Western Desert Of Iraq Research Articles

Sand and Dust Storms (SDS): Types, Characteristics, and Indications

Sand and dust storms (SDS) is a common weather phenomenon in the Middle East. Topography and the northern or northwesterly wind are the main control factors for types of SDS trajectories. The main SDS corridors in the Middle East were classified and spotted from March 2000 to March 2017. The SDS can be classified in the region in accordance to shape and magnitude into three main types namely; Small with 3 subtypes (Arrow shape-straight, Arrow shape-curved and Needle like), Intermediate with 3 subtypes (Curved, Hook and Straight), and Extensive with 6 subtypes (Spiral, Agglomerated-Dense, Agglomerated-Dispersed, Wavy, Hook-Single head, and Hook-multiple heads). Most of the trajectories are located within the northeastern parts of the Middle East. Dust properties led us to sort SDS and their indications. Dust deposits in the eastern Mediterranean Sea and the Red Sea and are initiated from Northern Desert of Africa (NDA). On the other hand, dust deposits in the Middle East originate from NDA, Western Desert of Iraq (WD), Mesopotamian Flood Plain (MFP), Ahwaz (HZ), Ahwar (HR) and Baluchistan Desert (BSH). The deposited dust in coastal areas is categorized as trimodal particle size distribution, finer mean size fractions with higher values of particles surface area and contains more carbonates and less quartz percentages compared to fallen dust in inland regions which is dominantly initiated from Western Desert of Iraq (WD), Nafud Desert (NFD) and Empty Quarter (EQ)..

Groundwater Site Prediction Using Remote Sensing, GIS and Statistical Approaches: A Case Study in the Western Desert, Iraq

Combination of remote sensing data and geographical information system (GIS) for the investigation of groundwater has become an advance approach in the researches of groundwater. The purpose of this research is to apply statistical models such as Evidential Belief Function (EBF) and Logistic Regression (LR) for mapping groundwater potential sites at Iraqi western desert (located at Al-Ramadi and Shithatha). The potential of the groundwater areas were determined depending on the spatial relationship between groundwater wells and different conditioning factors. These factors include altitude, curvature, aspect, slope, soil, normalized difference vegetation index (NDVI), topographic wetness index, fault, rainfall, stream density, stream power index, and lithology. The algorithms were used to model all layers of groundwater conditioning factors to generate groundwater probability areas. Then, the final maps included five potential classes i.e., very high, high, moderate, low and very low susceptible zones were generated. The final outcomes were validated using Area Under the Curve (AUC) algorithm. The values of success rates were 76.5% and 71.5% for EBF an LR respectively. The prediction rates for the same methods were 73.7% and 70%, respectively. The thematic maps attained from the present study indicated the capability of EBF and LR methods in groundwater potential mapping.

Experimental Investigation about the Parameters that Effect on Evap-oration from Sub-storage Reservoir

Management of water resources become one of the most important subjects in the human's life. The water sustains life on earth, therefore; more care for water management is necessary. In the last years, studies show water use will be more in the world as result of rapid increase in population, industrialization, and urbanization etc. The evaporation losses from dam's reservoirs and lagoon form very huge losses in water resources. The annual evaporation depth losses in Iraqi Western Desert is about (2.25 -3) meter, this depth store the highest percentage of the small dams. Sub-surface storage reduces evaporation losses and maintains water quality by minimizing salt concentration. In present study, three tanks are used to simulate the subsurface reservoirs to study the effectiveness of underground storage on reducing the evaporation loss. Each tank have squares cross section tanks of (80) cm length and (40) cm depth and filled up to (34) cm with different graded soil (labeled as A, B with coarse soil, and D with fine soil) to simulate the storage below the ground. While the forth tank filled with water (labeled as C) to represent the reservoir of direct evaporation for comparison study. The present study considers three parameters that can controlled the evaporation from subsurface reservoirs: (a) temperature variation, (b) water table variation, and (c) material properties such as porosity. The field study continues for four months, it was started at Jun.11, 2016 and ended at Dec. 15, 2016 in the Erbil city at north of Iraq. The results showed evaporation losses are reduced by using subsurface storage reservoir with gravel in comparison with free surface evaporation. The evaporation losses are reduced about 46 % , 39% , 64% when the water table below gravel surface range from 5 to 10 cm , while at 20 cm depth of the water table the evaporation reduction is about (85 % to 86% 95%) from A, B and D tanks with porosity 0.65 ,0.67 and o.35 for A ,B and D tanks, respectively..

