الفهرس 
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Abstract
The study area occurs at the South Eastern Desert to the south of Marsa
Alam City along the Red Sea Coast and covers an area about 739.5 km2.
The area is delineated by the latitudes 24º 20’-24º 30’ N and longitudes 34º
50’ – 35º 10’ E. It forms a part of the exposed Pan-African basement of the
South Eastern Desert of Egypt.
The area is relatively low to moderate hilly area. There are five main
wadies run into the area; Wadi Abu Ghusun, Wadi Rumayt, Wadi Shawab,
Wadi Umm Sayal and Wadi Abu Ghalqa.
Field observations and relations in addition to using the landsat thematic
mapper indicate that the area of Wadi Shawab is intensively sheared,
depressed and principally affected by hydrothermal actions.
The area is mainly covered (from older to younger) by rock varieties;
metavolcanics, epidiorites, amphibolites, grey granites, gneissose granites,
red granites and post orogenic dykes.
Metavolcanics outcrop along Wadi As-Surubi and are surrounded by the
grey granites whereas small partition is exposed along the eastern part of
Wadi Abu Ghalqa. Metavolcanics are low hilly hard, highly sheared,
massive, dense and fine grained rocks with blackish grey to grey colors.
Epidiorites are located mainly along Wadi Abu Ghalqa; these epidiorites
are the host rocks of ilmenite ore deposits (Abu Ghalqa ilmenite mine).
Epidiorites are generally massive, medium to coarse grained with dark grey
color and speckled with white patches. Epidiorites are metamorphosed,
sheared and are invaded by felsites. Field relations clear that the epidiorites
have intrusive contact with the surrounding grey granites.
Amphibolites occur either as lens-shape masses associated with
epidiorites or as dykes-like bodies protruding epidiorites. They are hard,
dense and fine grained rocks with dark colors.
Grey granites occur as an extended belts that trending NW-SE and occupy
the north eastern and a part of the south eastern parts of the study area,
whereas they are separated by Wadi Abu Ghusun which drained SW- NE.
CHAPTER 7 SUMMARY and CONCLUSION
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The grey granites form moderate relief with medium grained size and grey
color while their altered surfaces show yellowish brown colors. These rocks
are blocky and have no gneissose or foliation textures compared with the
gneissose granite. Grey granites show ambiguous gradational contacts with
the gneissose granites, whereas grey granites enclose enclaves of epidiorites
ranging in diameter nearly about 5 cm to 20 cm.
Gneissose granites form the main rock unit in the Wadi Shawab area that
occupies the major part of the mapped area. They form mountainous chains
with elevations increasing from east to west. Gneissose granites are
represented by some mountains features such as Gabal Hashanit, Gabal
Ushush and Gabal Shawab. They are deformed, foliated, exfoliated, highly
sheared and weathered as they exhibit spheroidal and cavernous weathering.
Occasionally the gneissose granites are intensively affected by
hydrothermal solutions especially in the highly sheared places and along
joint planes. They may show ambiguous gradational contact with the grey
granites whereas they exhibit sharp contact with each of the epidiorite and
red granite.
Red granites occur as isolated pluton in the north east of the studied area
at the end of Wadi Umm Sayal. It forms high ridged mountain with pink to
slightly red colors. It has sharp intrusive contact with the gneissose and grey
granites.
Petrographiclaly metavolcanics are represented by meta-andesites. Metaandesites
exhibit blasto- porphyritic texture. They mainly consist of
porphyroblasts of saussuritized plagioclases, altered hornblende and some
quartz in a fine grained groundmass of hornblende, laths of plagioclases and
quartz grains. These rocks show considerable amount of amygdals which
are filled with secondary quartz, epidote and chlorite.
Petrographically epidiorites exhibit hypidiomorphic granular texture.
They essentially consist of plagioclases, hornblende, ±quartz, ± tremoliteactinolite.
