#Off The Water with Charlotte Jackson


Charlotte Jackson at Jesus College studies within the Earth Sciences Department.

The mantle comprises over 80% of the solid Earth, yet what do we know about it?

The answer to that is not much! So, when I’m not on the water, rowing with CUWBC, I spend my time trying to find out a bit more about it. The mantle is a reservoir for many important elements for life on Earth, such as Carbon, Hydrogen and Fluorine; as well as the rare metals that we require for our smart phones and modern technology.

My PhD looks at how and where these elements are stored in the mantle and how they are concentrated by melting events that bring them to the surface.

Diamond mine in Botswana

During the first half of the season I went to Edinburgh to use a Secondary Ion Mass Spectrometer to measure Hydrogen, Fluorine and Chlorine concentrations in mantle minerals from samples that I collected from Botswana. Science is not always so glamorous, but I was lucky enough to visit five of the largest diamond mines in Botswana to collect material for my PhD.

Diamonds are formed in the Earth’s mantle, at depths greater than 150 km, by fluids rich in the elements I am interested in (H, F and Cl). They are brought to the surface by magmas that erupt at very explosive volcanoes called Kimberlites. The diamonds are carried within mantle rock, luckily for me the diamond companies aren’t too bothered about this cargo and therefore I am able to study material that has come from depths up to 200 km and is around 3 billion years old!

I am now able to use the data collected in Edinburgh to assess where Hydrogen, Fluorine and Chlorine are stored in the crystal structures of minerals in the mantle and how they are transported to the surface.

My aim is to produce a model of the fluxes of volatile elements (H, F, Cl) through the Earth’s mantle. How much is input at subduction zones? How long does it stay in the mantle? And how much is released during volcanic eruptions? I hope to have the answers to these questions, and more, by the time I finish my PhD!

Charlotte attended Ousedale School, Newport Pagnell, and learned to row with Jesus College Boat Club. Charlotte is now in the third year of her PhD in the Earth Sciences Department.