Optimum Groundwater Pumping Rate in Safwan-Zubair Area, Basrah Province, Using Simulated Annealing Technique

Safwan-Zubair area is located in the south –west part of Basrah Province in the south of Iraq, this area is involved within the Dibdibba plain which is considered as a part of Iraqi Western Desert. Dibdibba formation consists mainly from sand and gravel with some cementing materials like silt and clay, especially in the west of Zubair area. A linked simulation-optimization model for obtaining the optimum pumping rate of groundwater is presented in this paper. Processing Modflow for Windows (PMWIN v.5) is selected to simulate the aquifer behavior being studied. This model is integrated with an optimization model which is based on the simulated annealing (SA) technique. The calibrated values of hydraulic conductivity vary over the range (15-150) m/day; while, the calibrated values of specific yield vary over the range (0.125-0.45). The objective function converges to a maximum value of (0.636925E+8 m3/year). The percentage ratio of inactive wells is 10.9 %, many wells in the study area that occupy incorrect positions, these wells must be turn off for obtaining optimum pumping rate in the study area.

Mapping groundwater quality Index for irrigation in the Dibdibba aquifer at Karbala - Najaf plateau, central of Iraq

Mapping groundwater quality Index for irrigation is of great importance for agricultural issues. As groundwater is a vital source of water for domestic and agricultural activities in Iraqi Western Desert area, where the study area (Dibdibba aquifer) represents the extreme eastern part of it, evaluation of groundwater quality and its suitability for irrigation is important. This study aims to develop decision support tools for identifying the optimal locations of groundwater regarding its quality to meet the future demands of the study area. Samples were collected during the wet season (April-May 2017 (and analyzed for determining the physicochemical properties. The indices used in the quality assessment were the sodium adsorption ratio (SAR), sodium percentage (%Na+), magnesium hazard (MH), and irrigation water quality index (IWQI), incorporating the spatial variation using the GIS-based multi-criteria system highlighted the spatial variation of groundwater quality for irrigation in the study area. This spatial distribution indicated that groundwater is generally of moderate quality in the Dibdibba aquifer.

A GIS-based approach for identifying potential sites for harvesting rainwater in the Western Desert of Iraq

People living in arid and semi-arid areas with highly variable rainfall and unforeseeable periods of droughts or floods are severely affected by water shortages and often have insecure livelihoods. The construction of dams in wadies to harvest rainwater from small watersheds and to induce artificial groundwater recharge is one of the solutions available to overcome water shortages in the Western Desert of Iraq. The success of rainwater harvesting (RWH) systems depends heavily on their technical design and on the identification of suitable sites. Our main goal was to identify suitable sites for dams using a suitability model created with ModelBuilder in ArcGIS 10.2. The model combined various biophysical factors: slope, runoff depth, land use, soil texture, and stream order. The suitability map should be useful to hydrologists, decision-makers, and planners for quickly identifying areas with the highest potential for harvesting rainwater. The implementation of this method should also support any policy shifts towards the widespread adoption of RWH.

Beneficiation of Low Grade Calcium Bentonite Claystone

The beneficiation of Ca-bentonite claystone has been studied with dispersion sedimentation technique using polyionic salts as dispersant.The claystone is located in the Western Desert of Iraq. It is of a low grade, associated with different amount of clay and non-clay mineral impurities. Calcite (CaCO3) constitutes the major proportion of these impurities. Various parameters; solid concentration, dispersant amount (e.g. sodium tripolyphosphate, and tetrasodium pyrophosphate), conditioning time, and centrifugal sedimentation speed and time on the efficiency of the beneficiation process were investigated and followed through the measurement of CaO% and cation exchange capacity (CEC) values of the upgraded claystone concentrate. Centrifugal sedimentation were tested to separate the impurities from the clay suspension. Design experiments by Taguchi method, orthogonal array L16, was used for optimizing the different process parameters of the beneficiation process. Experiments were conducted at different solid concentrations (1, 3, 5, 7) wt.%, dispersion agent amount (0.2, 0.4, 0.6, 0.8) wt.%, conditioning time (5, 10, 15, 20) min, centrifugal sedimentation speed (500, 600, 700, 800) rpm, and centrifugal time (5, 10, 15, 20) min. The optimum beneficiation conditions obtained from the experimental work are, 7 wt.% solid concentration, 0.8 wt.% of dispersant, 15 min conditioning time attachment of the dispersant agent with the bentonite slurry, 800 rpm centrifugal speed, for 10 min time. Under studied condition, tetrasodium pyrophosphate showed better output t for achieving good beneficiation of bentonite clay from dilute crude slurry.

A preliminary assessment of the geochemical factors affecting groundwater and surface water quality around the rural communities in Al-Anbar, Western Desert of Iraq

