Crustal Evolution of the Egyptian Precambrian Rocks

Stern, Robert J.; Ali, Kamal A.

doi:10.1007/978-3-030-15265-9_4

Cited by 25 publications

(12 citation statements)

References 105 publications

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“…These deposits include the auriferous Algoma-type BIF, where gold occurs in these deposits either restricted stratigraphically (strata-bound) within the BIF or is concentrated in quartz veins adjacent to or within the BIF (Botros, 1991(Botros, , 1995El Shimi, 1998;El Shimi and Soliman, 2002;Botros, 2021), as well as disseminated in the auriferous tuffaceous metasedimentary rocks (Botros, 1993) and gold-bearing VMSDs in the Um Samiuki and Hamama districts (Searle et al, 1976;Botros, 2003;Johnson et al, 2017;Bampton, 2017). The suggested age for these exhalites in the Eastern Desert is compatible with the age suggested for the genesis of the BIF in the Eastern Desert (Ali et al, 2009;Stern et al, 2013;Stern, 2018;Stern and Ali, 2020) and the ages suggested for other VMSDs in the ANS such as Jabal Sayid, Shayban and Baydan (~745Ma); Shiab Lamisah and As Safra (750Ma) (Volesky et al, 2017 and references therein).…”

Section: Tectonic Settings Of Gold Deposits In Egyptsupporting

confidence: 79%

“…Tectonically, volcanic rocks of the island arcs in the Eastern Desert show strong affinities to lavas from modern arcs and back-arc basins (Ali et al, 2009). The metabasalts and the meta andesites (~750 Ma, Ali et al, 2009;Stern and Ali, 2020), are overlain by tuffaceous metasediments which are intercalated with the BIF. Auriferous exhalative deposits were formed concomitant with the arc volcanicity at ~750 Ma as a result of interaction between volcanically derived fluids (hot brines) and sea water (Botros, 1995(Botros, , 2003.…”

Section: Tectonic Settings Of Gold Deposits In Egyptmentioning

confidence: 99%

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Intrusion‐related Gold Deposits in Egypt

Botros

2021

Acta Geologica Sinica (Eng)

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Intrusion‐related gold deposits (IRGDs) occur in the Eastern Desert (ED) of Egypt within magmatic districts that are exploited for tungsten and tin mineralization. IRGDs and intrusion‐related rare metal deposits (IRRMDs) are almost invariably linked with the late to post collisional Younger Granites (YGs) that have three successive phases (I, II and III). At ∼635–630 Ma, the ED underwent a transition in deformation style from compressional to extensional and a switch from subduction with crustal thickening to delamination with crustal thinning. This transition was concurrent with the emplacement of a short magmatic pulse (∼635–630 Ma) that represents a transition between orogenic gold deposits and IRGDs. K‐rich calc alkaline granites (phase I and II of the YGs) hosting IRGDs like the Hangalia deposit were emplaced during the time span 630–610 Ma. Alkaline magmatism began at 610 Ma, coexisting with the K‐rich calc‐alkaline magmatism over the 610–590 Ma time span, where the Fawakhir (598 ± 3 Ma) and Um Had (596 ± 2 Ma) granites that host the IRGDs were emplaced. In time, the alkaline magmatism became more alkaline giving rise to phase III of the YGs that hosts IRRMDs. A distinct metallogenic epoch comprising both IRGDs and IRRMDs, was undergoing extreme growth at ∼600 Ma.

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Section: Tectonic Settings Of Gold Deposits In Egyptsupporting

confidence: 79%

Section: Tectonic Settings Of Gold Deposits In Egyptmentioning

confidence: 99%

Intrusion‐related Gold Deposits in Egypt

Botros

2021

Acta Geologica Sinica (Eng)

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“…The Egyptian Nubian Shield (ENS) covers ~100,000 km 2 , cropping out mainly in southern Sinai, the Eastern Desert and small areas in the southern part of the Western Desert (Oweinat area) (Hassan and Hashad, 1990;El Gaby et al, 1990;Stern and Ali, 2020). The Precambrian complex of the ENS comprises five main tectonostratigraphic units (Hamimi et al, 2019) from bottom upwards as follows: (1) high-grade gneisses and migmatites, (2) arc volcaniclastic metasediments, (3) dismembered ophiolites, (4) the Ediacaran Hammamat and Dokhan Volcanics, and (5) syn-tectonic, late and posttectonic granitoids.…”

Section: Geology Of the Egyptian Nubian Shieldmentioning

confidence: 99%

“…They were derived from an old sedimentary succession intercalated by basic igneous sills (ortho-amphibolites), marls (paraamphibolites) and quartzite layers. The sedimentary sequence was accumulated along a passive continental margin and then subjected to high-T and low-P regional metamorphism up to the upper amphibolite facies (Abd El -Wahed et al, 2016Hamimi et al, 2019;Fowler and Hamimi, 2020;Hamimi and Abd El-Wahed, 2020;Stern and Ali, 2020;El-Bialy, 2020). The gneisses and migmatites occur as antiforms and domed structures in the ENS (e.g.…”

