Constraining large igneous province volcanism and global weathering rates during super-greenhouse climates

 

PhD Candidate: Giorgia Ballabio

Supervisor: Dr. Weimu Xu, Prof. Frank McDermott

Funded by: UCD Ad Astra Fellowship

Abstract:

The Earth's history is marked by major climatic and environmental change events, often associated with major global carbon cycle perturbations, widespread marine anoxia and ecological/biological disturbance. These events have been linked to Large Igneous Province (LIP) volcanism, through which millions of cubic kilometres of volcanic (basaltic) rock were emplaced onto the Earth's surface, potentially leading to the rapid and massive release of greenhouse gasses. Increases in atmospheric carbon dioxide concentrations resulted in global warming and intensified hydrological cycling, thereby enhancing physical/chemical weathering and nutrient supply to marine and continental basins. Silicate weathering is an important carbon sink in the global carbon cycle at geological timescales. A novel geochemical proxy used to trace changes in the contribution of continental silicate-weathering and/or the weathering of subaerial/marine LIPs through time is the change in the Osmium (Os) isotopic composition of global seawater, as
recorded in sedimentary archives. My project employs inorganic isotope geochemistry to trace changes in the silicate-weathering rates throughout some of the largest global change events in Earth's history, including the end-Triassic mass extinction, the Toarcian Oceanic Anoxic Event and the Paleocene/Eocene Hyperthermals.