Tectonic evolution of the Meatiq infrastructure, Central Eastern Desert, Egypt
Habib, Mohamed E.; Ahmed, A. A.; El Nady, Osman M.
Журнал:
Tectonics
Дата:
1985
Аннотация:
The Pan‐African basement exposed in the Meatiq area, Central Eastern Desert, Egypt, was found to possess tectonic styles belonging to infrastructure, transition and super‐structure levels. Tectonic style of the infrastructure was developed during an old orogeny in the Lower Pan‐African, and overprinted by those of the transition and superstructure levels of a younger orogeny in the Middle and Upper Pan‐African, respectively. In the Lower Pan‐African, old sequences of sediments and volcanics, together with ophiolitic rocks, were intensely deformed and regionally highly metamorphosed into gneisses and amphibolites. In the infrastructure level such rocks were migmatized, plastically deformed and intruded by synkinematic granitoid (diorite to alkali granite) lenses, sheets and plutons which were probably crystallized as amphibolite‐facies gneisses. Later on, these infrastructural rocks were cut by mafic to intermediate dykes and sills, isostically uplifted and cratonized. Parts were exposed to erosion. In the Middle Pan‐African the cratonized rocks sank into a transition tectonic level where they underwent large‐scale thrusting, varying degrees of cataclasis and mylonitization, and low‐ to medium‐grade regional metamorphism. An episode of plutonism guided by thrusts followed, mainly in the form of synkinematic intrusion of tonalite, granodiorite and quartz monzodiorite. In the Upper Pan‐African, isostatic uplift occurred and the mylonitic rocks attained the superstructure level. There they were subjected to two main phases of folding resulting in the major Meatiq domal structure. Subsequently, the folded rocks were intruded by a postkinematic quartz monzonite pluton.
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