The evolution of a magmatic plumbing system from inception to extinction: The case of the Aegina magmatic province (Greece)

• Eruption frequency linked to dissolved water content and type of recharge. • Zircon U-Pb and εHf unravel the temporal evolution of a magmatic system. • Water content as a key factor for the longevity of a magmatic system. The Aegina Magmatic Province, located within the South Aegean Volcanic Arc, is offering a unique window into the evolution of a magmatic plumbing system in a subduction zone, from inception to extinction. This study examines the entire volcanic life cycle of the province utilizing zircon U-Pb geochronology and extensive geochemical data on multiple samples to uncover the factors that influence magma compositions, reservoir evolution, and eruptability during the area's magmatic lifespan. The volcanic system was active for approximately 2.5 My, with the first eruptions beginning around 4.3 Ma, after a prolonged phase of magma reservoir nucleation and growth in the crust lasting over 0.5 My. This nucleation period did not produce eruptions and was identifiable only by zircon antecrysts found in the subsequent deposits. The volcanic history includes two distinct eruptive phases characterized by having different eruption frequencies. Mineral chemistry indicates stable upper-crustal storage conditions, at around 2 kbar, throughout Aegina's lifetime. However, significant temperature and water content fluctuations were linked to magma recharge events. Initially, the recharge involved hydrous, volatile-rich magmas, which facilitated crustal magma storage and differentiation to andesitic/dacitic compositions, resulting in intermittent eruptions of these intermediate compositions as crystal-rich lava domes. Over time, the influx of drier magmas (< 4 wt.% dissolved H 2 O) increased, leading to more frequent eruptions and a progressive dilution of volatiles in the upper-crustal reservoir. This trend towards drier magma continued into the final phase, with the last eruptions (around 2.1 Ma) being characterized by dry, crystal-poor basaltic andesites (< 3 wt.% dissolved H 2 O). This drying out trend towards the cessation of magmatic activity may indicate a progressively depleted mantle source under Aegina, and a transition to magmatic activity more to the South, in the region of the presently active Peninsula of Methana.