Many seismic tomography studies have indicated that the African Large Low Velocity Province (LLVP) extends from the lower mantle beneath southern Africa into the upper mantle beneath eastern Africa; however, it has been questioned whether the LLVP structure may also extend to the north or northwest beneath south-central Africa. Debates regarding the upper mantle structure beneath the Damara Belt contribute to this uncertainty. Some studies suggest the Damara Belt is underlain by thermally perturbed upper mantle; however, other studies indicate the region is not associated with anomalous structure. Here, we use a comprehensive P-wave travel-time data set and an adaptive model parameterization to develop a new tomographic model for the Damara Belt and surrounding regions. Our results show that seismically slow structure beneath the Damara Belt is relegated to depths greater than ∼1,200 km, indicating that the LLVP is not significantly affecting this region. However, further to the northeast, the LLVP structure obliquely rises and crosses the mantle transition zone near the Irumide Belt, where it then extends into the upper mantle. The seismic structure beneath the Damara Belt and neighboring areas in our model correlates well with tectonic observations at the surface, including variations in heat flow, the distribution of geothermal features, the locations of rifts, and estimates of dynamic topography.

中文翻译：

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使用自适应参数化 P 波层析成像技术对非洲中南部达马拉带下方的地幔结构进行成像

许多地震层析成像研究表明，非洲大低速省（LLVP）从南部非洲下方的下地幔延伸到东部非洲下方的上地幔；然而，有人质疑 LLVP 结构是否也可能延伸到非洲中南部下方的北部或西北部。关于达马拉带下方上地幔结构的争论加剧了这种不确定性。一些研究表明，达马拉带下方是受热扰动的上地幔。然而，其他研究表明该区域与异常结构无关。在这里，我们使用全面的 P 波走时数据集和自适应模型参数化来开发达马拉带及周边地区的新层析成像模型。我们的结果表明，达马拉带下方的慢震构造被降级到大于~1,200 km的深度，这表明LLVP并没有显着影响该地区。然而，再向东北方向，LLVP结构倾斜上升并穿过伊鲁米德带附近的地幔过渡带，然后延伸到上地幔中。我们的模型中达马拉带和邻近地区下方的地震结构与地表构造观测密切相关，包括热流变化、地热特征分布、裂谷位置和动态地形估计。