Abstract
The intent of the present study is to elicit the subsurface shear (wrench) zones that affected in the northeastern part of the Sirte Basin area, which is considered one of the most important oil-producing regions, and its impact on similar areas around the world. Several techniques have been applied to gravity and reduced to the magnetic pole data to achieve this goal, such as least squares, tilt angle derivative, horizontal gradient, source edge detection. In addition, Euler deconvolution and power spectrum analyses were carried out with a view to depict clearly faulting pictures along successive depths of deep-seated structures. 2D modeling has been constructed along two profiles and four drilled wells in the study area.
New eleven sets of wrench zones that have not been extracted before were revealed from the interpreted tectonic map and faulting pictures of the study area, mostly of sinistral and dextral strike-slip. Also, these zones were traced on six successive levels to know whether they are superficial or deep. Seven sets were revealed from gravity data and six from RTP data. Two sets of shears traced from gravity coincide with two shears from the RTP map. Some of these zones intersect with each other, these intersection points weakened the Earth's crust which in turn becomes tectonically unstable in this area. These wrench zones are predicted to be due to tectonic movements of the Arabian and African plates and additionally the ensuing East African Rift gadget which led the North African Megashear System to reactivate in a dextral strike-slip pattern. Sinistral transtensional reactivation of north-west putting faults arose from the dextral reactivation of the North African Megashear System.