Magnetic and Geoelectric characteristics of East Rosetta sand placer deposits, Egypt

Geologic Resources in the Arab World Conference, 24-29 Feb., 2007, Cairo University

1

Magnetic and Geoelectric characteristics of East Rosetta sand placer deposits, Egypt

Ahmed A. Ammar*, Mohamed A. Elsadek* Abbas M. Sharaky**, Ahmed N. Shahein**,

and Sayed A. Elkhateeb* *Exploration Division, Nuclear Materials Authority, Cairo, Egypt

**Department of Natural Resources, Institute of African Research and Studies, Cairo University, Giza 12613, Egypt

ABSTRACT

The black-sand beach deposits are known for many decades of years as a source

of strategic and economic heavy minerals. The present study deals with the analysis

and interpretation of the results of field geophysical survey and laboratory

geophysical measurements conducted on Koam Mashaal area, east Rosetta

Mediterranean Sea coast Egypt. These include field measurements of total magnetic-

field intensity and laboratory geoelectric measurements including resistivity and

chargeability.

The analysis and interpretation of the field and laboratory magnetic and

geoelectric maps demonstrated that the studied black-sand beach deposits of Koam

Mashaal area can be subdivided according to their geophysical response into three

main zones striking nearly parallel to the shoreline of the Mediterranean Sea. The

deep-seated magnetic response was interpreted at an average depth of 239.6 m.

Meanwhile, the near-surface magnetic responses were interpreted at average depths of

9.1, 57.9 and 81.8 m, respectively.

1. INTRODUCTION

1.1. General

The black-sand beach deposits are known for many decades of years as a source

of strategic and economic heavy minerals that are considered as raw materials for

nuclear energy. Besides, they are considered of thorough importance in many of the

metallurgical and engineering industries. The mineralogical analyses identified six

main minerals accompanied by some other minor ones. According to their relative

frequencies and economic importance, the six main minerals are: ilmenite, magnetite,

zircon, monazite, garnet and rutile. Traces of cassiterite and gold as well as some rare

earth minerals are also present.


2

The main objectives of the present study are:

1) Evaluation of surface extensions of the black-sand beach deposits in the Koam

Mashaal area, using ground total magnetic survey, and laboratory geoelectric

measurements.

2) Mapping the spatial distribution patterns of the heavy mineral concentrations in the

study area.

3) Identifying various depositional phases

4) delineation of the subsurface (shallow and deep-seated) magnetic sources.

1.2. LOCATION OF THE STUDY AREA

Koam Mashaal area lies on the coastal plain of the Mediterranean Sea, 15 km to

the east of Rosetta mouth of the River Nile, Egypt (Fig. 1). It is located between

longitudes 30 32′ 10″ E and 30 34′ 08″ E and latitudes 31 26′ 59″ N and

31 27 ′ 59″ N). The study area extends for about 3.0 km along the coast, 1.8 km.

inland and forms 5.4 km2 in surface area that is mostly covered by beach sands.

Cairo

Location of study area

Figure 1. Part of northern Egypt showing location of the study area, Koam Mashaal, east Rosetta,

Mediterranean Sea coast.

1.3. Geology

Black sand deposits in the northern Nile Delta, especially in Koam Mashaal area

have received the attention of several researchers since early 20th century. The most

recent researches carried out on the black sands include Elhadary (1998), Abu-Diab

(2001), Abdelhady et al. (2002), Elsadek and Elkhateeb (2002), Abdelhady et al.

(2004), Mahmoud et al. (2004), Bakheit (2004) and Elkhateeb (2005) . The black-sand

deposit east Rosetta has high mineral productivity. These minerals could be easily


3

mined. Alaskary and Freihy (1986) identified three depositional phases in the upper

30 m at Rosetta and Damietta promontories. These are from base to top: transgression,

regression and erosional transgression phases. The beach is generally flat in the

Rosetta area where seawater crosses the beach during winter stormy conditions and

high tide periods (Elhadary, 1988).

