近日，法国巴黎城市大学G. M. Kent团队研究了轴向火山下方岩石圈-软流层边界沿线的熔体聚焦。相关论文于2025年4月23日发表在《自然》杂志上。

在海洋扩张中心下方，岩石圈-软流层边界（LAB）充当渗透屏障，将熔体从地幔深处输送到扩张轴。在中间扩展到快速扩展的脊顶，多通道地震反射技术成像了一个几乎平坦的1-2km宽的轴向岩浆透镜体（AML），它定义了LAB的最上部，但地壳深处LAB的性质更难以捉摸，从断层图像中获得了一些线索，只能提供AML下方更宽的低速物质晕的漫射视图。研究组展示了LAB的3D地震反射图像，该LAB延伸至Axial火山下方地壳深处（5-6km），位于Juan de Fuca山脊和Cobb–Eickelberg热点的交叉处。

LAB的3D形状与热控岩浆同化锋相吻合，将热点相关和大洋中部扩张中心相关的岩浆活动集中在火山中心，控制着喷发和热液过程以及喷发熔岩的化学成分。在这种情况下，LAB可以被视为“岩浆域”的上表面，这是一个熔体驻留的区域（取代了单个“岩浆储层”的概念）。研究组发现了一个漏斗形的地壳LAB，这表明在其他火山系统（如冰岛）中，热控制的岩浆同化可能沿着这个表面发生。

附：英文原文

Title: Melt focusing along lithosphere–asthenosphere boundary below Axial volcano

Author: Kent, G. M., Arnulf, A. F., Singh, S. C., Carton, H., Harding, A. J., Saustrup, S.

Issue&Volume: 2025-04-23

Abstract: Beneath oceanic spreading centres, the lithosphere–asthenosphere boundary (LAB) acts as a permeability barrier that focuses the delivery of melt from deep within the mantle towards the spreading axis1. At intermediate-spreading to fast-spreading ridge crests, the multichannel seismic reflection technique has imaged a nearly flat, 1–2-km-wide axial magma lens (AML)2 that defines the uppermost section of the LAB3, but the nature of the LAB deeper into the crust has been more elusive, with some clues gained from tomographic images, providing only a diffuse view of a wider halo of lower-velocity material seated just beneath the AML4. Here we present 3D seismic reflection images of the LAB extending deep (5–6km) into the crust beneath Axial volcano, located at the intersection of the Juan de Fuca Ridge and the Cobb–Eickelberg hotspot. The 3D shape of the LAB, which is coincident with a thermally controlled magma assimilation front, focuses hotspot-related and mid-ocean-spreading-centre-related magmatism towards the centre of the volcano, controlling both eruption and hydrothermal processes and the chemical composition of erupted lavas5. In this context, the LAB can be viewed as the upper surface of a ‘magma domain’, a volume within which melt bodies reside (replacing the concept of a single ‘magma reservoir’)6. Our discovery of a funnel-shaped, crustal LAB suggests that thermally controlled magma assimilation could be occurring along this surface at other volcanic systems, such as Iceland.

DOI: 10.1038/s41586-025-08865-8

Source: https://www.nature.com/articles/s41586-025-08865-8