Constraints on Magma Pressure Distribution During Long Range Lateral Propagation of Giant Radial Dyke Swarms

Journal article

Plain Language Summary: Giant dyke swarms are some of the largest, yet least‐understood volcanic features on Earth, Venus or Mars. These dykes are rock fissures which can be as much as 2,000 km long, 100 m wide and extend deeper than 50 km. They carry significant amounts of molten rock which travels sideways, for extensive distances, rather than flowing out at the surface as with volcanoes and lava flows. The big question is, why do they do this? As these dykes are the biggest movers and shakers of the molten rock world, we need to answer this question if we are going to be able to predict volcanic eruptions accurately. We studied a 58 million year old dyke swarm in Britain and, using multi‐sourced geological information, we modeled the pressure within these propagating dykes. This showed that they ought to have erupted but when the fissures approached the surface and met cold groundwater, this cooled the molten rock and prevented eruption. If you imagine dropping molten metal into a bucket of cold water, this will cause a release of steam and the metal (here, molten rock) will cool and freeze. We argue that the same process was responsible for preventing eruptions from the dyke swarms.

Authors: Foschi, M; Cartwright, JA

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Geophysical Union
• Journal: Journal of Geophysical Research (JGR): Solid Earth
• Volume: 130
• Issue: 10
• Article number: e2025JB031995
• Publication date: 2025-10-08
• Acceptance date: 2025-09-24
• DOI: 10.1029/2025jb031995
• EISSN: 2169-9356
• ISSN: 2169-9313
• Language: English
• Keywords: volcano; dykes; pressure; level of neutral buoyancy; sills