University of Mansoura Damietta Faculty of Science Department of Geology

ENVIRONMENTAL GEOLOGY AND

ENVIRONMENTAL GEOPHYSICS OF NORTHERN NILE DELTA IN TERMS OF

NEOTECTONICS AND PHYSICAL PROCESSES

BY

WAEL ABDEL WAHAB MAHMOUD IBRAHEM

(Damietta Faculty of Science)

(B. Sc. In Geology)

A Thesis Submitted in Partial Fulfillment for the

Degree of Master of Science in Geology

(2002)

ACKNOLEDGEMENT

All gratitude is due to almighty God, who guided and aided me to

bring-forth to light this thesis.

I wish to express my great indebtedness and heartfelt thanks to Prof.

Dr. Zaki M. Zaghloul, Professor of Geology, Faculty of Science, Mansoura

University, for his critical comments, valuable suggestion, and supervising

the entire work.

Sincere thanks are due to Dr. Moharm M. Elgamal, Associate

Professor of Geology, Damietta Faculty of Science, Mansoura University,

for his useful advice, valuable suggestion, and guidance during the

supervision of this work.

I thank Dr. Hesham El- Arabey, Associate Professor of Geophysics,

Faculty of Science, Cairo University, for supervising this thesis.

My warmest thanks are due to Dr. Magdi M. Khalil, Associate

Professor of Geology, Damietta Faculty of Science, Mansoura University,

for the use of many facilities and his friendly cooperation.

Deep thanks are also due to Dr. Abu Mandour Abdel Daiem,

Associate Professor of Geology, Faculty of Science, Mansoura University,

for his continuous encouragement, which are much appreciated.

I am also grateful to all staff members of the Geology Department,

Damietta Faculty of Science, Mansoura University, for their kind help,

facilities offered during the work of this thesis.

The Author

Wael Abdel Wahab

CONTENTS Acknowledgement List of figures

CHAPTER I INTRODUCTION

I.1: Introduction ………………………………………………………………. 1

I.1.1: The scope of the present study …………………………………. 4 I.2: Geomorphology of the Nile Delta ……………………………………….. 9

I.2.1: The shoreline of the Nile Delta ………………………………… 11 I.2.2: Beach ridges ……………………………………………………. 11

I.2.3: Strand plains ……………………………………………………. 11 I.2.4: Sand dunes …………………………………………………….... 11

I.2.5: Northern lakes ………………………………………………….. 12 I.2.6: Sabkhas …………………………………………………………. 13 I.2.7: Promontories and headlands ……………………………………. 13

I.3: Stratigraphy of the Nile Delta ……………………………………………. 15

I.3.1: Pre Tertiary deposits …………………………………………… 15 I.3.2: Early Tertiary deposits …………………………………………. 17 I.3.3: Neogene deposits ……………………………………………….. 17

I.4: Tectonic and Structure Setting of the Nile Delta ………………………… 19

I.4.1: Basement tectonics ……………………………………………... 21 I.4.2: Phanerozoic Tectonics ………………………………………….. 21 I.4.3: Major structure elements ……………………………………….. 23

CHAPTER II

NEOTECTONICS (Generality and Surface Investigation)

II.1: Neotectonics …………………………………………………………….. 26 II.2: Surface investigation of lineations as indication for neotectonics ………. 31

II.2.1: lineaments of tectonic significance ……………………………. 35

CHAPTER III QUATERNARY OF NORTHERN NILE DELTA

III.1: Quaternary subsurface investigation of northern Nile Delta …………… 38

III.1.1: Quaternary lithostratigraphy of northern Nile Delta ………… 38 III.1.2: Early Quaternary structures …………………………………... 41 III.1.3: Geologic investigation of northern Nile Delta Holocene Sequence ………………………………………………………………. 44

III.1.3.1: Isopach map of the Holocene sediments of northern Nile Delta ……………………………………………………... 44

II.1.3.2: Holocene lithofacies map of northern Nile Delta …… 46 II.1.3.3: Holocene structures of northern Nile Delta ……….… 47

III.2: Neotectonic inversion …………………………………………………… 54

CHAPTER IV

MORPHOTECTONICS

IV: Morphotectonic features of northern Nile Delta …………………………. 59

IV.1: Present day Delta branches …………………………………….. 59 IV.2: The historic branches ……………………………………….…... 60

IV.2.1: The tectonic control on the defunct distributaries ……. 61 IV.2.2: Avulsion of the historic branches …………………….. 63

IV.3: The lagoons ………………………………………………….…. 64

IV.3.1: Manzala Lake ………………………………………… 64 IV.3.2: Burullus Lake ………………………………………… 69 IV.3.3: Idku Lake ……………………………………………... 71

IV.4: The coastal plains ………………………………………………. 72

IV.4.1: The western delta plain ………………………………. 72 IV.4.2: The central delta plain ……………………………….. 76

IV.4.2.1: Baltim- Gamasa coastal plain ………………. 78 IV.4.4.2.2: Gamasa- Ras El Bar coastal plain ………... 80

IV.4.3: Tinneh plain …………………………………………... 80

CHAPTER V REGIONAL TECTONIC ELEMENTS

V.1: The inheritance of the structural elements ………………………………. 83 V.2: Tectonic relationship between the Nile Delta and East Mediterranean …. 87

CHAPTER VI ACTIVE TECTONISM

VI.1:Seismicity events 91

VI.1.1: Historical seismicity events …………………………………… 91 VI.1.2: Tsunamis ……………………………………………………… 95 VI.1.3: Space distribution of recent earthquakes ……………………… 97

VI.2: Seismicity hazard assessment in the Nile Delta …………….………….. 103

CHAPTER VII NILE DELTA BUILD UP

VII.1: Delta build up process …………………………………………………. 107 VII.2: Present Delta destructive phase ………………………………………... 121

CHAPTER VIII SEA LEVEL CHANGES

VIII.1: Quaternary sea level oscillations ……………………………………... 127

VIII.2: Sea level curves ………………………………………………………. 128

III.2.1: Sea level changes curve in northern Nile Delta .………………. 128 VIII.3: Present day sea level trends …………………………………………... 131

