THE GEOMORPHOLOGICAL DEVELOPMENT OF EPHEMERAL AND RELICT RIVER VALLEY SYSTEMS IN THE NORTH PART OF THE IRAQI WESTERN DESERT
By
Waleed Hanosh Hamed
A thesis submitted to the University of Plymouth
in partial fulfilment for the degree of
Doctor of Philosophy
School of Geography, Earth and Environment Sciences
Plymouth University
United Kingdom
January 2015
Abstract
THE GEOMORPHOLOGICAL DEVELOPMENT OF EPHEMERAL AND RELICT RIVER VALLEY SYSTEMS IN THE NORTH PART OF THE IRAQI WESTERN DESERT
Waleed Hanosh Hamed
This research project provides a geomorphological and geological analysis of ephemeral and relict river valley systems in the north part of the Iraqi Western Desert. The area surveyed covers approximately 30 000 km2 and is one of the remotest and least studied parts of the Arabian Peninsula. Part of the reason for the lack of research in this area in recent years has been the ongoing security problems and all fieldwork undertaken for this thesis was carried out with the support of armed guards and police. In addition much of the work on the geology and geomorphology of the region is in confidential files commissioned by oil companies, and in MSc and PhD theses held in Iraqi Universities. A significant part of this work and indeed many scientific papers, are only available in Arabic. Therefore a major element of the work for this thesis has been to translate this material and make the results available in English for the first time.
The study demonstrates that the present surface of the Iraqi Western Desert overall forms an incised plateau developed during two phases of continental erosion and deposition during the Tertiary and Quaternary periods. The first phase started after Oligocene uplift formed an older plateau within the Oligocene Tayarat formation. This plateau is characterized by denudation processes associated with a semiarid climate, including the formation of subsurface hollows and caves. The second phase, which began after the last Alpine Orogenic movement, and includes the Pliocene and Quaternary periods, formed a younger plateau developed on the Zahra formation. This younger plateau is characterized by processes indicative of climatic fluctuations from wet to arid and semiarid, which induced denudation in places and deposition in others. However, in terms of the geomorphological landforms present in the Western Desert they can be broadly divided into:
i) Structural and erosion-denudation forms
ii) Accumulation forms
Lithology landform in these two categories has resulted in the production of a new geomorphological map of the Iraqi Western Desert. A key component of this map uses the drainage networks. Four distinct drainage systems were identified:
1. The valleys which descend from west to east. These valley systems are located to the south and south east town of Rutba
2. The valleys which descend from south to north. These lie to the west and southwest of Rutba and are controlled by the north to south strike of exposed Palaeogene strata.
3. The valleys which descend from east south to north west, located north of the Garaa area like Ratga and Akash.
4. The valleys which descend from east to west. These valley systems are located to the south and south west town of Rutba, like Swab and Wallaj valleys.
