Mohamed Zaki Khedr

Kanazawa University

Author Statistics

Papers

Citation

H-Index

i-10 index

Research Trends

Author Order

Document Type

Co-Authors

Shoji Arai

Kanazawa University

Akihiro Tamura

Kanazawa University

Robert J. Stern

The University of Texas at Dallas

Eiichi Takazawa

Niigata University

Hadi Shafaii Moghadam

Xinjiang Institute of Ecology and Geography

Amr El-Awady

Zagazig University

Tomoaki Morishita

Kanazawa University

Ghasem Ghorbani

Damghan University

Scott Whattam

King Fahd University of Petroleum and Minerals

Christoph Hauzenberger

University of Graz

Cooperative Institutions

Kanazawa University

Chinese Academy of Sciences

Macquarie University

ARC Centre of Excellence for Core to Crust Fluid Systems

Damghan University

Port Said University

Institute of Geology and Geophysics

Japan Agency for Marine-Earth Science and Technology

Australian Research Council

Centre National de la Recherche Scientifique

Author Statistics

Papers

Citation

H-Index

i-10 index

Research Field

Mineral chemistry and melt evolution of the mantle wedge peridotites in the Late Cretaceous Zagros Belt ophiolites (Iran): clues for the subduction initiation-induced forearc magmatism

Journal of the Geological Society (2024)

Ghasem Ghorbani Hadi Shafaii Moghadam Yıldırım Dilek Shoji Arai Mohamed Zaki Khedr

We investigate in this paper mineral compositions and geochemical evolution of the mantle wedge peridotites preserved in the Late Cretaceous Zagros ophiolites of SW Iran. Mantle peridotites above subduction zones commonly experience distinct melting, depletion and refertilization processes as a result of the circulation of fluids derived from subducting slabs and flux melting. Our results reveal that the mantle wedge peridotites in the Zagros ophiolites are characterized mainly by residual and impregnated types. Residual peridotites resulted from early depletion and later refertilization processes, whereas impregnated peridotites developed due to episodic melt impregnations within and across the mantle. Mg#s and NiO contents, spinel Cr#, Mg#, and TiO 2 in olivines, Mg# and Al 2 O 3 contents of orthopyroxenes, and Mg#, TiO 2 and Al 2 O 3 contents in clinopyroxenes of dunites, harzburgites and lherzolites indicate the significant role of re-equilibration processes among different mineral phases and interactions with basaltic melts percolating within the host peridotites. The observed geochemical variations in the mineral chemistry of the Zagros peridotites reflect changes in magma chemistry and fluctuations in the degree of melt extraction and melt–rock interactions within the mantle peridotites. However, our data suggest that Mg–Fe distribution in the spinels of some dunites and harzburgites might also have resulted from subsolidus redistribution and exchange with surrounding olivine grains. Spinel and clinopyroxene phases in gabbroic rocks and ultramafic cumulates within the Zagros ophiolites also show significant variations in their compositions, suggesting that their magmas evolved from MORB-like to IAT, calc–alkaline and boninite suites, typical of subduction initiation-generated melts. Hence, the Zagros ophiolites present a case study of time-progressive melt evolution of the forearc oceanic lithosphere. Supplementary material: Datasets of the mineral chemistry and melt evolution of the mantle wedge peridotites in the Late Cretaceous Zagros Belt ophiolites (Iran) are available in tabular and figurative form at https://doi.org/10.6084/m9.figshare.c.7093528 . Thematic collection: This article is part of the Ophiolites, melanges and blueschists collection available at: https://www.lyellcollection.org/topic/collections/ophiolites-melanges-and-blueschists

Forearc

10.1144/jgs2023-209

Cite

Citations (0)

Mineralogy and Geochemistry of Jasperoid Veins in Neoproterozoic Metavolcanics: Evidence of Silicification, Pyritization and Hematization

Minerals (2024)

