Iraqi Bulletin of Geology and Mining

The Cretaceous carbonates are of unique significance in the stratigraphic succession of the Middle East, because much of the discovered prolific carbonate reservoir facies are in the rudist bearing formations. The Late Cretaceous carbonates of the Mishrif Formation are one of these prolific reservoir facies, which extends along the southern parts of Iraq and the Arabian Gulf.
Five subsurface sections were selected from wells of three fields in south and southeastern parts of Iraq, including West Qurna 21, 57 and 215, Tuba 4 and Nasiriyah 2, to determine the radiation and the demise of the rudists in the Mishrif Formation.
This study showed that the rudists of the Mishrif Formation were affected in two stages of demise. The first (Fd) took place during the early Late Cenomanian, recorded by a drastic decline in the abundant occurrence of the recumbent rudists (Caprinidae and Ichthysarcolitidae), which together represent Cenomanian species of the Mishrif Formation. Consequently, the followed Cenomanian – Turonian transition was not only a significant crisis in the abundance of the rudists, but also the benthic foraminifera were affected. The second demise of the rudists was recorded by the disappearance of elevator Hippuritidae and Radiolitidae; represented by these species: Durania araudi, Sauvagesia sharpie, Praeradiolites echennesis, Praeradiolites sarladensis and benthic foraminifera, specially Miliolids, with abundance of planktonic foraminifera of the Khasib Formation, this demise took place during the late Early Turonian.

The Greater Zab River is one of the main tributaries of the Tigris River. The river runs in the central northern part of Iraq, and then joins the Tigris River south of Mosul city, in the northern central part of Iraq. It has four main tributaries, called; Shamdinan, Haji Beg, Rawandooz and Khazir – Gomal rivers, beside tens of small tributaries and ephemeral streams, which drain directly in the main river. The studied catchment area of the Greater Zab River; in Iraq attains about 13708 Km2, and extends in the northern and northeastern parts of Iraq, and farther more in Turkey and Iran. The basin of the river is divided into four sub-basins of the aforementioned tributaries and a fifth one, which includes the catchment area that drain directly in the Greater Zab River. The widths of the five sub-basins range from (1.54 – 6.19) Km, whereas their lengths range from (41.4 – 108.3) Km.
The catchment's areas of the Greater Zab River and its four tributaries are covered mainly by carbonate rocks of many formations, which range in age from Triassic to Pliocene – Pleistocene, beside igneous and metamorphic rocks, especially in the northeastern parts. Moreover, fine clastics of Injana and Mukdadiya formations, coarse clastics of Bai Hassan Formation, and marl, limestone and gypsum of the Fatha Formation cover considerable area. Through the courses of the Greater Zab River and its four tributaries, they cross tens of anticlines, almost perpendicularly; some of them have gorge forms, forming 34 water gaps and 15 air gaps, in the studied area. The geomorphology and morphotectonics of the Greater Zab River basin are studied. Six Morphometric indices have determined in this study, using ArcGIS technique, which indicated High, Moderate, Very High, Very High and High relative tectonic activity for the five sub-basins, respectively. Geomorphological and basin drainage maps of the studied area are prepared, too.

The study of the slope stability within and around the reservoir of the proposed Basara dam near Delaizha village, Sulaimaniyah District, Kurdistan Region, NE Iraq is carried out. To evaluate the stability of slopes in the studied area, sixteen stations were selected within and in the vicinity of the reservoir area, fourteen stations in the rock slopes, and two stations in the soil and talus sediments.

