Abstract
The compilation of a fault map from field work and photo interpretation for part of the northeastern flank of Al Kufrah Basin in southeast Libya, together with the kinematic analyses of several rhomboid structures, showed the following major fault sets: dextral NW strike-slip faults; sinistral NE strike-slip faults; and EW faults as subsidiary sets of either the NW or NE trends. The NS trend, mainly as normal faults, is represented by a north-south, right-stepping set of well-defined en echelon grabens. These fault sets revealed a NE sinistral wrench system, about 30 km-wide, made up of four belts of almost equal width, each delimiting or controlling the distribution of the NW faults. The NS grabens, which are filled with Upper Ordovician sediments, mark the initiation of the wrench system as early as Late Cambrian or Early Ordovician, because they control, restrict, or confine the distribution of all the other fault sets in the area.
The basement configuration as interpreted from a total intensity aeromagnetic map for the area confirmed the existence of this wrench system, where the median of the proposed wrench system at the surface coincides with a NE-trending deep valley on the magnetic map. Several magnetic anomalies were tested against the kinematic model for the area and were found to comply with the proposed wrench system, with identical structural manifestations on the surface.