Gabbros versus granites of the subduction regime of South Sinai, Egypt: discrimination and geochemical modelling

Lebda, El-Metwally M.; Ghoneim, Mohamed F.; Abdel‐Karim, Abdel‐Aal M.

doi:10.1007/s12517-019-4695-3

Cited by 2 publications

(2 citation statements)

References 68 publications

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“…Almost all of the available Zr/Hf ratios of the analyzed samples (31.08-58.65, average = 36.7; Table S2) center around the chondritic values (36.6 and 34.3, respectively [71,72]), continental crust (Zr/Hf = 33; [73]), and the limited range (33)(34)(35)(36)(37)(38)(39)(40) characterizing most magmatic rocks [74]. However, many of them (13 out of 31) surpass the chondritic values (>36), are comparable to those of OIB and E-MORB (34-42; [75]), and approach the depleted mantle Zr/Hf values (35.7-45.53; [76]).…”

Section: Trace Elementsmentioning

confidence: 99%

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Continental Arc Plutonism in a Juvenile Crust: The Neoproterozoic Metagabbro-Diorite Complexes of Sinai, Northern Arabian-Nubian Shield

El-Bialy,

Khedr,

El-Bialy

et al. 2024

Minerals

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Based on new field, petrographic, and whole-rock geochemistry data, we investigated three discrete metagabbro-diorite complexes (MGDC) across the E-W Sinai to contribute to increasing knowledge of the evolution of the juvenile continental crust of the Neoproterozoic Arabian–Nubian Shield. The three MGDCs vary in the dominance of the gabbroic versus dioritic rock types among each of them. Gabbroids are distinguished into pyroxene-hornblende gabbros and hornblende gabbros, whereas dioritic rocks have been subdivided into diorites and quartz diorites. The studied MGDC rocks are almost metaluminous and possess prevalent calc-alkaline characteristics over subsidiary tholeiitic and alkaline affinities. The most distinctive feature in the profiles of the investigated MGDCs on the N-MORB-normalized spider diagrams is the coincidence of stout negative Nb anomalies and projecting positive Pb spikes, which is typical of igneous rocks evolved in subduction zones. The three MGDC samples exhibit variably LREE-enriched patterns [(La/Yb)N = 4.92–18.55; av. = 9.04], either lacking or possessing weak to negligible positive and negative Eu anomalies. The calculated apatite and zircon crystallization temperatures reveal the earlier separation of apatite at higher temperatures, with the obvious possibility of two genetic types of apatite and zircon in the magma (cognate vs. xenocrystic) since both accessories have yielded very wide ranges of crystallization temperatures. The investigated MGDCs were formed in a continental arc setting, particularly a thick-crust arc (>39 km). The parent magmas comprised components derived from the melting of the mantle wedge, subducting oceanic lithosphere, and subducting overlying sediments. The mantle input was from a spinel–garnet transitional mantle source at a depth of ca. 75–90 km. The impact of slab-derived fluids was much greater than that of slab-derived melts, and so subduction-related fluids had a crucial effect on metasomatizing the partially melted mantle source. The parent mantle-derived magma has been subjected to substantial crustal contamination as a dominant mechanism of differentiation.

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Section: Trace Elementsmentioning

confidence: 99%

“…Recent studies on the metagabbro-diorite complexes (MGDC) are limited both in the Eastern Desert (e.g., [29][30][31][32][33][34][35]) and Sinai (e.g., [19,[36][37][38]). The metagabbro-diorite complex rocks are of widespread distribution in the Precambrian Egyptian basement relative to the post-collisional gabbros.…”

Section: Introductionmentioning

confidence: 99%

Continental Arc Plutonism in a Juvenile Crust: The Neoproterozoic Metagabbro-Diorite Complexes of Sinai, Northern Arabian-Nubian Shield

El-Bialy,

Khedr,

El-Bialy

et al. 2024

Minerals

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The role of post-collisional mafic magmatism in the late stages of evolution of the northernmost Arabian-Nubian Shield (ANS): A case study from Isla Complex, Wadi Isla, South Sinai, Egypt

Ragab

2020

Journal of African Earth Sciences

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Gabbros versus granites of the subduction regime of South Sinai, Egypt: discrimination and geochemical modelling

Cited by 2 publications

References 68 publications

Continental Arc Plutonism in a Juvenile Crust: The Neoproterozoic Metagabbro-Diorite Complexes of Sinai, Northern Arabian-Nubian Shield

Continental Arc Plutonism in a Juvenile Crust: The Neoproterozoic Metagabbro-Diorite Complexes of Sinai, Northern Arabian-Nubian Shield

The role of post-collisional mafic magmatism in the late stages of evolution of the northernmost Arabian-Nubian Shield (ANS): A case study from Isla Complex, Wadi Isla, South Sinai, Egypt

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