Heterogeneously depleted Precambrian lithosphere deduced from mantle peridotites and associated chromitite deposits of Al'Ays ophiolite, Northwestern Arabian Shield, Saudi Arabia

Ahmed, Ahmed H.; Habtoor, Abdelmonem M.

doi:10.1016/j.oregeorev.2014.12.018

Cited by 38 publications

(13 citation statements)

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“…Fields of abyssal and forearc peridotites are after Parkinson and Pearce (1998), Pearce et al (2000), and Niu (2004). ANS ophiolitic peridotite field is after Ahmed and Habtoor (2015) the investigated serpentinites, which are similar to peridotites from contemporary for-arcs and Neoproterozoic serpentinized peridotites from the Eastern Desert, Egypt (Figure 8D).…”

Section: Geotectonic Environments and Petrogenesis Of The Serpentinitesmentioning

confidence: 85%

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Ultramafic Rocks and Their Alteration Products From Northwestern Allaqi Province, Southeastern Desert, Egypt: Petrology, Mineralogy, and Geochemistry

et al. 2022

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The ophiolitic rocks, island arc metasediments, and granitic rocks are encountered in the study of the Allaqi province. The present study concentrated on ultramafic rocks and their various forms of hydrothermal alteration. Ophiolites commonly occur as dismembered rock sequences and have different types of hydrothermal alteration products. Ophiolites contain the essential type as serpentinites and talc-carbonate rocks, listwaenites, and amphibolites along shear zones and faults. Listwaenite is one of the most significant rocks in this area because it contains gold. The whole serpentinite rocks are affected by regional metamorphosis into greenschist facies. Geochemically, Neoproterozoic serpentinites fall into SSZ ophiolites, alpine-type peridotite, formed in the forearc peridotite tectonic environment. Regardless, the listwaenite and talc-carbonate rocks revealed that they trend to silica, carbonate, and talc. Listwaenites are classified into two types: carbonate-rich listwaenites and silica–carbonate-rich listwaenites. Magnetite, chromite, galena, and gold are the most typical ores recorded in this research.

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Section: Geotectonic Environments and Petrogenesis Of The Serpentinitesmentioning

confidence: 85%

“…Fields of abyssal and forearc peridotites are after Parkinson and Pearce (1998),Pearce et al (2000), andNiu (2004). ANS ophiolitic peridotite field is afterAhmed and Habtoor (2015) and Abdel-Karim et al (2018). (C) SiO 2 /MgO ratios versus the Al 2 O 3 diagram.…”

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confidence: 99%

Ultramafic Rocks and Their Alteration Products From Northwestern Allaqi Province, Southeastern Desert, Egypt: Petrology, Mineralogy, and Geochemistry

et al. 2022

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“…From the petrographic observations, we can say that the inclusion‐bearing chromites might be those with comparatively lower Mg# and higher Cr#, while the inclusion‐free chromites belong to the second category. The Al 2 O 3 contents vary from 0.32 to 4.73 wt%, while the TiO 2 contents are very low (≥0.37) in both types of chromites, which can generally be observed in refractory peridotites (Ahmed & Habtoor, 2015; Arai & Yurimoto, 1994; Singh, 2013). In the Cr# versus Mg# plot, category‐I chromites fall in and around the boninite field (Dick & Bullen, 1984), while the category‐II chromites fall in the field of metamorphic spinel with lower greenschist‐facies metamorphism (Irvine, 1967; Figure 9d).…”

Section: Resultsmentioning

confidence: 98%

Evidence of melt– and fluid–rock interactions in the refractory forearc peridotites and associated mafic intrusives from the Tuting–Tidding ophiolites, eastern Himalaya, India: Petrogenetic and tectonic implications

et al. 2020

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Rock type Section Sample Nos. GPS location Petrography Whole-rock geochemistry Mineral chemistry Peridotites Tidding AML14A 27 58 0 52.9 00 N 96 24 0 03.7 00 E Yes Yes AML14B Yes Yes AML14C Yes Yes Yes 6TH-32X Yes Yes Yes Mayodia KMH9A 28 16 0 49.3 00 N 95 54 0 35.9 00 E Yes Yes KMH10A 28 16 0 05.5 00 N 95 54 0 20.1 00 E Yes KMH10B Yes Yes Yes KMH13 28 14 0 48.1 00 N 95 54 0 33.6 00 E Yes Yes Yes KMH14 28 14 0 32.2 00 N 95 55 0 24.8 00 E Yes Yes KMH17 28 14 0 28.7 00 N 95 55 0 47.2 00 E Yes Yes KMH20 28 14 0 33.3 00 N 95 53 0 37.6 00 E Yes Yes Mafic intrusives Tidding AML14D 27 58 0 52.9 00 N 96 24 0 03.7 00 E Yes Yes Yes AML14E Yes Yes Yes AML14G Yes Yes Mayodia KMH11 28 15 0 34.7 00 N 95 54 0 15.2 00 E Yes Yes KMH12 28 15 0 31.0 00 N 95 54 0 15.5 00 E Yes Yes

