Taking the Pulse of Salt-Detached Gravity Gliding in the Eastern Mediterranean

Abstract

Despite having a profound impact on the structural evolution of salt-influenced basins, spatial and temporal variations in rates of salt flow, and their key controls, remain largely unconstrained. We investigate early stage salt-detached gliding using a 3D seismic data set from the Levant Margin in the Eastern Mediterranean, where gravitational instability due to margin uplift has caused north-westward translation of the Messinian salt sheet and its overburden. Large base-salt anticlines mean that basinward translation is recorded by the development of supra-salt ramp syncline basins (RSBs) and fluid escape pipes, the latter forming due to the leakage of fluid from the anticline crests. The trails of pipes provide kinematic vectors of transport direction, while the stratigraphic record of the RSBs not only constrains the relative ages of the pipes, but allows us to quantify the magnitude and approximate rate of translation. We correlate intra-RSB horizons across the margin to analyze lateral variations in translation rate, and how these vary through time. We show that translation rates are broadly uniform on the length-scale of individual anticlines (c. 10 km), but that there is significant margin-scale (c. 100 km) lateral variability in both the direction and magnitude of translation. We attribute temporal variations in local rates of translation to cyclical “pulses” of salt flow due to volumetric flux imbalances across the anticlines, while the distribution of elastic strain in the overburden modulates the overall basin-scale trend. These results demonstrate the importance of local stresses in controlling the local direction and rate of salt flow, and further our understanding of salt and overburden rheology.