Geological setting of the Meatiq metamorphic core complex in the Eastern Desert of Egypt based on amphibolite geochemistry

Neumayr, Peter; Mogessie, Aberra; Hoinkes, G.; Puhl, J.

doi:10.1016/s0899-5362(97)00005-5

Cited by 57 publications

(42 citation statements)

References 31 publications

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“…The structural thickness of the mylonitic carapace is typically100-200 m, where traversed by us. Amphibolitic and dioritic enclaves or xenoliths occur locally within the Um Ba'anib Orthogneiss (Neumayr et al 1996) as do mafic dikes. The mafic dikes are altered to biotite schists, and the foliation defined by biotite is oriented subparallel to the foliation in the surrounding, mylonitized Um Ba'anib Orthogneiss.…”

Section: Geology Of the Meatiq Gneiss Dome And Surrounding Areamentioning

confidence: 99%

“…Garnet-mica-schists are relatively common in the same area and have been interpreted as paragneisses (e.g. Neumayr et al 1996). Other gneisses clearly are fine-grained, recrystallized ultramylonites (Figs.…”

Section: Geology Of the Meatiq Gneiss Dome And Surrounding Areamentioning

confidence: 99%

“…Our interpretation is that most of the rocks included in the Abu Fannani Thrust Sheet are strongly mylonitized magmatic rocks and not metasediments. A detailed description of the metamorphic evolution of the rocks within the Abu Fannani Thrust Sheet is given by Neumayr et al (1996Neumayr et al ( , 1998 and Loizenbauer et al (2001). Both the Um Ba'anib Orthogneiss and rocks of the Abu Fannani Thrust Sheet are characterized by a well-developed, elongation lineation formed under amphibolite facies conditions.…”

Section: Geology Of the Meatiq Gneiss Dome And Surrounding Areamentioning

confidence: 99%

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U–Pb TIMS age constraints on the evolution of the Neoproterozoic Meatiq Gneiss Dome, Eastern Desert, Egypt

Andresen

El-Rus

Myhre

et al. 2007

Int J Earth Sci (Geol Rundsch)

173

121

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Ages are used to constrain the temporal evolution of the Meatiq Gneiss Dome, Eastern Desert, Egypt, by dating (ID-TIMS) pre-, syn-, and post-tectonic igneous rocks in and around the dome. The Um Ba'anib Orthogneiss, comprising the deepest exposed structural levels of the dome, has a crystallization age of 630.8 ± 2 Ma. The overlying mylonites are interpreted to be a thrust sheet/ complex (Abu Fannani Thrust Sheet) of highly mylonitized metasediments (?), migmatitic amphibolites, and orthogneisses with large and small tectonic lenses of lessdeformed intrusives. Two syn-tectonic diorite lenses in this complex have crystallization ages of 609.0 ± 1.0 and 605.8 ± 0.9 Ma, respectively. The syn-tectonic Abu Ziran diorite, cutting across the tectonic contact between mylonite gneisses of the Abu Fannani Thrust Sheet and a structurally overlying thrust sheet of eugeoclinal rocks (''Pan-African nappe''), has a magmatic emplacement age of 606.4 ± 1.0 Ma. Zircons from a gabbro (Fawakhir ophiolite) within the eugeoclinal thrust sheet yielded a crystallization age of 736.5 ± 1.2 Ma. The post-tectonic Fawakhir monzodiorite intrudes the ophiolitic rocks and has an emplacement age of 597.8 ± 2.9 Ma. Two other post-tectonic granites, the Arieki granite that intrudes the foliated Um Ba'anib Orthogneiss, and the Um Had granite that cuts the deformed Hammamat sediments, have emplacement ages of 590 ± 3.1 and 596.3 ± 1.7 Ma, respectively. We consider formation of the Meatiq Gneiss Dome to be a young structural feature (\631 Ma), and our preferred tectonic interpretation is that it formed as a result of NE-SW shortening contemporaneous with folding of the nearby Hammamat sediments around 605-600 Ma, during oblique collision of East and West Gondwana.

