The Environmental Proxies In Karst group, led by Dr Chris Day, develops and applies proxies for understanding environmental processes in the top few tens of meters of the Earth’s surface. This small subset of the Earth’s geology is extremely active, key to many major environmental cycles such as the carbon cycle, the water cycle, physical & chemical weathering and is therefore often referred to as the Critical Zone. We focus primarily on karstic regions, where we use secondary calcium carbonate deposits (known as speleothems) to record and reconstruct changes in the environment (e.g. rainfall amount, vegetation properties, weathering intensity) over thousands to millions of years.
A key component of our work is the development of experiments in which we grow minerals under carefully controlled laboratory conditions. These experiments are careful to closely follow the natural mechanisms of mineral formation, whilst controlling the composition of the fluids and the environmental parameters (e.g. temperature, fluid flow rate, gas compositions) in which these minerals form. Together with our collaborators, we help to calibrate the use of trace-elements for reconstructing relative changes in rainfall amount & temperature and we develop novel proxies such as the use of Ca-isotopes for reconstructing absolute changes in rainfall amount.
We apply these proxies for reconstructing environmental-conditions and climate in e.g. Chile, Morocco and China. In addition, work is ongoing in the Stable Isotope lab & others to develop new ways of measuring stable isotopes in view of improving environmental and palaeoclimate reconstruction.