2. METHODOLOGY

2.1. SURVAY PROCEDURE AND SAMPLING

The ground magnetic survey was conducted along a set of equally-spaced (100 m)

parallel traverses oriented N-S, a direction which is perpendicular to the general

extension of the Mediterranean Sea coast in the area. The general strike of the

lithological units in the study area was determined according to the general elongation

of the black-sand lenses, occurring along the Mediterranean Sea coast, which

approximately extends in an E-W direction. Magnetic measurements were made at

regular intervals of 10 m. The survey data were tied along one tie line perpendicular

to the direction of the survey traverses. A base station (reference point), far from

artificial magnetic disturbances within the surveyed area, was chosen. The total

magnetic-intensity measurements, collected at the survey stations, were regarded as

positive or negative deviations from that at the reference point. The ground raw

magnetic survey measurements in Koam Mashaal area were magnetic data, since the

surveyed area is characterized by smooth terrain and the elevation differences

between the survey stations are not significant. The geomagnetic correction was

calculated at the central point of the study area, where IGRF equals 43,519.12 nT,

inclination angle equals 45.89○, declination angle equals 2.78○ at a latitude of 31.46○N

and a longitude of 30.55○E and the date was Oct. 30, 2001 (GM. SYS. Program,

1997). The IGRF value was subtracted from the readings of the whole survey stations.

The survey data were transformed from the field magnetometer to a desk top

computer, where data reduction was performed using a set of computer programs

(Microsoft Excel, MDA1-Ver.1.97 and MDA2-Ver.1.97).

A 12-channal Global Positioning System (GPS) instrument was used to set up the

survey grid with a Universal Transverse Mercator (UTM) coordinate system, using

World Grid (WG84) as datum. All samples were put in plastic bags and labelled by

their UTM positions.

The laboratory geoelectric (resistivity and chargeability) measurements were

applied to 966 quartered samples taken from large samples collected at depths up to


4

50 cm. The large samples were taken along 32 equally-spaced (100 m apart) profiles,

at equally-spaced (50 m apart) stations. These profiles were oriented in a N-S

direction covering an area reaching about 5.4 km2. The samples were taken by

bushing a rigid plastic tube, with a diameter of 5 cm and a length of 70 cm till 50 cm

mark on the tube, in the ground. The collected samples were quartered by John's

splitter.

2.2. INSTRUMENTATION

2.2.1. Total Magnetic Field Instruments

The total magnetic field intensity measurements were performed using a portable

proton-precession magnetometer, model PMG-1, Geofyzika Brno, Czeck Republic,

having a sensitivity of 0.1 nT and a measuring range from 25,000 to 100,000 nT.

(PMG-1 Manual, 1997).

Another magnetometer of the same type has been used as a base station for

automatic monitoring and recording of diurnal variations in the Earth’s magnetic

field. The measuring time was set for one minute at the base station as a matter of

diurnal variation and storage capacity of the instrument.

2.2.2. Geoelectric Instruments

The used IP-L system is a sample resistivity and IP testing system, manufactured

by IRIS Instruments, France. It has been designed to measure the electric resistivity

and induced polarization (IP) parameters on rock samples or drill-hole cores. It

consists of three units: a sample holder frame, an IP-L low power time domain

transmitter, and an ELREC-2 as a time-domain IP receiver (IRIS Instruments, 1993).

The sample holder was modified to be compatible with friable sand samples. The

new holder is a rigid plastic tube, with a plastic piston to compress the friable sand.

This plastic tube possesses four minute holes at equal distances (4 cm) as a Wenner

array and four electrode terminals for connecting the electric current. The two current

electrodes are connected to the external holes and the two potential electrodes to the

central holes.

