A brief history of ocean drilling (1/3)

Did you know the oceans are great story tellers?! Curators of Earth’s history. And by taking a peak below the seafloor we can reconstruct the history of submarine landslides, and volcanic eruptions, the pattern and rate of seafloor spreading, the climate enjoyed by the dinosaurs and the vegetation present when the humans took their very first steps on planet Earth.

This week in the MOOC is all about looking forward; how we can work together to protect our oceans. Over my next three blog posts I am going to encourage you to think about the past to help us think about the future. Disclaimer: I am a palaeoceanographer (read my confession here) and I spend much of my getting lost in the past to better understand the future.

First up: a brief history of ocean drilling.

Back in January I was fortune enough to be out on the RRS Discovery in the South Georgia basin (read our cruise blog here) as part of a team of scientists gathering geophysical data and sediment cores from this region to understand when and how the Drakes Passage opened and the implications for this on the inception of Antarctic glaciation. However, there is a long history to ocean exploration through scientific drilling which (as with all great science!) is rooted in truly collaborative scientific research…..

Stormy skies above Punta Arenas as we waited to leave port in January 2018 to go and explore the South Georgia basin aboard the RRS Discovery

Over geologic time, sediments slowly accumulate on the seafloor. These sediments are comprised of differing components of aeolian dust, clays, sands and microscopic fossils (both calcareous e.g. foraminifera and coccolithophores, and siliceous e.g. radiolarian diatoms). In the 1940s scientists discovered how to routinely recover long continuous sections of these sediments from the seafloor by essentially having a long metal hollow cylinder with a large weight at the top drop from the ship into the seafloor (piston coring).

Example of a sediment core collected from the North Atlantic, J-Anomaly Ridge (Newfoundland; IODP Expedition 342)

As ship science developed and scientific interest in the stories buried beneath the seafloor increased the US National Science Foundation (NSF) launched a project known as Project MoHole in the 1960s, which aimed to drill straight through the ocean floor, through the Mohorovicic discontinuity (marking the boundary between the oceanic crust and mantle). Needless to say, they never got there!…..or more correctly, we have not got there yet! Read about current progress on drilling to the MoHo here: http://www.bbc.co.uk/news/science-environment-34967750

What they did recover during Project MoHole was a succession of sedimentary sequences from below the seafloor and a realisation of the scientific value of these sediments. For the first time, we had the opportunity to reconstruct the history of Earth at unprecedented resolution and continuity.

Examples of some of the drill bits used by the ships that are on display in GCR, College Station, Texas

From this was born the Deep Sea Drilling Project (DSDP) using the Glomar Challenger. Driving further advancements of ocean drilling and recovering sedimentary records from all around the world, DSDP expeditions recovered valuable sediments that scientists are still working on today.

Some of the cores collected on the Glomar Challenger as part of DSDP that I went to look at in Texas last year

Next up came the Joides Resolution (JR) and the Ocean Drilling Program (ODP) which continued on from the work of DSDP with an international effort to increase ocean exploration and discovery through the recovery of sediments and rocks from below the seafloor.  This international effort managed to embark on 110 expeditions, covering all the world’s oceans. Through this not only did we gain an ever increasing understanding of Earth processes past, present and future, but a deeper understanding of the best approaches to ocean drilling and how to maximise use of the material recovered.

Jodies Resolution (source: www.iodp.tamu.edu)

Again, building on from this, the international community launched the Integrated Ocean Drilling Program (IODP), adding further drill ships and machine-specific platforms (an example of a recent MSP expedition: http://www.bbc.co.uk/news/av/science-environment-35953976/drillers-to-target-chicxulub-crater) to target more sites around the oceans. These expeditions are years, often decades in the planning. The scientific findings from the cruise I participated on this year contribute towards efforts to get the JR back to this region to recover even longer sedimentary sequences than we did on board the RRS Discovery.

This work is still ongoing today and we continue to recover more ocean sediments, discover more things about the past, and gain an understanding of how to best move forward in the future.  In addition to IODP, most research vessels have the capacity to recover these sedimentary snapshots of Earth history. Excitingly, the new RRS Sir David Attenborough is having a new giant piston coring device installed that will routinely recover 40m cores with a 80% recovery rate and in addition to the other UK research vessels continue to provide value insights to the oceans of the past.

Together the science community is piecing together, chapter by chapter, the story of Earth. Hundreds of years from now, scientists will be able to do the same, to piece together the story of our generation from the imprint we leave on the planet. The question is: what story do we want to leave behind……

 

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