Petrological and mineralogical studies of Pan-African serpentinites at Bir Al-Edeid area, central Eastern Desert, Egypt

Azer, Mokhles K.; Khalil, Ahmed E.

doi:10.1016/j.jafrearsci.2005.09.008

Cited by 59 publications

(24 citation statements)

References 29 publications

(32 reference statements)

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“…Majority of the studied samples show mesh ( Figure 2A) and bastite textures. According to Shervais et al (2005) mesh texture are developed after olivine while bastite texture formed after the alteration of orthopyroxene (Azer and Khalil, 2005). Samples BN2 and BL1 are fine grained serpentine, sample BN2 possesses few relics of pyroxene phenocrysts showing parallel arrangement of minerals with mesh texture groundmass ( Figure 2B) while BL1 exhibits relatively coarse hourglass-mesh texture.…”

Section: Petrographymentioning

confidence: 99%

“…It is also reflected from medium correlation matrix (r = 0.393). The high concentrations of Ni in the rocks reflect their development from a depleted-mantle peridotite source (Azer and Khalil, 2005). The Al 2 O 3 vs. SiO 2 /MgO cross plot is valuable to infer the parent compositions of olivine, orthopyroxene and clinopyroxene in rocks from orogenic peridotites.…”

Section: Geochemistrymentioning

confidence: 99%

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Study of Serpentinized Ultramafic Rocks of Bela Ophiolite, Balochistan, Pakistan

Bashir¹,

Naseem²,

Kaleem³

et al. 2012

JGG

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Section: Petrographymentioning

confidence: 99%

Section: Geochemistrymentioning

confidence: 99%

Study of Serpentinized Ultramafic Rocks of Bela Ophiolite, Balochistan, Pakistan

Bashir¹,

Naseem²,

Kaleem³

et al. 2012

JGG

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“…In the past, studies of the Egyptian ophiolites have focused on volcanic rocks for evaluating their tectonic setting and petrogenesis. The ophiolitic peridotites have been largely ignored until recently (Azer and Khalil 2005;Azer and Stern 2007;Farahat 2008;Hamdy et al 2013;Khedr and Arai 2013), although the mantle peridotites provide complementary information about the petrogenesis and tectonic setting of the ophiolitic rocks.…”

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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“…Pagé et al (2008) for (a) and by Stern et al (2004) for (b). Field for chromite compositions occurring in serpentinites from the Central Eastern Desert of Egypt (CED) is also shown (Khudeir 1995;Ahmed et al 2001;Azer and Khalil 2005;Khalil and Azer 2007;Farahat 2008). Experimental equilibriummelting trend annotated by melting % is from Hirose and Kawamoto (1995).…”

Section: Alteration Effectmentioning

confidence: 93%

“…Takla and Noweir 1980;Khudeir 1995;Ahmed et al 2001;El Bahariya and Arai 2003;Azer and Khalil 2005). These studies focused on small areas that cannot reflect regional variations, nor did the small number of studies reveal compositional differences within each mantle section, which is a significant petrogenetic factor.…”

Section: Introductionmentioning

confidence: 99%

Petrogenetic and geotectonic significance of Neoproterozoic suprasubduction mantle as revealed by the Wizer ophiolite complex, Central Eastern Desert, Egypt

Farahat

Hoinkes

Mogessie

2010

Int J Earth Sci (Geol Rundsch)

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Ophiolite complexes, formed in a suprasubduction zone environment during Neoproterozoic time, are widely distributed in the Eastern Desert of Egypt. Their mantle sections provide important information on the origin and tectonic history of ocean basins these complexes represent. The geochemistry and mineralogy of the mantle section of the Wizer ophiolite complex, represented by serpentinites after harzburgite containing minor dunite bodies, are presented. Presence of antigorite together with the incipient alteration of chromite and absence of chlorite suggests that serpentinization occurred in the mantle wedge above a Neoproterozoic subduction zone. Wizer peridotites have a wide range of spinel compositions. Spinel Cr# [100Cr/(Cr ? Al)] decrease gradually from dunite bodies (Cr# = 81-87) and their host highly depleted harzburgites (Cr# = 67-79) to the less depleted harzburgites (Cr# = 57-63). Such decreases in mantle refractory character are accompanied by higher Al and Ti contents in bulk compositions. Estimated parental melt compositions point to an equilibration with melts of boninitic composition for the dunite bodies (TiO 2 = *\0.07-0.22 wt%; Al 2 O 3 = 9.4-10.6 wt%), boninitic-arc tholeiite for the highly depleted harzburgites (TiO 2 = \0.09-0.28 wt%; Al 2 O 3 = 11.2-14.1 wt%) and more MORB-like affinities for the less depleted harzburgites (TiO 2 = *\0.38-0.51 wt%; Al 2 O 3 = 14.5-15.3 wt%). Estimated equilibrium melts are found in the overlying volcanic sequence, which shows a transitional MORB-island arc geochemical signature with a few boninitic samples. Enrichment of some chromites in TiO 2 and identification of sulfides in highly depleted peridotites imply interaction with an impregnating melt. A two-stage partial melting/melt-rock reaction model is advocated, whereby, melting of a depleted mantle source by reaction with MORB-like melts is followed by a second stage melting by interaction with melts of IAT-boninitic affinities in a suprasubduction zone environment to generate the highly depleted harzburgites and dunite bodies. The shift from MORB to island arc/boninitic affinities within the mantle lithosphere of the Wizer ophiolite sequence suggests generation in a protoarc-forearc environment. This, together with the systematic latitudinal change in composition of ophiolitic lavas in the Central Eastern Desert (CED) of Egypt from IAT-boninitic affinities to more MORB-like signature, implies that the CED could represent a disrupted forearc-arc-backarc system above a southeast-dipping subduction zone.

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Petrological and mineralogical studies of Pan-African serpentinites at Bir Al-Edeid area, central Eastern Desert, Egypt

Cited by 59 publications

References 29 publications

Study of Serpentinized Ultramafic Rocks of Bela Ophiolite, Balochistan, Pakistan

Study of Serpentinized Ultramafic Rocks of Bela Ophiolite, Balochistan, Pakistan

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

Petrogenetic and geotectonic significance of Neoproterozoic suprasubduction mantle as revealed by the Wizer ophiolite complex, Central Eastern Desert, Egypt

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