PALEOMAGNETIC ROTATIONS AND FAULT KINEMATICS IN THE RIF ARC OF MOROCCO

Palaeomagnetic and structural investigations in the Rif arc of Morocco indicate that there have been large rotations associated with a patte rn of outwardly directed thrusting. Rock magnetic experiments in conju nction with thermal and alternating field demagnetization demonstrate that eight sites in Jurassic and Cretaceous limestones along the Inter nal/External boundary have a stable remanent magnetization. This is, i n most cases, rotated anticlockwise by as much as 100-degrees from the expected Mesozoic declination but in the Tetuan area there are large clockwise rotations. Kinematic indicators from fault surfaces indicate the following. (1) In the eastern Rif there has been predominantly so uth-directed thrusting, partly overprinted by extensional and sinistra l strike-slip faults. (2) At the eastern end of the N 70-degrees-E str iking Jebha Fault zone there is a pattern of dominant sinistral NE-tre nding and subsidiary dextral SE-trending strike-slip faults, overprint ed by normal faults while at the western end deformation consists larg ely of south directed thrusting. (3) In the northern section of the ch ain, where the structural trends are dominantly N-S, thrusting is dire cted W to NW. It is suggested that the data are best explained by diff erential motion and rotation of thrust sheets during outwardly directe d thrusting around the arc.