3. INTERPRETATION OF THE GROUND MAGNETIC SURVEY DATA

3.1. General

The intensity of magnetization of a rock is largely dependent upon the amount,

size, shape and distribution of its content of ferromagnetic minerals, that usually

represent only a small proportion of its mineralogic composition. Much qualitative

information may be derived from magnetic contour maps. Such qualitative


5

interpretation may be greatly facilitated by the use of digital image-processing

techniques similar to those used in the display of remotely-sensed data (Kearey and

Brooks, 1998).

The corrected ground magnetic data were subjected to various techniques of

analysis in order to get qualitative and quantitative parameters, which can describe

well the subsurface magnetic sources and consequently guide the exploratory drilling

for the buried heavy mineral lenses in the study area. These techniques involved the

application of spectral analysis and matched filtering.

In the present study, the analysis of ground magnetic survey data including

spectral frequency analysis and isolation of magnetic anomalies have been carried out

using the Magnetic Data Analysis (MDA2-Ver 1.97) software (Badokhon, 1998),

which is based on Filon Fourier Transform. This program designs the suitable filter

and separates the regional and residual components.

3.2. Total Magnetic-Field Intensity Map

The correlation between the magnetic features recorded on the total magnetic field

intensity contour map (Fig. 2) and the electric resestivity, IP chargeability and

calculated metal factor maps of the study area (Figs. 8, 9 and 10) was found to agree

to some extent. Due to the existence of magnetite and other magnetic minerals in the

black-sands on the surface and at very shallow depths, and near surface depth, the

magnetic response is mainly due to these sands. Therefore, the magnetic response is

chiefly, and for the most part, due to the black-sand beach and lenses dunes. On the

total magnetic field intensity contour map (Fig. 2), the magnetic high and low

responses are arranged parallel to the Mediterranean Sea shore and more or less in the

northwestern direction.

The magnetic field intensity registered over the area under consideration ranges

from 35 to 115 nT. It can be divided into two main zones: the first zone is located in

its northern part parallel to the Mediterranean Sea coast and the other is located in its

southern part. The northern part contains the expected major black-sand beach lens

and the Koam Mashaal old sand dunes. This part is mainly magnetically high, while

the southern part is mainly magnetically low.

3.3. Regional Magnetic-Field Intensity Map

Frequencies of magnetic anomalies could reveal the depths of their magnetic

sources. The regional magnetic intensity contour map (Fig. 3) represents the relatively

deep-seated magnetic response of the black-sand beach and dune deposits, at an


6

average depth of 239.6 m. This map shows that the Koam Mashaal area could be

divided into two main zones according to magnetic causative sources. The first zone,

located in the northern part of the study area, is characterized by high magnetic-

amplitude anomalies with low frequencies and long wavelengths, which refer to deep-

seated black-sand deposits in the form of lenses. It is also characterized by high to

very high magnetic response, ranging in amplitude from 76 to 88 nT. The second

zone, located in the southern part of the study area, is characterized by low, medium,

high and very high magnetic responses with higher frequencies and longer

wavelengths which may refer lesser depth values. They range intensity from 64 to

88 nT. The high and low magnetic areas within the second zone are arranged in

elongated shapes having two major trends in the NE- and NW- directions.

3.4. Residual Magnetic-Field Intensity Map

An important interpreting technique in geophysical exploration is residual

mapping, in which local anomalies are separated from regional ones. According to

Burger (1992), the definition of residual depends on the exploration target. Generally,

on the magnetic maps of local areas, the regional trend may show uniform variations

represented by parallel, evenly-spaced contours. A local anomaly, which ordinary

would be indicated by closed contours, appears as a "nose" on the regional anomaly

field (Sharma, 1976).

