David Cavell

University of Birmingham


Investigating the role of oceanic plateaus in early continental growth


Dr Alan Hastie Dr Sebastian Watt

PhD Summary

How and why the first continents formed on Earth is an open question in geoscience. The majority of continental crust preserved from early Earth history (4.0 – 3.0 Ga) is composed of a suite of rocks known as trondjhemites, tonalities and granodiorites (TTG). The geological setting for generation of this material remains controversial. Though some workers favour remelting of basalt at the base of thickened crust, most workers view a subduction setting as more likely. This is partly based on the fact that the TTG suite has a distinct chemical composition similar to rare modern arc lavas known as adakites. Recent work in Jamaica has described a sub-type of adakites derived from underplating of arc crust by oceanic plateau. Underplating or subduction of oceanic plateau is increasingly seen as a likely mechanism for generation of the earliest (4.0 – 3.6 Ga) continental crust. As the Caribbean plate is largely composed of oceanic plateau, material with a similar origin and geochemistry could exist elsewhere in the Caribbean and the margin of South America. This could provide a possible large-scale analogue for production of the earliest TTG. I have conducted extensive fieldwork in both Panama and Colombia as part of this research, as the geochemistry of rocks of the Northern Volcanic Zone of the Andes in Colombia and related rocks in the Panama isthmus may provide possible analogues for the Earth’s first stable continents.

What inspires you?

Coming from the South Wales, I spent a lot of time during my childhood on the Glamorgan coast valleys where you find plenty of fossils and tangible links to Earth history. Economic geology was never far away either living in former coal mining areas. That made me think about how much geology impacts people’s lives, how much we rely on natural resources and understanding them.

Previous Activity

After I left college with my A Levels, I did my undergraduate degree in geology at the University of Leicester. This included a master’s research project, which involved me working on volcanoes in the South Atlantic with the British Antarctic Survey. This was exciting because I got to work on volcanoes that no one had ever studied before. I have also had a lot of involvement in student politics, and I was part of the National Executive Committee of NUS Wales before my degree. I was an elected officer in a number of roles at Leicester Students’ Union and was awarded their Officer of the Year award (2015) for my work on their Steering and Scrutiny Committee.

Why did you choose Docotoral Research?

Research was not the first thing I thought of when I started my degree. I had good tutors and supervisors who encouraged me that I had the ability to do scientific research, but my undergraduate dissertation was a real turning point. I went looking for a research question that really bothered me and ended up with “Why do we have continents?” Though the dissertation was obviously narrower than this, it taught me how much I enjoy investigating the topic, and I first talked to my supervisor at Birmingham because of the dissertation, and things just went naturally from there.

Why did you choose a CENTA Studentship?

The project itself was the real draw for me in applying, but being part of such a diverse and well-resourced consortium was definitely a big factor. Having the training and resources that CENTA allows for benefits me and my project, and the ability to interact with so many other CENTA doctoral researchers outside my field adds a new perspective to the research that I would not otherwise have.

What are your future plans

I hope to continue working on the geology of the Caribbean, and especially Colombia. The research community there is full of amazing people who were a real pleasure to work with, and I’d love to go back to continue working with them after the project. There is so much we don’t know about the region, and I think this PhD will really enable me to be involved in that continuing research, inside and outside academia. Communication of science is something I’m really passionate about, and I would relish the opportunity to be able to do more of it.