Extensive investigation of continental rift systems has been fundamental for advancing the understanding of extensional tectonics and modes of formation of new ocean basins. However, current rift classification schemes do not account for conjugate end members formed by Large Igneous Province crust, referring to thick mafic crust, sometimes including continental fragments. Here, we investigate the rifting of William's Ridge (Kerguelen Plateau) and Broken Ridge, components of the Kerguelen Large Igneous Province now situated in the Southeast Indian Ocean, and incorporate these end members into the deformation migration concept for rifted margins. We use multichannel seismic reflection profiles and data from scientific drill cores acquired on both conjugate margins to propose, for the first time, a combined tectono-stratigraphic framework. We interpret seismic patterns, tectonic features, and magnetic anomaly picks to determine an across-strike structural domain classification. This interpretation considers the rift system overall to be “magma-poor” despite being located proximal to the Kerguelen plume but suggests that syn-rift interaction between the Kerguelen mantle plume and the lithospheric structure of William's Ridge and Broken Ridge has controlled the along-strike segmentation of both conjugates. We integrate seismic reflection and bathymetric data to test the hypothesis of predominantly transform motion, between the Australian and Antarctic plates, in Late Cretaceous and Paleogene time.

中文翻译：

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凯尔盖朗大型火成岩省的构造地层演化：威廉岭-破碎岭裂谷边缘的共轭

对大陆裂谷系统的广泛研究对于增进对伸展构造和新洋盆形成模式的理解至关重要。然而，当前的裂谷分类方案并未考虑大火成岩省地壳形成的共轭端元，指的是厚的镁铁质地壳，有时包括大陆碎片。在这里，我们研究了威廉岭（凯尔盖朗高原）和断岭（凯尔盖朗大型火成岩省的组成部分）的裂谷，并将这些端元纳入裂谷边缘的变形迁移概念中。我们使用多道地震反射剖面和在两个共轭边缘获取的科学钻芯数据，首次提出了组合的构造地层框架。我们解释地震模式、构造特征和磁异常特征，以确定跨走向构造域分类。这种解释认为，尽管裂谷系统位于凯尔盖朗地幔柱附近，但整体上“岩浆贫乏”，但表明凯尔盖朗地幔柱与威廉岭和断岭岩石圈结构之间的同裂谷相互作用控制了沿走向两个缀合物的分割。我们整合地震反射和测深数据来检验白垩纪晚期和古近纪时期澳大利亚板块和南极板块之间主要变换运动的假设。