近日，英国南安普顿大学Emma J. Watts团队研究了由上覆板块动力学形成的阿法尔三结地幔上涌。这一研究成果于2025年6月25日发表在《自然—地球科学》杂志上。

地幔上升流驱动大规模地表火山活动，促进大陆裂解和洋盆形成。然而，这些上升流的空间特征和内部组成以及它们如何被板块构造所改变的问题还没有得到很好的解决。东非的阿法尔是一个典型的三联点，由三个处于不同进化阶段的裂谷组成，被认为是地幔上升流或地幔柱的下方，可以检查地幔上升流的控制因素。

研究组展示了来自跨越界定三联点的裂谷的130多个“年轻”火山样本的地球化学数据，以表明下伏地幔由一个单一的不对称上升流组成。使用统计建模将该数据与现有的地球化学和地球物理约束相结合，研究组认为阿法尔是由空间和化学上不均匀的上升流提供的，这控制了所有三个裂谷臂中熔体的成分和相对丰度。

研究组识别出裂谷地区地幔成分中的重复特征，其变异性是在延伸较快的裂谷臂中波长较长。这表明，在裂谷速率较高、板块较薄的地方，会发生更快速的通道化地幔流，有助于上升流向更快扩张的红海裂谷流动。该研究结果表明，地幔上升流的演化是如何受到上覆板块动力学的影响的。

附：英文原文

Title: Mantle upwelling at Afar triple junction shaped by overriding plate dynamics

Author: Watts, Emma J., Rees, Rhiannon, Jonathan, Philip, Keir, Derek, Taylor, Rex N., Siegburg, Melanie, Chambers, Emma L., Pagli, Carolina, Cooper, Matthew J., Michalik, Agnes, Milton, J. Andrew, Hincks, Thea K., Gebru, Ermias F., Ayele, Atalay, Abebe, Bekele, Gernon, Thomas M.

Issue&Volume: 2025-06-25

Abstract: Mantle upwellings drive large-scale surface volcanism and facilitate continental breakup and ocean basin formation. However, the spatial characteristics and internal composition of these upwellings alongside how they are modified by plate tectonics are poorly resolved. Afar, East Africa, is a classic triple junction comprising three rifts at various stages of evolution thought to be underlain by a mantle upwelling or plume, allowing examination of the controls on the mantle upwelling. Here we present geochemical data from >130 samples of ‘young’ volcanoes spanning the rifts defining the triple junction to show that the underlying mantle comprises a single, asymmetric upwelling. Using statistical modelling to integrate our data with existing geochemical and geophysical constraints, we suggest that Afar is fed by a spatially and chemically heterogeneous upwelling, which controls the composition and relative abundance of melt in all three rift arms. We identify repetitive signatures in mantle compositions in rift regions, whose variability is a longer wavelength in faster-extending rift arms. This suggests more rapid channelized mantle flow occurs where rifting rates are higher and the plate is thinner, aiding flow of the upwelling towards the faster-spreading Red Sea Rift. Our findings demonstrate how the evolution of mantle upwellings is influenced by the dynamics of overriding plates.

DOI: 10.1038/s41561-025-01717-0

Source: https://www.nature.com/articles/s41561-025-01717-0