Ophiolites components occur in Pan-African belt in
Central Eastern Desert (CED) and South Eastern Desert
(SED. The ultramafic components are severely
serpentinized and in some areas occur as small fresh
bodies in Serpentintes. These ultramafic bodies are
characterized by the harzburgite-dunite –chromite
association. The ophiolite components occur as thrust
sheets along suture zone or as blocks in volcano-
sedimenatry mélange or as nappe as Gebel Sol-Hamed and
Gebel Gerf as largest Neoproterozoic (~750 Ma) mantle
rocks in SED of Arabian Nubian Shield.
The occurrences of the Neoproterozoic chromitites in
Central Eastern Desert (CED), Egypt (Fig. 1) include
Gabal El-Rubshi, Wadi Sodmein (Qift-Quseir road), Wadi
Sephene, Wadi Beziah, Baramiya, Wadi Huitate (Idfu-
Marsa Alam road), Wadi Lawi and Wadi El Zarka (South
Marsa Alam). The occurrences in SED include Gebel Abu
Dahar, Gebel Arais, Gebel Belmhandeit, G. Meqium,
Gebel Abu Siayil, Gebel Um Thager, Gebel Gerf and
Gebel Sol Hamed
Chromitite deposits occur mainly as lenticular bodies of
variable dimensions in ultramafic component
(serpentinites) in Pan-African belt in CED and SED,
Egypt. The pods appear to be concordant to sub-
concordant with the host rocks as in Wadi Sephane and
Gebel Gerf (Fig. 2a, b, c, d). The pods are commonly
hosted by serpentinites probably derived from dunite.
There are also micro-lenses, linear and planar segregations
and disseminated chromite grains in meta-peridotite as
shown in Wadi El Sodmin (Fig. 2e). They contact with
meta-peridotite layers, where the abundance of chromite
decreases upwards. Also Away from the main body of the
chromitite lens, chromitite thin layers (in the order of a
few centimeters thick) also occur. Podiform chromitite
usually has gradational contacts with the adjacent meta-
peridotite grading up to the disseminated-type chromite
(Fig. 2f).
The podiform chromitite deposits exhibit a wide range
of compositions from high Cr to high Al varieties. The Cr
of chrome spinel ranges from 0.67 to 0.88 in olivine-
dunite, quite similar to that of the high-Cr chromitite,
whereas it is around 0.62 in lherzolite- harzburgite (Saleh,
2006). Textural and mineralogical evidence indicates that
podiform chromities were formed by crystallization of
mafic magmas in the upper mantle (Lago et al., 1982).
Reaction between the magmas and wall rocks is believed
to have played an important role in the production of these
deposits by modifying the melt composition and moving it
into the field of chromite crystallization (Zhou et al., 1994,
1996). Chromite compositions are believed to be related to
the degree of partial melting of host peridotites, with
chrome numbers increasing as the degree of melting
Mohamed Metwaly ABU ANBAR, 2016. The Chromitites Associated with the Pan-African Ophiolites in Egypt. Acta Geologica Sinica
(English Edition), 90(supp. 1): 206-208.
The Chromitites Associated with the Pan-African Ophiolites in Egypt
Mohamed Metwaly ABU ANBAR
Geology Department, Faculty of Science, Tanta University, Tanta, Egypt
Vol. 90 Supp. 1
* Corresponding author. E-mail: mmanbar@yahoo.com
206
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Fig. 1 Locations of Chromitites in SED and CED