Research

The coupling of silicate weathering and organic matter burial in soil 

Soils are hubs of nutrient cycling across Earth's surface and store a vast amount of organic matter. As Earth warms and extreme climate events occur with increasing frequency, the stability of organic carbon in soil (a potent source of atmospheric CO2) remains in question. Clay minerals that form from the chemical weathering of primary silicates in soil can protect organic carbon from oxidation, but the formation of clay minerals is often fueled by acids generated when organic carbon is oxidized. This tension complicates how we predict the net impact of soil formation on global climate in a warming world. Our group aims to understand how silicate weathering and organic matter burial operate across Earth's surface in order to build better conceptual and mechanistic models of soil formation.

Silicate weathering responses in fluvial systems to climate change

Over Earth's history, sudden and large emissions of CO2 from the solid Earth into the ocean and atmosphere induce a cascade of environmental crises. The chemical weathering of silicate minerals in Earth's crust helps regulate atmospheric CO2 levels and enables climate to recover to its pre-perturbed state. Yet, how climatic and geologic conditions at the Earth's surface modulate these weathering reactions remain hotly debated. Our group seeks to elucidate how fluvial processes, namely the transmission of water and sediment across floodplains, regulate the capacity of watersheds on Earth to sequester CO2 via silicate weathering.

Shale weathering and rock organic carbon oxidation

Shale and other siliciclastic sedimentary rocks contain organic carbon that has not participated in Earth's carbon cycle for millions of years. When exhumed, these rocks react with acids and oxidants, generating chemical species and gases that either enhance or suppress weathering-driven atmospheric CO2 drawdown. Our group seeks to understand the controls of rock organic carbon oxidation across geomorphic scales (e.g., hillslope vs. floodplain) and timescales of observation (e.g., modern vs. geologic). We are particularly interested in how the intrinsic quality of organic matter in rock, the presence of primary phyllosilicates, and the redox conditions within the Critical Zone factor in the breakdown of organic matter.

Hydrothermal water-rock reactions 

Hydrothermal systems in active margins vigorously transmit elements and water between the solid Earth and the ocean-atmosphere system. On continents, magmatic arcs poised with carbonate-rich sedimentary rocks can yield huge fluxes of metamorphic CO2 to the atmosphere, but only when large volumes of meteoric water circulate through the hydrothermal system. When hydrothermal fluids breach the crust, they can complicate the solute composition of rivers and thus inferences about low-temperature water-rock reactions (i.e., weathering). In oceanic crust, the infiltration of ocean water can hydrate the lower mantle and drive reactions that can consume alkalinity (e.g., carbonate formation, clay formation, serpentinization) and possibly dissolved carbon (e.g., carbonate formation). Our group aims to understand the role of hydrothermal water-rock reactions in the global carbon cycle.