Geological Atlas of Africa (eBook)

Acknowledgements 6
Preface 7
Contents 9
Chapter 1 12
Aims and Concepts of the Atlas 14
1 Geological Maps 14
2 Accompanying Text 14
2.1 Stratigraphy and Tectonics 14
2.2 Economic Geology 14
2.3 Geoenvironmental Hazards 15
2.4 Geosites 15
3 Conclusions 16
4 References 16
Chapter 2 18
Early Geological Maps of Africa 20
References 22
Chapter 3 24
Tectonostratigraphic Synopsis 26
1 Introduction 26
2 Archean Cratonic Nuclei 26
2.1 General 26
2.2 Greenstone Belts 26
2.3 Granitic Series (Including Gneisses) and Late Minor Intrusions 27
2.4 Tectonothermal Events 27
2.5 The Limpopo Mobile Belt 29
3 Paleoproterozoic Basement Development 29
4 Mesoproterozoic Basement Development 31
5 Neoproterozoic Basement Development 33
6 Phanerozoic Development 35
6.1 General 35
6.2 Orogenic Activity 37
6.3 Anorogenic Magmatism 37
6.4 Phanerozoic Rifts and Associated Magmatism 37
6.5 Sedimentary Basins 39
6.6 Phanerozoic Marine Cover Sequences 39
6.7 Karoo Supergroup 39
6.8 Interior Sag Basins 40
6.9 Quaternary 40
References 40
Chapter 4 Review of Countries and Territories 41
Algeria 43
1 General 43
2 Summary of Geology 43
3 Stratigraphy and Tectonics 43
4 Economic Geology 46
5 Geohazards 47
6 Geosites 47
7 References 47
Angola 49
1 General 49
2 Summary of Geology 49
3 Stratigraphy and Tectonics 49
4 Economic Geology 51
5 Geohazards 51
6 Geosites 51
7 References 52
Benin 53
1 General 53
2 Summary of Geology 53
3 Stratigraphy and Tectonics 53
4 Economic Geology 53
5 Geohazards 55
6 Geosites 55
7 References 55
Botswana 57
1 General 57
2 Summary of Geology 57
3 Stratigraphy and Tectonics 57
4 Economic Geology 59
6 Geosites 59
7 References 60
Burkina Faso 61
1 General 61
2 Summary of Geology 61
3 Stratigraphy and Tectonics 61
4 Economic Geology 61
5 Geohazards 61
6 Geosites 61
7 References 61
Burundi 63
1 General 63
2 Summary of Geology 63
3 Stratigraphy 63
4 Tectonics 63
5 Economic Geology 65
6 Geohazards 65
7 Geosites 65
8 References 65
Cameroon 67
1 General 67
2 Summary of Geology 67
3 Stratigraphy 67
4 Tectonics 69
5 Economic Geology 69
6 Geohazards 70
7 Geosites 70
7 References 70
Canary Islands (Spain) 71
1 General 71
2 Summary of Geology 71
3 Stratigraphy and Tectonics 71
4 Economic Geology 71
5 Geohazards 71
6 Geosites 73
7 References 73
Cape Verde 75
1 General 75
2 Summary of Geology 75
3 Stratigraphy and Tectonics 75
4 Economic Geology 75
5 Geohazards 75
6 Geosites 75
7 References 75
Central African Republic 77
1 General 77
2 Summary of Geology 77
3 Stratigraphy and Tectonics 77
4 Economic Geology 77
5 Geohazards 77
6 Geosites 77
7 References 77
Chad 79
1 General 79
2 Summary of Geology 79
3 Stratigraphy and Tectonics 79
4 Economic Geology 81
5 Geoenvironmental Hazards 82
6 Geosites 82
7 References 82
The Comoros 83
1 General 83
2 Summary of Geology 83
3 Stratigraphy and Tectonics 83
4 Economic Geology 83
5 Geohazards 83
6 Geosites 83
7 References 83
Democratic Republic of Congo (DRC) 85
1 General 85
2 Summary of Geology 85
3 Stratigraphy and Tectonics 85
4 Economic Geology 88
5 Geohazards 89
6 Geosites 90
7 References 90
Republic of Congo 91
1 General 91
2 Summary of Geology 91
3 Stratigraphy and Tectonics 91
4 Economic Geology 93
5 Geohazards 93
6 Geosites 93
7 References 93
Djibouti 95
1 General 95
2 Summary of Geology 95
3 Stratigraphy 95
4 Tectonics 95
5 Economic Geology 95
6 Geohazards 97
7 Geosites 97
8 References 97
Egypt 99
1 General 99
2 Summary of Geology 99
3 Stratigraphy and Tectonics 99
4 Economic Geology 101
