Earlier this year Barbara wrote about ‘Life on board of a scientific drilling vessel’. That interview gave some hints in the unique experience my colleagues and I shared on board the Joides Resolution. Now, you might wonder what Joides Resolution (JR) exactly is. The JR is a drilling vessel dedicated to scientific research on ocean and ocean crust dynamics. Different disciplines are involved, from geology (to elucidate the formation of the oceanic crust), to climate change science (to understand how the Earth handled past climatic events), oceanography (to study global water circulation), or microbiology (to track extreme life in rocks forming the ocean floor).Cores of rocks are drilled under the ocean floor, giving scientists a glimpse into Earth’s dynamics. The JR works for the international research program IODP (International Ocean Discovery Program), a marine research collaboration that aims at recovering data recorded in seafloor sediments and rocks, and monitoring subseafloor environments. Every year, hundreds of scientists around the world develop drilling proposals, sail and collect data on IODP expeditions, analyse samples and data, and finally disseminate results to the scientific community. The consortium for Ocean Leadership provided this video to introduce the program.
It was this past 30th of November when we celebrated the anniversary of the beginning of the most unforgettable two months-long adventure I had at sea, on board the Joides Resolution. Exactly one year ago I was in the middle of the Indian Ocean travelling with my colleagues from Colombo (Sri Lanka) to the site where we spent one month and a half in “the middle of nowhere”, surrounded by water at 32°42.3622′S, 57°16.6880′E (Southeast Madagascar, Figure 2). Enthusiasm was strong on board. We were all ready to achieve our unique objective for this IODP Expedition 360: unravel the nature of the oceanic crust in terms of lateral variability, and drill as deep as possible.
The same location was already investigated during past expeditions, providing a vertical one-dimensional view of the oceanic crust: a new drill was proposed for a three-dimensional view. IODP Expedition 360 was intended as the first expedition out of three composing the SloMo Project, a multi-phase drilling program that aims ultimately to drill for the first time through the Moho seismic discontinuity (a holy Grail for marine geologists!). The Moho, or better said the Mohorovičić discontinuity, is a boundary defined by an increase in seismic waves velocity due to a change in the nature of the crust-forming rocks: this has long been interpreted as the limit between the Earth’s crust (mainly made of basalts and gabbros) and the underlying mantle (composed of peridotites). Please visit the post ‘Ocean crust: What is beneath the seafloor?’ for more information on the rocks generally found throughout the oceanic crust down to the mantle
The success of our work as a team during Expedition 360 can be summarized by a single Hole drilled to 789.7 meters below seafloor, with a total of 469.4 m of collected rocks. This is on average 60% recovery, an excellent result for drilling into hard rock. We achieved the ‘world record’ of the deepest igneous rock penetration from the seafloor during a single JOIDES Resolution Expedition.
We collected gabbroic rocks, containing mainly olivine (present at low percentage, post, make up the lower part of the oceanic crust. They record processes forming the oceanic crust that are otherwise hidden from us. Studying gabbroic rocks, as we did on board the JR, can reveal new constraints on how oceans form and on plate tectonics in general (the large-scale motion of large and small plates of the outermost shell of Earth) .
The global media impact was significant during Expedition 360. Journalists interviewed our Co-chiefs to better understand what we were looking for. We received attention by internationally recognized media such as BBC and the Smithsonian Magazine. We, the scientists, also worked together with the Education and Outreach Team on board to share our interests with schools all over the world.
On board the Joides Resolution science never ceases. Samples are drilled 24h non-stop, and groups of researchers work in repeated shifts of 12 h (take a look at the video at the end of this post to have an insight into the life on board the JR). For the best time-work efficiency our job never changes: for two months I woke up, I entered the “core laboratory”, I described and measured the structure of rocks collected. The vessel becomes a place of permanent scientific exchange between researchers of all ages and different countries. Each person on board contributes with their specific expertise: we observe and describe the same object from different points of view, to achieve a comprehensive understanding of what it is made of and how it formed. Being part of an international scientific program as IODP is a unique experience for a PhD student like me. It is an extraordinary accelerated training, which gives the opportunity to meet researchers from different laboratories and to nurture future collaborations.
The story is repeated: a non-stop collection of rock samples
Fun fact: the origin of the word “gabbro”
The term “gabbro” was used for the first time in the 1760s to name a set of rock types that were found in the ophiolites of the Apennine Mountains in Italy. It is after the German geologist Christian Leopold Von Buch, in 1809, that we now use the term gabbro, named after Gabbro, a village in the Rosignano Marittimo municipality of Tuscany.