Opaque minerals, zircon, fluorite, titanite and apatite are the
common accessories. Secondary biotite, chlorite, epidote and saussurite are
the alteration products.
Amphibolites are essentially composed of hornblende and plagioclases.
Opaque minerals, zircon and apatite are the common accessories. Biotite
and epidote are the alteration products.
Petrographically grey granites are classified into quartz diorite to tonalite
and exhibit hypidiomorphic granular texture. Compared with the white
gneissose granites, these rocks are highly deformed and barren of
gneissosity. Grey granites mainly consist of highly turbid feldspars due to
kaolinitization and saussuritization, quartz, hornblende, minor k-feldspar ±
biotite. Opaque minerals, apatite, fluorite, zircon, allanite and titanite are
the common accessories whereas saussurite, chlorite, carbonates and
epidote are the alteration products.
Gneissose granites are characterized by foliation textures and mainly
composed of plagioclases, quartz, k-feldspar, and biotite. Opaques, titanite,
zircon, apatite, fluorite and garnet are the main accessories. Muscovite,
clinozosite, chlorite, sericite and carbonates are the alteration products.
Red granites petrographically are graded from monzogranites to
granodiorites. Red granites are generally medium grained rocks which are
essentially composed of quartz, perthitized k- feldspar, plagioclases,
muscovite and few biotites. Apatite, zircon, garnet and opaque minerals are
accessories. Sericite and kaolinite are the alteration products. These rocks
exhibit hypidiomorphic granular texture.
Geochemically epidiorites and amphibolites are of igneous source with
trends similar to that of early stage differentiates of basic igneous rocks.
The epidiorites and amphibolites plot in the oceanic field with tholeiitic
affinity. According to the differentiation trends, TiO2, Fe2O3total, MgO
decrease with SiO2 increase from epidiorites to amphibolites, whereas
Al2O3, CaO, Na2O, K2O and P2O5 show increase from epidiorites to
amphibolites correlation with silica content.
The values of Rb, Sr, Nb, Zn, Ni, Hf and Co decrease with the increase in
the silica content, whereas the values of Ga, V, Cr and Sc increase with the
increase of silica content. Harker variation diagrams of epidiorites and
amphibolites together with their magma type insure their origin from one
igneous source by differentiation processes.
The epidiorites and amphibolites are characterized enrichment in large ion
lithophile (LIL) elements (Sr, K, Rb and Ba) relative to high field strength
(HFS) elements (Nb, Y, Hf, Ce and Ti).
Geochemical data declare a distinct variation between the three granitic
rock types which can be observed from major oxides as SiO2, Fe2O3, MgO,
CaO and K2O. In general the grey granites seem to be the least
differentiated than the gneissose granites, whereas the red granites are the
most differentiated type. TiO2, Fe2O3total, MgO, CaO, MnO and P2O5
decrease with differentiation from grey granites to gneissose granites.
Al2O3, Na2O and K2O slightly increase with SiO2 increase from the grey
granites to the gneissose granites. The high values and scatter relation of
Na2O of the gneissose granites may be due to Na- metasomatism.
The red granites contain lower content of TiO2, Fe2O3total, MgO, CaO,
MnO, P2O5 and Al2O3 than the older granitoids and higher K2O declaring
its more differentiated magma.
The negative correlation of CaO, MgO and Fe2O3total and positive
correlation of K2O with SiO2 content favors an evolution of Wadi Shawab
older granitoids (grey and gneissose granites) through fractional
crystallization. The depletion of CaO and Sr with increasing SiO2 content
and positive correlation of Sr and Cao are consistent for plagioclase
fractionation.
The older granitoids are enriched in LILEs (Rb, Ba and Th) and HFSEs
(Nb, Hf, Zr, Y and Yb). The red granites are enriched in LILEs (Rb, Ba and
Th) and HFSEs (Nb, Hf, Zr, Y and Yb). Red granites are more enriched in
K relative to the primitive mantle normalizing values as the behavior
noticed for older granites, but the red granites are more enriched in LILEs
than the older granitoids.
