Arnould Maëlis, Ganne Jérôme, Coltice Nicolas, Feng Xiaojun
Laboratoire de Géologie, École Normale Supérieure, CNRS UMR 8538, PSL Research University, 75005, Paris, France.
Laboratoire de Géologie de Lyon, Terre, Planètes, Environnement, École Normale Supérieure de Lyon, Université de Lyon, Université Claude Bernard, CNRS UMR 5276, 2 rue Raphaël Dubois, 69622, Villeurbanne, France.
Nat Commun. 2019 Jul 19;10(1):3235. doi: 10.1038/s41467-019-11127-7.
Mantle plume fixity has long been a cornerstone assumption to reconstruct past tectonic plate motions. However, precise geochronological and paleomagnetic data along Pacific continuous hotspot tracks have revealed substantial drift of the Hawaiian plume. The question remains for evidence of drift for other mantle plumes. Here, we use plume-derived basalts from the Mid-Atlantic ridge to confirm that the upper-mantle thermal anomaly associated with the Azores plume is asymmetric, spreading over ~2,000 km southwards and ~600 km northwards. Using for the first time a 3D-spherical mantle convection where plumes, ridges and plates interact in a fully dynamic way, we suggest that the extent, shape and asymmetry of this anomaly is a consequence of the Azores plume moving northwards by 1-2 cm/yr during the past 85 Ma, independently from other Atlantic plumes. Our findings suggest redefining the Azores hotspot track and open the way for identifying how plumes drift within the mantle.
长期以来，地幔柱固定性一直是重建过去板块构造运动的一个基本假设。然而，沿太平洋连续热点轨迹的精确地质年代学和古地磁数据显示，夏威夷地幔柱发生了显著漂移。其他地幔柱是否存在漂移的证据仍是一个问题。在此，我们利用来自大西洋中脊的地幔柱衍生玄武岩，证实与亚速尔群岛地幔柱相关的上地幔热异常是不对称的，向南延伸约2000公里，向北延伸约600公里。我们首次使用一种三维球形地幔对流模型，其中地幔柱、洋中脊和板块以完全动态的方式相互作用，我们认为这种异常的范围、形状和不对称性是亚速尔群岛地幔柱在过去8500万年中以每年1-2厘米的速度向北移动的结果，这一移动独立于其他大西洋地幔柱。我们的研究结果表明需要重新定义亚速尔群岛热点轨迹，并为确定地幔柱在地幔中的漂移方式开辟了道路。
