Ivrea Zone

Download the field guide: Hutton-field-Ivrea_Zone

This field trip will take you in one day from the crust-mantle transition of the Adriatic plate to the surface of a Permian volcanic system offering the opportunity to investigate trans-crustal magmatic systems and the complicated evolution of crustal migmatites. We will examine the different structural levels of this unique magmatic system from the bottom of the crust to the surface (or vice versa), looking at the world famous
continental mantle rocks in Balmuccia with several generations of pyroxenites, through lower crustal gabbros, mid-crustal migmatites, upper crustal granites and metasedimentary xenoliths including garnet xenocrysts, to associated ignimbrites and obsidian flows that are assembled in large Permian calderas. This will also lead us to discuss the complex nature of the continental crust in space and time and the role of the lower continental crust for bulk crust compositions.

We will investigate the genetic links between mantle and crust, the processes of melt generation and assimilation in the lower crust and the relations of pyroxenites in the mantle with the large mafic complex. We will discuss tempos and rates of magmatic accretion in transcrustal magmatic systems and possible transport rates of lower crustal xenocrysts that are now found in upper crustal granites. We will address
the relationships between magmatic underplating and potential links to migmatite formation and (the lack of) links between granulite facies metamorphism and igneous underplating. Eventually, we will discuss the importance of the later Mesozoic and Alpine evolution for the emplacement of a near continuous section of the Permian continental crust in the context of major (micro-) plate re-organization.

The field trip will take place along the Sesia Valley between Balmuccia and Borgosesia, home of the Permian Sesia ‘Supervolcano’ and home of a large lower crustal intrusion into the metasedimentary basement of the Southern Alps. In addition to visiting fascinating outcrops of magmatic rocks and migmatites, you will have the opportunity to discover a region of beautiful landscapes, traditional small villages, a clear mountain stream, and experience the local production of Italian vine during a vine tasting event at the end of the field trip. Enjoy one of the most famous lower crustal section in the world.

Presentation of the trip by O. Müntener (two parts):