VIII.3.1: Stric changes ………………………………………………... 132

VIII.3.2: Use of tide gauge records in sea level changes measurement 133 VIII.1.3.3.3: Satellite altimetry measurement geometry ……………... 135

VIII.4: Nile Delta areas at risk from sea level rise ……………………………. 136

CHAPTER IX SUBSIDENCE

IX: Subsidence rates of northern Nile Delta …………………………………. 138

CHAPTER X

SUMMARY AND CONCLUSION

X: Summary and Conclusion ………………………………………………… 148

REFERENCE APPENDIX I: Description of Northern Nile Delta Smithsonian Sediment Cores

APPENDIX II: Sedimentation Rates of Smithsonian Cores

ARABIC SUMMARY

List of Figures Page

Fig. 1 Land- Sat image of northern Nile Delta (compiled from Atlas of Land Sat images of Egypt, NARSS, 1990) 6

Fig. 2 Northern Nile Delta Boreholes Location Map 6

Fig. 3 Nile Delta Landsat 1990 Image 10

Fig. 4 Geomorphologic features of Northern Nile Delta detected from Landsat Image 10

Fig. 5 General Nile Delta strtigraphic column 16

Fig. 6 Nile Delta tectonic setting map, after Abdel Aal et al, 1994. 24

Fig 7 Migration of the Cenozoic Deltas along the Pelusium Line 28

Fig. 8 Regional tectonic elements affect the Nile Delta. 30

Fig. 9 Major Structure Elements Controled Nile Delta Development 32

Fig. 10 Linear Features of Northern Nile Delta Detected from Land Sat Images 34

Fig. 11 Lineation Types of Northyern Nile Delta 34

Fig. 12 Extended Lineaments of Tectonic Signficance. 36

Fig. 13 Isopach Map of Quaternary Deposits of Northern Nile Delta 42

Fig. 14 The Influence of Structures affecting on Early Pleistocene Northern Delta Basin 42

Fig. 15 Isopach map of Holocene Deposites of Northern Nile Delta 45

Fig. 16 The Influences of Structure and Old Distributaries 45

Fig. 17 Soft sediments classification according to Chamley (1990) 47

Fig. 18 Holocene Lithofacies Map of Northern Nile Delta 48

Fig. 19 Geological Cross Section across Nile Delta Coast 50

Fig. 20 Geological Sections across the Southern Margins of Northern Delta Lakes 51

Fig. 21 Neotectonic Elements of Northern Nile Delta 52

Fig. 22 Location map of uplifted shorelines and sketch of plate boundaries in the Eastern Mediterranean region (Modefied after Pirazzoli et al. 1996a) 55

Fig. 23 Examples of Holocene uplifted shorelines in Eastern Mediterranean region (from Pirazzoli, 1998: Figs. 23,96,91) 55

Fig. 24 Cross Section along Eastern Mediterranean 56

Fig. 25 3-D plot of Early Quaternary paleogeographic depositional basin 57

Fig. 26 3-D plot of Early Holocene paleogeographic depositional basin 57

Fig. 27 Old Distributaries of the Nile Delta Detected from Landsat Image 62

Fig. 28 Morphotectonic Features of Manzala Lake 67

Fig. 29 Geological sections across the Manzala Lake 67

Fig. 30 Morphotectonic features of Burullus Lake 70

Fig. 31 Geologic Section in Burullus Lagoon Region 70

Fig. 32 Morphotectonic features of western Nile Delta 73

Fig. 33 Geological section along western Nile Delta 73

Fig. 34 Epicenteral Distribution of the Earthquakes, 100 Km around Alexandria 75

Fig. 35 Centeral Delta Coastal Plain 77

Fig. 36 Morphotectonic Features of Gamasa Area 77

Fig. 37 Morphotectonic Features of Teneh Plane 81

Fig. 38 Last- squars second- order residual anomaly map of the Nile Delta 85

Fig. 39 A tentative basement topgraphic map of the Nile Delta region 85

Fig. 40 Basement structural lineament detected from RTP magnetic map 86

Fig. 41 Regional tectonics of East Mediterranean Sea 88

Fig. 42 Regional tectonic elements of East Mediterranean affecting The Nile Delta region 90

Fig. 43 Epicenteral Distribution of Instrumental Earthquakes in Northern Egypt (1900 -1997) and Active Seismic Trends 99

Fig. 44 Structural influence on intinsity distributions of some Delta's earthquakes 104

Fig. 45 Example of circular isoseismal lines 104

Fig. 46 Average pattern of intensty distributions for earthquakes in and around the Nile Delta, after Al Ibiary, 2001 106

Fig. 47 Agents controlled delta development 108

Fig. 48 Nile Delta build up stages 109

Fig. 49 Paleo- Geography of Northern Nile Delta during Early Holocene (7500 yrs B.P). 117

Fig. 50 Paleo- Geography of Northern Nile Delta during Mid Holocene (5000 yrs B.P). 118

Fig. 51 Paleo- Geography of Northern Nile Delta during Late Holocene (1500 Yrs B.P.) 119

Fig. 52 Morphotectonic features of Nile Delta Shelf Zone 123

Fig. 53 Currents along the Egyptian coast in relation to the neotectonic elements. 124

Fig. 54 Pattern of Erosion and Acretion Along the Nile Delta Coast 125

Fig. 55 Methods of plotting sea level curve 129

Fig. 56 Fairbanks sea level curve compared to the peat curve of northern Nile Delta 129

Fig. 57 Long term climatic variations over the past 400 Ka and prediction for the next 60 Ka according to Berger, 1988 131

Fig. 58 Distribution of average long term sea level change; after Pirazzoli, 1986 134

Fig. 59 Potential impact of sea level rise on the Nile Delta; UNEP/GRID- Arendal, 2000 137

Fig. 60 Peat location map 141

Fig. 61 Peat of southwest Manzala 141

Fig. 62 Peat around Burullus 142

Fig. 63 Peat of west Rosetta Branch 143

Fig. 64 Relative Subsidence rates in northern Nile Delta 145

Fig. 65 Relative Subsidence rates related to neotectonc elements of northern Nile Delta 147

1

I INTRODUCTION

I.1: General Introduction

This study aims to shed light on the environmental geology and

environmental geophysics of the northern plain of the Nile Delta. The

environmental changes either natural or human impacts leave their marks that

alter the province today and in the future. The quest of environmental geology

and geophysics is multidiscipline approach to understand the ongoing changes.

