[ESAC Seminar] Dominic Hildebrandt

“The Role of the Smectite–Illite Transition in the Global Carbon Cycle”

Although mineral transformations have long been recognized, their connection to large-scale tectonic forcings and the resulting feedbacks on Earth’s climate has only lately come into focus. Smectite, a clay mineral generated by weathering of mafic and ultramafic rocks, has an exceptionally high specific surface area of up to 800 m2/g and therefore efficiently adsorbs organic carbon, shielding it from biological breakdown and oxidation to CO2. Mountain building in low latitudes can amplify this process: tectonically exposed mafic and ultramafic rocks weather rapidly under warm, humid conditions and thereby exert a first-order control on global climate. Such mechanisms have been invoked to explain major phases of climate cooling, including the Mid-Ordovician glaciation, and even shifts in Mars’ climate. Given the size of this carbon reservoir, understanding its stability is essential for determining the timescales over which it acts as a sink or source. While we assume that Mars lacks active plate tectonics, Earth’s lithosphere is continually recycled. Clay-rich weathering products are transported to the oceans and ultimately enter subduction zones, where increasing temperature and burial drive the transformation of smectite into illite. This reduces the specific surface area by almost two orders of magnitude and raises a key question: What is the fate of organic carbon bound to smectite surfaces during this transition? In this presentation, I will explore different trajectories for this carbon, drawing from previous work and new kinetic models, and discuss their contrasting implications for long-term climate evolution. I will further outline experimental and field-based strategies to test these pathways and constrain carbon mobility across the smectite–illite transition.

ESAC Early-Career Seminar Series —

A forum for students and postdocs to share recent research, hone presentation skills, and build community among peers, sponsored by the EAPS Student Advisory Committee. Open to current EAPS graduate and undergraduate students and postdocs. Typically hosted on Thursdays during the semester, including pizza lunch.

Contact: esac.officers@gmail.com