Carbonate formation in modern marine sediments and oceanic crust – an isotopic approach.

The carbon cycle refers the exchange of carbon between the surface and subsurface of Earth, as well as the various fluxes that redistribute carbon among the many different surface reservoirs. Over the course of Earth history, carbon leaving the surface of the planet into the semi permanent rock archive does so through the burial and lithification of organic carbon and carbonate carbon largely in marine sediments but also in oceanic crust. One important removal mechanism, the formation of carbonate minerals within the pore fluids of marine sediments, remains exceptionally poorly understood. This ‘authigenic’ carbonate formation may play a critical role in the balance of carbon removal from the surface of the planet. Its importance in the long-term carbon cycle remains a point of considerable debate. This project will use isotope measurements in modern marine pore fluids and sediments and basaltic crust to understand the constraints on the formation of ‘authigenic’ carbon and assess its importance in carbon cycle over the course of Earth history. In addition, the student will analyse and characterize the isotope composition of pore fluids and sediments in a range of marine environments to understand the global spatial distribution of authigenic carbonate formation.