SUTURES AND SHEAR ZONES IN THE ARABIAN-NUBIAN SHIELD

Deformational belts in the Arabian-Nubian Shield (ANS) are divided int o: (1) those associated with sutures, both are-are and are-continental ; and (2) post-accretionary structures which include north trending sh ortening zones and northwest trending strike-slip faults. The are-are sutures manifest collision between are terranes at similar to 800-700 Ma. They are orientated east to northeast in the northern part of the ANS and north to north-northeast in the south. North or south verging ophiolitic nappes are associated with the east to northeast trending s utures. These nappes were steepened by upright folds associated with t he final stages of collision between terranes. East or west verging op hiolitic nappes are associated with the north to north-northeast trend ing sutures. These were deformed by upright folds and strike-slip faul ts related to oblique collision between terranes and/or post-accretion ary deformations. The are-continental sutures define the eastern and w estern boundaries of the ANS and are marked by north trending deformat ional belts which accompanied collision of the ANS with east and west Gondwana at similar to 750-650 Ma. The post-accretionary structures we re developed between similar to 650-550 Ma due to continued shortening of the ANS. This produced north trending shortening zones which offse t the east to northeast trending sutures in the northern part of the A NS but were superimposed as co-axial deformation on the north to north -northeast trending sutures in the south. The shortening deformation c ulminated with the development of northwest trending strike-slip fault s and shear zones. Copyright (C) 1997 Elsevier Science Ltd.