Structure of the Ajdabiya Trough, NE Sirt Basin-Libya, Derived from Gravity and Magnetic Data

This paper presents an interpretation of integrated potential field dataset from Ajdabiya Trough, northeast Sirt Basin Libya. The trough is a 7, 000 m thick aborted NW-trending rift that was formed during the Early Cretaceous time (the collapse of Sirt Arch). The study aimed to assess the role of basement structures in the development of the Ajdabiya. Our results indicate that the major fault systems of the Ajdabiya Trough were superimposed on Precambrian Pan-African basement fabric. A NW-SE trending structures are predominant, along with subordinate of E-W trending features parallel to structures formed during early rift stage. The results of the combined gravity and magnetic modelling reveal an extended graben structures that comprises an elongated depocentres that are separated by intra-rift horsts and bald basement highs. In addition, part of the Moho topography within the study area is controlled by a shear zones and developed during periods of crustal extension during the Mesozoic time. The gravity and magnetic signatures, suggest that Mesozoic Cenozoic mafic intrusive possibly constitute the basement blocks and possibly play a significant roles during subsequent stages of extension and fault reactivations. ENE-WSW trending shear zones as it appears on the gravity and the magnetic maps may have facilitated the emplacement of Pre-Cambrian intrusions and accommodated NW-SE extension within the Ajdabiya Trough and reactivated pre-existing fabric during the Early Mesozoic time.