الفهرس 
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Abstract
from the preceding discussions.it is dear that both GebelE1hadidand
UmmNar areas have undergone a quite similar history of deformation.
CORCLUSIORS :
L The area is covered mainly by two allochthonous terrlans, juxtaposed
alOl18 a major E-W thrust. The southern terrain represents the
hanging wall of the thrust and is comPOsedof metagreywaekes and
metamudstones associated with Algoma-type banded iron-formation.
The footwall to the north is occupied by ultramafic- mafic
(metaserpentinitesi metapyroxenites and metagabbros) and
metabasaltic fragments incorporated in a matra of sheared
serpentinites and slates.
2. Analysis of a composite sample representing three chip samples
collected along the exposed pyrite-bearing iron-formation horizon in
the southern terrian gave 0.53 ppm gold and 2.15 ppm silver. The
gold value indicates an enrichment about three times the average
world value of the Algoma-type banded iron-formation. More
analyses are needed to determine the exact.gold content.
3. The ophiolitic melaDaerocks are considered to represent an ocean- or
back-arc lithosphere. while the iron bands-bearing metasediments are
considered to be of island-arc affinity.
4. The structural contact between the two terrians is inferred by the
presence of a narrow zone of mylonite separating the two terrains.
and also by the remarkable differences in nature. extension and
distribution of the rocks on both sides of the myloniticzone.
94
~. The iron bands-bearing metasediments were folded forming a major
anticline. plunging moderately SE.
6. Tbe area has undergone a structural history involving three
deformational pbases Df• D2 and D3,
L The first phase of deformation D. is manifested by few isoclinal
and recumbent fold closures refolded by and included within the
limbs of D2 folds. such refolded folds are not recorded in the melange
rocks,
b. The serond phase or deformation D2 is a major event in intensity
and extent and resulted in the Corm.ationor tight overturned and
isoclinal folds. plunging moderately SE. The maior overturned
anticline occupyingthe southern terrain is couial with D2 folds,
c. D
3
deformation is of much less intensity than D2, It is not a
widespread feature throughout the area, represented by open folds
plunging SW, D3 folds are nicely sbown in the micaceous scl1ists
present in the ertreme southern part of the area