Geophysical overview of the planned phase 2 drilling sites of projet DIVE in Val Sesia, Italy

The Drilling the Ivrea-Verbano zonE (DIVE) project focuses on the continental lower crust from petrological, geophysical, fluid and gas, as well as microbiological perspectives in the framework of ICDP expedition 5071. Two scientific boreholes of DIVE phase 1 have cored 578.5 and 909.5 metres of lower crustal rocks in Val d’Ossola, Italy, and preparations for DIVE phase 2 have already started. The primary goals are to continuously sample the crust–mantle transition, and to test the suitability of a natural peridotite body for serpentinization and hydrogen production.

The structural characterization of the drilling target and the assessment of the subsurface physical properties has been ongoing for several years, and at various spatial scales. Up to date, three active seismic campaigns, one passive seismic profile, regional and local gravity campaigns, and drone-based photogrammetry (digital outcrop model based fracture network analysis) have been undertaken under the umbrella of, or in connection with, project DIVE. Furthermore, aeromagnetic data is available over the region, and geological mapping is being refined in the area planned for drilling. This contribution will present the results reached so far, the differences between them as a function of spatial resolution, models of the Balmuccia peridotite body and related questions, as well as the currently ongoing efforts of geophysical imaging and modelling to reduce the uncertainties. Ultimately, we present the current drilling strategy of the 5071_2 borehole(s).