Magmatic underplating, extension, and crustal reequilibration: Insights from a cross-section through the Ivrea Zone and Strona-Ceneri Zone, northern Italy

The thermal impact of magmatic underplating at various crustal levels is studied along a traverse through the Ivrea-Verbano Zone and Strona-Ceneri Zone in northern Italy. Geochronological and petrologic data are compared to a two-dimensional thermal-kinematic model. Field data and numerical simulation show the strong disturbance of the temperature field in the lower and intermediate crust in relation to magmatic underplating leading to granulite- to amphibolite-facies metamorphism as well as reequilibration of mineral chemical and isotopic systems. Magmatic underplating leaves a crust with an apparently heterogeneous tectonometamorphic evolution, as information on the earlier history is preserved only at upper crustal levels.