266000 m 266500 m 267000 m 267500 m 268000 m 268500 m 269000 m

3482

200

m34

8270

0 m

3483

200

m34

8370

0 m

0 250 500 750 1000 mUnsurveyed Area

35

45

55

65

75

85

95

30° 32' 15" E 30° 32' 45" E 30° 33' 15" E 30° 33' 45" E

31° 27' 45" N31° 27' 15" N

Figure 5: Filled gray-tone contour map of the total magnetic field intensity, Koam-Mashaal area, east Rosetta, Mediterranean Sea coast, Egypt. Contour interval = 5 nT.

nT

Figure 2: Filled gray-tone contour map of the total magnetic field intensity, Koam-Mashaal area, east Rosetta, Mediterranean Sea coast, Egypt. Contour interval = 5nT


7

266000 m 266500 m 267000 m 267500 m 268000 m 268500 m 269000 m

3482

200

m34

8270

0 m

3483

200

m34

8370

0 m


40

44

48

52

56

60

64

68

72

76

80

30° 32' 15" E 30° 32' 45" E 30° 33' 15" E 30° 33' 45" E

31° 27' 45" N31° 27' 15" N

Figure 6: Filled gray-tone contour map of the regional component of magnetic-field intensity, at an average depth (h) of 239.6 m, Koam-Mashaal area, east Rosetta, Mediterranean Sea coast, Egypt. Contour interval = 2 nT

nT

The residual magnetic intensity contour maps (Fig. 4, 5 and 6) represent the

near-surface magnetic responses of the black-sand deposits at average depths of 9.1,

57.9 and 81.8 m, respectively. The contour lines are either elongated parallel to the

Mediterranean Sea shore (i.e., ENE – WSW) or in the NW- and NE- directions,

representing the sedimentation and concentration agents of black-sands, either due to

wave or wind actions, respectively. Near the Mediterranean Sea coast, the contours

are elongated parallel to the coast, due to the dominance of wave action. Away from

the Sea shore, the influence of wind action increases and the contours take the

direction of the prevailing wind, following either the NW or the NE directions. The

great similarity between the three maps at the three computed near-surface depths

might be due to the continuity of sedimentation and concentration environments. The

magnetic intensity over these three residual magnetic component maps ranges from

-25 to 45 nT on the shallowest map (9.1 m), from -40 to 30 nT on the intermediate

one (57.9 m) and from -16 to 12 nT on the deepest one (81.8 m).

3.5. Depth Estimation of the Subsurface Magnetic Sources

The general object of ground magnetic interpretation is the delineation of buried

contacts, locations of probable areas of rock differentiation or mineralization. By

following bands of steep gradients across the magnetic maps and distinct types of

Figure 3: Filled gray-tone contour map of the regional component of magnetic-field intensity, at an average depth (h) of 239.6 m, Koam-Mashaal area, east Rosetta, Mediterranean Sea coast, Egypt. Contour interval = 2nT


8

magnetic features, it is possible to define the boundaries of major rock units (Reford

and Sumner, 1964).

The total intensity magnetic field recorded over the Koam Mashaal area (Fig. 2)

represents the combined contributions of all the magnetic sources (mainly bodies of

high heavy (economic) mineral concentrations) lying at depths computed by the

application of spectral analysis of magnetic data.

266000 m 266500 m 267000 m 267500 m 268000 m 268500 m 269000 m

3482

200

m34

8270

0 m

3483

200

m34

8370

0 m


-12

-8

-4

0

4

8

12

30° 32' 15" E 30° 32' 45" E 30° 33' 15" E 30° 33' 45" E

31° 27' 45" N31° 27' 15" N

Figure 7 A: Filled gray-tone contour map of the residual component magnetic-field intensity, at an average depth (h) of 9.1 m, Koam Mashaal area, east Rosetta, Mediterranean Sea coast, Egypt. Contour interval = 2 nT

nT

The resulting regional and residual magnetic-component maps were

interpreted in terms of lithology and structure. Deep major lithologies and structures

will be resolved and interpreted through the regional (deep-seated) magnetic-

component map (Fig. 3). Meanwhile, the near-surface (shallow) lithologies and

structures will be detected through investigation of the three computed residual

magnetic-component maps (Figs. 4, 5 and 6).

