Mineralogy of the Sand Fraction of Some Dry Valleys in the Eastern Desert of Egypt

P.H. Soban , R.R. Shahin and Y.A. Nasr

Soils Depurfment, Faculty ofdgriculture, Cairo University, E.YP f -

T HE STUDY is undertaken on thirteen profiles representing the main four dry valleys which lie on the easternside of the Nile

valley between Ghamaza El-Kobra and Kafr-Halawa, Giza.

The obtained results indicate that opaque minerals, straulite and hornblend are the most abundant followed by zircon, biotite, garnet and monazite. The distribution of heavy minerals varied throug- hout soil profiles aswellas their respective horizons. The weathering ratios among resistant minerals reveal that these soils are derived on stratified parent materials and exhibits geogenetic relations rather than pedogenetic ones. It is concluded that the soils of the invest igated dry valleys were formed through alternative deposition of the eroded materials by water and wind actions.

Key-word. Sand fraction, Eastern Desert, heavy and light minerals.

The eastern side of the Nile valley is characterized by numerous openings. These openings are found to be the mouths of the dry valleys which form a considerable area in the Eastern Desert. The soils of these wadis are composed of eroded materials derived from the denudation of the Red Sea mountains.

Few soil investigators studied the -wadis in Egypt. Mehanny (1966) stu- died tbe soils of wadi Qena, Kasim (1971) the eastcrn nadih of Sharkia Gover- norate ; Bayougy (1971) the wadis of Salhia area east of the Nile Delta. Recently, Sawy (1959) used aerial photos in studying tbe soils of Wadi El-Qm area east of Cairo. Also, Sadek (1981) studied the interference zone between Eastern Desert and Nile Valley and described two dry valleys; namely, Wadi El- Werg and El-gorimate. Most of the pervious studies revealed that these soils often prove to be productive when irrigated and properly managed. Ther- fare, the agricultural extension is found to be beore successful in the soils of these wadis than the other desert soils.

The investigated region lies between Ghamaza EI-Kobra and IKafr-Hala- wa at Giza Governorate, with an area of about 95.3 km2. The dry valleys occupy about 14 -3 kma (3410 fed). The plan for using these dry valleys in agricultural purposes needs integrated studies, first of all the pedological and mineralogical studies. .

The present work is carried out to study the mineralogy of the fine sand fractian and its use as a criterion for the genesis and profile uniformity of the soils of the studied dry valleys.

64 F.H. SOLIMAN st al.

M a t e r i a l a n d M e t h o d s

Thirteen profiles were selected from the main four dry valleys in the studied area (Fig. 1). Wadi El-Heiza is represented by four profiles (No. 1, 2.3 and 4). Three profiles a r e chosen in each of Wadi =-%'erg (No. 5,6 and 7) ; Wadi El-Rishrash (No. 8,9 and 10) ; and Wadi Atpheh [No. 11,12 and 13). The profiles were m i n e d thoroushly and the samples werc taken according to the mo*phological variations within the profile. The detailed morphoiogicaldescription of these profiles are given elsewhere (Nasr, 1981). The main pro- perties of the investigated profiles are preseated in Table 1 .

Fig. 1. l hjsiography ard mil map of El-SaiT area.

E g y p . 1. Sodl Sci. 26, No. 1 (1986)

MINERALOGY OF THE SAND FRACTION 65

TAB= 1. Different soil characteristics of the hvestigsted pMBles.

a n d % send % - -- - i Fin

€

Silt % -

I

Prof No. -

1

2

3

4

5

6

7

8

9

10

11

12

% E.C. rnohslcm

Depth b cm --

0-30 30-60 6%

0 4 0 40-90

0 - 4 40-50 50-90

0-15 15-90 90-120

a-15 15-33 33-53 53-90

0-60 60-70 70-100

0-30 3o-m -90

6 3 0 30-50 5 0 4 5 65-100

6 1 5 15-30 3[)--40 4&90

0-20 2 a - 4 40-50 50-90

0-35 35-50 5 6 9 0 ,

-5 45-75 75-10

&50 50-70 70-90

20.39 39.914 28.871 4.540 6.587 26.66 3 .60 1 7.50 I 18.76 48.726 25.354 2,958 4 101 24 20 7.70 4 . 4 I a . 2 7 2 I 1 8.1@41 2 . 2 , 3 .270124 .40 1 i:;i 1 7.50

Egyfit. J . Soil Sci. 26, No. 1 (19861

P.H. SOLIMAN et a/.