5 Geohazards 102
6 Geosites 102
7 References 102
Equatorial Guinea 103
1 General 103
2 Summary of Geology 103
3 Stratigraphy 103
4 Tectonics 103
5 Economic Geology 105
6 Geohazards 105
7 Geosites 105
8 References 105
Eritrea 107
1 General 107
2 Summary of Geology 107
3 Stratigraphy and Tectonics 4 Economic Geology 107
5 Geohazards 107
6 Geosites 107
7 References 107
Ethiopia 109
1 General 109
2 Summary of Geology 109
3 Stratigraphy and Tectonics 109
4 Economic Geology 111
5 Geohazards 112
6 Geosites 112
7 References 113
Gabon 115
1 General 115
2 Summary of Geology 115
3 Stratigraphy and Tectonics 115
4 Economic Geology 115
5 Geohazards 117
6 Geosites 117
7 References 117
The Gambia 119
1 General 119
2 Summary of Geology 119
3 Stratigraphy and Tectonics 119
4 Economic Geology 119
5 Geohazards 119
6 Geosites 119
7 References 119
Ghana 121
1 General 121
2 Summary of Geology 121
3 Stratigraphy and Tectonics 121
4 Economic Geology 123
5 Geohazards 124
6 Geosites 124
7 References 124
Guinea 125
1 General 125
2 Summary of Geology 125
3 Stratigraphy 125
4 Tectonics 127
5 Economic Geology 127
6 Geohazards 128
6 Geosites 128
7 References 128
Guinea Bissau 129
1 General 129
2 Summary of Geology 129
3 Stratigraphy 129
4 Tectonics 129
5 Economic Geology 129
6 Geohazards 129
7 Geosites 129
8 References 129
Ivory Coast - Cote d.Ivoire 131
1 General 131
2 Summary of Geology 131
4 Stratigraphy and Tectonics 131
4 Economic Geology 131
5 Geohazards 133
6 Geosites 133
7 References: 133
Kenya 135
1 General 135
2 Summary of Geology 135
3 Stratigraphy and Tectonics 135
4 Economic Geology 138
5 Geohazards 140
6 Geosites 140
7 References 140
Lesotho 141
1 General 141
2 Summary of Geology 141
3 Stratigraphy 141
4 Tectonics 141
5 Economic Geology 141
6 Geohazards 143
7 Geosites 143
8 References 143
Liberia 145
1 General 145
2 Summary of Geology 145
3 Stratigraphy 145
4 Tectonics 145
5 Economic Geology 145
6 Geohazards 147
7 Geosites 147
8 References 147
Libya 149
1 General 149
2 Summary of Geology 149
3 Stratigraphy 149
4 Tectonics 151
5 Economic Geology 151
6 Geohazards 151
7 Geosites 151
8 References 152
Madagascar 153
1 General 153
2 Summary of Geology 153
3 Stratigraphy 153
4 Tectonics 155
5 Economic Geology 155
6 Geohazards 155
7 Geosites 155
8 References 156
Madeira (Portugal) 157
1 General 157
2 Summary of Geology 157
3 Stratigraphy and Tectonics 157
4 Economic Geology 157
5 Geohazards 157
6 Geosites 157
7 References 157
Malawi 159
1 General 159
2 Summary of Geology 159
3 Stratigraphy 159
4 Tectonics 161
5 Economic Geology 161
6 Geohazards 161
7 Geosites 162
8 References 162
Mali 163
1 General 163
2 Summary of Geology 163
3 Stratigraphy and Tectonics 163
4 Economic Geology 165
5 Geohazards 165
6 Geosites 165
7 References 165
Mauritania 167
1 General 167
2 Summary of Geology 167
3 Stratigraphy and Tectonics 167
4 Economic Geology 169
5 Geohazards 170
6 Geosites 170
7 References 170
Mauritius 171
1 General 171
2 Summary of Geology 171
3 Stratigraphy and Tectonics 171
4 Economic Geology 171
5 Geohazards 171
6 Geosites 171
7 References 171
Morocco 173
1 General 173
2 Summary of Geology 173
3 Stratigraphy and Tectonics 173
4 Economic Geology 176
5 Geohazards 177
6 Geosites 177
7 References 177
Mozambique 179
1 General 179
2 Summary of Geology 179
3 Stratigraphy and Tectonics 179
4 Economic Geology 179
5 Geohazards 182
6 Geosites 182
7 References 182
Namibia 183
1 General 183
2 Summary of Geology 183
3 Stratigraphy and Tectonics 183
4 Economic Geology 183