Figure 4: Filed gray-tone contour map of the residual component magnetic-field intensity, at an average depth (h) of 9.1 m, Koam Mashaal area, east Rosetta, Mediterranean Sea coast, Egypt. Contour interval = 2nT


9

266000 m 266500 m 267000 m 267500 m 268000 m 268500 m 269000 m

3482

200

m34

8270

0 m

3483

200

m34

8370

0 m


-12

-8

-4

0

4

8

12

30° 32' 15" E 30° 32' 45" E 30° 33' 15" E 30° 33' 45" E

31° 27' 45" N31° 27' 15" N

Figure 7 B: Filled gray-tone contour map of the residual component magnetic-field intensity, at an average depth (h) of 57.9 m, Koam Mashaal area, east Rosetta, Mediterranean Sea coast, Egypt. Contour interval = 2 nT

nT

266000 m 266500 m 267000 m 267500 m 268000 m 268500 m 269000 m

3482

200

m34

8270

0 m

3483

200

m34

8370

0 m


-18

-14

-10

-6

-2

2

6

10

14

30° 32' 15" E 30° 32' 45" E 30° 33' 15" E 30° 33' 45" E

31° 27' 45" N31° 27' 15" N

nT

Figure 7 C: Filled gray-tone contour map of the residual component magnetic-field intensity, at an average depth (h) of 81.8 m, Koam Mashaal area, east Rosetta, Mediterranean Sea coast, Egypt. Contour interval = 2 nT

Figure 5: Filed gray-tone contour map of the residual component magnetic-field intensity, at an average depth (h) of 57.9 m, Koam Mashaal area, east Rosetta, Mediterranean Sea coast, Egypt. Contour interval = 2nT

Figure 6: Filed gray-tone contour map of the residual component magnetic-field intensity, at an average depth (h) of 81.8 m, Koam Mashaal area, east Rosetta, Mediterranean Sea coast, Egypt.

Contour interval = 2nT


10

Review of the estimated depths values indicates that the magnetic signals in the

studied area originate from four average depth levels attaining 239.6 m, 81.8 m, 57.9

m and 9.1 m from the mean measuring surface. The ore bodies in the study area might

take the form of a series of thin lenses and thus, the average depths of burial could be

calculated to the top surface of these bodies. These average depths are denoted as h1,

h2, h3 and h4, respectively (Table 1).

Regarding the heavy mineral exploration in the investigated area, spectral

analysis of the ground magnetic survey data provided useful information about the

lateral changes in the depths to the bodies of high heavy (economic) mineral

concentrations within this zone (Table 1 and Fig. 7).

The interpreted depths (Fig. 7) might represent three shallow and one deep

sedimentation cycles of black-sand beach deposits. The near-surface (more recent)

cycle, with a depth (h4) is the more interesting horizon for its relatively small depth

(ranging from 7.8 m to 10.7 m.), which takes a big lens shape or a series of lenses.

The heavy mineral concentrations at the two other near-surface depths could be

checked and used later, due to their relatively depths (from 12.5 m to 118.5 m and

from 37.2 to 137.5 m, respectively). The residual magnetic intensity maps (Fig 4, 5

and 6) represent the most probable occurrence and distribution of the black-sand

deposits on and near the surface. The deepest calculated level (ranging from 174.7 m

to 334.4 m)) represents the more ancient cycle of sedimentation of black-sand beach

deposits. It wroths mention that the configuration of the Sea shore was really different

at that time. The comuted arithmetic mean values of four depths reach 239.6 m, 81.8

m, 57.9 m and 9.1 m, respectively.

Calculated Depths

050

100150200250300350400

265900 266400 266900 267400 267900 268400 268900

Destance, in m

Dep

th, i

n m

h 1 h2 h3 h4

Figure 7: The spatial subsurface configuration of the computed depth estimates to the magnetic sources, Koam Mashaal area, east Rosetta, Mediterranean Sea coast, Egypt.