Grey granites and gneissose granites are calc- alkaline rocks, whereas the
red granites are calk- alkaline to alkaline. The so-called older granitoids of
Wadi Shawab area are metaluminous, whereas red granites are
metaluminous to peraluminous.
The studied older granitoids are I- type granitoids and the red granites are
highly differentiated I- type granites. Grey and the gneissose granites are
syn- collision to late orogenic, while the red granites tend to be post
orogenic.
Grey granites suggest the silification trend and gneissose granites follow
Na-metasomatism trend according to K% vs. Na% variation diagram
showing the alteration type for the altered granitoids.
Fluid inclusions are studied in quartz of most investigated samples; only
five representative samples are selected for detailed study; two samples of
gneissose granite, one sample of red granite, and two samples represent
mineralized quartz and pegmatite veins.
Fluid inclusions in quartz of gneissose granite are high saline (brines) H2O
fluid inclusions. The fluid inclusions occur as primary isolated idiomorphic
form and secondary trails. Quartz contains two types of fluid inclusions.
The first type is bi-phases fluid inclusions that consist of H2O liquid (L),
and H2O vapor (V) or solid NaCl salt cubes. The second type is tri-phase
fluid inclusions H2O liquid (L), H2O vapor (V) and solid NaCl salt cubes as
daughter minerals.
Quartz in red granite contains fluid inclusions that occur as isolated,
idiomorphic, primary bi-phase and tri-phase fluid inclusions they occur as
irregular, sub rounded and elongated form. The bi- phases fluid inclusions
consist of H2O liquid (L), and H2O vapor (V). The tri-phases fluid
inclusions composed of H2O (L), CO2 (L) and CO2 gas, (G). Also it
contains few secondary trails of H2O and CO2 fluid inclusions that are
intersected. Fluid inclusions in red granite are less saline than those in
gneissose granite.
Quartz in quartz veins contains primary and pseudo- secondary fluid
inclusions. There are two types of primary fluid inclusions: a) saline fluid
inclusion that contains about 2 to 4 salt cubes in the fluid and does not
contain any opaques. b) Low saline fluid inclusions that contain about 1 to
2 salt cubes. Primary fluid inclusions are tri-phases that contain H2O (L),
and H2O (V) and NaCl salt cubes.
Fluid inclusions in pegmatite occur as idiomorphic negative crystal shape
primary bi-phases CO2 (L) and CO2 (G), H2O (L.), H2O (V.) and salt cubes.
Few mono-phase fluid inclusions are found in this sample.
A general model for the fluid rock interaction is given, from this model it
can be concluded that the measured P-T conditions of the intrusion of the
red granite into the gneissose g
- meteoric
origin.
The opaque minerals and copper ore minerals occur in the different rock
units especially the gneissose granites and the quartz veins which dissected
through them. Ore minerals are represented by Cu-Fe-sulphides, Cusulphides,
Cu-carbonates and iron oxides minerals. The Cu-Fe- sulphides
and iron oxides in gneissose granites are disseminated, fine to medium
grains occasionally oriented parallel to the gneissosity, whereas the Cucarbonate
minerals occurred mostly in quartz veins. They are medium to
coarse grained which arranged along fractures and shearing.
Ore minerals in the gneissose granites are represented by Cu-Fe-sulphides
(by primary bornite, tetrahedrite and pyrite), Cu- sulphides (secondary
chalcocite), whereas Cu- carbonates are mainly represented by malachite.
Iron oxides are represented by magmatic magnetite, secondary hematite and
few goethites.
The only ore minerals in the epidiorites and amphibolites are the iron
oxides minerals represented by magnetite and secondary hematite.
Ore minerals in the quartz veins are considered chronologically secondary
ores in relation to other ores in the different rock units. They are classified
as Cu-Fe sulphides (bornite, atacamite), Cu-sulphides (covellite,
chalcopyrite) and Cu-carbonates (malachite)