Carbonatites in the Ivrea–Verbano Zone? A critical reassessment of field, petrographic and geochemical evidence supporting crustal rather than mantle origin

Carbonatites are a hot topic in petrological studies. Their occurrences have been re-evaluated in recent years due to the importance of volatile and critical elements cycles through mantle and crust. A recent study has proposed the occurrence of Jurassic carbonatites in the Ivrea–Verbano Zone (IVZ). Here we reassess the available evidence and show that: (i) most carbonate-rich rocks can be interpreted as late-metamorphic anatectic dykes intruded into high-grade gneisses and calc-silicate rocks; (ii) trace-element and C-O isotopic imprinting are different from primary carbonatitic, mantle - derived magmas; (iii) there is no evidence for systematic fenitization or intrusive associations typical of carbonatitic intrusions; (iv) the chronology of the IVZ is dominated by Mesozoic extensional regime characterized by abundant high-T shear zones which locally exceeded the melting T of marbles. We conclude that the carbonatites in the IVZ can be explained by marble anatectic melting induced by late-tectonic reworking during the Triassic-Jurassic exhumation of the western paleomargin of Adria.