Investigation of these four networks established that they were relict systems that still carried ephemerally active misfit rivers and stream. The overall control on their form was the alternating sequences of variable strength rocks that were exposed and eroded as part of the uplift of an anticlinorium (Houran) and anticline (Garaa), associated with the Alpine Orogeny .However, the unclearing Structures were much older and can be traced back to Permian tectonic processes. The drainage of the Western Desert, therefore, is antecedent and controlled by Tertiary and Quaternary tectonics. The rivers appear to have active throughout the Pleistocene incising into the Western Desert plateaux. Highest incision rates probably occurred during more pluvial periods in the Pleistocene which may have been coincident with glacial marine in the Northern Hemisphere. The contemporary rivers are misfit within larger valleys although still subject to flash floods under the right metrological condition
List of contents
List of Figures ............................................................................... XIV
List of Pictures: ........................................................................... XVIII
List of Tables: ............................................................................... XIX
Author’s declaration ................................................................... XXIV
Chapter 1-Introduction to the thesis and the field area ............... 1
1.1 General Introduction ............................................................................................ 2
1.2 Aims and objectives ............................................................................................. 3
1.3 Thesis structure ................................................................................................... 3
1.4 Field area .............................................................................................................. 4
1.5 The Iraqi Western Desert .................................................................................... 5
1.6 Location of Iraq .................................................................................................. 10
1.7 Summarizing the purpose of this research ...................................................... 11
Chapter 2-The Geomorphology of Hot Deserts………………….…..12
2. 1 Introduction ........................................................................................................ 13
2.2 The Definition and distribution of Hot Deserts ................................................ 14
2.3 Typical models of dry lands environments ...................................................... 16
2.4 Long term evolution of drylands ....................................................................... 22
2.4.1 Climatic fluctuations during the Cenozoic………………………………24
2. 4. 2 climate Changes in Iraq in the Cenozoic……………………………...30
2.5 Previous Geological and Geomorphological studies in Iraq .......................... 33
VII
2.6 Drainage in the contemporary desert fluvial environment ............................. 35
2.6.1 Desert drainage systems ........................................................................... 36
2.6.2 Dryland Channel forms and processes .................................................... 37
2.6.3 Alluvial fans ................................................................................................. 39
2.6.4 Pediments ................................................................................................... 40
2.6.5 Playas and Sabkhas ................................................................................... 42
2.7 Summary ........................................................................................................... 44
Chapter 3-Methodology ................................................................ 45
3.1 Introduction ......................................................................................................... 46
3.2 Desk Study ......................................................................................................... 47
3.2.1 Scientific documents ................................................................................. 49
3.2.2 Topographic maps ..................................................................................... 51
3.2.3 Geological maps ........................................................................................ 54
3.2.4 Geomorphological maps ........................................................................... 55
3.2.5 Google Earth images................................................................................. 55
3.2.6 CorelDraw .................................................................................................. 56
3.2.7 Geographical Information System (GIS) ................................................. 57
3.2.8 Data in Geo Map ........................................................................................ 58
3.3 Field studies ....................................................................................................... 59
3.3.1 Ground truth mapping ............................................................................... 61
3.3.2 Logging river terraces ................................................................................ 63
VIII
3.3.3 Discussions with local people .................................................................... 63
3.4 Methods of data analysis .................................................................................. 64
3. 4. 1 Translations from Arabic .......................................................................... 65
3.4.2 Terrain classification ................................................................................... 65
3.4.3 Analysis of river valleys and drainage ...................................................... 66
3.4.4 The GIS ........................................................................................................... 67
3.5 Summary………………………………………………………………………….69
Chapter 4-Geology of the field area ............................................ 70
4.1 Introduction ......................................................................................................... 71
