Reconstructing weathering environments using clay triple-​oxygen isotopes (ClayOx)

The chemical breakdown of rocks on land and under the ocean removes carbon dioxide from the atmosphere through a process known as “silicate rock weathering,” which acts to counter-balance any changes to carbon dioxide levels over million-year timescales. Additionally, weathering on land releases nutrients to the environment and forms clay minerals that are crucial for the development of healthy soils. Although silicate weathering is an important process that keeps Earth’s climate habitable, little is known about how the amount of weathering has changed through time and how this might change in the future in response to anthropogenic activity.

Contents and goals

Our overarching goal is to build a new “proxy” method to quantify silicate rock weathering in the geologic past. We will achieve this by measuring the isotope composition of oxygen atoms in clay minerals, which record information about the climate that was experienced when the weathering reaction occurred. Specifically, we will combine (i) updated theoretical isotope models, (ii) new laboratory synthesis experiments, and (iii) analysis of soil modern samples from different climates to calibrate this proxy. This information will allow us to determine how weathering changes in response to changing climate, with the long-term goal of reconstructing this process through time.

Scientific and societal context

Our work will provide new insights into the natural processes that regulate Earth’s climate and habitability over long timescales. This will update our collective understanding of long-term climate change and help to contextualize ongoing anthropogenic climate changes.