MINERALOGY AND RADIOACTIVITY STUDIES OF WADI ABU HAMUR-SAFAGA STREAM SEDIMENTS, CENTRAL EASTERN DESERT, EGYPT

The studied area covered by igneous and metamorphic rocks represented by Metagabbro, Metavolcanic, Older Granite, Dokhan Volcanics, Hammamat Sediments, and Younger Granite. Faults are essential structural features in the study area. The strike-slip faults of NW trends are right-lateral, while those of E-W, NE, and NNE trends are left-lateral faults. The normal faults are only preserved on a minor scale along these strike-slip faults represented by nearly vertical slicken-sides that indicate substantial vertical displacement. The grain size analysis and its distribution is a fundamental descriptive measure of clastic sediments. The results of statistical parameters a graphic mean (M z ) ranging from 0.04φ to 1.8φ, which means that it lies in coarse and medium sand size classes represented by 70% and 30%, respectively; inclusive graphic standard deviation (σ I ) ranging from 0.88 to 1.8. The samples could be categorized in the poorly sorted class and moderately sorted represented by 75% and 25%, respectively; inclusive graphic Skewness (Sk I ) ranging from 0.03 to 0.33, the samples could be categorized in fine skewed, near symmetrical, and strongly fine skewed classes represented by 55% ,40%, and 5%, respectively. Inclusive graphic Kurtosis (K g ) ranging from 0.68 to 2.05, the samples could be categorized in the platykurtic; mesokurtic, very lepto kurtic and lepto kurtic classes represented by 35% , 25% , 15% and 25%, respectively. The average content of total heavy minerals is 4.5% while the heavy content is ranging from 2% and 10.5%. Opaque minerals represented by magnetite, hematite, ilmenite constituents have an average of 1.07 %, 0.1 %, and 0.286%, respectively. Abrasive minerals as garnet constituents has an average of 0.13%, and pigment minerals as rutile and titanite constituents have an average of 0.188%, and 0.23%, respectively. Radioactive minerals as fluorites, zircon, and thorite constituents have an average of 0.0075%, 0.184%, and 0.001 %, respectively. Amphiboles and pyroxene constituents range from 0.1% to 3.78% with an average of 2.22 %. The eU contents range between 1 and 4ppm with an average of 1.76ppm, while eTh is between 2 and 29 ppm with an average of 10.75ppm. The average Ra average content for these sediments is 2.89 ppm, while the average content of K% is 1.16%.


INTRODUCTION
The study area represented by wadi abu hamur-wadi safaga which has long 30km and width reach to 50m (Fig. 1).These wadis lies roughly south of the Safaga-Qena road in unpaved road about 10km.The study area is bordered to the east by the Tertiary clastics and Cretaceous phosphatic deposits of Wadi Muhammad Rabah.The area are characterized by high rugged topographic area includes different mountains as G. um tagher, G. abu furad, G. wairah and G. muhammad rabah.The area in upstream reaches to 700m 118 ASHRAF EL AZAB a.s.l. and in downstream reaches to 200m a.s.l. at wadi Muhammad rabah and reaches to 4m at the end of wadi safaga (um huwaytat) (Figs.2&3).So the drainage pattern in the area started from the west and ended in the east due to the different in topographic elevation.
In the following description of the rock units of the area according to the Geological map of Abd El Rahman Fowlar et.Al., 2006, (Fig.1).

GEOLOGIC SETTING Metagabbro
It is present in central part of wadi Abu Hamur and the end of wadi safaga.A wide strip of green-schist facies metamorphosed weakly deformed gabbro.
Massive to weakly deformed gabbro, and form xenoliths in older granites and younger granites.Small intrusions and dyke networks of tonalite, granodiorite, granite, aplite within the mafic rocks are also characteristic (Fig. 2).

Metavolcanic
The exposed Metavolcanics in the study area represent a part of geosynclinal volcanic activity (El Shazly, 1964).According to the latter author, the main geosynclinal volcanics can be distinguished into an older basic series, associated with ultramafics, and a younger series of intermediate composition dominated by andesite together with subordinate diabase and tuffs.Stern (1981) divided the Metavol-canics cropping out in the area between lat.25° 30′and 26° 30′N in the Eastern Desert into Older Metavolcanics (OMV) and Yo u nger Metavolcanics (YMV).It covered the vast part of wadi safaga and the mouth of wadis Al Bulah and Abu Furad.The metavolcanics intruded by younger granite (Fig. 3).

