Shear wave velocity structure of the lower crust in southern Africa: evidence for compositional heterogeneity within Archaean and Proterozoic terrains
Shear wave velocity structure of the lower crust in southern Africa: evidence for compositional heterogeneity within Archaean and Proterozoic terrains
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DOI：
10.1029/2008jb006217
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发表时间：
2009-12
影响因子：
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通讯作者：
E. Kgaswane;A. Nyblade;J. Julià;P. Dirks;R. Durrheim;M. Pasyanos
中科院分区：
文献类型：
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作者：
E. Kgaswane;A. Nyblade;J. Julià;P. Dirks;R. Durrheim;M. Pasyanos
[1]通过联合反演位于博茨瓦纳、南非和津巴布韦的89个宽带地震台站的接收器函数和瑞利波群速度，研究了南部非洲地盾的下地壳的性质。对于太古代和元古代的大部分地区，从反演中获得的速度模型显示，在20-30 km深度以下的剪切波速度为4.0 km/s，表明主要是镁铁质下地壳。然而，在南非的金伯利地体大部分地区和海斯省邻近地区以及威特沃特斯兰德地体，以及津巴布韦的托克韦地体西部，在20-30公里深度以下发现的剪切波速度为3.9公里/秒，表明下地壳为中长英质。南非中酸性下地壳的区域与保存有文特斯多普岩石的区域相吻合，这表明下地壳更演化的成分可能是在c. 2.7佐治亚州引文：Kgaswane，E. M.，A. A. Nyblade，J. Julia`，P. H. G. M.德克斯河Durrheim和M. E. Pasyanos（2009年），南部非洲下地壳的剪切波速度结构：西太平洋和元古代地形成分不均匀性的证据，地球物理学杂志。结果：114，B12304，doi：10.1029/2008JB006217。
[1] The nature of the lower crust across the southern African shield has been investigated by jointly inverting receiver functions and Rayleigh wave group velocities for 89 broadband seismic stations located in Botswana, South Africa and Zimbabwe. For large parts of both Archaean and Proterozoic terrains, the velocity models obtained from the inversions show shear wave velocities 4.0 km/s below 20–30 km depth, indicating a predominantly mafic lower crust. However, for much of the Kimberley terrain and adjacent parts of the Kheis Province and Witwatersrand terrain in South Africa, as well as for the western part of the Tokwe terrain in Zimbabwe, shear wave velocities of 3.9 km/s are found below 20–30 km depth, indicating an intermediate-to-felsic lower crust. The areas of intermediate-to-felsic lower crust in South Africa coincide with regions where Ventersdorp rocks have been preserved, suggesting that the more evolved composition of the lower crust may have resulted from crustal reworking and extension during the Ventersdorp tectonomagmatic event at c. 2.7 Ga. Citation: Kgaswane, E. M., A. A. Nyblade, J. Julia`, P. H. G. M. Dirks, R. J. Durrheim, and M. E. Pasyanos (2009), Shear wave velocity structure of the lower crust in southern Africa: Evidence for compositional heterogeneity within Archaean and Proterozoic terrains, J. Geophys. Res., 114, B12304, doi:10.1029/2008JB006217.