Understanding how Earth’s surface processes respond to extreme warming is critical for predicting long-term carbon cycle dynamics and the resilience of landscapes to rapid climatic change. Silicate weathering acts as a key negative feedback by sequestering CO₂ over geological timescales. The Paleocene–Eocene Thermal Maximum (PETM), a rapid global warming event ~56 Ma ago, offers a valuable natural experiment for assessing Earth’s response to abrupt climate perturbations.
This thesis investigates the silicate weathering response to the PETM across a source-to-sink transect in the Southern Pyrenees, a region with a semi-arid Paleocene–Eocene climate and exceptional preservation of diverse depositional environments. Using a multiproxy approach, the study reconstructs regional climate dynamics, evaluates continental weathering responses, traces the transfer of signals to the deep-marine sink, and compares the Pyrenean system with a more lithologically reactive setting on the North American continent recorded in the Gulf of Mexico. Integrated analyses of major and trace elements, clay mineralogy, and stable (δD, δ⁷Li, δ¹⁸O) and radiogenic (εNd, εHf) isotopes capture spatial and temporal variability in climate, weathering intensity, and denudation.
The results constrain the magnitude of temperature and precipitation perturbations in the Tremp-Graus basin, revealing intensified rainfall variability despite stable mean annual precipitation, and quantify temperature shifts in both sediment source and sink. Increased clay formation, together with enhanced sediment reworking, indicates a moderate, incongruent weathering regime in terrestrial to coastal settings (Esplugafreda and Rin). These patterns are echoed in the marine record at Campo and Zumaia, where δ⁷Li and ΔεHf (εNd–εHf decoupling) show coherent excursions, consistent with increased continental clay production and rapidly rising weathering fluxes and reworking. Comparisons with North America highlight the strong influence of initial climatic, lithologic, and geomorphic conditions on regional weathering responses. In more reactive settings, such as the Gulf of Mexico, weathering fluxes appear to increase substantially, potentially amplifying climate feedbacks.
By refining our understanding of climate–weathering feedbacks during the PETM, this thesis provides insights into how Earth’s surface processes may respond to anthropogenic global warming, underscoring the need to integrate geological perspectives into climate prediction and strategies for mitigating future extreme events.