The Nile Delta like any other delta in the world is a battle land of fighting forces

in order to leave their signs of victory. Such signs show as positive or negative

alteration for the Delta.

Physical geologists and geomorphologists prescribe what on the face of the

earth. They describe the shorelines, coastal geomorphology, deltas plain, etc.

They may approach the issues with little attention to human impacts or the

tectonism.

Structural geologists are lenient on the study for recognizing the structural

elements on the surface of the deltas. Their excuse is always a handy one, that

surface of the deltas are covered by alluvium, salt marshes, sabkhas, lagoons,

urbanization and sub- urbanization. Crops and agricultural activity are obstacles

for structural geologists to examine the face of the deltas. The structural

geologists have their reliance on the information they can get from the subsurface

through boreholes or the geophysical results. Therefore their approach is looking

to the far past not to the present or the near past. They draw their own conclusion

about what happened in the far past not those of today concerns.

2

The geophysicists, in their various approaches, do not scratch the surface.

They always look deeper and deeper. They do not do that by choice. They are

confined to the limitations of their tools. For example, those who work with

reflective seismic do not have data most of the time above 0.5 second on their

seismic profiles. That is translated to about 850 meters from the surface. They are

lucky if they get data below 0.1 of a second. Meaning the lack of the information

for about 170 meters from the surface. The picture gets darker, since there is no

bother to carry out seismic interpretation for the shallow part of the vertical

seismic profiles. That is merely because the interpretations are mostly carried out

for oil companies looking for relative deep oil and gas. Other geophysicists,

occupied by the study of the gravity and magnetic data, their concern is mostly

devoted to determine the depth to the basement, nature of the crust “continental or

oceanic”, deep structural elements, and anomalies of interest in search for oil and

gas. Subsurface geologists and stratigraphers rely on data from boreholes that

often are not logged in the shallow intervals and discard to collect near surface

samples. Even shallow boreholes drilled for ground water have their lithologic

logs vaguely described in order to comply with governmental regulations. The

samples of such lithologies are often disposed. Civil engineers, on taking shallow

cores, have their sight only focused on suitability of the soil and remedies to carry

out their own projects. Beyond that these cores are wasted.

The scenario of the study of the modern deltas gets vague when deltaic

geologists approach the subject. Their dealing emphasizes the role of the physical

process in building up or destruction of the deltas. They talk about the alluvial

sedimentation, waves, currents, tides, climate, sea level, etc. even in classifying

the deltas. There is a description for wave, tide, or alluvium dominated deltas.

Inspite of recognizing the role of tectonism in forming deltas which are

commonly along the edge of the continents, there is a little mentioned about this

role.

3

Going further through the scenario of the modern deltas, environmentalists

tend to cry “wolf” about the eminent danger of rising sea level, drowning good

portions of the modern delta and coastal erosion. They draw a gloomy picture

about destroying many major cities and lively- hood of populations living on the

deltas. In this regard, they ignore the present day sea level rise is a part of the

fluctuations of geologic history and its cyclicity. Since the beginning of the

Mesozoic about 220 million years ago, the continents have a continuous general

trend to grow ocean ward. Another issue of a major concern is the subsidence of

the deltas compiled with the present sea level. This issue has been in circulation

adding to the picture of the doom day waiting for the submergence of the deltas

under water. Subsidence under the isostatic load of sediments has been generally

devoted by deltaic geologists and gaining wide acceptance. They disregard that

under the load of the sediments subsidence could be inverted and reversed.

Contrary to the alarm of the environmentalists about the eminent dangers

and hazards, developers and business people tend to be pacifiers by emphasizing

the benefits and the cash return from their projects. They often don’t show respect

for the environment and the nature.

As example of this disrespect is the development of El Tinneh plain to the

northeast of Suez canal. It is another attempt going on today to gain hold of once

the fertile flood plain of the historic the Pelusiac Branch, a defunct distributary of

the Nile Delta. The Pelusiac Branch ceased to exist about the 10th century A. D.

The digging of the Suez Canal in the Nineteenth century A. D. dried out el

Tinneh plain of the larger Manzala Lake. The excavated soil from the Suez Canal

cut off the plain from the lake. It dried out, and a layer of salt widely spreads over

El Tinneh plain especially in the Mallaha area.

4

I.1.1: THE SCOPE AND MATERIAL OF STUDY

The author has chosen the northern part of the Nile Delta to tackle the

environmental changes affecting the province. The area of study is bounded by

latitudes 30o 45` and 31o 45` N and longitudes 30o 00` and 32o 45` E. The area

extends for a straight distance of about 240 Kilometers from Tinneh Plain to the

east and Abu Qir Bay to the west. Geology and geophysics are the media utilized

here to approach the environmental changes. The present author realizes that the

work in this Thesis is a simple humble step in a long passage to reach a complete

comprehensive picture toward understanding the environmental geology and

environmental geophysics of the Nile Delta. This step also may provide some

basics for future developmental planing of the Nile Delta. The author feels today

that the title of his thesis was an ambitious dream to be accomplished in a single

study. It may take a lifetime and a whole life career as well as concerted efforts

with other scientists to reach the goal implied by the title of the Thesis. Therefore

the present author selected some geological and geophysical approaches to be

covered in the present work. He emphasizes the geomorphology as an expression

for the ongoing changes that are caused by the physical process and / or the

tectonism.

The author relied on two Land-sat MSS mosaic images published by the

Remote Sensing Center of the Academy of Scientific Research and Technology

in (1990). One mosaic was the sheet no.: NH36N, path: 176, row: 38, date:

1/6/1984. It covered the northeastern Nile delta. The other one was the sheet no.:

NH36M, path: 177, row: 38, date: 12/7/1985. It covered the northwestern part of

the region under the study. The two mosaics were compiled together, Fig. 1. In

addition to the use of land-sat images to draw a compiled picture for the

geomorphology, they turned to be useful in predicting the defunct historic

branches and their migrating courses.

