Using the example of the conjugate Mozambique-Antarctica rifted margins, we investigate how mantle plume magmatism interacts with extensional processes during lithospheric rifting and breakup. The presence of extensive plume related magmatic additions formed during rifting masks the edges of the continental margins, making it difficult to determine a tight conjugate margin restoration and hindering the evaluation of their pre-breakup evolution. Based on rift domain mapping from seismic reflection interpretation, crustal thickness mapping using gravity inversion, lithosphere thinning from subsidence analysis, and the testing of different plate kinematic scenario, we develop a tight initial fit of the conjugate Mozambique-Antarctica margins and describe their evolution by a three stage model. These three stages consist of: i) during early rifting, the filling of accommodation space created by continental crust thinning with Karoo related magmatism resulting in a hybrid crust that maintains bulk crustal thickness producing shallow bathymetry or emergence and allowing SDR formation; ii) the decrease of magmatic budget relative to extension rates leading to bulk crustal thinning and increased bathymetries; and iii) the transition to seafloor spreading with a steady state magmatic budget resulting in normal thickness (6,5 ± 1 km) oceanic crust. This study not only adds new constraints on the regional breakup of Gondwana but also presents a new multidisciplinary methodology for restoring magma rich rifted margins formed in the presence of mantle plumes and for improving the understanding of the nature of such hybrid magma-rich crust.

以共轭莫桑比克-南极裂谷边缘为例，我们研究了岩石圈裂谷和破裂过程中地幔柱岩浆岩浆作用与伸展过程的相互作用。在裂谷过程中形成的大量与羽状岩浆有关的岩浆物质掩盖了大陆边缘的边缘，使其难以确定紧密的共轭边缘恢复性，并阻碍了对它们破裂前演化的评估。基于地震反射解释的裂谷域测绘，重力反演的地壳厚度测绘，沉陷分析中的岩石圈变薄以及不同板块运动学场景的测试，我们开发了共轭莫桑比克-南极边缘的紧密初始拟合，并通过以下方法描述了它们的演化：一个三阶段模型。这三个阶段包括：i）在早期裂谷期间，通过与Karoo相关的岩浆作用使大陆地壳变薄而形成的居住空间被填充，从而形成了混合地壳，该地壳保持了地壳的整体厚度，从而产生了浅测深或出现并允许SDR形成；ii）相对于扩展速率而言，岩浆预算减少，导致地壳整体变薄并增加了测深仪；iii）在稳定的岩浆预算下向海底扩散的过渡导致正常的洋壳厚度（6.5±1 km）。这项研究不仅为冈瓦纳的区域破裂增加了新的限制，而且提出了一种新的多学科方法，用于恢复在存在地幔柱的情况下形成的富含岩浆的裂谷边缘，并提高了对这种富含岩浆的杂化壳的性质的认识。