42
E. A. Zaghloul
escarpment while the Abu Minqar is located at the eastern edge of the Great Sand
Sea.
The Great Sand Sea formed of similar northwest-southeast running dunes mainly
of the seif type and extends for more than 200 km to the Libyan border. Occasional
gaps or corridors between the dunes are present which are covered by different rock
units. Salt crusts resulting from capillary rising groundwater build up 10–20 cm thick
layers and in some places intercalate the lacustrine deposits (Embabi 2004; Haynes
et al. 1979).
4 Geologic Structures
The structural elements in the Dakhla area are the result of typical of the stable shelf
tectonic elements. Faults and a large scale gentle fold are reflected on the surface.
The area characterized by a simple geologic structure and very gentle northwardly
regional dips. According to Hermina et al. (1961), Dakhla Oasis can be considered as
a major broad syncline and the area structurally characterized by symmetrical folds
with gentle dips. At Edmonstone area, a broad syncline with NE- SW axial trend and
plunging towards the northeast is recorded.
Faults are located in the southeastern part of the study area. These faults were also
recorded by Hermina et al. (1961) and Omar et al. (1976) and they have a limited
vertical displacement. A series of small faults were observed west of Qur al-Malik
area, where they dip towards the northeast. All these faults are nearly vertical and of
the normal type. They run for a distance of about 40 km., in a northeast-southwest
direction. The downthrows range from 15 to 25 m.
El Deftar et al. (1978), measure a group of mega-joints possesses very high angles
of dip up to vertical. The joint having a N 45 W, N 20 E and extends up to 1000 m
The NW- SE joints dissecting the hard limestone plateau forming prominent narrow
furrows and ridges which have a local name “Kharafish” at the top of the plateau
(Fig. 2).
The morphological shape of the escarpment northwest of West Mawhub area
suggests the presence of a fault running parallel to the scarp in a northwest direction.
5 Conclusions
The Quseir Formation is the oldest rock unit exposed in the study area underlain by a
thick succession of the Taref Formation and overlain by the phosphate bearing rock
unit Duwi Formation.
The Duwi Formation is overlain by a thick sequence of Dakhla Formation which
divided into three members, i.e., the Mawhub Shale Member at the base, Baris
Mudstone Member at the middle and the Kharga Shale Member at the top.
E. A. Zaghloul
escarpment while the Abu Minqar is located at the eastern edge of the Great Sand
Sea.
The Great Sand Sea formed of similar northwest-southeast running dunes mainly
of the seif type and extends for more than 200 km to the Libyan border. Occasional
gaps or corridors between the dunes are present which are covered by different rock
units. Salt crusts resulting from capillary rising groundwater build up 10–20 cm thick
layers and in some places intercalate the lacustrine deposits (Embabi 2004; Haynes
et al. 1979).
4 Geologic Structures
The structural elements in the Dakhla area are the result of typical of the stable shelf
tectonic elements. Faults and a large scale gentle fold are reflected on the surface.
The area characterized by a simple geologic structure and very gentle northwardly
regional dips. According to Hermina et al. (1961), Dakhla Oasis can be considered as
a major broad syncline and the area structurally characterized by symmetrical folds
with gentle dips. At Edmonstone area, a broad syncline with NE- SW axial trend and
plunging towards the northeast is recorded.
Faults are located in the southeastern part of the study area. These faults were also
recorded by Hermina et al. (1961) and Omar et al. (1976) and they have a limited
vertical displacement. A series of small faults were observed west of Qur al-Malik
area, where they dip towards the northeast. All these faults are nearly vertical and of
the normal type. They run for a distance of about 40 km., in a northeast-southwest
direction. The downthrows range from 15 to 25 m.
El Deftar et al. (1978), measure a group of mega-joints possesses very high angles
of dip up to vertical. The joint having a N 45 W, N 20 E and extends up to 1000 m
The NW- SE joints dissecting the hard limestone plateau forming prominent narrow
furrows and ridges which have a local name “Kharafish” at the top of the plateau
(Fig. 2).
The morphological shape of the escarpment northwest of West Mawhub area
suggests the presence of a fault running parallel to the scarp in a northwest direction.
5 Conclusions
The Quseir Formation is the oldest rock unit exposed in the study area underlain by a
thick succession of the Taref Formation and overlain by the phosphate bearing rock
unit Duwi Formation.
The Duwi Formation is overlain by a thick sequence of Dakhla Formation which
divided into three members, i.e., the Mawhub Shale Member at the base, Baris
Mudstone Member at the middle and the Kharga Shale Member at the top.