Section: High-grade Gneisses and Migmatitesmentioning

confidence: 99%

Neoproterozoic Tectonic Events of Egypt

El‐Wahed

Hamimi

2021

Acta Geologica Sinica (Eng)

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The Egyptian Nubian Shield (ENS) represents the northwestern part of the Arabian‐Nubian Shield and the northern extension of the East African Orogen. The ENS is regarded as being formed due to northward‐directed escape tectonics. It is characterized by mild accretion and suture zones dominated by major strike‐slip zones with a commonly sinistral sense of movement; some shear zones display a dextral sense of shear. It is dominated by gneisses and migmatites in the south, arc volcaniclastic metasediments and highly dismembered ophiolites in the central parts, whereas its northern part is dominated by late‐ to post‐tectonic granitoids. In southern Sinai, the Neoproterozoic rocks are grouped into four complexes, namely Feiran–Solaf, Sa'al–Zaghra, Kid and Taba. The ENS ophiolites were formed between 730–750 Ma, mainly in a supra‐subduction zone setting. The ENS has undergone a Neoproterozoic deformation history involving three successive phases: (1) Early N–S shortening phase (D1), (2) Syn‐accretionary phase (D2) and (3) Post‐accretionary phase (D3). The initial island‐arc stage (780–730 Ma) is a N–S shortening phase initiated by collision between the Eastern Desert tectonic terrane to the north with both the Gebeit and Gabgaba terranes to the south (830–720 Ma). During the arc‐splitting and back‐arc spreading stage (730–620), voluminous syn‐tectonic granitoids intruded into the ENS (750–610 Ma). The E–W‐directed compressional/transpressional phase (620–450 Ma) led to the overall uplift of the central part of the ENS and consequently the development and exhumation of the core complexes in oblique convergent zones. The E–W intense shortening deformation resulted also in the formation of NW‐ and NE‐striking sinistral and dextral strike‐slip shear zones, respectively. The latest periods of the E–W‐directed compressional/transpressional regime were characterized by deposition of the molasse‐type Hammamat Sediments unconformably over the Dokhan Volcanics, or interbedded with them. The combined thrusting, folding and sinistral‐reverse shearing structures have been interpreted to resulted from the E–W‐directed compressional/transpressional phase in response to the oblique shortening of the Arabian‐Nubian Shield between East and West Gondwana.

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“…Metavolcanics, volcanogenic metasediments and diorite-granodiorite-trondhjemite intrusives are also recorded in a few areas of the NED (Eliwa et al 2014). In the CED, ophiolitic mélanges and arc assemblages predominate, while the SED is characterized by a high proportion of Cryogenian granites and a relatively high abundance of gneisses and migmatites (El Bahariya, 2018;Stern, 2018;Stern & Ali, 2020).…”

Section: Introductionmentioning

confidence: 99%

Petrogenesis of contrasting magmatic suites in the Abu Kharif area, Northern Eastern Desert, Egypt: implications for Pan-African crustal evolution and tungsten mineralization

et al. 2021

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The Abu Kharif area in the Northern Eastern Desert consists of contrasting granitic magma suites: a Cryogenian granodiorite suite (850–635 Ma), an Ediacaran monzogranite suite (635–541 Ma) and a Cambrian alkali riebeckite granite suite (541–485 Ma). Tungsten mineralization occurs within W-bearing quartz veins and a disseminated type confined to the monzogranite. Whole-rock geochemical data classify the granodiorite as a late-orogenic I-type with calc-alkaline affinity, while the monzogranite and alkali riebeckite granite represent respectively a post-orogenic highly fractionated I-type with calc-alkaline affinity and an anorogenic A1-subtype with alkaline affinity. Geochemical modelling indicates that the three intrusions represent separate magmatic pulses where the granodiorite was generated by ∼75 % batch partial melting of an amphibolitic source followed by fractional crystallization of hornblende, biotite, apatite and titanite. The monzogranite was formed by 62 % batch partial melting of the normal ‘non-metasomatized’ Pan-African crust of calc-alkaline granite composition followed by fractional crystallization of plagioclase, biotite, K-feldspar, magnetite, ilmenite, with minor apatite and titanite. The alkali riebeckite granite was generated by 65 % batch partial melting of metasomatized Pan-African granite source followed by fractional crystallization of plagioclase, K-feldspar, amphibole and biotite with minor magnetite, apatite and titanite. In general, the parent magmas of the three intrusions were originally enriched in W, but with different concentrations. This W-enrichment would be caused by magmatic-related hydrothermal volatile-rich fluids and concentrated within the monzogranite.

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Crustal Evolution of the Egyptian Precambrian Rocks

Cited by 25 publications

References 105 publications

Intrusion‐related Gold Deposits in Egypt

Intrusion‐related Gold Deposits in Egypt

Neoproterozoic Tectonic Events of Egypt

Petrogenesis of contrasting magmatic suites in the Abu Kharif area, Northern Eastern Desert, Egypt: implications for Pan-African crustal evolution and tungsten mineralization

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