Dokhan Volcanics
It represented by Calc-alkaline andesitic to rhyolitic rocks.They are located at the end of wadi safaga contacted by metagabbro (Fig. 1).

Hammamat Sediments
It located in wadi safaga and extended to south in wadi wasif.The Hammamat metasediments consist mainly of planar bedded and laminated greyish to greenish metasiltstone, phyllite and greywacke with minor conglomerate.Graded bedding in the sandstone metasediments indicates consistent upward younging for the sequence (Fig. 7 ).

Younger Granite
This granite restricted in the mouth of wadi safaga.This rock type represented by calc-alkaline, weakly deformed, and deeply weathered (Fig. 8).It is intruded in all oldest rocks and intruded by acidic dykes (Fig. 9).

Structure
Faults are essential structural features in the study area (Fig. 10).These faults have been well studied in the present work, with emphasis on fault slip.Slickensides and grooves are commonly associated with brittle Fig. 5:Felsite dike intruded in tonalite granite

SAMPLING AND TECHNIQUES
A total of 40 stream sedimentary samples were collected from Wadi Abu Hamur-Wadi Safaga through an open bit samples of 50cm diameter and depth of about 80cm., the samples spacing were 750m apart (Fig. 1).The average weight of each sample is about 10kg.The obtained samples were dried, sieved using 2mm sieve to remove gravel fraction and the rest of samples were quartered to obtain representative from 120gm up to 200gm from each.The representative samples were prepared for mechanical analysis and mineralogical investigation, where most of the silt and all of the clay were removed by decantation method.A representative sub-sample weighting about 60 gm was taken from each prepared sample and subjected to grain size analysis.The different percentiles were obtained in phi units from the cumulative curves using the phi scale.The four sedimentological statistical parameters namely: the Graphic Mean (M z ), the Inclusive Graphic Standard Deviation (σ I ), the Inclusive Graphic Skewness (Sk I ), and the Graphic Kurtosis (K G ) were faulting.These kinematic indicators indicate the direction and sense of maximum resolved shear stress in that plane (Carey and Brunier, 1974).Slickensides are often composed of fibrous crystals of chlorite, epidote, calcite and quartz that stretch from one side of the fault plane to the other (Fig. 11).
The strike-slip faults of NW trends are right-lateral, while those of E-W, NE, and NNE trends are left-lateral faults.These strike-slip faults dislocate the intrusive rocks.Fortunately, the rock exposures provided criteria to evaluate the activity along these faults in chronological order.The NW-trending faults are the oldest fracture planes, followed by the faults of E-W orientation, and ending with the NNE-trending faults (Fig. 10).The NNE-trending faults dislocate the older, differently oriented faults.The normal faults are only preserved on a minor scale along these strike-slip faults represented by nearly vertical slickensides that indicate to substantial vertical displacement.Determinations of the eU, eTh, Ra (ppm) and K ( %) concentrations of the studied stream sediments were carried out using a Bicron Scintillation Detector NaI ( T I) 76x76mm.They were packed in plastic containers, sealed carefully, and stored for thirty days prior to counting.

Grain Size Analyses
The grain size analysis and its distribution is a fundamental descriptive measure for clastic sediments.It is an important parameter in understanding and interpreting the operative mechanism during transportation and for reflecting the sedimentary environments and the processes of sedimentation, as well as, the dynamics affecting of the area.calculated for each sample, according to the equations quoted by Folk and Ward (1957).The calculated grain size statistical parameters for the sand size fraction are represented in Table (1).
Quantitative mineralogical analyses for the stream sedimentary samples were carried out by gravity separation using a Wilfley Shaking Table (Size No.13), heavy liquid separation using bromoform solution (Sp.Gr. 2.86g/cm 3 ), methylene iodide (Sp.Gr. 3.3g/cm 3 ), and magnetic fractionation using a Frantz Isodynamic Magnetic Separator (Model L-1) to fractionate heavy minerals according to their magnetic susceptibilities.First, magnetite was collected by a hand magnet, and then the magnetite free samples were subjected to the magnetic separation.The condition characterized a Frantz Isodynamic Magnetic Separator transvers slop 5, longitudinal slop 20 and step of current 0.2, 0.5, 1.0, 1.5 magnetic and 1.5 non magnetic current amperes.
Each fraction obtained from the magnetic separation process was microscopically studied under binocular stereomicroscope and investigated to calculate the frequency distribution of the concerned minerals in the studied stream sediment samples.The grain size parameters (Mz, σ I , Sk I , K G ) were calculated, and the results of these parameters are discussed, and described according to the limits of Folk and Ward (1957), and tabulated in (Table 1) as the follows: The samples have a graphic mean (M z ) ranging from 0.04φ to 1.8φ (Table 1) which means that it lies in coarse and medium sand size classes represented by 70% and 30% respectively (Table 2).