Mohamed Zaki Khedr Mahmoud A. Sayed Shehata Ali Mokhles K. Azer Yuji Ichiyama

The Wadi Ranga sulfidic jasperoids in the Southern Eastern Desert (SED) of Egypt are hosted within the Neoproterozoic Shadli metavolcanics as an important juvenile crustal section of the Arabian Nubian Shield (ANS). This study deals with remote sensing and geochemical data to understand the mechanism and source of pyritization, silicification, and hematization in the host metavolcanics and to shed light on the genesis of their jasperoids. The host rocks are mainly dacitic to rhyolitic metatuffs, which are proximal to volcanic vents. They show peraluminous calc-alkaline affinity. These felsic metatuffs also exhibit a nearly flat REE pattern with slight LREE enrichment (La/Yb = 1.19–1.25) that has a nearly negative Eu anomaly (Eu/Eu* = 0.708–0.776), while their spider patterns display enrichment in Ba, K, and Pb and depletion in Nb, Ta, P, and Ti, reflecting the role of slab-derived fluid metasomatism during their formation in the island arc setting. The ratios of La/Yb (1.19–1.25) and La/Gd (1.0–1.17) of the studied felsic metatuffs are similar to those of the primitive mantle, suggesting their generation from fractionated melts that were derived from a depleted mantle source. Their Nb and Ti negative anomalies, along with the positive anomalies at Pb, K, Rb, and Ba, are attributed to the influence of fluids/melt derived from the subducted slab. The Wadi Ranga jasperoids are mainly composed of SiO2 (89.73–90.35 wt.%) and show wide ranges of Fe2O3t (2.73–6.63 wt.%) attributed to the significant amount of pyrite (up to 10 vol.%), hematite, goethite, and magnetite. They are also rich in some base metals (Cu + Pb + Zn = 58.32–240.68 ppm), leading to sulfidic jasperoids. Pyrite crystals with a minor concentration of Ag (up to 0.32 wt.%) are partially to completely converted to secondary hematite and goethite, giving the red ochre and forming hematization. Euhedral cubic pyrite is of magmatic origin and was formed in the early stages and accumulated in jasperoid by epigenetic Si-rich magmatic-derived hydrothermal fluids; pyritization is considered a magmatic–hydrothermal stage, followed by silicification and then hematization as post-magmatic stages. The euhedral apatite crystals in jasperoid are used to estimate the saturation temperature of their crystallization from the melt at about 850 °C. The chondrite (C1)-normalized REE pattern of the jasperoids shows slightly U–shaped patterns with a slightly negative Eu anomaly (Eu/Eu* = 0.43–0.98) due to slab-derived fluid metasomatism during their origin; these jasperoids are also rich in LILEs (e.g., K, Pb, and Sr) and depleted in HFSEs (e.g., Nb and Ta), reflecting their hydrothermal origin in the island arc tectonic setting. The source of silica in the studied jasperoids is likely derived from the felsic dyke and a nearby volcanic vent, where the resultant Si-rich fluids may circulate along the NW–SE, NE–SW, and E–W major faults and shear zones in the surrounding metavolcanics to leach Fe, S, and Si to form hydrothermal jasperoid lenses and veins.

10.3390/min14070647

Cite

Citations (0)

Petrology and geochemistry of prograde peridotites from Happo-One, Japan evidence of element mobility during deserpentinization

Mohamed Zaki Khedr Shoji Arai

10.14824/jakoka.2010.0.174.0

Cite

Citations (0)

Tectonic-Thermal Evolution of the Wadi El-Dahal Area, North Eastern Desert, Egypt: Constraints on the Suez Rift Development

Minerals (2023)