In this study, the stability of the rock slopes have evaluated by a new system, known as Landslide Possibility Index (LPI), as well as the approach of Hoek and Bray for those stations that are near the proposed dam site and need a detailed study. Moreover, the soil and talus slopes have evaluated by conventional methods.
The application of the LPI system leads to the conclusion that the possibility of failures and the degree of hazard in the eight rock slopes, Stations No. 2, 5, 8, 9, 11, 12, 13 and 15 is Moderate, while in the six remained rock slopes, Stations No. 1, 3, 4, 6, 7 and 10; the possibility of failures and the degree of hazard is High.
Detailed study of rock slopes in the vicinity of the proposed Basara dam (Stations No. 1 and 2) revealed that they are unstable, where toppling, rock fall, rock rolling have occurred. Further failures will occur in the future, which might affect the stability of the dam, because during toppling and/ or rock fall; some of the blocks may roll down into the reservoir of the dam, when it is filled by water, where the consequences will be very hazardous.
The study of the soil and talus slopes revealed that soil slump had occurred in Station No. 14, which is recognized by leaning of the trees down slope and the moved soil left a scar due to movement. While in the talus slope (Station No. 16) rock rolling and falling have occurred, because the slope has a direct contact with the valley floor and being continuously under-cut by water currents during floods, thus the water currents have removed, the fine materials between large blocks.

This study is concerned with the heavy minerals (HM) of the + 63 micron fraction of the sand dune sediments, which cover 608.686 Km2 of an area from Najaf to Samawa, and the southern borders of Al-Qadissiya Governorate. Moreover, grain size analysis, chemical and XRD analysis are carried out. HM analysis indicates that the proportion of the unstable minerals makes about 12.7% for Najaf dunes and 44.83% for Samawa – Qadissiya dunes, whereas the metastable minerals make about 15.81% and 21.03% and the ultra stable minerals make about 16.83% and 3.01% for Najaf and Samawa – Qadissiya dunes, respectively. Opaques are present in high proportions reaching about 34.04% for Najaf dunes and 28.54% for Samawa – Qadissiya dunes.
Grain size analysis indicates that the sediments of Najaf dunes are coarser than the sediments of Samawa – Qadissiya dunes and the sorting of sediments of Najaf dunes are medium, while sediments of Samawa – Qadissiya dunes are fine. Moreover, the sediment of Najaf dunes are more mature than the sediment of Samawa – Qadissiya dunes due to the ZTR index.
Chemical and XRD analysis revealed that the sediments of the studied dune fields are composed essentially of quartz, feldspar; as the dominant minerals with a paucity of carbonate and sulphate minerals, in addition to heavy minerals. Clay minerals occur in Najaf dune fields represented by montmorillonite, palygorskite and kaolinite and the same clay minerals except montmorillonite occur in Samawa – Qadissiya dune fields.
All results indicate that Najaf sand dunes are derived from felsic igneous rocks (granitoid rock), metamorphic rocks (schist and gneiss) and older sedimentary rocks, while Samawa – Qadissiya dunes are essentially derived from metamorphic rocks (schist and gneiss), basic igneous rocks (Basalt and Gabbro) and older sedimentary rocks.
The Dibdibba Formation (Pliocene – Pleistocene) in Tar Al-Najaf, where the sediments are transported from the Arabian Shield, is the most important source for supplying sand forming the dune fields of Najaf, while the source area that supplies the sediments of Samawa dunes is mixed, the essential one is the surrounding formations, where the sediments are transported from Arabian Shield and the second source is the Euphrates River, where sediments are transported from the north (Syria and south of Turkey).