The samples have inclusive graphic stan-
The four different sedimentological statistical parameters namely: the Graphic Mean (M z ), the Inclusive Graphic Standard Deviation (σ I ), the Inclusive Graphic Skewness (Sk I ), and the Graphic Kurtosis (K G ) were calculated for each sample, according to the equations quoted by Folk and Ward (1957) as follows:  1), the samples could be categorized in the poorly sorted class and moderately sorted represented by 75% and 25%, respectively (Table 2).
The samples have inclusive graphic Skewness (Sk I ) ranging from 0.03 to 0.33 (Table 1), the samples could be categorized in fine skewed, near symmetrical, and strongly fine skewed classes represented by 55% ,40%, and 5%, respectively (Table 2).
Shape and size are quite important for measuring of the textural maturity of the sediment and the texture as a key of the sedimentary deposit history.So the sorting is reflected the sedimentary history of the deposit.It shows the nature and magnitude of the weathering (transportation, and deposition processes and their duration).The sediments are characterized by poorly to moderately sorted sediment texture and medium to coarse grain size that reflect their immature texture.
The skewness is a measure of the symmetry of the frequency curve.The frequency curve is represented by bolymodal.The bimodal curve may be due to the following: a)Effect of source rock: b y m e chanical weathering of rocks such as granite where two major size are present (medium and coarse), the resulting sediments will have two large amounts related to the two different major sizes (bimodal).b)Turbulant transportation: Turbidity currents can cause the admixing of sediments from different environments.Turbulent flow is a motion in which velocity fluctuates and direction changes during flow.The material carried is usually of mixed nature and accordingly of less sorted type.The turbulent flow is the ability to carry coarse-grained materials.

EVALUATION OF THE STREAM SEDIMENTS Heavy Minerals Distribution
To obtain the heavy minerals from the studied stream sediment samples gangue minerals should be removed, especially quartz and feldspars which constitute more than 90% of the stream sediments of Wadi Abu Hamur-Safaga by using the shaking table, then path through the heavy liquid as bromoform and methyline.
The percent of the heavy minerals content in the studied stream sediments are tabulated in Table 3.The heavy minerals content ranging from 2% and 10.5% with an average of 4.5% (Fig. 12 ).The high content of the heavy minerals in the studied stream sediments restricted in some localities near the acidic rocks.

Graphic Mean M z Inclusive Graphic The Inclusive Graphic T h e Inclusive Kurtosis
The obtained fractions were weighted and their percentages were calculated (Table 4).It is obviously noted that the heavy minerals are concentrated mainly in 0.2 amp and 0.5 amp magnetic fractions; while 1.5amp magnetic and non-magnetic fractions contains the lowest concentration of the heavy minerals.
A considerable number of grains from each magnetic fraction were counted (about 1500 grains).The weight percentage of each concerned mineral relative to the corresponding original sample was calculated according to Stakhove equation:

Magnetite
It represents the major part of opaque grains of the studied samples.It is black granular masses (Fig. 13), and strongly magnetic, sometimes with zircon or garnet inclusions.It separated using small hand magnet.These mineral constituents range from 0.1% to 2.3 % with an average 1.07 %, and are represented by histogram (Fig. 14).
The low uranium and thorium contents in magnetite of the stream sediments indicate that uranium in magnetite is mostly of the adsorbed type which is liable and easily leachable under the weathering conditions

Hematite
Hematite has at wide range of distribution as magnetite and both are present in the first two fractions in the stream sediments samples.It is considered as the major heavy mineral in the host rock samples (Fig. 15).These mineral constituents range from 0.01% to 0.4% with an average of 0.1 %, and represented by histogram (Fig. 16).The Semi quantitative analy-ses (EDX) show high iron content with low content of Titaniume, Manganese (Fig. 17).

