Contribution of gravity and aeromagnetic data to the structural modeling of the hidden faults in Guercif Basin, northeastern Morocco

Abstract

The Guercif Basin of the northeastern Morocco is regarded as a particular sedimentary basin influenced by the tectonics of the Middle Atlas Fault Zone, the Rif orogenic belt and the stable eastern Meseta. Its faulting structures are poorly perceived on surface because of the thick recent sedimentary cover that overlies the Mesozoic-Paleozoic basement. The interpretation of potential field data shows relevant results in deciphering the basement structure of a complex sedimentary basin, such as the Guercif Basin. In order to understand the structural framework of this basin and to establish its subsurface structural map, gravity and magnetic data were processed using various edge detection techniques accomplished by an extensive geological data and seismic interpretations.A new subsurface structural map was established where many faults already recognized or supposed by traditional structural studies have been confirmed and new major ones by specifying their trends and depths have been emphasized. In addition, this new map demonstrates that the Guercif Basin is affected by several major faults elongated in three main trends: NE-SW, E-W and NW-SE, inherited from Variscan tectonics and reactivated in relation with atlasico-alpine tectonics.The established referential map reveals that the study area is subdivided into two different structural domains; a western one principally affected by NE-SW trending faults representing the northeastern extension of the Middle Atlas Fault Zone, and an eastern domain belonging to the stable eastern Meseta and characterized in general by large E-W trending faults. It allows us also to identify a sinistral fault zone in Tafrata area which we have labeled “Tafrata Fault Zone” and to define the continuity of the North Middle Atlas Fault (NMAF), the Central Middle Atlas Faults (CMAF) and the South Middle Atlas Fault (SMAF) which presents very likely the limit between the two identified domains. The elaborated map will be a useful document for all future petroleum explorations or hydrogeological investigations.