E


11

Table 1: Summary of the depth levels as estimated from the application of spectral analysis technique to the individual magnetic survey profiles, Koam Mashaal area, east Rosetta, Mediterranean Sea Coast, Egypt

Depth (m) Depth (m) Profile

No. h1

(239.6) h2

(81.8) h3

(57.9) h4

(9.1)

Profile No h1

(239.6) h2

(81.8) h3

(57.9) h4

(9.1) 265900 174.7 63.6 50.5 9.6 267700 258.9 137.5 118.5 8.3

266000 195.8 82.2 71.6 7.8 267800 223.7 125.3 84.3 7.8

266100 203.4 37.2 29.6 10.4 267900 213.5 83.4 53.1 8.4

266200 198.3 44.5 12.5 9.3 268000 230.8 67.3 57.6 9.4

266300 191.0 122.1 69.4 10.2 268100 334.4 63.3 38.4 8.4

266400 215.3 75.3 44.4 9.3 268200 240.8 93.4 64.1 9.4

266500 242.2 107.6 61.3 9.4 268300 253.2 128.9 112.6 8.2

266600 206.3 86.3 53.1 9.8 268400 229.2 91.5 85.0 8.3

266700 221.9 45.2 20.9 10.7 268500 277.0 107.4 77.3 9.7

266800 250.9 68.0 31.1 8.7 268600 282.3 65.4 37.9 8.6

266900 254.7 50.4 19.7 9.1 268700 324.3 105.3 91.8 8.5

267000 243.8 100.8 67.1 10.1 268800 212.3 51.9 42.5 9.6

267100 229.4 49.2 27.5 9.5 268900 255.8 69.2 48.0 9.1

267200 238.1 44.9 30.7 9.1 269000 265.9 68.1 66.0 9.3

267300 232.0 68.4 46.9 10 Minimum 174.7 37.2 12.5 7.8

267400 244.4 108.4 88.9 8.6 Maximum 334.4 137.5 118.5 10.7

267500 260.3 80.7 70.2 8.3 Mean 239.6 81.8 57.9 9.1

267600 261.0 125.3 81.0 9.4Standard deviation

34.9 28.3 26.3 0.7

4. INTERPRETATION OF THE LABORATORY GEOELECTRIC

MEASUREMENTS

4.1. General

Electrical measurements are among the most difficult of all geophysical methods

to interpret quantitatively, because of the complex theoretical bases of the technique.

Electric IP quantitative interpretation is considerably more complex than the electric

resistivity method. Much electric IP interpretation is, however, only qualitative

(Kearey and Brooks, 1998).

Data of the measured and calculated electric resistivity and IP chargeability as

well as metal factor were finally displayed in the form of filled colour contour maps,

with a scale of 1:25,000 (Figs. 8, 9, and 10). The electric resistivity measurements

were found to range from 0.1 to 200 Ohm m. To avoid this wide variation and, hence,


12

the wide range of electric resistivity measurements, logarithmic, contours were

computed and drawn for both the electric resistivity and metal factor maps (Figs. 8

and 10).

4.2. Electric Resistivity Laboratory Measurements

The electric resistivity filled-colour contour map (Fig. 18) indicates the presence

of one prominent broad zone of low resistivity values, occupying major part of the

study area. This zone coincides quite well with the economic (heavy) mineral deposits

in the study area. A central high resistivity zone – parallel to the Mediterranean Sea

shore - separates this prominent low resistivity zone into two subzones. This central

zone takes the form of a narrow strip of an elongated shape, and shows very high

electric resistivity values more than 100 Ohm.m, especially in its eastern part, which

trends perpendicularly , i.e., in the NNW direction. This zone represents an old

excavated drainage channel as well as the western part of some old sand dunes. There

is also a relatively moderate to high electric resistivity zone delimiting the northern

part of the study area, running parallel to the Mediterranean Sea shore.