Sherif Mansour Noriko Hasebe Mohamed Zaki Khedr Akihiro Tamura Amer A. Shehata

The Suez Rift developed as a northern extension of the Red Sea rift during the Oligocene-Miocene, whose flanks were constructed from the Neoproterozoic basement rocks of the Arabian–Nubian Shield. These basement rocks are comprised of the whole tectonic history since their formation. The Suez Rift initiation model and proposed thermal overprint role in the rifting process and flank development remain uncertain. Additionally, the amplitude of different regional tectonic events’ effects on the region is still debatable. Integration of fission-track thermochronology data with modeling of the time-temperature history has demonstrated efficiency in addressing such issues. In the context of this study, eleven representative samples were collected from the different rock units in the Wadi El-Dahal area at the northern tip of the western flank of the Suez Rift. These samples revealed Carboniferous zircon fission-track cooling ages of 353 ± 9 Ma and 344 ± 11 Ma. Meanwhile, the apatite fission-track analysis provided two spatially separated age groups: Permian-Triassic and Late Cretaceous, with average ages of 249 ± 11 Ma and ca. 86 ± 10 Ma, respectively. The time-temperature modeling revealed four possible cooling pulses representing exhumation events, which were initiated as a response to four tectonic activities: the accretion-subsequent event of erosion during the Neoproterozoic, the Hercynian (Variscan) tectonic event during the Devonian-Carboniferous, the Mid-Atlantic opening during the Cretaceous, and the Suez Rift opening during the Oligocene-Miocene. The western flank of the Suez Rift suggests a passive mechanical type with no extra thermal overprint, as indicated by the dominance of older thermochronological ages, modest rift flank elevations, and a reduction in the heat flow.

Thermochronology

Fission track dating

Devonian

Basement

10.3390/min13081021

Cite

Citations (9)

Supra-subduction zone magmatism of the Neyriz ophiolite, Iran: constraints from geochemistry and Sr-Nd-Pb isotopes

International Geology Review (2014)

Hadi Shafaii Moghadam Mohamed Zaki Khedr Massimo Chiaradia Robert J. Stern Farzaneh Bakhshizad

The Neyriz ophiolite along the northeast flank of the Zagros fold-thrust belt in southern Iran is an excellent example of a Late Cretaceous supra-subduction zone (SSZ)-related ophiolite on the north side of the Neotethys. The ophiolite comprises a mantle sequence including lherzolite, harzburgite, diabasic dikes, and cumulate to mylonitic gabbro lenses, and a crustal sequence comprising a sheeted dike complex and pillow lavas associated with pelagic limestone and radiolarite. Mantle harzburgites contain less CaO and Al2O3, are depleted in rare earth elements, and contain spinels that are more Cr-rich than lherzolites. Mineral compositions of peridotites are similar to those of both abyssal and SSZ- peridotites. Neyriz gabbroic rocks show boninitic (SSZ-related) affinities, while crustal rocks are similar to early arc tholeiites. Mineral compositions of gabbroic rocks resemble those of SSZ-related cumulates such as high forsterite olivine, anorthite-rich plagioclase, and high-Mg# clinopyroxene. Initial εNd(t) values range from +7.9 to +9.3 for the Neyriz magmatic rocks. Samples with radiogenic Nd overlap with least radiogenic mid-ocean ridge basalts and with Semail and other Late Cretaceous Tethyan ophiolitic rocks. Initial 87Sr/86Sr ranges from 0.7033 to 0.7044, suggesting modification due to seafloor alteration. Most Neyriz magmatic rocks are characterized by less radiogenic 207Pb/204Pb (near the northern hemisphere reference line), suggesting less involvement of sediments in their mantle source. Our results for Neyriz ophiolite and the similarity to other Iranian Zagros ophiolites support a subduction initiation setting for its generation.

Pillow lava

Dike

10.1080/00206814.2014.942391

Cite

Citations (56)

Spatial distribution and origin of mantle heterogeneity in the Oman ophiolite : evidence from basal peridotites

Mohamed Zaki Khedr Shoji Arai

Basal (medicine)

10.14824/jakoka.2012.0_202

Cite

Citations (0)

Corrigendum to “Devonian to Permian evolution of the Paleo-Tethys Ocean: New evidence from U–Pb zircon dating and Sr–Nd–Pb isotopes of the Darrehanjir–Mashhad “ophiolites”, NE Iran”,Gondwana Research, 28, 2015, 781–799