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Abstract
The evolution of transcrustal magmatic systems is fundamental in understanding the formation of volcanoes, yet magmatic processes in the roots of these systems are not fully constrained. The lower crustal Mafic Complex of Ivrea-Verbano Zone (Alps, Italy), which fed volcanism during the Permian, provides an excellent opportunity to evaluate the role of magmatic differentiation in forming eruptible melts. Studies over the past five decades have provided an exceptional history of the growth, evolution, and timing of the magmatic system, yet questions remain. Textural, in-situ geochemical, and bulk rock analyses of a suite of ultramafic to mafic rocks from the Upper Mafic Complex show that fractional crystallization and liquid immiscibility can explain the heterogeneous nature of these rocks. Statistical analysis of bulk rock analyses of the entire Mafic Complex shows an overall tholeiitic trend of differentiation and the presence of discrete magmatic differentiation at higher levels, contrasting recent ideas.