Speaking: Gino de Gelder, IRD-Univ. Grenoble Alpes
The next Landscapes Live online seminar will be by Gino de Gelder, IRD-Univ. Grenoble Alpes. This seminar will be live on Zoom and open to anyone interested (with a limit of 300 participants). Register in advance for this meeting.
Abstract
Quantifying paleo sea-level variations is of fundamental importance to understand the complex relations between paleo-climate, -ice-sheets and geodynamics, yet uncertainties prior to the Holocene currently span several tens of meters. The world’s coastlines present an enormous geomorphologic dataset of relative sea-level changes, and recent studies have shown how they can be used within forward landscape evolution models. We take a next step, and apply a Bayesian approach to invert the geometry of marine terrace sequences to paleo sea-level. Using a Markov chain Monte Carlo sampling method, we test our model on both synthetic profiles and observed marine terrace sequences from Santa Cruz (Ca, US) and the Corinth Rift (Greece). The synthetic profiles – with known input parameters – show that there are optimal values for uplift rate and erosion rate to obtain a well-constrained inversion. Both the inversion of synthetic profiles and real sequences show how sea-level peaks are easier to constrain than sea-level troughs, but that also solutions for peaks tend to be non-unique. Synthetic profiles and profiles from several sites in the Corinth Rift both show how inverting multiple profiles from a sequence can lead to a narrower range of possible paleo sea-level, especially for sea-level troughs. This last result emphasizes the potential of inverting coastal morphology, suggesting that joint inversion of globally distributed marine terrace profiles may eventually catalyse a better understanding of local/global paleo sea-level and glacio-isostatic adjustments.