266000 m 266500 m 267000 m 267500 m 268000 m 268500 m 269000 m

3482

200

m34

8270

0 m

3483

200

m34

8370

0 m

0 250 500 750 1000

Ohm.m

munsurveyed area

-0.5

-0.3

-0.1

0.1

0.3

0.5

0.7

0.9

1.1

1.3

1.5

1.7

1.9

2.1

30° 32' 15" E 30° 32' 45" E 30° 33' 15" E 30° 33' 45" E

31° 27' 45" N31° 27' 15" N

Figure 18: Filled-colour contour map of the electric resistivity ( ) laboratory measurements, Koam-Mashaal area, east Rosetta, Mediterranean Sea coast, Egypt. logarethmic contour interval. = 0.1 Ohm.m


13

4.3. Electric (IP) Chargeability Laboratory Measurements

The electric IP chargeability filled gray-tone contour map (Fig. 9) indicates that

the low electric IP chargeability values agree well with the high electric resistivity

values at the narrow zone located in both the central and eastern parts of the study

area as well as its northern parts. The moderate and high electric IP chargeability

zones are also well agreeable with the moderate and low electric resistivity zones,

which are associated with the economic (heavy) mineral deposits.

Two relatively high electric IP chargeability zones can be distinguished at the

central northern and southern parts of the study area, with electric IP chargeability

values reaching more than 11 mV/ V and coincide well with the zones of very high

content of heavy minerals.

4.4. Calculated Metal Factor

The calculated metal factor filled-colour contour map (Fig. 10) indicates high

values that agree well with high electric IP chargeability and low electric resistivity

values. Moreover, the three figures (8, 9 and 10) show the same results and confirm

the existence of the anomalous zones that occur at the central, northern and southern

parts of the study area, which agree well with the zones of anomalous content of

heavy (economic) minerals.

266000 m 266500 m 267000 m 267500 m 268000 m 268500 m 269000 m

3482

200

m34

8270

0 m

3483

200

m34

8370

0 m


0

2

4

6

8

30° 32' 15" E 30° 32' 45" E 30° 33' 15" E 30° 33' 45" E

31° 27' 45" N31° 27' 15" N

Figure 19: Filled-colour contour map of the electric chargeability (M ) laboratory measurements. Koam Mashaal area, east Rosetta, Mediterranean Sea coast, Egypt Contour interval = 1 mV/V

mV/V

M


14

SUMMARY AND CONCLUSIONS The correlation between the magnetic features recorded on the total magnetic

field intensity, the electric resistivity, IP chargeability and calculated metal factor

maps of the study area was found to agree to some extent. Field and laboratory

magnetic and geoelectric maps demonstrated that the investigated beach-alluvial

deposits of Koam Mashaal area can be subdivided into three main zones striking

nearly parallel to the shoreline of the Mediterranean Sea. The northern zone is more

enriched in black-sands than the central or southern zones. However, the heavy

minerals show parallel zones below the surface, suggesting similar sedimentation

environments. The deep-seated magnetic response was interpreted at an average depth

of 239.6, while the near-surface magnetic responses were interpreted at average

depths of 9.1, 57.9 and 81.8 m, respectively.

266000 m 266500 m 267000 m 267500 m 268000 m 268500 m 269000 m

3482

200

m34

8270

0 m

3483

200

m34

8370

0 m


0.4

0.8

1.2

1.6

2.0

2.4

2.8

3.2

3.6

4.0

30° 32' 15" E 30° 32' 45" E 30° 33' 15" E 30° 33' 45" E

31° 27' 45" N31° 27' 15" N

Figure 20: Filled-colour contour map of the calculated metal factor (MF) values from laboratory measurements, Koam Mashaal area, east Rosetta, Mediterranean Sea coast, Egypt Logarethmic Contour interval. = 0.2


15

REFERENCES

Abdelhady, H. M., Hossny, A. A., Gharieb, A. G., Elsadek, M. A., Elkhateeb, S.

