Research Fellows Directory
Dr Rosalind Coggon
University of Southampton
The long-term cycling of carbon (C) between the solid Earth, oceans and atmosphere over millions of years controlled past atmospheric carbon dioxide (CO2) levels and hence climate. Knowledge of how contributions to this C-cycle have varied allows the processes responsible for past global change to be investigated. My research focuses on the role of submarine volcanism in the long term C cycle.
Submarine volcanism along mid-ocean ridges produces new ocean crust, and is a key component of the plate tectonic cycle, repaving two thirds of the Earth’s surface every 200 million years as crust spreads towards subduction zones. Seawater circulates through cracks in the ocean crust, where it is heated and reacts with the rock. Minerals are deposited in the crust from these fluids, changing the chemistry of the fluid and rock. This processes is known as ‘hydrothermal circulation’. During the volcanism CO2 gas is released from the crust. During ‘hydrothermal circulation’ calcium carbonate (CaCO3) forms from the fluid, storing CO2 in the crust. Hence, submarine volcanism contributes to the long-term C-cycle.
My research uses chemical analyses of ocean crust rocks and CaCO3 to investigate: past changes in ocean chemistry; how much CO2 is released from/stored in the ocean crust; and which processes control CaCO3 formation. These results will be used to study how variations in the extent of mid-ocean ridge volcanism affected the C-cycle and climate.
This research will improve our understanding of the long-term C-cycle that influences climate. In addition, knowledge of the physical and chemical controls on the CaCO3 formation will benefit attempts to recreate and accelerate this process to store industrial CO2 as CaCO3, to prevent future climate change. Knowledge of how hydrothermal circulation affects the ocean crust, which ultimately gets subducted, will aid studies of subduction zones where major earthquakes occur and their associated natural hazards (e.g. tsunamis).
Interests and expertise (Subject groups)