Neoproterozoic ophiolitic peridotites along the Allaqi-Heiani suture, South Eastern Desert, Egypt

M. K. Azer, M. D. Samuel, K. A. Ali, H. A. Gahlan, R. J. Stern, M. Ren, H. E. Moussa

Research output: Contribution to journalArticlepeer-review

37 Citations (Scopus)

Abstract

The Wadi Allaqi ophiolite along the Egyptian-Sudanese border defines the southernmost ophiolitic assemblage and suture zone in the Eastern Desert. Ophiolite assemblages comprise nappes composed mainly of mafic and ultramafic rocks that were tectonically emplaced and replaced by serpentine and carbonates along shear zones probably due to CO2-metasomatism. Serpentinites, altered slices of the upper mantle, represent a distinctive lithology of dismembered ophiolites of the western YOSHGAH suture. Microscopically, they are composed of more than 90 % serpentine minerals with minor opaque minerals, carbonate, brucite and talc. The mineral chemistry and whole-rock chemical data reported here indicate that the serpentinized peridotites formed as highly-depleted mantle residues. They show compositions consistent with formation in a suprasubduction zone environment. They are depleted in Al2O3 and CaO similar to those in fore-arc peridotites. Also, high Cr# (Cr/ (Cr+Al)) in the relict chrome spinels (average ~0.72) indicates that these are residual after extensive partial melting, similar to spinels in modern fore-arc peridotites. Therefore, the studied serpentinites represent fragments of an oceanic lithosphere that formed in a fore-arc environment, which belongs to an ophiolitic mantle sequence formed in a suprasubduction zone.

Original languageEnglish
Pages (from-to)829-848
Number of pages20
JournalMineralogy and Petrology
Volume107
Issue number5
DOIs
Publication statusPublished - Oct 2013
Externally publishedYes

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology

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