FAULTING HISTORY AT THE EASTERN TERMINATION OF THE HIGH ATLAS FAULT (WESTERN HIGH ATLAS, MOROCCO)

At its eastern termination, the High Atlas Fault in the Western High A tlas in Morocco, consists of a splay of three faults. In the interjace nt fault blocks, Neo-and Paleoproterozoic basement, forming the northe rnmost extremity of the NW-African Craton, is cropping out. The Precam brian basement witnesses a long history of brittle deformation startin g at the end of the Pan-African Orogeny. A subsequent episode of norma l faulting can be related to the development of a Hercynian basin alon g the northern passive margin of the cratonic promontory. With regard to the main tectonic activity in the Western High Atlas, basically two models exist: one emphasising block tectonics reflecting Mesozoic rif ting followed by Alpine uplift and inversion, the other emphasising La te Paleozoic dextral wrench tectonics. The analysis of the fault activ ity along the splay faults reveals a predominantly Alpine history, con sisting of the Triassic development of the 'Atlas Rift' along the axia l zone of the orogen, followed by uplift and inversion. The Late Juras sic to Cenozoic fault activity took place in a sinistral transpressive regime and was partitioned over the three splay faults. Dextral strik e-slip fault activity could not be demonstrated in the fault blocks no r along the splay faults. Therefore the faults were probably not invol ved in Late Paleozoic dextral wrench tectonics.