Separation of the fine sand fraction (0.25.0036 mmd) was conducted by decantation using hexametaphosphate (USSL Staff, 1954). The sand frac tions were fractionated into light and heavy subfractions using bromoform (Sp. Gr. 2.84 + 0.02) as a heavy liquid after the removal of carbonates The particles of light and heavy minerals were permanently mounted by Cana- da Balsam (Brewer, 1964). About 500 grains were identified by polarizing microscope with a graduated mechanical stage. Systematicidentfication of heavy and light minerals was undertaken accordiilg to the principles outlined by Kerr (1959), Milner (1962) and El-Hinnawi (1966). The frequency percen- tage was calculated excluding carbonates and opaques.

R e s u l t s a n d D i s c u s s i o n

Mineralogy of the light fraction

The frequency distribution of the different types of quartz and feldspars is given in Table 2. Data reveal that the investigated soils are dominated by the normal quartz which forms 74.6 to 91.9 % of the light fractions. Un- doluse quartz is also detected in most samples but in less quantities as it ranges between 1.4 to 17 -9 %. Considering feldspars, it is evident that they forms 4,l to 15.7 %. However, the frequency distribution of light minerals in the investigated profiles with depth shows no specific pattern.

Mineralogy of the heavy fraction

The data presented in Table 3 indicate that opaques, straulite and horn- blend are the most abundant minerals. Pyroxenes, zircon, biotite, garnet and monazite are present in relatively moderate amounts. Rutile, tourmaline and epidotes are found in less pronounced amounts. Opaques (magnetite, hematite and illmenite) are subrounded but in some casts they are angular and constitute 27 to 64 %. The optial properties which recorded for the iden- tified mineral grains can be summarized as follows :

Straulite : yellow and gold yellow irregular grains ; Amphiboles : light green hornblends ; Pyroxenes : subrounded to sub-angular augite grains ; Monazite : yellow, high relief and rounded grains ; Garnet : pink and pale red, high relief,and angular grains ; Zircon : clear white to turbid prismatic grains or rounded with

high relief ;

Egypt. J . Soil Sci. 26, No. 1 (1986)

MINERALOGY OF THE SAND FRACTION 67

TABLE 2. Frepumcy disribtllon of light miner&.

Profile Depth No. --- --

Egypt. 7. Soil Sci, 26, No. 1 (19061

TA

BL

E 3

. Frequency

dktr

htio

11 o

f he

avy

min

eral

s.

I I D

eptb

in

m O

wa

/A&

e Ha

01

00

-I-

c?

-- -4 3'

1 N

-9' Z *

2 .

w

h

C

.-

3

Y

Rat

3 / la

. I

Zim

m

( Bpid

iot

1 Game1

0-30

30

-40

60--

100

040

40

40

040

43-5

0

-

50.7

0 52

.14

51.6

8

50.8

0 49

.50

56.8

0 55

.10

Meu

azit

S(. B

ioti

te

50

-90

1

33

.20

I

I

Oth

er

1 --I--

2.47

\ -

0.5

6

9.92

3

M

49.5

8 60-90

1 50.

56

-

1.41

0

.85

-

4.2

2

2.56

5

.62

4.23

5.

05

1.14

2.

72

3.45

2.47

3.

93

11.2

7 5.

98

6.74

7.94

12

.12

13.6

4 7.

18

20.6

0

-_

1.41

1 1.41

0.85

1.

71

- 4.

50

11

.13

20.5

0

14.6

0

3.20

-

I 2.

27

2.72

1.

15

3.27

1.

11

1.04

1.96

1.

70

-

0.80

1.1

9

2.80

3.

12

.-

4 5

-

1.41

7.

69

5.60

--I

17.3

5 4.

95

23.8

6 3.

97

0.8

3

0,5

6

el

5

15-9

0 %

I20

0-1

5 15

-33

52.4

5 6.

55

/ 8.

19

51

97

1 1.73

10.5

3

5.7

8

4.54

1.41

1.

71

1.12

__I i

2.12

4.

76

16.9

3 3.

29

4.23

2.

10

6 7 0.

83

1.70

-

-

1.12

4.2

2

2.56

4.

50

-

2.72

2

.30

-

0.60

6.

25

0.65

-

2.44

1

.58

1.19

-

4.68

-

0.95

3.

