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The role of the crustal stress field in the incremental growth of plumbing systems

Eleonora Rivalta1,2, Katy Chamberlain3

  • Affiliations: 1GFZ Helmholtz Centre for Geosciences, Potsdam, Germany; 2University of Bologna, Italy; 3University of Liverpool, UK

  • Presentation type: Plenary talk

  • Presentation time: Monday - 30.06.25, 12:05 – 12:30, Room R380

Abstract

Magmatic plumbing systems exhibit a wide range of forms and geometries. A fundamental question is what controls their incremental growth from individual intrusions, and the resulting diversity in geometry and degree of chemical evolution within these systems. Furthermore, the processes that lead to magmas becoming trapped, or escaping from the traps, remain poorly understood. In this study, we have adopted a mechanical perspective to investigate magma ascent in immature systems, where the crust behaves as a strong, brittle-elastic medium. We have calculated the crustal stress field expected for simple ‘archetypal’ configurations of continental rifts (extension plus topographic unloading due to a deepening basin) and volcanic arcs (compression/extension plus loading due to the growth of a volcanic chain), and examined the role of these stress fields in trapping ascending magmas as dike and sill intrusions. We quantified the time scales of magma migration and identified the conditions leading to trapping, and subsequent escape, of magma-driven fractures. Horizontal trapping (magmas getting arrested as sill intrusions) is favored in compressive regimes with near-flat topography, and also beneath negative topographic features such as rift basins or calderas, in both compressional and extensional settings. We find these configurations are particularly effective at arresting magma ascent even if magma buoyancy develops, promoting prolonged residence times and significant chemical evolution. Vertical trapping (magmas getting arrested as sub-vertical dike intrusions), is favored in extensional regimes with flat topography, as well as beneath large volcanic edifices, in both compressional and extensional settings. In case of sub-vertical dike arrest, magmas can escape more easily once sufficient buoyancy accumulates. Overall, considering the ambient crustal stress field in studying the construction of plumbing systems provides a mechanical framework to explain their diverse geometries and their progressive assembly over time.