Roots Eric A, Hill Graham J, Frieman Ben M, Smith Richard S, Craven James A, Snyder David B, Calvert Andrew J
Mineral Exploration Research Centre, Harquail School of Earth Science, Laurentian University, Sudbury, ON, Canada.
Institute of Geophysics, Czech Academy of Sciences, Prague, Czech Republic.
Nat Commun. 2025 Aug 19;16(1):7701. doi: 10.1038/s41467-025-62912-6.
Archean cratons represent stable continental domains which form the nuclei of the Earth's continents due to their thick ( >200 km), mechanically resistant keels. Cratons and their stable roots form through melt and fluid depletion processes. However, metasomatic refertilization may occur due to processes coeval with craton construction and/or overprinting episodes. Magnetotellurics, a geophysical method measuring subsurface electrical resistivity, is sensitive to the compositional and thermal states of the lithosphere and is useful in mapping depleted and refertilized cratonic domains. Here we show the results of a 3D anisotropic inversion to image the lithospheric resistivity structure of the western Superior Craton. The resistivity model reveals widespread (500×300 km) anisotropy with a north-south conductive axis at depths ~100-200 km, inferred to represent phlogopite-bearing channels emplaced during mantle plume activity. The results have implications for our understanding of the modification and long-term stability of cratonic lithosphere, and the imaging and interpretation of their preserved geophysical signatures.
太古宙克拉通代表了稳定的大陆区域，由于其厚厚的（>200公里）、机械强度高的岩基，它们构成了地球大陆的核心。克拉通及其稳定的根部是通过熔体和流体亏损过程形成的。然而，交代再富集作用可能由于与克拉通构造同时期的过程和/或叠加事件而发生。大地电磁测深法是一种测量地下电阻率的地球物理方法，对岩石圈的成分和热状态敏感，有助于绘制亏损和再富集的克拉通区域图。在这里，我们展示了一个三维各向异性反演的结果，以成像苏必利尔湖西部克拉通的岩石圈电阻率结构。电阻率模型揭示了广泛的（500×300公里）各向异性，在深度约100-200公里处有一个南北向的导电轴，推断其代表了地幔柱活动期间就位的含金云母通道。这些结果对于我们理解克拉通岩石圈的改造和长期稳定性，以及对其保留的地球物理特征的成像和解释具有重要意义。
