Structural geology, single zircon ages and fluid inclusion studies of the Meatiq metamorphic core complex: Implications for Neoproterozoic tectonics in the Eastern Desert of Egypt

Loizenbauer, Jürgen

doi:10.1016/s0301-9268(01)00176-0

Cited by 208 publications

(170 citation statements)

References 69 publications

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“…The age of the oldest cale-alkaline orthogneisses (495-500 Ma; Abati et al, 2010) establishes a minimum depositional age for the Lower sequence.…”

Section: The Lower Sequencementioning

confidence: 98%

“…1 b and c). The Upper units, on top of the nappe pile, are pieces of a Cambro Ordovician ensialic island arc (Abati etal., 1999(Abati etal., , 2003Andonaegui et al, 2002;Santos et al, 2002) inferred to have been detached from northern Gondwana by the roll-back of the subducting slab of the Iapetus Tornquist ocean, to leave a new oceanic realm, the Rheic Ocean, in its wake (Stampfli and Borel, 2002;Winchester et al, 2002;von Raumer et al, 2003;Abati et al, 2010).…”

Section: Geological Settingmentioning

confidence: 99%

“…Since the Lower sequence is intruded by late Cambrian cale-alkaline granitoids (ca. 495 Ma; Abati et al, 2010), and its youngest detrital zircon population is 566 Ma for the greywackes and 557 Ma for the quartzites, deposition is bracketed between the Neoproterozoic and the middle Cambrian. The Lower sequence represents deposition in a tectonically active setting, so the youngest population likely represents a good approximation of the age of sedimentation.…”

Section: The Sediments Of the Upper Sequencementioning

confidence: 99%

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U–Pb ages of detrital zircons from the Basal allochthonous units of NW Iberia: Provenance and paleoposition on the northern margin of Gondwana during the Neoproterozoic and Paleozoic

et al. 2010

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Keywords: NW Iberia Variscan allochthonous terranes Detrital zircons JA-ICP-MS U-Pb dating GeodynamicsLA-ICP-MS U-Ph ages of detrital zircons from eight silicic1astic samples from the Basal units of the Variscan allochthonous complexes of NW Iberia are used to establish the maximum depositional age and provenance of two tectonically-stacked metasedimentary sequences deposited on the outermost margin of Gondwana, and subsequently involved in the Rheic Ocean suture. The maximum depositionai ages for the two sequences is latest Neoproterozoicand latest Cambrian, respectively. The age spectra are also used to discuss the paleoposition of the NW Iberian basement on the continental margin ofGondwana prior to the opening of the Rheic Ocean, which is tentatively placed in northern Africa, between the West African and Saharan cratons. Based on similarities and differences with age data from the NW Iberian autochthon and other allochthonous terranes involved in the Rheic suture, the relative proportions of Mesoproterozoic zircons in both assemblages are proposed as markers of proximity to the eastern part of the West African craton during late Neoproterozoic and late Cambrian. The geodynamic processes that took place along this part ofGondwana during the late Neoproterozoic, late Cambrian and Early Ordovician are discussed in the light of the LA-ICP-MS results, as well as the sedimentological record, magmatic evolution and plate tectonic setting of NW Iberia. These processes are linked to late Neoproterozoic and Cambro-Ordovician subduction events beneath the northern Gondwanan margin.

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“…The age of the oldest cale-alkaline orthogneisses (495-500 Ma; Abati et al, 2010) establishes a minimum depositional age for the Lower sequence.…”

Section: The Lower Sequencementioning

confidence: 98%

Section: Geological Settingmentioning

confidence: 99%

Section: The Sediments Of the Upper Sequencementioning

confidence: 99%

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U–Pb ages of detrital zircons from the Basal allochthonous units of NW Iberia: Provenance and paleoposition on the northern margin of Gondwana during the Neoproterozoic and Paleozoic

et al. 2010

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“…Kröner et al 1992;Shackleton 1994;Zimmer et al 1995;Loizenbauer et al 2001;Ali et al 2010). They have isotopic ages range from 890 to 690 Ma, documenting a 200 Ma year period of oceanic magmatism.…”

mentioning

confidence: 99%

Petrological studies of neoproterozoic serpentinized ultramafics of the nubian shield: spinel compositions as evidence of the tectonic evolution of egyptian ophiolites

Azer¹

2014

Acta Geologica Polonica

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The mafic-ultramafic rocks of the Gabal El-Degheimi area, Central Eastern Desert of Egypt, are parts of an ophiolitic section. The ophiolitic rocks are dismembered and tectonically enclosed within, or thrust over, island arc assemblages. Serpentinites, altered slices of the upper mantle, represent a distinctive lithology of the dismembered ophiolites. Some portions of the serpentinized rocks contain fresh relicts of primary minerals such as chromian spinel and olivine. The abundance of bastite and mesh textures suggests harzburgite and dunite protoliths, respectively, for these serpentinites. Some fresh cores of chromian spinel are rimmed by ferritchromite and Cr-magnetite. The development of alteration rims around chromian spinel cores indicates their formation during prograde alteration and under oxidizing conditions during lower amphibolite facies metamorphism. Fresh chromian spinels are characterized by high contents of Cr2O3 (48.92-56.74 wt. %), Al2O3 (10.29-20.08wt. %), FeO (16.24-28.46 wt. %) and MgO (4.89-14.02 wt. %), and very low TiO2 contents (<0.16 wt. %). The analyzed fresh chromian spinels have high Cr# (0.62-0.79) characteristic of spinels in mantle peridotite that has undergone some degree of partial melting. The data presented here suggest that the mantle peridotites of the Gabal El-Degheimi area are similar to forearc peridotites of suprasubduction zone environments.

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“…1) to fault-bend folding, whereas Fowler and El Kalioubi (2002) favoured a model involving refolding of sheath folds to explain the appearance of 5 or 6 subdomes in the area. Diapiric rise of late orogenic magmas is a third model which has been proposed to explain the Meatiq and El-Sibai gneissic complexes (Fritz and Messner 1999;Loizenbauer et al 2001;Neumayr et al 1998). Another group of authors explain the gneiss complexes as a result of orogen-parallel extension caused by oblique collision (Abd Ell Wahed 2008;Bregar et al 2002;Fritz et al 1996Fritz et al , 2002Walbrecher et al 1993).…”

Section: Introductionmentioning

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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Structural geology, single zircon ages and fluid inclusion studies of the Meatiq metamorphic core complex: Implications for Neoproterozoic tectonics in the Eastern Desert of Egypt

Cited by 208 publications

References 69 publications

U–Pb ages of detrital zircons from the Basal allochthonous units of NW Iberia: Provenance and paleoposition on the northern margin of Gondwana during the Neoproterozoic and Paleozoic

U–Pb ages of detrital zircons from the Basal allochthonous units of NW Iberia: Provenance and paleoposition on the northern margin of Gondwana during the Neoproterozoic and Paleozoic

Petrological studies of neoproterozoic serpentinized ultramafics of the nubian shield: spinel compositions as evidence of the tectonic evolution of egyptian ophiolites

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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