A more detailed gravity and ground magnetic surveys have been executed in a mostly agricultural area, which covers (28 × 40) Km and lies between Al-Nasiriya and Al-Kut Governorates, close to Al-Gharraf River and towards west. The surveys aim to determine deep structures within the sedimentary cover, by following-up a deep source anomaly, which appears in aeromagnetic and Unified Bouguer gravity maps. A net of polygons, including 868 gravity and magnetic stations with spacing interval of 0.5 Km, has been measured. Bouguer anomaly and total magnetic intensity (TMI) maps are constructed. Filters for enhancing shallow and deep source anomalies and high gradient areas were applied to Bouguer anomaly and TMI maps. The Bouguer anomaly map shows a prominent gravity high in ENE – WSW direction. In addition, residual anomalies that may reflect antiforms and synforms or faults are pointed out on this map. Gravity profiles across the gravity high and some residual positive anomalies are plotted. On the other hand, the TMI map shows a magnetic high, which has the same direction, extension, length and location of the gravity high. The magnetic high is, essentially, related to a basement intrusion, and it may be a causative source for the gravity high. Two magnetic profiles across and along this high are displayed. The study of depth maps of four seismic reflectors showed no anomalous structures down to the Permian surface (~ 6000 m deep), while it shows considerable paleostructures on this surface. Moreover, the magnetic high (the intrusion) is older than the Permian, which is (6000 – 9000) m deep. However, local magnetic anomalies (LMA) related to Quaternary gray sand sediments, can easily be recognized throughout the area. The LMA tend to disturb the earth’s magnetic field. However, upward continuation filter is applied to remove the effect of these anomalies.

Kurdistan Region is characterized among the rest of Iraqi territory, by the presence of metallic mineral deposits such as Zn, Pb, Cu, Cr-Ni and Mn, together with some unique non-metallic minerals and industrial rocks such as barite, asbestos and marble. The formation of these mineral deposits is associated with the geological and tectonic development of northern Iraq including the major tectonic events associated with the Tethys development and movement of the Arabian Plate. Most of the metallic mineralizations were developed during the Cretaceous Period. Some Zn-Pb deposits are older and may be related to the Triassic and Jurassic Periods.
The actual mineral wealth of the region is not really known, in view of the lack of detailed geological mapping, geochemical survey and air-born geophysical survey. However, based on the available information it is expected that the province is promising for Zn, Pb, Cu, Cr, marble and barite deposits. Building raw materials are available to maintain cement industry and other construction materials. It is essential to start a comprehensive exploration program in Kurdistan Region in order to have a better view of its mineral potential.

In this study, light and dead-burned magnesia (MgO) were prepared from the sea-bittern residual from the production of NaCl; extracted from sea water (Arabian Gulf) in Al-Basrah saltern in the south of Iraq. Dead burned magnesia of pure and dense form assaying 96.8% MgO, with a bulk density of 3.7 gm/cm3 was prepared at optimum conditions, including pre-treatment of the sea bittern of 26 Baume with calcium chloride at a ratio of 1.05:1.00 (CaCl2:MgSO4) to remove calcium sulfate, addition of precipitant (dolime) at a molar ratio of 1:1 (CaO.MgO:MgCl2), and precipitation temperature of about 70 °C for 60 minutes. The precipitated Mg(OH)2 was subjected to calcination at 1000 °C for 60 minutes, whereby a milky soft powder of light-burned (active) magnesia was produced. Dead-burned (inactive) magnesia was then obtained by burning the light-burned magnesia at 1650 °C for 60 minutes. This study provides further benefit, of producing a high purity calcium sulfate (≥ 98%) as a byproduct of the MgO production.

All irrigation waters contain some dissolved salts. Dissolved salts are present because some chemical elements have a strong attraction for water and a relatively weak attraction for other elements. The total amount and kinds of salts determine the suitability of the water for irrigation use. Water may contain so much salt that it is unsuitable for irrigation because of potential danger to the soil or crop.
A study of groundwater use for irrigation purposes was carried out within the first aquifers in Iraq, this study depends on the evaluation of the hydrogeological information for the last ten years of more than 12000 wells include most part of Iraq. This study includes the determination of the parameters that affected the suitability of the groundwater use such as electric conductivity, concentration of sodium ion in percent, sodium adsorption ratio in addition to chloride ion concentration within the upper aquifers. Accordingly, a map of the groundwater use for irrigation purposes in Iraq was prepared according to Richard classification on scale 1: 6000 000, which depends on the values of water's electrical conductivity (salinity) and sodium adsorption ratio. The results showed that most of the groundwater within upper aquifers in Iraq is of poor quality, to be used for irrigation purposes, unless the nature of the soil and the used irrigation methods are improved.

