Abstract

Palaeomagnetic and structural investigations in the Rif arc of Morocco indicate that there have been large rotations associated with a pattern of outwardly directed thrusting. Rock magnetic experiments in conjunction with thermal and alternating field demagnetization demonstrate that eight sites in Jurassic and Cretaceous limestones along the Internal/External boundary have a stable remanent magnetization. This is, in most cases, rotated anticlockwise by as much as 100° 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 south-directed thrusting, partly overprinted by extensional and sinistral strike-slip faults. (2) At the eastern end of the N 70°E striking Jebha Fault zone there is a pattern of dominant sinistral NE-trending and subsidiary dextral SE-trending strike-slip faults, overprinted by normal faults while at the western end deformation consists largely of south directed thrusting. (3) In the northern section of the chain, where the structural trends are dominantly N-S, thrusting is directed W to NW. It is suggested that the data are best explained by differential motion and rotation of thrust sheets during outwardly directed thrusting around the arc.