5

The same land-sats were utilized to recognize the surface lineations, which

were differently categorized. Lineations that appeared to be structural elements

were checked through subsurface geologic study of the Holocene sediments. The

most reliable source for the subsurface data is lithologic logs of 87 Smithsonian

boreholes that were amply described in Stanley et al. (1996). These boreholes

range in depth from 12 to 60 meters. They are evenly spaced by almost 10

kilometers across the Nile delta. Another source for the subsurface information is

the lithologic logs of 25 boreholes drilled for water in the northern Nile delta. The

latter were documented in Attia’s work (1954). The locations of the boreholes of

both Smithsonian and Attia’s work are shown in Fig. 2. The data obtained from

these boreholes have been used to prepare an isopach map for the Holocene

sediments of northern Nile delta, in addition to constructions a structure contour

map on top of Mit Ghamr formation. They are also used to construct cross

sections. The subsurface geology should elaborate, confirm or deny the linear

features that could be of structural origin. They also assist in determining the

areas of differential vertical and lateral land motion during the Holocene. They

are also beneficial in defining areas of subsidence and those of uplifting in the

Nile delta as well as average rate of the motion.

Published magnetic and gravity maps were also critically analyzed by the

present author to define the structural components that left inheritance on the

recent structural elements.

Other few published data on the stratigraphy and structural geology were

integrated together and reinterpreted to establish the history of the northern Nile

Delta province. The same is done on evaluating the physical processes happening

in the modern Nile Delta.

Compiled sources for the historic and recent earthquakes were used to

validate the active structural elements that are associated with active tectonism

and neotectonism.

6

7

Summing: the approach in the present work is collecting various sources of

data, integrating and interpreting them, then finally, an attempt to draw

conclusions on the geoenvironmental aspects north Nile Delta is mode.

The Nile Delta is of prime importance to study the environmental changes.

That is due to its status as a classic example for deltas around the world. The

Greek letter was in the mind of Herdotus in 450 BC to describe the shape of the

region of the ancient Nile Delta. Subsequently the term delta has been in use to

describe many plains where the rivers unload their sediments in their receiving

basins of oceans, seas, etc. Also the environmental changes mean a lot to about

40 millions of the current total population of Egyptian Nile Delta.

The Nil Delta has been witnessing during the 20th century major changes.

The most apparent serious one is its coastal erosion on heals of the irrigation

projects constructed during this century. The blame, regardless justifiable or

unjustifiable, was attributed to the construction of barrages, Aswan dam and the

High Dam. The latter has been taken most of the blame. The deprivation of the

offshore from the load of the sediments used to be carried by the river is often

considered the reason. This deprivation caused improper environmental

imbalance leading to the dominance of the physical destructive of the

Mediterranean Sea over the constructive aspects of sediment accumulation. The

loss of sediments accelerated the physical erosion endangering many coastal

cities e.g. Baltim and Ras El Bar. Coastal protection measurements have proven

no match for the nature. There is always a continuous, effort to protect one more

coastal area or to correct the negative impact of the protection measurement.

The loss of the sediments did not only affect the coast of the Nile delta, but

deprived the fish population in the offshore with the nutrition carried out with the

sediments. The result is a drop in fish population particularly after the

construction of the High Dam. Sardines disappeared in the off coastal water.

8

However it returned on the increase of discharge during the high flood of 1998.

There was also a drop in the population of the shrimp and fish.

The irrigation projects on the River Nile caused another environmental

imbalance, by reducing the amount of discharged fresh water in the

Mediterranean Sea. Increasing the salinity of the coastal water leads to invasion

of saline seawater into the fresh ground water aquifer. It is expected that this

situation will be aggravated by further reduction in the discharge of the fresh

water on completion of Toshka agricultural project in the south Western Desert of

Egypt.

Additional environmental changes include the recent completion of the

International Coastal Highway (I.C.H) along the northern coast of the Nile delta.

This highway altered too many features of the landscape, particularly the sand

ridges and sand dunes. The impact off the highway will be seen in the coming

near future. The impact will be also attenuated by the planned developments

along the highway by allocating parcels of the land for resort developments and

industrial zones. Prior to the building of (I. C.H.), new cities e.g. New Damietta,

and Damietta Naval port, were developed, modifying the landscape and

aggravating the human on the delicate zone of the northern Nile Delta.

Among the environmentally and ecologically sensitive areas in the Nile

Delta there are the coastal lagoons, salt marshes, and sabkhas. A good portion of

the lagoons have been artificially dried out and converted into agricultural land.

The marshes were dried out to attain parcels of land for home building and other

purposes. The lagoons also are suffocated by pollutants pouring from agricultural

drainage, industrial or even unsufficiently treated or totally untreated sewage.

The pollutants in their water or bottom sediments are easily leaked beyond the

limits of the lagoons, which are in great part neotectonic features. Among the

pollutant are nitrogen and nitrogen compounds causing eutrophication and

seasonal blooms of algae and bacteria leading to oxygen deficiencies in the

9

lagoonal waters. Both eutrophication and seasonal algal blooms lead to drop in

fish population and occasional mass killing fish. Water circulation in the lagoons

is often curtailed by widespread of fish farming using artificial partitions for the

lakes. Curtailing the water circulating aggravates the oxygen deficiency.

I.2: GEOMORPHOLOGY OF THE NILE DELTA

The Nile Delta is often termed the true delta with its arcuate or fan- shaped

configuration, Fig. 3. Various authors have treated the geomorphology of the Nile

delta e.g., Sestini (1976, 1989), El Fishawy (1985), El Askary and Lotfy (1980),

Abdel Kader (1982) and Zaghloul et al (1990). The area of the study almost falls

under the 1-meter contour line above sea level and nothing is more than 3-meter

contour, except for some scattered coastal sand dunes. The geomorphology of the

area under study is highly related to the depositional environment.

Apart from the coastal lagoons, there are two basic types of morphology

that are distinguished in the northern Nile delta area. These are: (I) the coastal

morphology of the sand barriers created by waves and wind, and (II) the properly

deltaic morphology created by river discharge behind the barrier (Abdel Kader,

1982).

