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- Title
Neoproterozoic ophiolitic peridotites along the Allaqi-Heiani suture, South Eastern Desert, Egypt.
- Authors
Azer, M.; Samuel, M.; Ali, K.; Gahlan, H.; Stern, R.; Ren, M.; Moussa, H.
- 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 CO-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 AlO 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.
- Subjects
EGYPT; PROTEROZOIC stratigraphic geology; PERIDOTITE; OPHIOLITES; SUTURE zones (Structural geology); PETROLOGY; SUBDUCTION; MORPHOTECTONICS; DESERTS
- Publication
Mineralogy & Petrology, 2013, Vol 107, Issue 5, p829
- ISSN
0930-0708
- Publication type
Academic Journal
- DOI
10.1007/s00710-012-0204-z