近日，英国牛津大学Martino Foschi团队报道了远距离侧堤的扩展与中性浮力水平无关。该项研究成果发表在2026年3月17日出版的《地质学》杂志上。

横向岩脉传播是岩浆管道系统的根本过程，也是大洋中脊和大型火成岩省地壳构建的关键机制。经典模型将岩浆横向运移的倾向归因于中性浮力面（LNB）——即岩浆密度与围岩密度相等的深度，垂向上升在此受阻，迫使岩浆转为侧向传播。这一概念虽能解释浅部岩浆系统的诸多观测现象，但其对远程岩脉群的适用性仍存争议。马尔岩脉群（MDS）提供了关键检验案例：该岩脉群发源于英国西北部马尔岛，延伸逾600公里，其顶端线持续保持浅层形态，近地表发育岩床侵位，且传播路径上未见喷发迹象。

基于伴生岩床复合体的压力重建表明，岩浆压力足以支撑前150公里范围内的喷发活动，但侧向传播仍在持续。此外，计算所得LNB深度与观测侵入体几何形态存在显著偏差。这些矛盾揭示LNB概念既非远程横向岩脉传播的必要条件也非充分条件。实际上，此类传播更宜描述为由岩浆超压、围岩强度和围压共同主导的断裂力学问题。马尔岩脉群由此成为更广泛岩浆系统的典型范例：在该类系统中，浮力对断裂扩展的影响甚微。研究组认为，地球及其他行星的横向岩脉侵位应以大长径比水力压裂的物理机制重新审视，而非归因于浮力驱动的上升过程。

附：英文原文

Title: Long-range lateral dyke propagation is independent of the level of neutral buoyancy

Author: Joseph A. Cartwright, Martino Foschi

Issue&Volume: 2026-03-17

Abstract: Lateral dyke propagation is a fundamental process in magmatic plumbing systems and a key process in crustal construction at mid-ocean ridges and large igneous provinces. Classical models attribute the tendency for magma to move laterally to the level of neutral buoyancy (LNB), where magma density equals host-rock density, and vertical ascent stalls, forcing lateral propagation. While this concept explains many observations in shallow magmatic systems, its applicability to long-range dyke swarms remains uncertain. The Mull Dyke Swarm (MDS) provides a critical test case. Extending over 600 km from its source on Mull in northwest Britain, the swarm exhibits a consistently shallow upper tip line, sill emplacement near the surface, and no evidence of eruption along its trajectory. Pressure reconstructions based on associated sill complexes indicate that magma pressures were sufficient to permit eruption over the first 150 km, yet lateral propagation continued. Moreover, calculated LNB depths diverge markedly from observed intrusion geometries. These mismatches suggest that the LNB concept is neither a necessary nor sufficient control on long-range lateral dyke propagation. Instead, propagation is better described as a fracture mechanics problem governed by the competition among magma overpressure, host-rock strength, and confining stress. The MDS thus exemplifies a broader class of magmatic systems in which buoyancy plays a minor role in fracture propagation. We argue that lateral dyke emplacement on Earth and other planets should be reframed within the physics of large-aspect-ratio hydraulic fractures, rather than buoyancy-driven ascent.

DOI: 10.1130/G54125.1

Source: https://pubs.geoscienceworld.org/gsa/geology/article-abstract/doi/10.1130/G54125.1/727695/Long-range-lateral-dyke-propagation-is-independentredirectedFrom=fulltext