4.2 Structural framework ......................................................................................... 71
4.2.1 Overall geological Structure of the Iraqi Western Desert ....................... 74
4.2.2 Tectonics ..................................................................................................... 76
4.2.2.1 Faults .................................................................................................. 81
4.2.3 Joints system .............................................................................................. 85
4.3 Stratigraphy (Type locations show in Figure 4.14) ......................................... 85
4.3.1 Stratigraphic Column .................................................................................. 85
4.3.2 The Palaeozoic Era (570-245) Ma ............................................................ 88
4.3.2.1 Garaa Formation (Early Permian-Late Carboniferous) .................. 90
4.3.3 Mesozoic Era (245-65 Ma) ........................................................................ 93
4.3.3.1 Triassic Period .................................................................................. 94
4.3.3.1.1 Mulussa Formation (late Triassic) ......................................... 94
IX
4.3.3.1.2 Zor Houran Formation (Late-Triassic, Rhaetian) ................. 95
4.3.3.2 Jurassic ............................................................................................. 98
4.3.3.2.1 Ubaid Formation (Early Jurassic) ............................................ 98
4.3.3.3 Cretaceous ......................................................................................... 99
4.3.3.3.1 Rutba Formation (Late Cretaceous-Cenomanian) ................. 100
4.3.3.3.2 Massad Formation (Late Cretaceous Cenomanian-Turonian)103
4.3.3.3.3 Marbat Beds (Late Cretaceous, Campanian-Maastrichtian) . 104
4.3.3.3.4 Hartha Formation (Campanian-Maastrichtian) ....................... 104
4.3.3.3.5 Tayarat Formation (Campanian-Maastrichtian) ..................... 105
4.3.3.3.6 Digma Formation (Late Cretaceous Maastrichtian) .............. 106
4.3.4 Cenozoic .................................................................................................... 107
4.3.4.1 Palaeocene ..................................................................................... 107
4.3.4.1.1 Umm Er Radhuma formation (Middle-Late Palaeocene) .. 107
4.3.4.1.2 Akashat Formation (Early-Late Palaeocene) ...................... 109
4.3.5 Eocene ..................................................................................................... 110
4.3.5.1 Ratga Formation (Early-Late Eocene) ......................................... 111
4.3.5.2 Dammam Formation (Middle-Late Eocene) ................................ 112
4.3.5.3 Jaddalah Formation (Middle Eocene) ......................................... 113
4.3.6 Oligocene ................................................................................................ 113
4.3.7 Miocene .................................................................................................. 114
4.3.7.1 Ghar Formation (Early-Middle Miocene) .................................... 114
X
4.3.7.2 Euphrates Formation (Early Miocene) ....................................... 115
4.3.8 Pliocene, Pleistocene and Holocene………………………………….117
4.3.8.1 Zahra Formation (Pliocene-Pleistocene)……………………..117
4.3.9 Quaternary including Pleistocene and Holocene Deposits………….120
4.3.9.1 Houran Gravels (Pleistocene)………………………………....120
4.3.9.2 Habbariyah Gravels (Pleistocene)…………………………….120
4.3.9.3 Terraces (Pleistocene)………………………………………....121
4.3.9.4 Valley Fill in Depressions (Holocene)………………………...121
4.3.9.5 Depression Fill Deposits (Holocene)..............................…...122
4.4 Economic Geology ………………………………………………….…………124
4.5 Summary and Conclusions ……………………………………………..…….126
Chapter 5-Geomorphological Investigations ............................ 127
5.1 Introduction ....................................................................................................... 128
5.2 Climatic data..................................................................................................... 129
5.2.1 Climate in Iraq ......................................................................................... 129
5.2.2 Climate in the Iraqi Western Desert ...................................................... 130
5.3 The Four Physiographic Regions of Iraq ……………………………………142
5.3.1 Desert ..................................................................................................... 142
5.3.2 Mesopotamian Alluvial Plain ................................................................. 143
5.3.3 Foothills (i.e. undulating terrain) ........................................................... 144
5.3.4 Mountainous highlands ........................................................................ 144
5.4 Preliminary subdivision of the terrain of the Western Desert ...................... 146
5.4.1 Hammad area ....................................................................................... 147
XI
5.4.2 Upper valleys area ................................................................................ 149
5.4.3 Parsons “Stone area” ........................................................................... 150
5.4.4 Lower Valleys area ............................................................................... 150
5.5 Geomorphology of the Iraqi Western Desert ................................................ 154
5.5.1 Geomorphic units of structural origin-the plateaux ............................ 155
5.5.1.1 Plateau on the Zahra Formation ................................................ 159
5.5.1.2 Plateau on the Euphrates formation .......................................... 159
5.5.1.3 Plateau on the Ghar Formation .................................................. 160
5.5.1.4 Plateau on the Dammam Formation .......................................... 160
5.5.1.5 Plateau on the Umm Er Radhuma Formation .......................... 160
5.5.1.6 Plateau on the Tayarat Formation ............................................. 161
5.5.1.7 Plateau on the Hartha Formation. .............................................. 161
