Crustal structure of the southern margin of the African continent: Results from geophysical experiments
Crustal structure of the southern margin of the African continent: Results from geophysical experiments
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非洲大陆南缘的地壳结构：地球物理实验结果
DOI：
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
M. Weber
中科院分区：
文献类型：
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作者：
J. Stankiewicz;N. Parsiegla;T. Ryberg;K. Gohl;U. Weckmann;R. Trumbull;M. Weber
[1]在Inkaba yeAfrica项目的框架内，沿沿着横跨非洲板块南缘的剖面进行了若干陆上和海上地球物理实验。折射地震实验表明，莫霍面深度从内陆的40多公里迅速下降到目前海岸的30公里左右，然后向标志着大陆地壳和海洋地壳之间过渡区的Agulhas-Falkland断裂带逐渐变薄。在莫霍面深度急剧下降的区域，在纳马夸-纳塔尔移动的带和开普褶皱带之间的边界附近，观察到较低的地壳P波速度高达7.4 km/s。这被解释为纳马夸-纳塔尔移动的带的前寒武纪变基性岩，或年轻岩浆活动增加到地壳底部的镁铁质侵入体。上地壳的速度模型具有很好的分辨率，与已知的地质记录相一致。联合解释的速度模型与电导率模型，从大地电磁研究中获得的，使得有可能相关的高速异常北的中心的贝蒂磁异常与高电阻体。
[1] A number of geophysical onshore and offshore experiments were carried out along a profile across the southern margin of the African Plate in the framework of the Inkaba yeAfrica project. Refraction seismic experiments show that Moho depth decreases rapidly from over 40 km inland to around 30 km at the present coast before gently thinning out toward the Agulhas-Falkland Fracture Zone, which marks the transition zone between the continental and oceanic crust. In the region of the abruptly decreasing Moho depth, in the vicinity of the boundary between the Namaqua-Natal Mobile Belt and the Cape Fold Belt, lower crustal P-wave velocities up to 7.4 km/s are observed. This is interpreted as metabasic lithologies of Precambrian age in the Namaqua-Natal Mobile Belt, or mafic intrusions added to the base of the crust by younger magmatism. The velocity model for the upper crust has excellent resolution and is consistent with the known geological record. A joint interpretation of the velocity model with an electrical conductivity model, obtained from magnetotelluric studies, makes it possible to correlate a high-velocity anomaly north of the center of the Beattie magnetic anomaly with a highly resistive body.