5 Geohazards 185
6 Geosites 186
7 References 186
Niger 187
1 General 187
2 Summary of Geology 187
3 Stratigraphy and Tectonics 187
4 Economic Geology 189
5 Geohazards 190
6 Geosites 190
7 References 190
Nigeria 191
1 General 191
2 Summary of Geology 191
3 Stratigraphy and Tectonics 191
4 Economic Geology 194
5 Geohazards 195
6 Geosites 195
7 References 196
Reunion (France) 197
1 General 197
2 Summary of Geology 197
3 Stratigraphy and Tectonics 197
4 Economic Geology 197
5 Geohazards 197
6 Geosites 197
7 References 197
Rwanda 199
1 General 199
2 Summary of Geology 199
3 Stratigraphy and Tectonics 199
4 Economic Geology 199
5 Geohazards 201
6 Geosites 201
7 References 202
São Tomé et Príncipe 203
1 General 203
2 Summary of Geology 203
3 Stratigraphy and Tectonics 203
4 Economic Geology 203
5 Geohazards 203
6 Geosites 203
7 References 203
Senegal 205
1 General 205
2 Summary of Geology 205
3 Stratigraphy and Tectonics 205
4 Economic Geology 5 Geohazards 207
6 Geosites 207
7 References 207
Seychelles 209
1 General 209
2 Summary of Geology 209
3 Stratigraphy and Tectonics 209
4 Economic Geology 209
5 Geohazards 209
6 Geosites 7 References 211
Sierra Leone 213
1 General 213
2 Summary of Geology 213
3 Stratigraphy 213
4 Tectonics 215
5 Economic Geology 215
6 Geohazards 215
7 Geosites 215
8 References 215
Socotra (Yemen) 217
1 General 217
2 Summary of Geology 217
3 Stratigraphy and Tectonics 217
5 Geohazards 217
6 Geosites 217
7 References 217
Somalia 219
1 General 219
2 Summary of Geology 219
3 Stratigraphy 219
4 Tectonics 221
5 Economic Geology 221
6 Geohazards 222
7 Geosites 222
8 References 222
South Africa 223
1 General 223
2 Summary of Geology 223
3 Stratigraphy and Tectonics 223
5 Geohazards 227
6 Geosites 227
7 References 228
Sudan 229
1 General 229
2 Summary of Geology 229
3 Stratigraphy and Tectonics 229
4 Economic Geology 231
5 Geohazards 232
6 Geosites 232
7 References 232
Swaziland 233
1 General 233
2 Summary of Geology 233
3 Stratigraphy 233
4 Tectonics 235
5 Economic Geology 235
6 Geohazards 236
7 Geosites 236
8 References 236
Tanzania 237
1 General 237
2 Summary of Geology 237
3 Stratigraphy 237
4 Tectonics 239
5 Economic Geology 239
6 Geohazards 241
7 Geosites 241
8 References 242
Togo 243
1 General 243
2 Summary of Geology 243
3 Stratigraphy and Tectonics 243
4 Economic Geology 243
5 Geohazards 243
6 Geosites 243
7 References 243
Tunisia 245
1 General 245
2 Summary of Geology 245
3 Stratigraphy and Tectonics 245
4 Economic Geology 247
5 Geohazards 248
6 Geosites 248
7 References 248
Uganda 249
1 General 249
2 Summary of Geology 249
3 Stratigraphy 249
4 Tectonics 251
5 Economic Geology 251
6 Geohazards 252
7 Geosites 252
8 References 252
Western Sahara 253
1 General 253
2 Summary of Geology 253
3 Stratigraphy and Tectonics 253
4 Economic Geology 253
5 Geohazards 253
6 Geosites 253
7 References 253
Zambia 255
1 General 255
2 Summary of Geology 255
3 Stratigraphy 255
4 Tectonics 257
5 Economic Geology 257
6 Geohazards 258
7 Geosites 258
8 References 258
Zimbabwe 259
1 General 259
2 Summary of Geology 259
3 Stratigraphy and Tectonics 259
4 Economic Geology 261
5 Geohazards 262
6 Geosites 262
7 References 262
Index 264
Geographical Index 266
A 266
B 266
C 266
D 266
E 267
G 267
H 267
I 267
J 267
K 267
L 268
M 268
N 269
O 269
P 269
R 269
N 269
T 270
U 270
V 270
W 270
Y 270
Z 270
Subject Index 272
A 272
B 273
C 273
D 274
E 275
F 275
G 275
H 276
I 276
J 276
K 276
L 277
M 278
N 279
O 279
P 280
Q 280
R 281
S 281
T 282
U 283
V 283
W 283
Y 283
Z 283