5.5.1.8 Plateau on the Rutba and Massd Formations .......................... 162
5.5.1.9 Plateau on the Ubide Formations .............................................. 162
5.5.1.10 Plateau on the Zor Houran Formation ..................................... 162
5.5.1.11 Plateau on the Mulussa Formation .......................................... 163
5.5.1.12 Plateau on the Garaa Formation.............................................. 163
5.5.2 Erosion-Denudation landforms ............................................................ 164
5.5.2.1 Remnant Erosional Hills ............................................................. 164
5.5.2.2 Badlands ...................................................................................... 167
5.5.2.3 Mesas and Buttes ....................................................................... 170
XII
5.5.2.4 Depressions ................................................................................ 170
5.5.2.4.1 The Garaa depression ................................................. 170
5.5.2.4.2 Umm Chaimin Depression ........................................... 175
5.5.3 Fluvial Landforms ................................................................................. 177
5.5.3.1 Ephemeral stream valleys ......................................................... 178
5.5.3.2 Alluvial fans and bajada ............................................................. 179
5.5.3.3 River terraces on the River Euphrates ..................................... 179
5.5.3.3.1 Al Qaiam terrace ........................................................... 184
5.5.3.3.2 Haditha terrace ............................................................. 185
5.5.3.3.3 Al Baghdadi terrace ...................................................... 186
5.5.3.3.4 Houran terrace .............................................................. 188
5.5.3.3.5 Al Mohamedi terrace .................................................... 189
5.5.3.4 Ephemeral lakes .......................................................................... 190
5.5.4 Solution features ............................................................................. 191
5.5.5 Evaporite landforms ........................................................................ 192
5.5.6 Aeolian features .............................................................................. 193
5.6 The New Geomorphological map of the Iraqi Western Desert (figure 5.18)196
5.6.1 Background data field observation ................................................. 196
5.6.2 Geomorphological Evolution ........................................................... 197
5.6.3 Comments on the Tectonic control on the geomorphology ......... 200
5.7 Summary of the future geomorphology investigation ................................... 201
XIII
Chapter 6-Drainage Investigation .............................................. 203
6.1 Introduction ....................................................................................................... 204
6.2 Drainage system types .................................................................................... 204
6.2.1 Parallel Drainage pattern ........................................................................ 204
6.2.2 Centripetal Drainage pattern ................................................................ 210
6.2.3 Radial Drainage pattern .......................................................................... 212
6.2.4 Dendritic Drainage pattern ...................................................................... 212
6.3 Morphometric Analysis of dry valleys ............................................................ 214
6.4 Valley systems that feed into the exogenic drainage ................................... 216
6.4.1 Houran valley network ............................................................................ 222
6.4.2 Al Qaiam valley network ........................................................................ 224
6.4.3 Al Rataga Valley network ....................................................................... 225
6.4.4 Al Manai valleys network ....................................................................... 227
6.5 Endoreic drainage valley system ................................................................... 233
6.5.1 Example of an endoreic valley system into the southern Gaara depression. ................................................................. 233
6.5.1.1 Al Mulusa valley ........................................................................... 235
6.5.1.2 Al Ojia valley ................................................................................ 235
6.5.1.3 Al Agrmyat valley ......................................................................... 235
6.5.1.4 Al Agrai valley .............................................................................. 236
6.5.2 Characteristics of the endoreic valley systems.......................................... 242
XIV
6.5.2.1 Bifurcation ratio ............................................................................ 242
6.5.2.2 Drainage Density and other Basin Characteristics ………….246
6.5.2.3 Deflection coefficient .................................................................. 248
6.5.2.4 Basin drainage form ................................................................... 249
6.6 How has the drainage network evolved over time ........................................ 250
6.7 Conclusion ........................................................................................................ 251
Chapter 7-Discussion and Conclusion ..................................... 254
7.1 Discussion ........................................................................................................ 255
7.2 Conclusions ...................................................................................................... 259
7.3 Recommended additional work in the Iraqi Western Desert ....................... 261
7.4 Final thoughts ................................................................................................... 262
References.............................................................................................................. 264
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