AAPG Geoscience Technology Workshop

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Structural Implications of Strain Localization to a Continental Transform: An Example From 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, this process leaves little evidence due to the erosive nature of the land environments. Investigation of a submerged passive continental margin adjacent to a transform plate boundary might provide estimates for the development of the transform. To examine this hypothesis, we analyze 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 shows that the Levant margin developed through four phases: (1) Late Miocene-Earliest Zanclean (~6-~5 Ma) NNE-SSW left-lateral strike-slip faulting, followed by (2) Zanclean-Late Gelasian (~5-1.8 Ma) syn-depositional folding striking in the same direction. The top Gelasian surface marks an abrupt change- (3) mass slumping that occurred due to regional basinward tilt; and (4) continuation of differential subsidence manifested as 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 resolved by the regional tilting of phase 4 which shifted the depocenter to the west. Correlations to onshore findings suggest that the faulting, folding and tilting observed on the continental margin manifest strain localization toward the DSF during the Pliocene-Gelasian (5.3-1.8 Ma). Strain localization 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.