Iceland and the encompassing Northeast Atlantic are characterized by abundant volcanism, anomalously high topography and, in many places, anomalously thick basaltic crust. This has been attributed to the Iceland Plume, rising from the deep mantle, though its structure and very existence are debated. Using seismic waveform tomography with massive datasets, we compute a new, detailed model of the crust and upper mantle beneath Iceland and the surrounding North Atlantic region. The model reveals a large, low-velocity anomaly, indicative of high temperatures, at 400-660 kilometers depth beneath eastern Greenland, where seismic receiver functions also indicate an extensive high-temperature region. The anomaly rises upwards and eastwards toward Iceland, deflecting around the thick lithosphere of Greenland's cratons, which we also image in detail. We interpret the major low-velocity anomaly as the Iceland Plume, ascending from under Greenland and captured by the Mid-Atlantic Ridge. The ascent of the plume beneath the western Northeast Atlantic is consistent with its thin lithosphere, documented by our tomography, and abundant seamounts. Our results reconcile previously contrasting views on the structure of the Iceland Plume: while the plume is clearly visible in the transition zone beneath Greenland, it is confined to the upper mantle beneath Iceland.

冰岛和环绕的东北大西洋以丰富的火山活动、异常高的地形以及在许多地方异常厚的玄武岩地壳为特征。这归因于冰岛羽流，它从地幔深处升起，尽管其结构和存在存在争议。使用具有大量数据集的地震波形断层扫描，我们计算了冰岛和周围北大西洋地区下方地壳和上地幔的新的详细模型。该模型揭示了格陵兰东部下方 400-660 公里深度处的一个大型低速异常，表明存在高温，那里的地震接收器功能也表明存在一个广泛的高温区域。该异常向冰岛向上和向东上升，在格陵兰克拉通厚厚的岩石圈周围偏转，我们也对其进行了详细成像。我们将主要的低速异常解释为冰岛羽流，从格陵兰岛下方上升并被大西洋中脊捕获。东北大西洋西部下方的羽流上升与其断层扫描记录的薄岩石圈和丰富的海山一致。我们的结果调和了之前对冰岛羽流结构的不同看法：虽然羽流在格陵兰岛下方的过渡带清晰可见，但它仅限于冰岛下方的上地幔。