Ilmenite [FeTiO 3 ]
The ilmenite grains of the stream sediments may be altered.It concentrated in a relatively the highly magnetic fraction at 0.2 amp.It is the most abundant Fe-Ti oxide mineral that occurs in a wide variety of igneous rocks, some metamorphic rocks, and as detritus mineral grains.Ilmenite in the studied stream sedi-    ments occurs as irregular, tabular or massive to subrounded, angular grains (Fig. 18).These grains exhibit black to brownish black colors and submetallic to metallic luster.The brownish tint of some ilmenite grains may be due to the partial alteration of these grains.These mineral constituents range from 0.07% to 0.9 % with an average of 0.29%, and represented by histogram (Fig. 19).

Garnet
The minerals of garnet group characterize some metamorphic rocks and in some igneous rock types, and can be noticed generally as detritus grains in sediments.It exhibits dif- ferent colors ranging from pale pink to dark brown with vitreous luster.Sometimes, garnet grains appear to be cloudy due to staining or inclusions (Fig. 20).The alamandine type is the common garnet mineral in the studied samples, probably due to the effect of contact or regional metamorphism.These mineral constituents range from 0.01% to 0.5% with an average of 0.13%, and represented by histogram (Fig. 21).The garnet in the studied stream sediments was confirmed either by ESEM (Fig. 22).

TITANIUM MINERALS Rutile [TiO 2 ]
It is the preferred mineral for the production of titanium dioxide.are commonly prismatic, elongated, tabular and massive granular in shape.The common colors of rutile are reddish brown grading into the red (Fig. 23) and black with adamantine luster.These mineral constituents ranged from 0.1% to 1.1% with an average of 0.188%, and represented by histogram (Fig. 24).

Titanite (Sphene) [CaTiSiO 5 ]
It is widespread in acidic and intermediate igneous rocks, and in several metamorphic rocks as accessory phase.It exhibits transparent to translucent yellow to yellowish brown colours (Fig. 25).Titanite mineral grains are subhedral to anhedral grains of adamantine luster and imperfect cleavage.The presence of titanite in the studied sediments was confirmed either by ESEM (Fig. 26), and X-ray diffraction (Table 6).These mineral constituents ranged from to 0.7% with an average of 0.23%, and represented by the histogram (Fig. 27).

Fluorites
Fluorite is present in the stream sediments as coarse grains.It is whitish or pale yellow in color and has irregular wedge shape (Fig. 28).Fluorite may have been originated from the granitic magma during the differentiation, or later at the deuteric stage forming the coarser fluorite sizes.These mineral con-  stituents ranged from 0.01% to 0.03% with an average of 0.0075%, and represented by the histogram (Fig. 29).

RADIOACTIVE MINERALS Zircon [ZrSiO 4 ]
Zircon is a remarkable mineral due to its ubiquitous occurrence in crustal igneous, metamorphic and sedimentary rocks, and in even mantle xenoliths, lunar rocks, meteorites and tektite (Speer, 1980).It occurs as an euhedral to subhedral grains, Prismatic with bi-pyramidal termination (Fig. 30a), and two bi-pyramidal (Fig. 30b).It is exhibiting brownish yellow colours of adamantine luster.These mineral constituents range from 0.01% to 0.9% with an average 0.184%, and represented by histogram (Fig. 31).ESEM cate that zircon consists mainly of ZrO 2 and SiO 2 with trace amounts of Ca, Hf, Fe and Al (Fig. 32).The Zr/Hf ratio is a principle indicator of magmatic differentiation.The average Zr/Hf of zircon from granitoid rocks is 37.3, while this ratio reaches to 49.6 for volcanic rocks, 55.7 for basic rocks and 67 for ultrabasic rocks (Lyakhvich and Vishneveskiy, 1990).For the studied zircon, Zr/Hf ranges from 31.15 to 41.78, indicating that they derived from granitoid rocks.It is one of the most important nuclear minerals, being a major host for REEs and actinides Th and U (Hinton and Paterson 1994, Bea et al., 1994and Bea 1996).Monazite in the studied samples is rare in the heavy minerals of these samples.It forms tabular and broken crystals.Most of these grains are characterized by pitted surfaces.It is pale yellow, honey yellow, greenish yellow and reddish yellow colour grains.These mineral constituents ranged from 0.001% to 0.07% with an average of 0.001% and represented by the histogram (Fig. 33 ).The EDX data (Fig. 34).