A., Abdelrazik, M. I., Eltarras M. M., and Mostafa, A. M. (2002): Analysis

and interpretation of the ground radiospectrometric and magnetic survey data of

the black-sand beach deposits of Abu Khashaba/Alburullus estuary, east Rosetta

area, Mediterranean Sea coast, Egypt. Internal Report Series, NMA-IRS-

4/2002, Nuclear Materials Authority, Cairo, Egypt, 29 p.

________________, Elsadek, M. A., Gharieb, A. G., Elkhateeb, S. A., Zaeimah,

M. A., and Gaafar, I. M., (2004): Analysis and interpretation of the ground

radiospectrometric and magnetic survey data of the black-sand beach deposits of

Abu Khashaba/Alburullus estuary, east Rosetta area, Mediterranean Sea coast,

Egypt. Final Stage, Internal Report, Nuclear Materials Authority, Cairo, Egypt

38 p.

Abu-Diab, A., A. (2001): Sedimentological studies and economic evaluation of the

coastal sand dunes between Elgadia and Idko, Rosetta, Egypt. M.Sc. Thesis, Fac. Sci., Mansuora Univ., Mansuora, Egypt 137p.

Alaskary, M. A. and Freihy, O. E. (1986): Depositional phases of Rosetta and

Damietta promontories on the Nile Delta coast., J. African Earth Sci., 5: pp.627- 633.

Badokhon, F. O. (1998): Geophysical exploration for oolitic iron deposit extensions

in the northern part of Wadi Ash-Shumaysi, Saudi Arabia. M. Sc. Thesis, King Abdulaziz University, Jeddah, Saudi Arabia, 276 P.

Bakheit, A.F. (2004): Mineralogy and concentration of economic heavy minerals,

northern Delta, Egypt. Ph.D. Thesis, Institute of African Research and Studies, Cairo University, Geiza, Egypt, 131 p.

Burger, H. R. (1992): Exploration geophysics of the shallow subsurface. Prentice

Hall International, Inc., London, UK, 489 p.

Elkhateeb S. A. (2005): Geophysical evaluation of some sand beach and alluvial deposits in northeastern Africa. Unpub. M.Sc. Thesis, institute of African research and studies, Cairo University, Giza, Egypt, 190 p.


16

Elsadek, M. A., and Elkhateeb S. A. (2002): Magnetic susceptibility of black-sand

beach deposits, Koam Mashaal area, east Rosetta, Egypt. Internal Report Series,

NMA-IRS-3/2002, Cairo, Egypt, 27 p.

GM. SYS. Program (1997): Definitive International Geomagnetic Reference Field.

Version 1.5, January 21, 1997, Computation Routines by Mike Gemperle and Rowland B. French, Interface by Pierre Doguin, Northwest Geophysical Associates Inc..

IRIS Instruments (1993): ELREC 2 Operating Manual, Revised. BRGM & OYO

Joint Venture, IRIS Instruments, Orleans, Cedex 2, France, 69 p. Kearey, P., and Brooks, M. (1998): An introduction to geophysical exploration.

Geoscience Texts, Second edition, Blackwell Science Ltd., London, UK, 254 p. Mahmoud, A. A., Moustafa, M. I., and Mahdy, A. I. (2004): Integrated geophysical

and mineralogical studies on the mineral sand deposits of Koam Mashaal beach,

east of Rosetta distributary, Egypt. Journal of Applied Geophysics, Vol. 3,

Egyption Society of Applied Petrophysics, Cairo, Egypt, pp.185-204.

Reford, M. S., and Sumner, J. S., (1964): Review article, Aeromagnetics. Vol. 29,

No. 4, pp. 482-516. Sharma, P. V. (1976): Geophysical methods in geology. Elsevier Scientific

Publishing Company, Amsterdam-Oxford-New York, 428 p.

Magnetic and Geoelectric characteristics of East Rosetta sand placer deposits, Egypt

Documents

Transcript of Magnetic and Geoelectric characteristics of East Rosetta sand placer deposits, Egypt