Egypt (p. 88-89)

1 General Area: 997,739 km²
Population: 65,700,000 (Estimate 2001)

2 Summary of Geology

The oldest rocks in Egypt occur as isolated Archean to Proterozoic inliers in the Western Desert, whereas the Egyptian part of the Arabian-Nubian Shield along the coastal Red Sea region is made up of Neoproterozoic Pan-African rocks. Paleozoic sediments often mantle the basement rocks. After a sedimentary hiatus due to the Hercynian orogeny Cretaceous sediments are well exposed in various parts of the country. The Cenozoic history is characterized by transgressions and regressions and their respective sediment types.


3 Stratigraphy and Tectonics

Much of northeastern Africa is mantled by thick sedimentary strata of Phanerozoic age, which form a generally undeformed cover to a deep crystalline basement. The older rocks are well exposed in eastern Egypt and Sudan, where they comprise part of the Arabian-Nubian Shield. Further into the interior of northeastern Africa they appear as isolated inliers, for instance the Uweinat inlier across the borders of Egypt, Libya and Sudan. The Uweinat inlier is also significant because it has provided the oldest ages from anywhere in northeast Africa: Granulite facies rocks in this area have yielded an average age of about 2,900Ma. No younger ages than about 1,800Ma have been obtained there, thus indicating the tectonic stability of the Uweinat inlier since that time. It is therefore probable that this region is to be considered part of a craton from thence on.

Till to date, no pre-Pan-African rocks have been identified in other regions of Egypt. The basement rocks in the Eastern Desert of Egypt can be subdivided from base to top into the Meatiq Group, the Abu Ziran Group and the Hammamat Group, all of Neoproterozoic age. The Meatiq Group comprises old crystalline basement outcropping in gneiss domes. These probably evolved in a mainly compressional tectonic environment during Neoproterozoic times and exhibit many of the basic structural and lithological characteristics of metamorphic core complexes of the Cordilleran type. They comprise an anticline with low dipping foliation and unidirectional mineralslickenside lineation. The core comprises granitic gneisses conformably overlain by a heterogeneous and isoclinically folded mylonitic material, which predates the doming event. This grades up into low-grade ophiolitic rocks.

The area lies in the foreland fold and thrust belt of a continental margin origin. Ophiolites outcrop along the thrust between the Meatiq infrastructure and the imbricated Abu Ziran nappe. Calc-alkaline magmatism occurred along two upwards and is associated with gold mineralization. The Abu Ziran Group comprises ophiolites overlain by metasediments, pyroclastics and local intermediate volcanics with island arc characteristics. The Hammamat Group includes molasse-type clastics and the penecoeval Dokhan volcanics of andesitic to rhyolitic composition, these being equivalent to plutonic, syn- to late-tectonic calc-alkaline granites.

The clastics are up to 5,000m thick, of Late Pan-African age and exposed in the coastel mountains of the Eastern Desert. There are four lithofacies, which are conglomerate, pebbly sandstone, sandstone and siltstone, respectively. The interrelationships suggest alluvial fan-braided stream deposition within several small-sized basins. The interbedding of conglomerate and thick siltstone units indicate the direct interdigitating of fans with playas or lake sediments. Discontinuous siltstone units are interpreted as cut-off channel deposits within braided streams. Debris flow sedimentation is not exhibited. Palaeomagnetic directions have been identified at several sites in the Dokhan volcanics and also from two dike swarms intruding the late orogenic (younger) granites.

The reported Rb-Sr ages for the Dokhan volcanics range from 660 to 603Ma. The dike swarms range from 530 to 480Ma in age. The Abu Zawal area is approximately 150km northeast of Luxor and is composed of a sequence of igneous and metamorphic rocks of Neoproterozoic age. The least radioactivity is associated with basic metavolcanics and the highest values relate to late orogenic plutonites, whereas the granodiorites possess a moderate level of radioactivity. Post-Hercynian structural realignments and resultant E-W trending structures in the Saharan platform determined the major depocentres until the disintegration of Pangaea in Jurassic to Cretaceous times created new structural trends. During the Mesozoic Egypt consisted of two main structural provinces, an unstable shelf to the north with complex NE-SW transcurrent faults and fault-bounded basins