Thorite [ThSiO 4 ]
It occurs widely in the form of accessory minerals, which belong to the most important basic commercial minerals of thorium.It occurs as brownish black to black opaque grains of greasy luster (Fig. 35).Most of thorite mineral grains are subhedral to anhedral corroded and cracked.These mineral constituents range from 0.001% to 0.03% with an average 0.001 %, and represented by histogram (Fig. 36).
They are strongly metamictized, as determined by X-ray diffraction.In nature, thorite, generally, occurs in metamict state, amorphous to X-ray and electron diffraction, even though,   (Palache et al. 1944, Pabst 1952, Ewing and Haaker 1980).Thorite was annealed at 1100˚C for approximately four hours preceding identification by XRD.The obtained data (Table 7) reveal the presence of thorite peaks (ASTM card 11-419) in addition to hematite peaks (ASTM card 13-534).The presence of hematite may be in the form of thin films coating thorite grains or as individual hematite grains.The ESEM analysis shows that thorite consists mainly of ThO 2 and SiO 2 .Minor and trace elements include Y, U, Ca, Fe and REE (Fig. 37).

Amphiboles and
These minerals consists of amphiboles, pyroxene, biotite, muscovite and epidote, and detected in the stream sediments.These minerals may have originated from igneous rocks.These minerals are characterized by coarse size detrital particles, black, green to pale green colour (Fig. 38) and has medium to high magnetic success-ability.These mineral constituents range from 0.1% to 3.78% with an average of 2.22 %, and represented by histogram (Fig. 39).

RADIOMETRIC STUDY
The collected samples has been subjected to radiometric analyses to the studied area determine variations in eU, eTh, Ra and K%.The obtained results from the radiometric measurements of the studied stream sediments are listed in Table 8, and calculate the ratios of eU/eTh and eU/Ra.Draw the histograms distribution for these elements and ratios (Figs. 40 & 41).
The examined stream sediments of Wadi Abu Hamur-Safaga are characterized by radiometrically (low to moderately) concentrations of eU and eTh.The radiometrically elemental concentration of eU range between 1 and 4ppm with an average of 1.76ppm, while eTh is between 2 and 29ppm with an average of 10.75 ppm.The average Ra content for these sediments is 2.89ppm, ranging between   Ivanovich (1994) concluded that a relatively constant Th/U mass ratio of around 3.5 is found in most natural systems.average of the corresponding value (eTh/eU ratio) for the sediments of Wadi Abu Hamur-Safaga is 5.48 varying between 1.33 and 12.5 which indicate that there is a significant fractionation during weathering of these sediments causing the depletion of U.   The main factors controlling the distribution of radioelements in sediments are the geomorphological features of the basin of deposition, radioelements content of the source rocks, grain size of these sediments, the alkalinity of the surface groundwater, and to a lesser extent effect of the organic matter. 238U/ 226 Ra activity ratios (ARs) can be used to ascertain equilibrium within the same decay series (Navas et al., 2002).If secular equilibrium prevails in the 238 U chain, ARs of 238 U/ 226 U will be approximately 1, ARs values other than 1 indicate disequilibrium.The ARs for the studied stream sediments of Wadi Abu Hamur-Safaga alternate lower and higher than 1, which indicate a state of disequilibrium in these sediments.

eU Versus eTh Variation Diagram
The relation between U and Th may indicate the enrichment or depletion of U because Th is chemically stable.The eU against eTh variation diagram for the studied samples is shown on Figure 42 , which indicates strong positive relationships between the two elements.This result explains the low alteration processes affecting these samples, and also indicates that magmatic processes played an important role in the uranium enrichment of these granites which represent the source of these sediments.

eU Versus Zr Variation Diagram
The eU versus Zr variation diagram shows strong positive correlation in the studied samples (Fig. 43).The uranium and zirconium enrichment in the studied samples, supports the concept that U was trapped in the accessory minerals as zircon and the uranium is magmatically.

