results strongly suggest that intrusion of mafic rock is absent or minimal, providing evidence that mechanical thinning accommodated the majority of crustal extension. From our observations we interpret that the western part of Socotra corresponds to the necking zone of a classic magma-poor continental margin, while the eastern part corresponds to the proximal domain. (C) 2014 Elsevier B.V. All rights reserved.