Fig. 4 represents geomorphologic map prepared by the writer for the

northern Nile Delta area, using the compiled landsat images and field inspection.

The different geomorphologic units were classified depending on the degree of

the tone and its brightness.

Accordingly the northern Nile Delta could be divided into two parts, the

southern part mostly occupied by old delta plain. This part is far from the sea and

is less affected by the most physical processes; and the northern part mostly

affected by the physico - hydrodynamic and neotectonic processes. The northern

10

Mediterranean N

Abu Qir

Rosetta Damietta

Port Said Manzala Lake

Burullus Lake

Canopic Br.

Bolpitic Br. Saitic Br. Sebennitic

Br. Athribitic

Br.

Bucolic Br.

Mendesian

BTanitic

Br.

Beach, Strand plain partially

overlain by dunes Lines indicate old beach ridges

Sabkhas

Longtiudinal coastal dunes

Areas for reclimation and partialy cultivated

Interdune wet lands

Noticeable reddish brown small units represent old branches

Low costal dunes, partially cultivated

Delta flood plain

0 24Km

31 00 32 00

3100

3130

30 00

Fig. 4 Geomorphologic features of Northern Nile Delta detected from Landsat Image 1990

Fig. 3 Nile Delta Landsat 1990 Image

11

part includes the shoreline, beach ridge, backshore plain, sand dunes, northern

lakes, sabkhas, and promontories.

I.2.1: The Shoreline of the Nile Delta

It extends from Abu Qir, east of Alexandria, to Port Said fore about 240

kilometer. However, the shoreline can be extended another approximately 40

kilometer east of Port Said to Tell El Mahamadiya, in Sinai, on Tinneh

embayment. The features of the shoreline are basically: cusps, spits, beaches, and

small shore line dunes.

I.2.2: The Beach Ridges

These occur at Rosetta and Damietta promontories and record the former

shoreline and the advance of the River mouths. They occupy a narrow zone of

low dunes (fore dunes) occasionally rich in black sand lamination, and shell

pavement. The old shorelines are recorded east of Rosetta, west of Gamasa, east

of Ras El- Barr and northeast of Tinneh plain. The development of ridges

indicates low wave energy, low tidal range, effective longshore currents and

predominantly fine-grained sediments (Abdel Kader, 1982).

I.2.3: The Back- shore Plains (Strand Plains)

These occur as flat areas of beach sand, sometimes superficially modified

by eolian deposits. They are usually made of finer sand than the beach sediments.

The backshore is narrow near Idku outlet, between Burullus - Kitchener drain,

and east of Ras El- Barr. It becomes wider in the area west of Rosetta, Burullus,

and between Kitchener drain to Ras El- Bar. These plains often bear traces of

former shorelines or occupied by depressions, which are flooded during stormy

seasons (Sestini, 1989).

I.2.4: Sand Dunes

They represent wind deposits. The dominating wind on the coast, mostly

from the northwest, has transported huge amounts of sand from the beaches by

12

traction particles of 0.1 – 0.3 mm size range (El- Gemmizi, 1995). These are

heaped as dunes of well-sorted particles. These dunes may include the following

classes:

I.2.4.i: continuous belts of complex dunes and barchans; reaching 25 m

high. These dunes can be seen at the northern coastal lagoons and depressions,

especially those of Idku and Baltim to Gamasa.

I.2.4.ii: Field of small dunes and sand sheets; occurring with

innumerable small depressions or flat floors. Some of them bear temporary or

permanent lakes. This type of dunes covers a large area of Baltim extending to 20

km east of Kitchener drain.

I.2.4.iii: Isolated or small groups of barchans and seif dunes; scattered

on the back- shore plains. the longest seif dunes are 1 km.

I.2.4.iv: A complex of low older dunes; found south the higher coastal

dunes at Rosetta, Kom Mastra, in the area of El Burg, Baltim and Gamasa. They

are usually vegetated and composed of reddish sand. At Rosetta and Damietta

these old dunes are 2 - 3 m above sea level.

I.2.5 :The Northern Lakes (Lagoon)

There are three lakes located in northern part of the Nile Delta. Along the

Mediterranean Sea shoreline and connected to the sea through minor Water

passes. These are from east to west: Lake Manzala, Lake Brullus and Lake Idku.

The lakes are shallow, their depth vary from 0.5 to 2m. Their outlets are coverd

by sand, but the bottom contains lagoonal clays. As the lakes represent restricted

environment, the water salinity is relativly high. In fact the water level of the

lakes and the flooding of the Nile and canals played the most important role in

this type of morphology. Lakes margins facing north and northwest winds are

rather high with ground covered by reeds. The areas sheltered from these winds

and Lake waves are marshy in nature. Many parts of the Lake shore were covered

13

by aquatic vegetation. Numerous islands are spread in Lakes Idku, Burullus,

Manzala and appear to be remnants of older features, possibly of beach ridges,

dunes or river banks. Westerly winds and lake waves modified the morphology of

these islands. The west or northwest shores are generally sharp with white,

convex eastward, shelly beaches (Abd el Kader, 1982). Eastward spits usually

developed at the north and south ends of the islands. The spits protect the islands'

eastern shores, which are marshy and irregular. Lagoons occupy large areas of

those islands' surface (El Askary and Lotfy, 1980). Many areas to the south of the

lakes are more or less permanently covered by water as a result of flooding from

the lakes and inland canals. Some areas develop salt flats, while others develop

marshes in the vicinity of the more permanently wet areas.

I.2.6: Sabkhas

They are generally a low surface of deflation formed by the removal of dry,

loose material down to the level of ground water or the zone of capillary water.

Within the framework of sedimentary materials of sabkhas, evaporite minerals

especially gypsum and anhydrite precipitate. Local depression may be

temporarily inundated by water to from playa lakes. The water lasts until

evaporation dries up the lakes again and leaves behind the suspension and

solution load. Sabkha sediments are heavily encountered southeast of Manzala

Lake and around the western side of Burullus Lake.

I.2.7: The Promontories and other Headlands

beside the two promontories of recent active Rosetta and Damietta

Branches, there are other three headlands related the ancient historical Nile

distributaries. These are the Abu Qir, Burullus, and Port Said headlands.

