Magmatism at Divergent Plate Boundaries: From Rifts to Ridges

Divergent plate boundaries are major sites of magma production and transport, heating and associated volatile release, and complex tectonic processes. Understanding the interactions and feedbacks between these processes is critical for addressing questions about how continental breakup and plate spreading are achieved, which is fundamental to the plate tectonic cycle.



A wealth of literature supports magmatism as playing a key role in rifting and spreading. The available tectonic forces required to initiate rifting in thick cold lithosphere are often too low, necessitating that additional processes help weaken and thin the lithosphere. Such weakening can be achieved through the mechanical damage and/or thermal effects of magma intrusion, which occurs over a range of spatial and temporal scales. Although magmatism clearly plays a key role in determining the compositional and structural configuration of continental rifts and oceanic spreading centres, questions remain over the extent to which different magmatic and volcanic processes control rift morphology and fault system characteristics. Observations of rifted margins reveal that magma involvement can be varied and still result in continental breakup, while many amagmatic or magma-poor rifts exhibit mantle thinning that cannot be explained by mechanical stretching alone. Tectonic extension in some systems may be augmented by currently undetected melts, and the extent and interconnectivity of subsurface magma systems is unconstrained in many rifts and ridges. Finally, the generation and source of many magmas in rifts are unclear, and it is challenging to ascertain why some systems experience more or less melt production than others, and how and why magma inputs vary as divergent boundaries evolve.



To address outstanding questions like these, this Research Topic addresses state-of-the-art research exploring the role of magmatism at divergent plate boundaries. We welcome contributions from the fields of geology, geophysics, geochemistry, and geodynamics, examining magmatic rifting using experimental, numerical and field approaches on local, regional, and continental scales.