Asynchronous transfer of magmas and mineralizing fluids in a plutonic-subvolcanic-volcanic plumbing system

The geochronological-geochemical interplay between magma transfer and mineralizing fluid is studied at Campiglia igneous complex, Tuscany. Here, crustal and mantle-derived magmas were emplaced at plutonic, subvolcanic, and volcanic level (5.4 to 4.4 Ma), and were quickly exhumed, thus allowing U-Pb CA-ID-TIMS zircon dating with error of ka to tens of ka. The igneous activity is intertwined with the genesis of Cu-Pb-Zn(-Ag) skarn deposits. A two-cycle scenario is reconstructed. In the first cycle, a bimodal deep magma reservoir remained in melt-present condition for ~ 500 ka. In this time interval, a peraluminous pluton is emplaced, followed by generation of distal skarn with related Zn-Pb(-Ag) sulfide ore. Later on, Fe-Cu ore is generated in association with mantle-derived mafic melts, and a peraluminous rhyolite eruption terminates the cycle. These crust- or mantle-derived igneous units show limited evidence for interaction. Early-crystallized, antecrystic zircons were recycled within portions of melts sequentially extracted from the reservoir. In the second cycle, during the following 500 ka, an independent reservoir freshly fed by interacting crustal and mantle melts gave eventually way to eruption of a hybrid rhyolite. Timescales of the Campiglia complex reveal significant asynchrony between magma feeding of the plutonic-subvolcanic-volcanic plumbing system and the mineralizing activity of igneous fluids.