I.2.7.i: Rosetta promontory; was built some 500 - 1000 AD, when water

from the Canopic and Sebennitic branches were diverted naturally and/or

artificially into an existing channel known as Rosetta (CoRI / UNESCO / UNDP,

1978). In early nineteenth century before controlling water for irrigation the fast

14

growing Rosetta promontory was characterized by a bifurcated channel and a

middle – ground mouth bar, which in 1957 has become a large E - W lunate bar

(Sestini, 1989). In the twentieth century the promontory has gradually retreated

with a sharp acceleration of retreat to over 200 m/yr, since 1980 after construction

of the High Dam. The Rosetta mouth tends to be blocked by a spit - submerged

bar extending southwards from the eroding foreland. Analyzing the course of

Rosetta Branch north of the Rosetta city shows Rosetta City River Bend ends

sharply by a straight River till the point of intersection with the sea. The point of

change of the course stream, that is aligned with the southern limits of the sand

dunes to the east of the promontory. Such relations are suggestive that might be a

strong structural element influencing the change of the stream and the distribution

of the eastern sand dunes. The straightened last segment of Rosetta Branch

couples with strong departure of western shoreline might be attributed to tectonic

influence and less likely to be due the strong water inflow in the stream.

I.2.7.ii: Damietta promontory; came into existence during the 10th

century A.D (CoRI / UNESCO / UNDO, 1978). The shape of the NE oriented

Damietta mouth was strongly influenced by the northwest ward wave approach.

Active growth occurred in the eastern side with beach ridges enclosing Manzala

lagoon, which remained partly connected to both the sea and the river (Sestini,

1989). The Damietta headland retreated by 140 – 160 m/yr. since 1964. In the

extensive beach – ridge system east of Damietta, discrete groups of former strand

lines are related to stages the shore advance and retreat. Beach ridges are added

where the shoreline turns SE; a conspicuous new set of spits has grown more than

7.5 km since the late 1950’s with a coastal advance of more than 2.5 km (Frihy,

1988).

I.2.7.iii: Burullus headland; was built by the sediments brought by once

the very active Sebennitic branch that only crossed the central Nile delta. It

formed the central bulge of the Nile delta east of lake Burullus (Orlova and

Zenkovich, 1974), since the defunction of the Sebennitic Branch about 1000 yrs

15

before present the Burullus promontory became subjected to erosion and

retreating at about 5 m /yr at present (Fanos et al, 1995).

I.2.7.iv: Abu Qir headland; marks the mouth of the historic and the

defunct Canopic Branch where the ancient town of Canope stood. This town is

presently submerged under Abu Qir bay 15 Kilometers offshore along the

extension of the western edge of Lake Idku (CoRI / UBESCI / UNDP 1978). The

headland also marks a contrast in the relief of the Abu Qir promontory, there

exists the raised Pleistocene coastal oolitic limestone ridges, commonly named

“Korkar ridges”, two other Holocene ridges exist submerged under the coastal

waters (Stanley and Hamza, 1992).

I.2.7.v: Port Said headland; is the last obvious promontory along the

shoreline of the Nile delta. It was built by the defunct Tanitic Branch. It marks the

boundary between Tinneh embayment and land strip bounding the lake Manzala.

I.3: STRATIGRAPHY OF THE NILE DELTA

The stratigraphic information of the Nile Delta was scanty until 1960’s

when interested oil companies began deep drilling in the Delta. Deep wells have

shed light on the stratigraphy of the Nile delta (Rezzini et al, 1976). The wells in

the northern part generally don’t reach strata older than the Middle Miocene

depths ranging from 4000 to 4600 m, except in Abu Qir (east of Alexandria) and

Tinneh Field where Oligocene strata were penetrated (Zaghloul, 1976). Fig. 5

shows general lithostratigraphy of the Nile Delta basin, based upon well data and

recent studies (e.g. Harms and Wray, 1990, El Heiny and Morsy, 1992 and

Zaghloul et al, 2001).

I.3.1: Pre-Tertiary Deposits

The geologic history of the Nile Delta area for the pre-Tertiary is not well

known (Zaghloul et al, 2001). Based on interpretation of seismic lines Harms and

16

Fig. 5 General Nile Delta strtigraphic column

FormationAgeSouth South North

LithologyNorth

Holocene

Ple

isto

cene

Plio

cene

Late

Mio

cene

Mid

dle

Mio

cene

Bilqas

Mit Ghamr

El Wastani

KafrEl Sheikh

Abu Madi

Rosetta

Qawasim

Sidi Salem

(modified after Said, 1981and El Hiny and Morsi, 1992)

Fine fluvial sediment

Shale

Evaporites

Coarse fluvial sediment Coarse sand

Fine sandFlood plain deposites

17

Wray (1990) reported that from the Jurassic through Cretaceous time, a carbonate

shelf has been developed along an east - west line through the middle part of the

Nile delta. This feature was interpreted as a major facies change where well –

bedded platform carbonates to the south change to finer- grained slope and

basinal facies to the north. Although no penetrations exist across the north delta,

Mesozoic strata were probably deposited in slope and deep oceanic environments

north of the carbonate shelf line.

I.3.2: Early Tertiary Deposits

The depositional history of the Nile delta area for Early Tertiary is less well

known, where Paleocene and Eocene strata are absent in most Nile delta wells,

except Monaga and Mit Ghamr wells. A relatively mild early Eocene Orogeny,

well known from folds formed across North Sinai and in the Western Desert (i.e.

Syrian Arc fold system) influenced the Delta area significantly and caused either

non- deposition or erosion during this time span.

Oligocene sediments are reported mainly in the middle and eastern delta,

while towards the south basalt of Oligocene age caps Oligocene or Eocene strata.

The Oligocene beds appear to have been deposited in depth ranges typical of

upper or middle slope (Harms and Wray, op. cit.).

I.3.3: Neogene Deposits

The Neogene history of the Delta area is much better known than that of

older units. Major unconformities of regional extent subdivide the Miocene and

Pliocene intervals. A major unconformity separates Middle and Late Miocene

strata. This unconformity has a significant brief duration northward. Another

unconformity separates Late Miocene and Pliocene strata and is a widespread

over the entire Mediterranean area, where it represents the Messinian desiccation

event.