97

1.38

5.23

6.

83

27.0

8

55.5

0 56

.40

1.41

3

.42

4

.50

0.83

0.

56

3.1

3

5.23

2.

50

3.41

3.66

7

.14

8.33

7.

04

10.9

4

-

7.32

3.

17

6.54

7.

04

4.68

-

53.6

6 6

1.m

2.27

3.

41

0-60

-7

0 70

--10

0

0-30

45.2

0 47

.88

43.7

5

-

3.40

15.9

1 0

.6S

1 4

.08

14.9

6

13.8

18.0

3 12

.30

29.1

6

13.7

2 17

.09

7.32

12

.69

23.2

1 16

.90

14.0

6

1.1

4

-

%

2-0

4

2.20

3.27

6.

43

14.5

8

4.57

2.

56

7.32

3.

17

1.7

8

7.04

4.

68

2.3

0

-

] 8.

04

1.7

2

11;6

,

. x

- 3.51

3.

13

, 1.

31

1.7

0

7.32

0

.80

0.5

9

- 1.56

-

6.55

I -

6.90

-

2.34

4

.16

5.88

2

.56

6.

10

0.8

0

3.57

1.

41

3<

12

-

5.8

4

2.08

2.61

5.

13

4.86

2.

38

5.35

5.

63

4.68

-

-

1.64

8

0.60

-

9

Z

1.2

0

1

2.5

5

q

-

3.96

1.78

1.

41

-

-

-

-

l.%

0.

85

1.58

1.1

9

2.8

0

4.68

-

MINERALOGY OF THE SAND FRACTION 69

70 F.N. SOLIMAN st a!.

Rutile : prismatic and rounded grains, red and red brown d o u r with high relief and non-pleochroic ;

Tourmaline : prismatic dark brown grains, strong pleochroism ; Epidotes : ziothite and clinozite, subrounded grains ; Biotite : ~ U o w ' brown 5akes with strong birefrengtnce.

Figure 2 shows that the distribution of the heavy minerals is extremely dif- ferent within the investigated profiles as well as to their respective horizons. Such distribution indiates the multi-depositional regime of these dry vdoyl.

&gyp. 1. Soil Sci, 86, N N ~ 1 (1986)

MINBRALOGY OF T m SAND FRACTION 7 1

From the detected heavy mineral association, it is evident that the eoils of the studied dry valleys are relatively more developed than the adjacent allu- vial soils in the Nile valley. This is indicated from the low contents of pyro- boles in these soils as compared with those in alluvial soils (Table 4), as the pyrobolas are considered to be the lowest stable minerals (Gewaifel et al., 1981). I t is also noticed that the studied soils contain very high amounts of the other stable minerals, i.e. straulite, zircon, futile and tourmaline. This is entirely related to that these soils were derived from the material composing the Red Sea hills of the Miocene and Pliocene Eras.

TABLB4. A m mhthc L s q u s n e i e s a n d ~ o f ~ h c a v y ~ o f r o m s r l l m - iai mile ( M - A d aud ILhalil, 1977) d thb h d @ W dry mbJI.

Opaque* percentage of total sample*

*. For athor heavy minerals the porcentags is that of the non-opaques.

According to the triangular presentation cited from Kholief et al. (1969), (Fig. 3a), it is quite clear that the soils of dry valleys are largely different from. Nile redimant& The relative distribution of pyroxene, amphibole and epidote

72 F.B. SOLIMAN et al.

in the alluvial soiIs seemed to be adequate, whiIe amphiboles dominated in the case of dry valleys. Another suggested triangle representing the relative dis- tribution of amphiboles, straulite and epidote (Fig. 3b), reveal t h e predorninan- ancy of amphiboles in the alluvial soils accordhg to the data presented by La- bib (19701, and AbdeI-Aal and Khalil (1977). On the other hand, straulite exhibited the large percent of t h i s relative distribution in the investigated soils. From Phase results it could be conciuded that the alluvial sojh are mostly youn- p s sad more uniform than the investigated soils of the eastern dry valleys.

f ' ~ Am= amphiboles Am

ydJ Zone cf Cstnbulon m Nlle sedmentr ~::?r xholef dd.0969).

&ne of dslrlbulron n Mile sedrmts after Mb;b ('970)iAM~.l-&I dwi! Khi?liI (1977).

