TY - JOUR
T1 - Neoproterozoic ophiolitic peridotites along the Allaqi-Heiani suture, South Eastern Desert, Egypt
AU - Azer, M. K.
AU - Samuel, M. D.
AU - Ali, K. A.
AU - Gahlan, H. A.
AU - Stern, R. J.
AU - Ren, M.
AU - Moussa, H. E.
N1 - Funding Information:
We highly appreciate thoughtful reviews by Kurt Stüwe (Associate Editor) and Shoji Arai (Kanazawa, Japan), which caused us to carry out a serious revision of the manuscript and improve it dramatically. This research was supported by NSF grant 0804749 (US-Egyptian Scientific Co-operation) to RJS and NSF EAR-0116660 for Electron Microprobe at UTEP.
PY - 2013/10
Y1 - 2013/10
N2 - 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.
AB - 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.
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U2 - 10.1007/s00710-012-0204-z
DO - 10.1007/s00710-012-0204-z
M3 - Article
AN - SCOPUS:84884812960
SN - 0930-0708
VL - 107
SP - 829
EP - 848
JO - Mineralogy and Petrology
JF - Mineralogy and Petrology
IS - 5
ER -