Gideon Henderson, Oxford University: our projects together include studying both modern rivers (in the mountainous regions of New Zealand), and the first ever study of speleothems (cave carbonates) as an archive of local chemical weathering over the past few ice ages. This is particularly important, because it allows us to determine the controls on weathering (and therefore climate) over warming and cooling periods, rather than just generating a record of changes.
Lithium isotopes in speleothems: Temperature-controlled variation in silicate weathering during glacial cycles
Terrestrial chemical weathering of silicate minerals is a fundamental component of the global cycle of carbon and other elements. Past changes in temperature, rainfall, ice cover, sea-level and physical erosion are thought to affect weathering but the relative impact of these controls through time remains poorly constrained. This problem could be addressed if the nature of past weathering could be constrained at individual sites. In this study, we investigate the use of speleothems as local recorders of the silicate weathering proxy, Li isotopes.