Lithospheric breakup is generally defined as the process that results in a new plate boundary and oceanic crust. However, how this process occurs in magma‐poor systems remains debated. As recently suggested, the J‐magnetic anomaly at the Iberia–Newfoundland margins has polygenic sources and therefore cannot be interpreted as an isochron. However, the presence of the J‐anomaly on both margins suggests a common origin. By using analytic signal map of magnetic data, we highlight landward zigzagged limits for the J‐anomalies at the Iberian–Newfoundland margins. The zigzag segments neither match the axis nor the transform systems of previously proposed plate reconstructions, but are aligned with NE‐SW Palaeozoic trends. However, they can be fitted using recently published plate restorations, as expected if they have a single origin. Therefore, a link between the location of syn‐ to post‐breakup magmatic additions along the J‐anomaly and an inherited lithospheric trend is proposed.

中文翻译：

---

锯齿形J型异常的磁性特征：对伊比利亚-纽芬兰边缘的运动学和破碎过程的影响

岩石圈破裂通常被定义为导致新的板块边界和洋壳的过程。但是，这个过程如何在贫岩系统中发生仍然有争议。如最近所建议的，伊比利亚-纽芬兰边缘的J磁异常具有多源源，因此不能解释为等时线。但是，在两个边缘上均存在J异常表明其起源相同。通过使用磁数据的分析信号图，我们突出了伊比利亚-纽芬兰边缘的J异常的陆上曲折极限。之字形段既不匹配轴也不匹配先前提出的板块重建的变换系统，但与NE-SW古生代趋势一致。但是，可以使用最近发布的板状修复体来进行装配，如果它们具有单一来源，则可以预期。因此，