Between sky and abyss

[Article] - Published on March 14, 2016 in Doctoral training and hdr

Carlotta Ferrando's scientific adventure was to take to the sea to try and understand the secrets of the earth. This is the story of a PhD student who has just completed two months of intensive research in the middle of the Indian Ocean.

Welcome aboard the Joides Resolution. At 140 m long, she is one of the scientific drillships of the IODP (International Ocean Discovery Program). A doctoral student at Géosciences Montpellier working on the European ABYSS project, Carlotta was part of the 360 Southwest Indian Ridge expedition, from November 30 to January 30. The aim of this offshore campaign was to drill into the rocks of the oceanic crust south of Reunion Island.

Understanding the formation of oceanic crust

What's at stake in this mission?
The main one: to study the processes involved in the formation of the Earth's oceanic crust. At the heart of the oceans, tectonic plates move apart at the ridges, bringing magma - produced by the partial melting of the Earth's mantle at a depth of just a few dozen kilometers - into contact with the marine environment. As this magma cools, it forms the oceanic crust.
What does your job involve?
It involves analyzing samples in the form of "cores" taken by drilling. The oceanic ridge is a unique place, the meeting point between the ocean and the depths of the earth. It's one of the few places where our planet's inner and outer shells interact! Magma, rocks and water form an astonishing ballet, bubbling with chemical reactions. My role is to identify the minerals present and analyze their chemical composition in order to study the interactions between magma and rock.

Messages from the heart of the earth

How deep do you drill?
On this expedition, we drilled 800 m deep into the oceanic crust. 700 m of water separate the boat's hull from the ocean floor... It's a record: the deepest drilling ever carried out in a single expedition in the rocks of the magmatic oceanic crust! The deepest scientific borehole ever drilled by the JOIDES Resolution is 2.1 km.
So what you're looking at under the microscope is the heart of the earth?
Far from it; the outer part of the Earth's core lies almost 2,900 km beneath our feet. What I'm looking for in minerals are messages from the depths. The mineralogical and chemical composition of rock samples can teach us a great deal, and change our vision of the dynamics of the formation of the Earth's crust.
What's next?
The samples have just arrived in the lab, and work is resuming, this time on land. It will take time to process and analyze all the samples. So no publication is expected for a few years. See you in 2018!

Floating laboratory

On board the Joides Resolution, 120 people of all nationalities, including 30 researchers from all disciplines. But also engineers, sailors, drillers, cooks...
In this floating factory entirely dedicated to research, work is intense, 24 hours a day, 7 days a week: "Nothing stops the drilling, apart from very bad weather or technical problems. Samples arrive all the time. Physical and chemical analyses: the labs are in full swing, day and night. The teams take it in turns to work 12-hour shifts... which quickly overflow: it's not uncommon to work 18 hours in a row!"
A sometimes difficult experience, but one that proves particularly valuable for a doctoral student. "We're all looking at the same thing, but from different angles.There'sso much to learn from this confrontation of ideas and points of view, and from this constant emulation".
Carlotta was a willing prisoner for two months of this "science bubble", where it's easy to forget the contingencies of "normal" life. Impressions on returning? "It's an extraordinary crash course!It's an ideal way to learn about scientific practice". It was also a marvelous adventure, of which some incredible images remain, "guitar evenings on deck with the setting sun as the horizon, off... nowhere!"