Hierarchic three‐dimensional structure and slip partitioning in the western Dead Sea pull‐apart

Abstract

Rifted basins are bounded by marginal belts with fault networks and flexures. We analyze the internal structure of such a belt, the western margins of the Dead Sea basin. This basin is 150 km long, 15–20 km wide with more than 10 km of sediment fill; and it is currently subsiding due to slip of the Dead Sea pull‐apart. The western margin of the Dead Sea basin is an elongated N‐S belt with an intricate three‐dimensional (3‐D) pattern of zigzag faults, flexures and joints. The dominant structures are four sets of oblique‐normal faults, arranged in orthorhombic symmetry. The faults are steep with prevalent strike directions of NNW and NNE. Large flexures developed along and above these faults, forming tilted blocks and localized asymmetric folds. Two sets of subvertical joints that dominate the area trend NNE and NNW, subparallel to the strikes of the dominant fault sets. The parallel relations between these structures at all scales suggest that they formed during a single tectonic phase. Three‐dimensional fault modeling reveals a 3‐D strain field with a large vertical shortening, a minor horizontal shortening in N‐S direction (belt‐parallel) and a large horizontal E‐W extension (basinward). The calculated stress fields associated with the zigzag fault segments are compatible with the observed fault‐parallel flexures. Further, the calculations predict the formation of local tensile belts above the faults, and these tensile belts could explain the penecontemporaneous development of the two joint sets. Architecture similar to the western margins of the Dead Sea basin is likely to develop on rifted margins wherever 3‐D deformation is required by the rifting kinematics.