Nature study Deep Diamond With Perovskite

Deep into the Earth: diamonds and surficial carbon down to 800 km depth in the Earth’s lower mantle.

A team of geologists from Italy (University of Padova, University of Pavia and CNR-IGG Padova), Canada (University of British Columbia and University of Alberta), UK (University College London), and South Africa (University of Cape Town and Rhodes University) definitively proved what geophysicists indirectly predicted so far, i.e. the oceanic crust and surficial carbon can reach the lower mantle (below 660 km depth) by subduction processes.
The discovery, published in Nature was possible thanks to the study of a special “super-deep” diamond from the famous Cullinan mine (South Africa), where the world’s largest 3107-carats Cullinan diamond was found more than 140 years ago. In detail, the research team, including Dr Martha Pamato from the Department of Earth Sciences at UCL, discovered, the first natural CaSiO3 mineral with a perovskite crystal structure still trapped within the diamond. Many deep Earth scientists had predicted that this mineral would never be found at the Earth’s surface, even though there are zetta tonnes (1021 tonnes) of this material buried deep in the Earth. This very high-pressure form of calcium silicate (CaSiO3) can be stable only from about 600 km depth in Earth’s mantle, continuing to be stable right through the lower mantle. This specific inclusion within diamond shows a chemical composition which would indicate that the diamond formed at about 780 km depth in the Earth’s lower mantle and, at the same time, that the inclusion is derived from oceanic crust (see the cartoon). The research team analysed the carbon forming the diamond, and this indicates its surficial derivation. The discovery is the first definitive prove of oceanic crust and surficial carbon recycled by subduction into Earth’s lower mantle as predicted by seismic images and geodynamic modelling.


Anoxic Event 2 - uranium isotope study

Study shows oxygen loss could be a huge issue for oceans.

A major study from universities including UCL, Birkbeck, Otago, Exeter and Oxford into an ancient climate change event that impacted a significant percentage of Earth’s oceans has brought into sharp focus a lesser-known villain in global warming: oxygen depletion. More...

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Crystallography and Mineral Physics

Our CMP group is internationally renowned for performing outstanding research into to the composition, structure, dynamics and evolution of the Earth and terrestrial planets. We combine both high P/T experimental techniques (DAC, MAP) with computational mineral physics. We regularly gain beamtime at the Rutherford ISIS facility and have access to high-performance computing via the UK Mineral Physics Consortium.