The Role of Crustal Contamination throughout the 1329–2005 CE Eruptive Record of Mt. Etna Volcano, Italy.

This article focuses on investigating the geochemical evolution of Mt. Etna volcano, particularly the post-1971 enrichment in alkali elements (potassium [K] and rubidium [Rb]) and radiogenic strontium isotopes (^87Sr/^86Sr) observed in its eruptive products. Using the Magma Chamber Simulator (MCS), a thermodynamic model integrating fractional crystallization, assimilation, and stoping processes, the study quantitatively evaluates the role of crustal contamination from the sedimentary basement—composed mainly of flysch and skarn lithologies—in shaping the post-1971 magma compositions. Results indicate that pre-1971 magmas can be modeled by fractional crystallization of a primitive parental magma similar to Etna’s ~4,000-year-old fall-stratified tephra, whereas post-1971 geochemical trends require assimilation of partial melts from a heterogeneous mixture of flysch and skarn wallrocks, with minor stoping (~2% by mass) also contributing. The study concludes that the alkali enrichment and increased eruptive activity after 1971 are best explained by combined effects of mantle source heterogeneity and crustal contamination via assimilation and stoping within Etna’s upper crustal magma storage system.