A Journey to the center of the Earth with scientists from the University of Lausanne

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Othmar Müntener and György Hetényi. (Fabrice Ducrest © UNIL)

Experts from UNIL are co-directing a scientific drilling project almost a kilometer deep, aimed at reaching and documenting, for the first time, the base of the continental crust and the transition to the Earth’s mantle. This international project is taking place in Piedmont, Italy, in an area where usually deep-seated rocks are accessible thanks to a natural shortcut.

What constitutes the interior of our planet? How was the Earth’s crust formed, and how deep can Life be found? For years, these fundamental questions have remained partly unanswered due to technical and financial obstacles. Despite several attempts, humans have never succeeded in continuously exploring the rocks beyond the Earth’s crust to reach the next layer: the mantle, usually some thirty kilometers below the surface.

Scientists from the University of Lausanne’s Faculty of Geosciences and Environment are coordinating an international project that could change the game. Project DIVE (for Drilling the Ivrea-Verbano zonE) carries out scientific drilling in the geological area in the Alps known as Ivrea-Verbano (Piedmont, Italy), the uniqueness of which should make it possible, as a world first, to cross the crust and reach the Earth’s upper mantle.

A region with virtually unique features in the world

“Since around 35 million years ago, the African (Adria) and European continental plates have been moving towards each other. When they collided, in this segment Adria stayed above Europe, contributing to the formation of the Alps,” explains György Hetényi, professor at UNIL and co-leader of the project. “This phenomenon, accompanied by surface erosion, brought up rocks that were usually at depths of tens of kilometers. In this way, over some fifty kilometers on the surface, the Alps form a “shortcut” to the Earth’s mantle  which is then practically within reach.   Another particular feature of this region is that the continental crust is exceptionally well preserved and intact, with little fragmentation.

In the village of Megolo di Mezzo, a borehole (the second in the DIVE project) was therefore initiated in November 2023 and will be completed in April 2024. From a current depth of 870 metres, the hole is expected to reach almost one kilometer, and will document the beginning of the transition between the continental crust and the mantle. In the field, specialists are already analyzing the cores extracted by the drillers, using two scientific containers, one dedicated to geological studies, the other to biology and gas analysis (such as hydrogen and other rare gases). A team of microbiologists is investigating whether there are organisms capable of surviving in extreme pressure conditions at depth.

The precious cores will then be transferred to the various universities, depending on their area of expertise. “At the University of Lausanne, we are studying in particular the chemistry and isotopic composition of rocks, as well as their thermal and seismic properties,” explains Othmar Müntener, professor at the UNIL, initiator and co-leader of the project. “These analyses will give us unprecedented information about the formation and composition of the Earth’s crust.”

The bulk of the work remains to be done, but the first results, notably from the first borehole – which reached a depth of 578 m – are starting to come out, and they are already bringing some surprises.  “There is more sulphur, carbon, fractures and above all a surprising spatial variability compared to what we expected in the lower crust”, observes György Hetényi. “We are also discovering the presence of minerals in unexpected amounts, such as graphite.”

The next step is to complete this second borehole and continue the scientific analyses. A third borehole is planned, dedicated to analyzing and fully crossing the entire crust–mantle transition.

DIVE Project

DIVE project on the ICDP website

DIVE is an international project funded by the International Continental Scientific Drilling Program (ICDP), which brings together multidisciplinary teams from seven countries and some twenty universities. Initiated by the University of Lausanne, this program aims to carry out scientific drilling to penetrate the lower continental crust, reach the upper mantle, and analyze the deep rocks of our planet. It is divided into two main phases. The first is currently underway with two boreholes, and the second is in preparation for a third borehole in a few years. The analyses carried out on these hitherto not studied rocks cover various fields such as geophysics, geochemistry, geodynamics, petrology, rheology (the way rocks deform) and microbiology.

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