Structure across a possible intra-oceanic suture zone in the low-grade Pan-African rocks of northern Ethiopia
✍ Scribed by T. Tadesse
- Book ID
- 104354184
- Publisher
- Elsevier Science
- Year
- 1996
- Tongue
- English
- Weight
- 583 KB
- Volume
- 23
- Category
- Article
- ISSN
- 1464-343X
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✦ Synopsis
Regional mapping in the northern Ethiopian basement rocks shows the occurrence of low-grade volcanic, volcano-sedimentary and plutonic rocks of typical Arabian-Nubian Shield assemblage. Within these low grade rocks, previously unrecognized belts of mafic and ultramafic rocks which have ophiolitic character were identified. Lithological variations and structural details across one of the mafic and ultramafic belts, which is exposed in the Zager area of the region, has been examined and is presented. The structural style of this zone is characterized by thrust and fold belt type tectonics with a predominant northwest directed sense of displacement. Linear and planar structures developed in this belt have produced complex structural interferences. Field relationships of these structures reveal progressive simple shear structures, possibly associated with oblique plate convergence. Lithological and structural data are interpreted as manifesting possible intra-oceanic suture zone processes. Copyright ~-1 997 Elsevier Science Ltd. All rights reserved R~sum6--La cartographie r~gionale des roches du soubassement du nord de I'Ethiopie montre la presence de roches volcaniques, volcano-s~dimentaires et plutoniques peu 6volu~es appartenant typiquement aux ensembles de roches connus dans le Bouclier Arabo-Nubien. Parmi celles-ci ont 6t~ identifi6es, des ceintures de roches mafiques et ultramafiques & caract~re ophiolitique, ant~rieurement non-reconnues. Les variations lithologiques et les d~tails structuraux de I'une de ces ceintures, affleurant dans la r6gion de Zager, ont 6t~ examines et d~crits. Le style structural de cette zone est caract~ris6 par une tectonique de plissement et de charriage d~versement essentiellement vers le NW. Les structures lin6aires et planaires de la ceinture ont produit des interferences complexes. Leurs relations de terrain indiquent un cisaillement simple progressif, peut-~tre en association avec une convergence de plaques oblique. Les donn6es lithologiques et structurales sont interpr~t~es comme la manifestation possible de processus de suture intra-oc~anique.