18

Early Miocene sediments rang from non- marine in the south to shelf and

slope in the north (Zaghloul et al, 2001). El- Heiny and Morsi (1992) considered

two formations of Early Miocene interval. Moghra Formation exists in the

western part of the Nile delta, and extends in the north Western Desert. It is

composed of fluvio- marine deposits. The Moghra seems to have been deposited

in a high- energy wave dominated delta, under a regime belonging to a river

system which must have flowed into the sea from the north of Fayium (Said,

1990). The second Qantara Formation exists in the eastern part of the Delta and

extends in North Sinai off- shore area. It is composed of open marine deposits.

Early Miocene beds were erosionally removed from the central part of the delta

around Bilqas by the Mid- Miocene unconformity (Harms and Wray, 1990).

Rezzini et al. (1976), studying the stratigraphy and sedimentation of the

Neogene - Quaternary section of the Nile Delta, suggested three cycles of

sedimentation; Miocene, Plio- Pleistocene and Holocene cycles. They

reconstructed a composite columnar section of the subsurface Neogene -

Quaternary deposits of the Nile Delta subdivided into eight formations, namely,

from the base to the top: Sidi Salim, Qawasim, Rosetta, Abu Madi, Kafr El-

Sheikh, El- Wastani, Mit Ghamr and Bilqas Formations. These formations

represent the above three cycles of sedimentation, distinguished on the bases of

environmental conditions of deposition. The first three bottom formations

represent Miocene transgression - regression cycle of the sea. The next four

formations represent Plio- Pleistocene cycle. The latest formation represents the

third Holocene cycle.

I.3.3.i: The Miocene Cycle, begins with a marine formation “Sidi Salim

Formation” which is overlain by a sandy formation “Qawasim Formation”. The

Qawasim underlies the evaporite deposits of Rosetta formation.

I.3.3.ii: The Pliocene- Pleistocene Cycle, comprises four formations two

of Pliocene interval (Abu Madi and Kafr El Sheikh) and the others of Pleistocene

19

interval (El- Wastani and Mit Ghamr). The Pliocene is characterized by

transgressive sea. The marine to fluvio- marine clays and sands of Abu Madi

Formation represent the base of the Lower Pliocene, overlying the Rosetta

Anhydrite or unconformably resting on the Qawasim Formation. Abu Madi

Formation is followed by the open marine clays of Kafr El- Sheikh Formation

With the gradual filling of the basin, the littoral and fluvial sands of El- Wastani

and Mit Ghamr Formations were deposited during the Pleistocene, which is

characterized by a regressive sea.

I.3.3.iii: Holocene Cycle, where the late marine transgression of the

Holocene brought lagoons and coastal deposits to the whole Delta area and

formed the Bilqas Formation, which caps the Delta area. It is equivalent to Neo-

Nile phase of Said (1981).

I.4: TECTONIC AND STRUCTURE

SETTING OF THE NILE DELTA

The Nile Delta region occupies a key position within the plate tectonic

development of the Eastern Mediterranean. It also lies on the Northern margin of

Africa plate which extends from the subduction zone adjacent to the Cretan and

Cyprus arcs to the Red Sea where it rifted apart from the Arabian plate (Said,

1990).

The northern part of the Nile Delta belongs tectonically to separate unit

forming a part of the Levantine basin which is characterized by oceanic type of

crust (Kenyon et al., 1965; Neev, 1975; 1976; Said, 1981 and Woodside and

Bowin, 1970).

The southern part of the Nile Delta region belongs to the stable shelf of the

African Platform which was elevated, during the Oligocene and the late Miocene

to great heights mainly along E - W faults. Subsurface Symmetrical folds of the

20

Aliane Orogeny were formed in Early Eocene time according to Meshref (1982)

and Orwig (1982).

According to Zaghloul, Elgmal, Shabaan, and Yousef (2001), a better

understanding of the tectonic events in the Nile Delta area provides clues to

reason and rational its geological and geophysical features as well as those of the

southeast Mediterranean basin. For example, the difficulty of locating the suture

between the African and European plates is due to the existence of the Levant

basin as a recognized tectonic unit separating between the two plates. They shed

light on the controversy of the nature of the crust of the northern delta and the

Levant basin that had gone through phases of slicing oceanic crust, into an

emerged micro- continent and then into a submerged platform. The low

geothermal gradient of the Nile delta and the Levant basin could be attributed to

thermal subsidence. The authors also recognized Mit Ghamr Shear Zone as a

probable seismicity trend in the Nile delta. Accordingly the Nile delta can be

subdivided tectonically into three major tectonic blocks, as follows:

1. The rim as the southern Delta which is bounded by the main alluvium

valley of the Nile before branching. The main tectonic feature of the Delta’s rim

is the imprint of the late Cretaceous- Early Tertiary Syrian arc folding. It is most

stable or least mobile block of the Nile delta.

2. The central block of Nile Delta situated to the north of the southern rim and

to the south of the Miocene hinge Zone to the North. It is nearly divided by the

Mit Ghamr shear.The Oligocene volcanicity is the most significant feature of the

central block, however it extends south ward into the southern block. A possible

Oligocen rift may have been in existence over the central block (Elgamal, 2001).

3. The northern Delta block which is a sub- unit of the Levant basin. It is

situated to the north of the Miocene hinge zone. This block is characterized by

thick Neogene sediments, growth faults, Oligocene diapric shale and the absence

21

of both the Paleocene and Eocene sediments. This block is the most active

tectonic block of the Nile delta.

I.4.1: Basement Tectonics

The basement structure map of Orwig (1982) shows that depth of the

basement in southern Nile Delta is about 3.000 - 4.500 Kilometers and 6.000 –

9.000 Kilometers in the central Delta. The latter is shallower than the estimate

given by Abdel Rahman et al. (1988) who calculated the thickness of the

sedimentary section in the Northern Delta to be 10.000 Kilometers at mouth of

the Nile.

