Isopach maps of the Triassic-Lower Liassic volcano-sedimentary successions in the Oujda Mountains (eastern Morocco) have been drawn and complemented by the study of the directions of the doleritic dykes. New interpretations of the dynamics of this part of the northern Gondwana margin during the beginning of the Mesozoic rifting are proposed. The tectonic pattern of the Oujda Mountains was controlled by the conjugate motion of N070 degrees E-N090 degrees E (Atlasic) and N150 degrees E-N160 degrees E faults. This extensional regime led to the differentiation of several strike-slip or pull-apart basins delimited by conjugate faults: Oujda, Ahajfoune, Oued El Himer, Tiouli, North Jerada and Metroh depocentres. Some of these are distinct from the others and have sustained a differential subsidence. They have undergone a differential subsidence but this is almost always balanced by the rate of sedimentation and by the basaltic flows which underline the palaeostructures.