Title:

Magma Assembly During Continental Rifting: Insights from the Limagne Graben and the Chaîne Des Puys

Though continental rifting is a key part of Earth’s tectonic processing, factors most influential in magma assembly, including magma source regions and the extensive magma networks that ultimately drive rifting, remain enigmatic. The westernmost graben in the European Cenozoic Rift System (ECRS), the Limagne Graben and the associated Chaîne Des Puys, are one such example where the reconstruction of the magmatic plumbing systems requires more clarity. Initiation of rifting is assumed to have started about 35 Ma, and magmatism has been active sporadically from 25 Ma down to approximately 5 ka. Magmatism started in the rift and migrated to the plateau des Dômes. ​Overall, lava geochemical compositions have evolved from undersaturated (basanite) for the oldest and/or those within the Limagne rift to saturated (basalt) for the least differentiated lavas of the Chaîne des Puys1. Such changes in composition suggest progressive rifting manifests both source region changes, potentially increasingly complex and extensive volcanic plumbing systems or both. Here we report geochemical data from clinopyroxene and amphibole phenocrysts within Puy de Corent (3 Ma) to provide insights into sources, timing, and petrogenetic processes associated with magmatism during rifting in the Limagne Graben. We then compare these lavas to other lavas in the ECRS.

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