Setto (1991) explained the crustal structure along a gravity profile, striking

N-S for a length of about 195 Kilometers. It crosses three blocks of Bouguer

anomalies (map of Abdel Rahman et al, 1988). This modeled gravity profile

shows two major breaks in the basement surface. Both associated with major

transverse faults cutting across the Nile Delta. Each is of about 4 Kilometers,

down throws to the north. This brings the basement surface from about 2

kilometers in the Southern Delta to about 9 Kilometers in northern delta block.

I.4.2: Phanerozoic Tectonics

During the Paleozoic the delta is thought to be the flank of a Paleozoic

basin that was centered around Abu Hammad well no. 1 and trending N.NE -

S.SW (Sestini, 1984).

Musconi et al. (1996) suggested that there are four consequent tectonic

episodes affecting the stratigraphic record of the north Sinai and the Nile delta

onshore and offshore from Early Mesozoic to present:

The Neo- Tethyan Rifting (early Triassic - early Jurassic)

The Neo- Tethyan closing event (Middle late Cretaceous - late Eocene)

22

The Gulf of Suez Rifting (late Eocene - late Miocene)

The Aqaba- Dead sea faulting (late Middle Miocene - Recent)

Zaghloul, Elgmal, Shabaan, and Yousef (2001) suggested five tectonic

stages that affected the development of the Nile delta as follows:

a. Part of an expanding sea since the opening of the Neotethys in the

Triassic through the Jurassic and most of the Cretaceous. Sedimentation during

this tectonic stage was tectonically controlled. Mit Ghamr Shear had played a

significant role as axis of the Cretaceous basin and the same time as the

Mesozoic shelf edge of the Delta. Both Mit Ghamr fault and the Mesozoic

Palaeolevant ridge were parallel to the Neotethys Mesozoic ridge.

b. Compressional foreland stage from Late Cretaceous to the end of the

Eocene periods, during which the northern delta and a great proportion of

southern Mediterranean were an emerged landmass termed as the Palaeolevant

microcontinent. This microcontinent was formed by thrust and slicing oceanic

mass.

c. A stage of vertical movement during the Oligocene where the southern

Nile delta was uplifted and Palaeolevant microcontinent was sunk down and

changed into a submarine platform. The latter process was due to change in the

suture of the Palaeolevant with African plate from a thrust zone into a normal

zone. The process was most likely accompanied by thermal subsidence of

Palaeolevant. The central block was a probable passive Oligocene rift.

d. Returns of collision and northward movement of the African plate

during the Neogene where the Palaeolevant was a growing basin ahead the

leading edge of Africa. This build- out stage extends from the Miocene to the

present during which Neogene hinge zone had been formed.

23

I.4.3: Major Structure Elements

Ben Avraham et al. (1987) reported that the tectonic deformation of the

Nile Delta is complex because of the interaction of differently oriented tectonic

fabric, such as following:

The differential vertical movement of E - W fault blocks and grabens

along the passive margin of the African plate, as the overall subsidence of the

Tethyan versus the Afro - Arabian margin.

The uplift of the Red Sea region, followed by NW - SE to NNE - SSE

rifting and sea floor spreading with NE movement of Arabia Relative to

Africa.

The effect of the sediment loading of the subsiding the Plio- Pleistocene

delta front, accompanied with the formation of growth faults, shelf margin

sliding normal faulting and holokinesis.

According to Abdel Aal et al. (1994) there are six major tectonic features

affecting the Nile Delta (Fig. 6). They are:

♦ The east-west Neogene hinge line

♦ The northeast trending; Rosetta fault

♦ The northwest trending; Temsah structural trend

♦ The northeast trending; Pelusium megashear structural trend

♦ The northwest trending; Red Sea- Gulf of Suez fault trend

♦ North-South Baltim fault trend

- The Nile Delta Hinge Line (belt) trends NW - SE in its western part and

E - W in the eastern side. It represents the boundary between the South Delta

Block and the Northern Delta Basin. It is a wide transtensive area, detectable on

the seismic as a zone of flexure, along which normal faults deepen to the Upper

Cretaceous - Eocene carbonate sequence. As a consequence, in the North delta

basin a thick wedge (up to 5000 - 6000 m) of a terrigeneous sediments from

.

24

Neogene Hing zone

Mediterranean Sea

Fig. 6: Nile Delta tectonic setting map, after Abdel Aal et al, 1994.

25

Oligocene to Recent occurs. Whereas the corresponding sequences in the South

Delta Block is only 500 - 1000 m thick. The Nile Delta hinge line is strongly

believed to be of Early Tertiary. It might be considered a pre- existing Mesozoic

major fault and facies boundary, between a carbonate platform to the south, and

more basinal facies northward (Mosconi et al, 1996).

- The NE trending (Rosetta fault trend) is parallel to the Pelusium line

and the Jurassic NE to ENE fault lineaments along the extension of north western

desert “Qatara- Alamein ridge”. It probably resulted in right lateral oblique slip

movement during the Early Miocene (Abdel- Aal et al., 1994). According to

Mosconi et al. (1996) the movement along Resetta fault began from Messinian

and probably still active. It causes an abrupt deepening and thickening of the

Tertiary section down to the NW. Embryonic extensional tectonics along the

Rosetta fault during Messinian is indicated by the presence of gravity gliding

structures at its downthrown towards the northwest.

- The Temsah fault trend is located parallel to the NW lineaments during

the Early Miocene (Abdel- Aal et al, 1994).

- The Pelusium Line is suggested to form a transcontinental arcuate shear,

which extends along the following three segments: (A) From Anatolia along the

eastern Mediterranean down to the eastern limit of the Nile delta; (B) across

Africa down to the Niger delta; and (C) across the Mid Atlantic Ridge along the

equatorial fracture zones (Neev, 1977). The Pelusium megashear system (Neev et

al, 1982) extends along eastern limit of the Nile delta as a system of en- echelon

left lateral faults active since Precambrian times.

- NNW normal faults parallel with the Gulf of Suez rift, late Eocene to

Miocene, are observed in the Nile Delta (Abdel- Aal et al, 1994).

- The NS Baltim structural fault trend thought to be formed by

rejuvenation and reactivating of older Pre- Tertiary structures during the Early

Miocene (Abdel- Aal et al, op. cit.).