The studied area is located between Mosul and Badoosh dams, 35 Km northwest of Mosul city, in north Iraq. The area is covered by rocks of the Fatha Formation, which are marl, gypsum and limestone, in addition to the Quaternary sediments (fluvial, alluvial and Tigris river terraces). The area is distinguished by the presence of two anticlines extending E – W, the first is Masarra anticline with western plunge located across Tigris River. The second one is Taira anticline, whose western plunge represents the eastern embankment of Mosul dam.For the detection and delineation of subsurface defects, seven sites were chosen in the studied area. Deep and shallow geophysical investigations using Electrical Resistivity Tomography (ERT) via Winner – Schlumberger system was conducted along 31 electrical profiles with lengths ranging between (290 – 3075) m and (4 – 13) levels. The continuous rolling-along technique was applied with new procedure in covering the triangular segments.

The ERT results of "Wana" site display four suggested channels and a fault. The profile of Mosul dam, points out two contiguous channels, which are being the most significant defects that have caused the development of the sinkholes, which are grouted nowadays. In the other sites (Dawasa, Kirj, Mostah, Sheheya, Filfale), many features of karst caverns were identified, beside dissolution channels and faults within rocks of the Fatha Formation. Those defect zones may lead to serious problems and developments, which could not be controlled and consequently the remedy may be costly as it is the case in Mosul dam project. Those problems must be taken into consideration in Badoosh project dam, where the up-stream lake will cover the studied area; leading to the importance of the present site investigation. Moreover, the seven profiles of the ERT (100 m spacing) covering the studied sites, have shown weakness zones extending from the ground surface to a depth of 99 m (the Quaternary sediments and Fatha Formation). Six profiles, indicated the homogeneity of the deep horizontal stratified rocks within Euphrates – Jeribe Formation (Lower – Middle Miocene respectively), while the seventh profile (ERT19) of "Dawasa" site, displays deeper changes (Heterogeneity) below 134 m, within the rocks of the Euphrates – Jeribe Formation.

In this study, the data of chemical analysis, grain size analysis and physical and mechanical properties of 268 clay samples collected and studied thrir suitability for bricks manufacturing, from different parts of Iraq were evaluated. Statistical analyses (correlation coefficient and factor analysis) were applied to correlate between these data to determine the effective variables that affect the bricks grade. The clays of Quaternary sediments, which are the traditional source of clays for bricks manufacturing, are used in most parts of Iraq. Since the studied samples were chosen from assorted parts of Iraq, therefore the results of this study could be applied as a general rules for the bricks manufacturing. The study revealed that the efflorescence and the mineralogical composition plays an important role and affects bricks grade.

The relationships between the chemical oxides could explain the mineral content and then its effect on the physical properties of bricks manufactured from them. The positive relationships between CaO, MgO and L.O.I., reflect presence of the carbonate minerals in the raw clay, which affects the longitudinal and volumetric shrinkage and water absorption, which in turn affects the bricks grade. Al2O3 is used to calculate the percentage of the clay minerals, which incorporate K2O in illite, MgO in palygorskite and CaO in montmorillonite. The presence of large quantities of palygorskite reduces the bricks grade and might lead to their failure. Also the presence of CaO and SO3 with positive relationship between them indicates the presence of gypsum, which causes the efflorescence and affects the bricks during firing at high temperatures. Na2O, MgO and Clˉ indicate for the chloride salts and Na2O with SO3 indicate the presence of sodium sulphate salt, which all cause efflorescence of the bricks. Carbonate minerals produces CaO and CO2 during the bricks firing. CaO, when absorbs water turns to Ca(OH)2, which has larger volume, leading to disintegration and breakage of the bricks. While CO2 produces pores, leading to an increase in porosity and water absorption and reduces the compressive strength. The high increase in the sand size percentage will decrease the compressive strength of the bricks and the high increase in the clay size percentage will lead to fracturing of the bricks during the drying process in air.