Inferring autogenically induced depositional discontinuities from observations on experimental deltaic shoreline trajectories

Abstract

Palaeo shoreline is a commonly used proxy for palaeo sea level, but only if deposition is continuous and constant will shoreline trajectory T(l) completely capture sea-level time-series E(t). Artificial deltas were generated in the Eurotank flume facility under stepwise tectonic subsidence, periodic sea-level fluctuation and two periodic water-discharge scenarios, one in-phase and the other out-of-phase with sea level. Independent input variables tectonic subsidence Y, sea level E and water discharge Q (controlling sediment supply S) were varied and dependent output variable shoreline trajectory T was monitored. These experiments confirm that deposition is discontinuous even for continuous sediment supply, and this hinders the inference of sea-level curve from shoreline trajectory. These results justify the here-developed methodology for converting shoreline trajectory from the space domain to the time domain, thereby improving the accuracy of the inferred sea-level curve.