A report on exploration of the moroccan western atlas basin using airborne gravity and magnetic survey data

Abstract

Over 10 000 miles of airborne gravity and magnet& were flown by Carson Geoscience Co. for the Moroccan National Office of Petroleum Research and Exploitation (ONAREP) in the Essaouira basin and adjacent regions, including the continental plateau and the western high Atlas Mountains. Used for the first time in Morocco, this airborne gravity survey collected in a very short time enough information to outline the regional basement geology, contribute to the establishment of new seismic programs, reveal new structures, and extend known ones. Exploration activity m the past concentrated generally in Jurassic and younger formations and yielded five Jurassic horizon discoveries. Since the discovery of the new Meskala gas field, interest has extended to Triassic and Paleozoic formations elsewhere. The Triassic is represented by red beds and it contains basaltic layers and a thick salt development. These horizon3 have been penetrated in many wells. Both the Triassic salt and Jurassic anhydrites are excellent seals for underlying rcservoirs. The density contrast between the saliferous Triassic (tl = 2.3 g/cm’) and the Paleozoic (ti = 2.7 g/cm’) gives a notable gravity expression of Paleozoic basement. The paper deals with the results of the combined airborne gravity and magnetic interpretation which shows several interesting new exploration prospects. In addition. the implied nature of the continental margin as indicated by magnetics is discussed.