CONCLUSIONS
This study of economic minerals in the stream sediments of wadi Abu Hamur-wadi Safaga which has long 30km and width reach to 50m.The area covered by igneous and met- The grain size analysis and its distribu-tion is a fundamental descriptive measure for clastic sediments.The results of statistical parameters a graphic mean (M z ) lies in coarse and medium sand size classes represented by 70% and 30%, respectively, inclusive graphic standard deviation (σ I ) could be categorized in the poorly sorted class and moderately sorted represented by 75% and 25% respectively, inclusive graphic Skewness (Sk I ) could be categorized in fine skewed, near symmetrical, and strongly fine skewed classes represented by 55% ,40%, and 5%, respectively, and inclusive graphic Kurtosis (K g ) could be categorized in the platykurtic, mesokurtic, very lepto kurtic and lepto kurtic classes represented by 35% , 25% , 15% and 25%, respectively.
The average content of total heavy minerals is 4.5% and the heavy content ranging from 2% and 10.5%.Opaque minerals represented by Magnetite, Hematite, Ilmenite constituents have an average 1.07 %, 0.1 % and 0.286% respectively.Abrasive minerals as Garnet constituents has an average 0.13% and pigment minerals as Rutile and Titanite constituents have an average of 0.188% and 0.23% respectively.Radioactive minerals as Fluorites, Zircon, and Thorite constituents have an average of 0.0075%, 0.184% and 0.001 %, respectively.Amphiboles and Pyroxene constituents range from 0.1% to 3.78% with an average of 2.22 %.
The eU c o ntents range between 1 a n d 4ppm with an average 1.76ppm, while eTh is between 2 and 29ppm for with an average 10.75ppm.The average Ra average content for these sediments is 2.89ppm, and the average content of K% 1.16%.
The concentration of minerals restricted in the west (upstream) and the east (downstream) parts of the area due to the present of acidic rocks and the geomorphology of wadis.The low concentration restricted in the center part of the area where the rocks represented by basic rocks (volcanics, metavolcanics, and gabbros).
The transportation agent is rare and consid-er seasonal so the sediment restricted near the source rock and transported short distance.

Fig. 1 :Fig
Fig.1: Google map of the area with samples distribution (Modified after Abd El Rahman Fowlar et al., 2006)

Fig. 10 :
Fig.10: Structure map of the area

Fig. 11 :
Fig.11:Slickensides on the fault plane Distribution of the different calculated grain size parameters of the studied samples among the different classes 125 MINERALOGY AND RADIOACTIVITY STUDIES OF WA D I ABU Q = [P.n m .dm / Σ(n o d o )].100 Where: Q = the weight percentages of the concerned mineral P = the weight percentage of the corresponding magnetic fraction.n m = the number of grains of the mineral.d m = specific gravity of the mineral.Σ(n o d o ) = the sum of the number of grains for each mineral multiplied by its specific gravity.The common heavy minerals in the studied stream sediments are zircon, titanite, monazite, garnet, rutile, fluorite, thorite, green silicates (amphipoles & pyroxenes) in addition to opaque minerals magnetite, ilmenite and hematite (Tables 5 a & b).
Fig.12:Histogram show the distribution of total heavy minerals in the study area

Fig. 43 :
Fig.42:Direct relationship between equivalent uranium and equivalent thorium

Table 1 :
Grain size parameters of the studied samples

Table 3 :
The percentages of the heavy minerals in the studied stream sediments of Wadi Abu Hamur-Safaga after Bromoform

Table 4 :
Frequency of the heavy minerals in the different magnetic fractions by meteoric water.

Table 5a :
The weight percentages of the concerned heavy minerals in the studied stream sediment samples.

Table 6 :
X-ray diffraction data of titanite of Wadi Abu Hamur-Safaga area a b

Table 7 :
X-ray diffraction data of the annealed thorite from the studied