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“…They have high Fo (89-92) and NiO contents (0.24-0.54 wt%) that are mostly similar to mantle olivine (Takahashi et al, 1987) and are comparable to olivines from the ophiolitic peridotite of the ANS (e.g. Pallister et al, 1988;Ahmed and Habtoor, 2015;Gahlan et al, 2018;Azer et al, 2019). They have higher NiO and Fo than the non-ophiolitic ultramafic rocks (e.g.…”

Section: Primary Minerals 511 Olivinementioning

confidence: 97%

Petrology and Geochemistry of Some Ophiolitic Metaperidotites from the Eastern Desert of Egypt: Insights into Geodynamic Evolution and Metasomatic Processes

Abdel‐Karim

Azer

El-Shafei

2021

Acta Geologica Sinica (Eng)

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Ophiolitic peridotites exposed in the Eastern Desert (ED) of Egypt record multiple stages of evolution, including different degrees of partial melting and melt extraction, serpentinization, carbonatization and metamorphism. The present study deals with metaperidotites at two selected localities in the central and southern ED, namely Wadi El‐Nabá and Wadi Ghadir, respectively. They represent residual mantle sections of a Neoproterozoic dismembered ophiolite that tectonically emplaced over a volcano‐sedimentary succession that represents island–arc assemblages. The studied metaperidotites are serpentinized, with the development of talc‐carbonate and quartz‐carbonate rocks, especially along shear and fault planes. Fresh relics of primary minerals (olivine, orthopyroxene and Cr‐spinel) are preserved in a few samples of partially‐serpentinized peridotite. Most of the Cr‐spinel crystals have fresh cores followed by outer zones of ferritchromite and Cr‐magnetite, which indicates that melt extraction from the mantle protolith took place under oxidizing conditions. The protoliths of the studied metaperidotites were dominated by harzburgites, which is supported by the abundance of mesh and bastite textures in addition to some evidence from mineral and whole‐rock chemical compositions. The high Cr# (0.62–0.69; Av. 0.66) and low TiO2 (<0.3 wt%) contents of the fresh Cr‐spinels, the higher Fo (89–92; Av. 91) and NiO (0.24–0.54 wt%, Av. 0.40) contents of the primary olivine relics, together with the high Mg# (0.91–0.93; Av. 91) and low CaO, Al2O3 and TiO2 of the orthopyroxene relics, are all comparable with depleted to highly depleted forearc harzburgite from a suprasubduction zone setting. The investigated peridotites have suffered subsequent phases of metasomatism, from ocean‐floor hydrothermal alteration (serpentinization) to magmatic hydrothermal alteration. The enrichment of the studied samples in light rare earth elements (LREEs) relative to the heavy ones (HREEs) is attributed to most probably be due to the contamination of their mantle source with granitic source hydrothermal fluids after the obduction of the ophiolite assemblage onto the continental crust. The examined rocks represent mantle residue that experienced different degrees of partial melting (∼10% to 25% for W. El‐Nabá rocks and ∼5% to 23% for W. Ghadir rocks). Variable degrees of partial melting among the two investigated areas suggest mantle heterogeneity beneath the Arabian‐Nubian Shield (ANS).

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Heterogeneously depleted Precambrian lithosphere deduced from mantle peridotites and associated chromitite deposits of Al'Ays ophiolite, Northwestern Arabian Shield, Saudi Arabia

Cited by 38 publications

References 96 publications

Ultramafic Rocks and Their Alteration Products From Northwestern Allaqi Province, Southeastern Desert, Egypt: Petrology, Mineralogy, and Geochemistry

Ultramafic Rocks and Their Alteration Products From Northwestern Allaqi Province, Southeastern Desert, Egypt: Petrology, Mineralogy, and Geochemistry

Evidence of melt– and fluid–rock interactions in the refractory forearc peridotites and associated mafic intrusives from the Tuting–Tidding ophiolites, eastern Himalaya, India: Petrogenetic and tectonic implications

Petrology and Geochemistry of Some Ophiolitic Metaperidotites from the Eastern Desert of Egypt: Insights into Geodynamic Evolution and Metasomatic Processes

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