Geology of Dakhla Oasis, Western Desert, Egypt
35
These two facies represented by rocks of various lithology overlying the following
units.
The Dakhla Formation
The Duwi Formation
The Nubian Sandstone
The age of each unit is determined by its stratigraphic position and its faunal contents.
Detailed descriptions are given in the following for each unit.
3.1 Upper Cretaceous—Paleocene Rock Units
3.1.1 Nubian Sandstone
The term “Nubian Formation” was first used by Russeger (1837) to denote a huge
sandstone section overlying the basement rocks in Nubian region in Upper Egypt.
The Nubian Sandstone section was divided into several mappable formations in the
field (Klitzsch et al. 1979 and others). In the present work, the Nubian Sandstone
(Group) is divided into two following distinctive formations:
3.2 Taref Formation
This formation represents the basal unit exposed in the southern and eastern parts
in Dakhla Basin (Fig. 5). Lithologically, the formation consists of yellowish to light
brown cross-bedded sandstone, fine to coarse grained, stained with iron oxide, contain
thin shale and marl intercalations. The top surfaces are covered with black color of
desert varnish. The formation is non-fossiliferous and contains plant remains and
petrified wood. The base is unexposed and the total thickness is about 100 m. as
measured at Gabal Taref type section (Awad and Ghobrial 1965; Issawi 1972). The
presence of Haplophragmoides spp. and Trochammina spp. within the shale interbeds
may indicate deposition in normal water salinity. The age of the Taref Formation was
previously assigned to the Senonian (Coniacian–Santonian) age. On the other hand,
the sandstone beds of the Taref Formation pass gradually upward into the overlying
Quseir Formation.
South of Dakhla Basin, the Taref Formation conformably overlying the older rock
units (Maghrabi and Sabaya Formations, Fig. 5).
35
These two facies represented by rocks of various lithology overlying the following
units.
The Dakhla Formation
The Duwi Formation
The Nubian Sandstone
The age of each unit is determined by its stratigraphic position and its faunal contents.
Detailed descriptions are given in the following for each unit.
3.1 Upper Cretaceous—Paleocene Rock Units
3.1.1 Nubian Sandstone
The term “Nubian Formation” was first used by Russeger (1837) to denote a huge
sandstone section overlying the basement rocks in Nubian region in Upper Egypt.
The Nubian Sandstone section was divided into several mappable formations in the
field (Klitzsch et al. 1979 and others). In the present work, the Nubian Sandstone
(Group) is divided into two following distinctive formations:
3.2 Taref Formation
This formation represents the basal unit exposed in the southern and eastern parts
in Dakhla Basin (Fig. 5). Lithologically, the formation consists of yellowish to light
brown cross-bedded sandstone, fine to coarse grained, stained with iron oxide, contain
thin shale and marl intercalations. The top surfaces are covered with black color of
desert varnish. The formation is non-fossiliferous and contains plant remains and
petrified wood. The base is unexposed and the total thickness is about 100 m. as
measured at Gabal Taref type section (Awad and Ghobrial 1965; Issawi 1972). The
presence of Haplophragmoides spp. and Trochammina spp. within the shale interbeds
may indicate deposition in normal water salinity. The age of the Taref Formation was
previously assigned to the Senonian (Coniacian–Santonian) age. On the other hand,
the sandstone beds of the Taref Formation pass gradually upward into the overlying
Quseir Formation.
South of Dakhla Basin, the Taref Formation conformably overlying the older rock
units (Maghrabi and Sabaya Formations, Fig. 5).