Abstract Understanding the evolution of ocean basins is critical for studies in global plate tectonics, mantle dynamics, and sea-level through time, and relies on identifiable tectonic plate boundaries. The evolution of the 2.5 million km2 Amerasia Basin in the Arctic Ocean remains largely unsettled due to widespread overprint by the Cretaceous High-Arctic Large Igneous Province. Traces of an extinct, but deeply buried, spreading centre (herein South Amerasia Ridge, SAR) has been shown to exist in the southern part of the Amerasia Basin, in the Canada Basin. However, structural details of the SAR and, hence, the kinematic evolution of the Canada Basin, are yet to be unraveled. Based on 3D gravity inversion and the vertical gravity gradient of the latest generation of satellite gravity models, we document new structures within the Canada Basin spreading system. Our results are supported by analysis of aeromagnetic and recent marine geophysical data. Evidence is shown of consistent oblique segmentation of the SAR spreading centre in a right stepping en echelon pattern. The spreading segments are offset by northeast-trending non-transforms that are traceable throughout the oceanic crustal domain and parallel to pre-oceanic strike-slip faults in the older part of the Canada Basin. We interpret the SAR to have formed by highly oblique spreading in a northeast-southwest direction. We compare the predicted SAR basement topography with the global ridge systems and produce a detailed magnetic modelling also constrained by the basement topography. The results indicate that the SAR crust formed by a slow-to-intermediate spreading regime and that sea-floor spreading terminated during a reverse polarity chron, most likely in the Early Cretaceous. Our novel plate reconstruction model, adopting a highly oblique spreading in Canada Basin, requires a translational motion of the Alaska/Chukotka tectonic block, replacing the decades-old rotational model of the Cretaceous High Arctic.

中文翻译：

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高北极白垩纪海洋的形成

摘要 了解海洋盆地的演化对于研究全球板块构造、地幔动力学和随时间变化的海平面至关重要，并且依赖于可识别的构造板块边界。由于白垩纪高北极大型火成岩省的广泛覆盖，北冰洋 250 万平方公里的亚美拉西亚盆地的演化在很大程度上仍处于不稳定状态。已经证明在加拿大盆地的亚美西亚盆地南部存在已灭绝但深埋蔓延的中心（此处为南亚美尼亚海岭，SAR）的痕迹。然而，SAR 的结构细节以及加拿大盆地的运动学演变尚未解开。基于最新一代卫星重力模型的3D重力反演和垂直重力梯度，我们记录了加拿大盆地扩散系统内的新结构。我们的结果得到了对航磁和最近海洋地球物理数据的分析的支持。证据表明 SAR 传播中心以右步进梯队模式一致倾斜分割。扩张段被东北向的非转换所抵消，这些非转换可追溯至整个大洋地壳域，并与加拿大盆地较旧部分的大洋前走滑断层平行。我们认为 SAR 是由东北-西南方向的高度倾斜扩散形成的。我们将预测的 SAR 基底地形与全球脊系统进行比较，并生成也受基底地形约束的详细磁建模。结果表明，SAR 地壳由缓慢到中度的扩张机制形成​​，海底扩张在反极性年代终止，最有可能发生在早白垩世。我们的新型板块重建模型在加拿大盆地采用高度倾斜的扩展，需要阿拉斯加/楚科奇构造块的平移运动，以取代白垩纪高北极的数十年历史的旋转模型。