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dc.contributor.authorZoheir, Basem
dc.contributor.authorDiab, Aliaa
dc.contributor.authorKoutsovitis, Petros
dc.contributor.authorAbu-Alam, Tamer
dc.contributor.authorFeigenson, Mark
dc.contributor.authorEl-Bialy, Mohammed
dc.contributor.authorAbdelnasser, Amr
dc.date.accessioned2023-02-27T12:58:56Z
dc.date.available2023-02-27T12:58:56Z
dc.date.issued2021-12-02
dc.description.abstractWadi Ghadir ophiolite in the Egyptian Eastern Desert, which forms the northern part of the Nubian Shield, is considered as one of the best-preserved segments of the Neoproterozoic oceanic lithosphere on Earth. Primary melt calculations and thermodynamic modeling of new geochemical data for the Wadi Ghadir pillow lavas and dike complexes, integrated with comprehensive petrographic investigations, are here employed to unravel the geodynamic evolution of this ophiolitic section. Whole-rock geochemical and clinopyroxene data indicate that the pillow lavas and sheeted dike complexes preserve geochemical signatures of N-MORB, E-MORB and OIB-like basalts. Less abundant, discrete dikes have a distinctly LILE-enriched island arc tholeiite (IAT) composition. The pillow lavas and sheeted dike complexes replicate mixed liquid lines of descent, whereas the discrete dikes exhibit a calc-alkaline differentiation trend. The pillow lavas were produced by limited (5–7%) mantle partial melting as a result of isothermal decompression over a wide pressure range (5 – 19 kbar) and restricted mantle potential temperatures (Tp ≈ 1260–1300 °C), suggesting ponding of rising melts from depths of ∼60 to 15 km in dry mantle. Primary melts of the sheeted dike complexes were produced by 9–11% partial melting at P ≈ 9.7 ± 2.5 kbar, Tp ≈ 1290 °C, and P ≈ 14.7 ± 1.4 kbar, Tp ≈ 1325 °C, suggesting a role of varying hydrostatic pressure. The magma source for the discrete dikes occurred at 10.7 ± 0.6 kbar and Tp of 1230–1300 °C by 11–13% partial melting of a metasomatized mantle region. The calculated Tp ranges for the different melts are consistently lower than temperatures of sub-ridge ambient mantle. Together with the variable concentrations of K2O and other incompatible elements, the estimated low temperatures of melt generation emphasize mixed sources and wet peridotite melting. The modeled primary melts designate crustal growth during back‐arc basin opening and closure. During the basin opening, decompression melting of mildly enriched mantle produced high-Ti tholeiitic (pillow lavas) and transitional (sheeted dike complexes) melts, whereas subduction initiation during basin closure promoted melt-peridotite interaction. Lowering of the solidus by subduction-related components triggered melting of a spinel lherzolitic mantle and produced low-Ti calc-alkaline melts that sourced the discrete dikes. The mixed MORB and SSZ geochemical characteristics of the studied volcanic rocks, coupled with the various modeled melts and lack of significant thermal anomalies in the mantle conditions, are here interpreted as manifestations of mantle source heterogeneity in a marginal oceanic basin during the accretionary stages of the Arabian-Nubian Shield.en_US
dc.identifier.citationZoheir B, Diab, Koutsovitis, Abu-Alam T, Feigenson, El-Bialy, Abdelnasser. Mantle source heterogeneity in a Neoproterozoic back-arc basin: Geochemical and thermodynamic modeling of the volcanic section of Wadi Ghadir ophiolite, Egypt. Precambrian Research. 2022;368en_US
dc.identifier.cristinIDFRIDAID 1968322
dc.identifier.doi10.1016/j.precamres.2021.106480
dc.identifier.issn0301-9268
dc.identifier.issn1872-7433
dc.identifier.urihttps://hdl.handle.net/10037/28618
dc.language.isoengen_US
dc.publisherElsevieren_US
dc.relation.journalPrecambrian Research
dc.relation.urihttps://www.sciencedirect.com/science/article/pii/S0301926821004083
dc.rights.accessRightsopenAccessen_US
dc.rights.holderCopyright 2022 The Author(s)en_US
dc.rights.urihttps://creativecommons.org/licenses/by/4.0en_US
dc.rightsAttribution 4.0 International (CC BY 4.0)en_US
dc.titleMantle source heterogeneity in a Neoproterozoic back-arc basin: Geochemical and thermodynamic modeling of the volcanic section of Wadi Ghadir ophiolite, Egypten_US
dc.type.versionacceptedVersionen_US
dc.typeJournal articleen_US
dc.typeTidsskriftartikkelen_US
dc.typePeer revieweden_US


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Attribution 4.0 International (CC BY 4.0)
Med mindre det står noe annet, er denne innførselens lisens beskrevet som Attribution 4.0 International (CC BY 4.0)