Pig . 3. Triangular repersentation of the distribution of pyroboles, cpidotes and atrauli tc.

Concerning the profile uniformity and development, the ratios Z/R, Z p and ZJRS-T, a s well as the weathering ratios Wr,, Wr, and Wr, are computed and set out in Table 5. Making use of such ratios one may conclude that these soils were derived on stsatified parent materials, subsequently soils profiles showed geogenetic reIations rather than pedo geneti c ones. Exception being noticed in profiI:% No. 3,9 and I I , which display apparenty homogeneity with only slight diifatnces rendered to the sedimentation process.

The weathering ratios Wr,, Wra and Wr, depend on the relative weather- ability of pyroxenes, amphiboles, hornblends and biotite as these minerals arc more weatherable than zircon and tourmaline. The calculated ratios for the different profiles provided a fairly good codrmation from the ratios bet- ween resistant minerals.

MINERALOGY OF THE SAND FRACTION 73

TABLE 5. Ratioa of rwbtant minerals and m-g arid f m c h m

P~lula ' ' No. -

From the above discussion, it is concluded that the soils of the studied dry valleys were formed by alternative water and wind actions. During the heavy rainfall seasons, the run-off resulted in water erosion which transported the weathered materials and deposited in the flood plain downsteream. In arid seasons, wind and gravity actions seems to be working together for< trans- porting fine soil materials along the gently slopes of the-eastern side*of Red Sea hills.

' Egypt. 1. Soil Sci. 26, No. 1 (1986)

74 F.B. 80LhZAlU a; d.

Potmrarcrr

Mql, Sh, L aud UWl, J.B (1977) Minatabgical studh on sand fraction of tbr Nib Valley and Delta soils of Egypt. Desert Zmt. Bull. Egypt, 27, 165.

Bayoumy, M.R. (1971) Padological studies in agricultural expansion a m wcrt of QUg Canal, A.R.R. M. Sc. Thenis, Fac. Agric., Cairo Univ.

B-, R. (1964) "Fabric and Minerd AnaIysiS". Wiley, NOW York. 470 pp. El-khtad, E.E. (1966) *'Metho& in Chemical and M i d Mtciv~cdpy". Elreria Publ.

Co.. Arnmtdam, London. Gewaifel, LM, Y d , MG., W-ZPbaby, EM. (1981) Haw m i n d study of lome Nile

alluvial soils in Egypt and Sudan. Egypt. J. Soll Sci. 21, 1 . P;*, Y.S. (1971) Pedological studies in agricultural expansion areas cast of Sharkis go=-

norate, U.A.R. Sc. l9ksis, Fac. Agric., Cairo Univ. k, P.F., (1959) ' 4 0 p ~ f d M k r a l ~ g l * ' . Mc Oraw-Hill Book Co. Inc., N w Yo& Tomto,

London. Polief, M. H i h y , L*, and ?ZbShahat, A (1969) C3cological and mineralogical -dim

on sand deposit6 In the Nile Delta. J. Seabwnt. Petrol. 39, 1520. UMb, F. (1970) Contribution of the mineralogical chamzterization of the moat irnmtarrt mil

parent materials in the U.A.R. Ph. D. ZIiesL, Fac. Agric., Ain Sham Univ., U.A.R. Mebaw, AH. (1966) Pedolugical, physical and chrmical characterization of the m h of

Wadi Qma. M. Sc. l&s&, Fac. Agric., Cairo Univ. M i b r KB., (1962) 'LSedimcntmy Perrography". Wol. 19). George AUm md Uamn

LW.. Museum etreet. London. Nw, Y.A.A.E (1981) Pedatogieal and mineralogical chamdmbtb of oomt dry d l * in

the Ea~tam D m , Egypt. M. Sc. Zhsb, Fac. Agric., Cairo Univ. Sadek, S,A. (1981) M~rphology and genesis of tho interference zone between hatem dwrt

formation and Alluvial soils of Egypt. M. Sc. nteslr, Fac. Agric., Caito Univ. Shw, S. (1979) Physiography of some dc8ertic valleyo of the Emtarn Derort of Egypt.

M.Sc. Thesis, Fac. Agric. di Cairo Univ. US. Salinity Labomtory Staff, (1954) "Diognosls md Imp70wment d Soline d Alkd

&f&' &rih m d Bodk NO. a. (Recsived 4lper)

Egypt. J. Soil Sd, 26, No. 1 ( 1 S )