Gneiss-cored interference dome associated with two phases of late Pan-African thrusting in the Central Eastern Desert, Egypt

Fowler, T.J.; Osman, A.F.

doi:10.1016/s0301-9268(00)00146-7

Cited by 86 publications

(56 citation statements)

References 27 publications

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“…Other gneisses clearly are fine-grained, recrystallized ultramylonites (Figs. 2, 3) (Sturchio et al 1983;Fowler and Osman 2001). Our interpretation is that most of the rocks included in the Abu Fannani Thrust Sheet are strongly mylonitized magmatic rocks and not metasediments.…”

Section: Geology Of the Meatiq Gneiss Dome And Surrounding Areamentioning

confidence: 59%

“…A high-strain zone separates the medium-to high-grade gneisses in the core of the domes from the greenschist grade rocks of the eugeoclinal thrust sheet (e.g. Fowler and Osman 2001). This high strain zone is variably interpreted as a thrust (Ries et al 1983;Sturchio et al 1983), an extensional fault (Fritz et al 1996, a transcurrent fault, or a combination of two or more of these types of shear zones (Loizenbauer et al 2001), depending on the gneiss dome under discussion.…”

Section: Regional Geologymentioning

confidence: 99%

“…Meatiq-, Hafafit-, and Sibai Gneiss Domes; Fig. 1) (Sturchio et al 1983;Fowler and Osman 2001;Greiling et al 1994). The appearance and formation of the gneiss domes are interpreted to be closely linked to tectonic activity along the northward continuation of the Najd Faults System (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…Based on the nature and structural position of ophiolites and associated island arc sequences we prefer to group them together and use the term the eugeoclinal thrust sheet/complex. Various tectonic models, including crustal extension, crustal shortening, transcurrent faulting, or a combination of these processes, have been proposed to explain the age and origin of the gneiss domes (Greiling et al 1994;Fritz et al 1996Fritz et al , 2002Fowler and Osman 2001;Loizenbauer et al 2001;Bregar et al 2002). Contributing to this lack of understanding is that the age, origin and plate tectonic setting of the orthogneisses exposed in the core of the domes remain unclear and the subject of debate.…”

Section: Introductionmentioning

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)

171

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: 59%

Section: Regional Geologymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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)

171

121

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“…Convergence and transpression along the Najd fault system buckled the upper crust, causing structural highs with domes of gneisses overlain by ophiolitic rocks and volcano-sedimentary assemblages of island-arc activity (Neumayr et al 1996a, b;Abdeen and Greiling 2005;Abdeen and Abdelghaffar 2011). Fowler and Osman (2001) described bedding, gneissosity, and complex mesoscopic folds within the high-grade metamorphic rocks exposed in the core of the gneiss dome in Wadi Um Had, and attributed these structures and metamorphism to the main collisional orogeny, and therefore to an age of ca. 640 Ma (Johnson et al 2011).…”

Section: Age and Tectonic Setting Of Gold Mineralizationmentioning

confidence: 99%

Nature and Geodynamic Setting of Late Neoproterozoic Vein-Type Gold Mineralization in the Eastern Desert of Egypt: Mineralogical and Geochemical Constraints

Khalil

Moghazi

Makky

2016

Mineral Resource Reviews

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The vein-type gold mineralization in the Eastern Desert of Egypt consists of sulphide minerals in stockwork quartz veins with hydrothermal alteration zones. The veins cut Neoproterozoic rocks along contacts between granite intrusions and island arc metavolcano-sedimentary sequence and ophiolitic rocks. Mineralization shows a clear structural control and is thus classified as orogenic gold. A post-peak metamorphic origin for the deposition of gold, sulphides, and carbonate gangue in the veins is suggested on the basis of various observations, such as: (1) gold mineralization is confined to quartz-bearing shear zones that cut host metamorphic rocks; (2) many sulphide minerals such as pyrite and arsenopyrite in addition to native gold and carbonate occur in different generations and parageneses; several of the sulphide generations are formed as a result of sulphidization of pre-existing metamorphic rocks; and (3) the depositional temperature of the hydrothermal minerals is commonly less than 400°C. Based on relationships to magmatism and geodynamic framework, the gold deposits formed during the post-collision stage (*640-590 Ma) of Neoproterozoic crustal evolution. Major and trace elements data for 848 gold-mineralized samples of host rocks and quartz veins are treated statistically utilizing multivariate methods including discriminant function and R-mode factor analyses. From the geochemical exploration point of view, the Au-mineralized alteration zones developed within granitoids and schists are the most

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Egyptian Hammamat molasse basins and their relations to arc collision stages: Implications for radioactive elements mineralization potential

2018

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Our understanding of the formation style and tectonic setting of Hammamat molasse sedimentary rocks (HMSR) as well as their chronological situation in the legend of the geologic maps is as yet deficient. The purpose of the work is to decipher the misinterpretation of the HMSR genesis. As such, we present a new classification for HMSR that provides answers about its significant field relationships with the mature island arc volcanics that obviously explains the changes in the depositional environments of HMSR, tectonic setting in addition to the shape and type of their constituents. In the light of our suggested thematic evolution model, the HMSR have been deposited in 3 different tectonic settings: (a) fore‐arc, intra‐arc, and back‐arc basins during pre‐collision stage; (b) fore‐arc basins and low land basins in accretionary prism during syn‐collision stage; and (c) low land and intramontane basins during late‐collision stage. The characteristics of HMSR in each stage differ according to the shape and type of basin and the source of sediments supplying. Thus, they show different types and sizes of clasts, mineralization, and radioactivity. The low radioactive potentiality of HMSR is entirely related to their composition, nature, and source of sediments. Generally, any radioactive anomalies are not related to HMSR themselves, but to the surrounding U‐rich rocks and/or the hydrothermal and super‐heated solutions. Siltstones of HMSR with their recognizable low permeability could be a good barrier for solutions carrying uranium and probably form visible uranium mineralization. Spots of visible uranium mineralization are scattered at the contact between HMSR and late‐collision granites within the southern periphery of Um Tawat Basin and at the contact between trachytes and HMSR within Wadi El Kareim Basin; the extension of this mineralization does not exceed more than few centimetres away from the contact.

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Gneiss-cored interference dome associated with two phases of late Pan-African thrusting in the Central Eastern Desert, Egypt

Cited by 86 publications

References 27 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

Nature and Geodynamic Setting of Late Neoproterozoic Vein-Type Gold Mineralization in the Eastern Desert of Egypt: Mineralogical and Geochemical Constraints

Egyptian Hammamat molasse basins and their relations to arc collision stages: Implications for radioactive elements mineralization potential

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