Structural implications of strain localization towards a continental transform fault: The example of the shift between the Levant margin and the Dead Sea Fault plate boundary

Abstract

Continental transform faults accommodate lateral motion between two adjacent plates. Often, evidence for such motion is hard to detect due to onland processes of erosion. Investigation of a submerged passive continental margin adjacent to a transform plate boundary might provide indications for the developmental stages of the transform. To examine this hypothesis, we analyzed the Messinian-to-recent stratigraphy and structure of the Levant continental margin that resides ca. 100 km from the Dead Sea fault (DSF) continental transform. The analysis is based on interpretation of seismic reflection data (2D and 3D time migrated, and pre-stack 3D depth migrated) and four boreholes. It includes construction of structural maps, tracking of stacking patterns and calculations of sedimentation rates. Data show that the Levant margin developed through three phases: (1) Late Miocene-Earliest Zanclean (∼6-∼5 Ma) NNE-SSW left lateral strike-slip faulting (2) Zanclean-Late Gelasian (∼5–1.8 Ma) syn-depositional folding striking in the same direction. The top Gelasian surface marks an abrupt change, which is expressed as (3) mass slumping that occurred due to regional basinward tilt. Continuation of differential subsidence is manifested by Calabrian-to-recent progradation (1.8–0 Ma). While Nile sediment flux peaked at 1.8 Ma and decreased during the Calabrian-to-recent, our data shows an increase in sedimentation on the Levant margin throughout the entire Plio-Pleistocene. This discrepancy is caused by the regional tilting of phase 3, which shifted the depocenter to the west. Correlations to onshore findings suggest that the faulting, folding and tilting observed on the continental margin represent localization of strain towards the DSF during the Pliocene-Gelasian (5.3–1.8 Ma). This is attributed to the consequent deepening of the DSF and the incipient collision of the Eratosthenes Seamount with the Cyprus Arc. The continental margin records the development of the nearby active transform through structural and sedimentary modifications.