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Section: Geology Of the Meatiq Gneiss Dome And Surrounding Areamentioning

confidence: 99%

Section: Geology Of the Meatiq Gneiss Dome And Surrounding Areamentioning

confidence: 99%

Section: Geology Of the Meatiq Gneiss Dome And Surrounding Areamentioning

confidence: 99%

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U–Pb TIMS age constraints on the evolution of the Neoproterozoic Meatiq Gneiss Dome, Eastern Desert, Egypt

Andresen

El-Rus

Myhre

et al. 2007

Int J Earth Sci (Geol Rundsch)

173

121

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“…The CED Hammamat metasedimentary rocks in general show anchizonal metamorphic grade indicated by the presence of montmorillonite and pumpellyite (Soliman, 1983;Osman et al, 1993;Osman, 1996). However, chlorite zone greenschist metamorphic facies is also found (El Kalioubi, 1996;Greiling et al, 1994;Neumayr et al, 1996;Fritz and Messner, 1999), with biotite zone or higher grades at distances up to 5 km from the MCC margin. Messner (1996) described somewhat higher grades in the lower stratigraphic sections of the Hammamat in the Wadi Hammamat-Wadi El-Qash area, and correlated this with increased shearing effects.…”

Section: Petrography and Metamorphismmentioning

confidence: 99%

Gravitational collapse origin of shear zones, foliations and linear structures in the Neoproterozoic cover nappes, Eastern Desert, Egypt

Fowler

Kalioubi

2004

Journal of African Earth Sciences

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“…Both these alternatives can explain the dramatic change in metamorphic grade (e.g. Neumayr et al 1996) between the gneisses and the island arc affined allochthon ). Andresen et al (2010) named the shear zone the Eastern Desert Shear Zone (EDSZ).…”

Section: Geological Settingmentioning

confidence: 99%

U–Pb ID-TIMS dating of igneous and metaigneous rocks from the El-Sibai area: time constraints on the tectonic evolution of the Central Eastern Desert, Egypt

Augland

Andresen

Boghdady

2011

Int J Earth Sci (Geol Rundsch)

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This paper presents new ID-TIMS U-Pb zircon and titanite ages from the El-Sibai gneiss complex in the Eastern Desert of Egypt. The zircon data support previous studies, indicating that the protoliths of the gneissic (oldest) units in the area were emplaced during the East African orogeny, and do not represent an older pre-Neoproterozoic, reworked cratonic basement. The crystallization ages of three compositionally distinct orthogneiss protoliths are c. 685, 682 and 679 Ma, respectively. A U-Pb titanite age from one orthogneiss overlaps with the protolith age, indicating that the gneisses did not undergo post-magmatic high-temperature metamorphism. The gneissic textures of the rocks are therefore interpreted to reflect syn-emplacement deformation. This, and evidence for static amphibolite facies metamorphism in country-rock metavolcanics, lead us to conclude that the gneisses of El-Sibai do not represent an exhumed middle crustal gneiss dome, but are part of the island arc affined allochthon into which they were emplaced synchronously with NW-ward nappe translation. We also report ages from rocks cross-cutting the gneisses and the surrounding island arc affined assemblages that yield the hitherto youngest robust preCretaceous intrusive ages in the Eastern Desert. The dated rocks are an anorthosite and a cross-cutting syenogranite giving ages of c. 541 and 540 Ma, respectively. We consider this late magmatic pulse to be anorogenic, most likely reflecting a separate extensional event involving asthenospheric upwelling and decompression melting of the mantle.

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Geological setting of the Meatiq metamorphic core complex in the Eastern Desert of Egypt based on amphibolite geochemistry

Cited by 57 publications

References 31 publications

U–Pb TIMS age constraints on the evolution of the Neoproterozoic Meatiq Gneiss Dome, Eastern Desert, Egypt

U–Pb TIMS age constraints on the evolution of the Neoproterozoic Meatiq Gneiss Dome, Eastern Desert, Egypt

Gravitational collapse origin of shear zones, foliations and linear structures in the Neoproterozoic cover nappes, Eastern Desert, Egypt

U–Pb ID-TIMS dating of igneous and metaigneous rocks from the El-Sibai area: time constraints on the tectonic evolution of the Central Eastern Desert, Egypt

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