This study aims to assess the suitability of surface water and groundwater resources for irrigation and potable use by the rural communities in the Western Desert of Iraq. Sampling was conducted during the wet season (Jan 2012). Duplicate water and sediment samples were collected from the Euphrates River, connate water springs and meteoric groundwater. Water samples were analyzed for a suite of physicochemical parameters and heavy metals (Fe, Cu, Pb, Co, Cd and Ni). The H2S content of water samples was also determined as were heavy metals levels in riverine sediments. The water in the Euphrates River is fresh (701 ppm) dominated by Ca–Na–Cl ions with elevated concentrations of PO4, Pb and Cd (2.0, 0.023 and 0.02 ppm, respectively) due to the effects of agricultural land uses in the region. Shallow groundwater in the region is fresh to brackish due to the water–aquifer interaction that resulted in heterogeneity groundwater dominated by Cl, Ca–Mg–Cl and Ca–HCO3. Connate water springs in the region are associated with deep circulation of groundwater. Springs are characterized by brackish to saline water type dominated by Na–Cl and typically have acidic pH values. They are not suitable for irrigation or potable use due to the high TDS (7182 ppm) and dissolved H2S gas contents (120–865 ppm). Low concentrations of H2S gas (4.0 ppm) were detected in the Euphrates River, while they were not detected in the meteoric groundwater. The meteoric waters from the Euphrates River and some groundwater wells are suitable for potable use, but all are suitable for irrigation with attention to the potential-Mg hazard.

Application of Monte Carlo Simulation to Find Travel Time of Groundwater in the Iraqi Western Desert

In this study, a computerized mathematical method represented by Monte Carlo simulation was used to predict the travel time of the groundwater flow in the Iraqi western desert. During the run of the simulations, all the hydraulic parameters of Darcy’s Law were fixed but the hydraulic conductivity. The input data of the hydraulic conductivity is compared to the triangular distribution function to find the best number of iteration to run the simulations. The results showed that an iteration number of 5000 was enough to achieve best match between the input data of the hydraulic conductivity and the fitted distribution function. In addition, the estimated travel time of the groundwater flow is broadly varied through the entire area and ranges from 1983 years to 113 741 years based on 10 000 m of travel distance. Furthermore, hydraulic conductivity of the aquifer has high impact on the estimated travel time of the groundwater flow. However, head difference of groundwater elevation among the selected wells considerably influences the expected travel time of the groundwater flow.

THE SPOTTED SANDGROUSE, PTEROCLES SENEGALLUS (LINNAEUS, 1771) AS A NEW HOST FOR THE SPIRURID NEMATODE HARTERTIA GALLINARUM (THEILER, 1919) IN IRAQ

In this work, the spirurid nematode Hartertia gallinarum was reported in the intestine of the spotted sandgrouse, Pterocles senegallus, collected in three different locations: Ga'ara Depression, Iraqi Western Desert, Zurbatiyah and Al-Attariyah, Middle of Iraq. Description and measurements of the nematode were given. The role of termites in the infection of P. senegallus with H. gallinarum was discussed. Occurrence of H. gallinarum in P. senegallus represents a new host record.

Optimization of area–volume–elevation curve using GIS–SRTM method for rainwater harvesting in arid areas

The major limitation in planning water harvesting is the lack of knowledge in the estimation of surface area and storage volume at any depth of dam reservoir. The area–volume–elevation (AVE) curve of a reservoir plays a key role in estimating the most suitable depth, optimum surface area and highest capacity of reservoir storage. The existing methods to estimate the AVE curve are costly and time-consuming and require laborious work. This study attempts to develop a method to optimize the AVE curve for earth dams, using the digital elevation model generated by the Shuttle Radar Topography Mission (SRTM) data, and integrate it with the geographic information system (GIS), known as the GIS–SRTM. The proposed method was tested using field data in the Western Desert of Iraq, which is an arid environment. Three constructed small earth dams were selected for this study. The AVE curves were extracted for Horan 2 (H2), Al-gara 2 (G2) and Al-gara 4 (G4) earth dams. Comprehensive analyses have been carried out to evaluate the performance of the AVE curves using the proposed GIS–SRTM method and the field data. From the comparison, the proposed GIS–SRTM method was able to produce reliable AVE curves with a relative error less than 20%. Additionally, the proposed method was less time-consuming and the AVE curves can be visualized immediately. The proposed GIS–SRTM method is relatively supportive in analyzing spatial data to select the optimal site for rainwater harvesting and prevent excessive evaporation losses.

The thickness of cover sequences in the Western Desert of Iraq from a power spectrum analysis of gravity and magnetic data

The Western Desert of Iraq is part of the stable shelf region on the Arabian Plate where the subsurface structural makeup is relatively unknown due to the lack of cropping out rocks, deep drill holes and deep seismic refraction and reflection profiles. To remedy this situation, magnetic and gravity data were analyzed to determine the thickness of the Phanerozoic cover sequences. The 2-D power spectrum method was used to estimate the depth to density and magnetic susceptibility interfaces by using 0.5° square windows. Additionally, the gravity data were analyzed using isostatic residual and decompensative methods to isolate gravity anomalies due to upper crustal density sources. The decompensative gravity anomaly and the differentially reduced to the pole magnetic map indicate a series of mainly north-south and northwest-southeast trending maxima and minima anomalies related to Proterozoic basement lithologies and the varying thickness of cover sequences. The magnetic and gravity derived thickness of cover sequences maps indicate that these thicknesses range from 4.5 to 11.5km. Both maps in general are in agreement but more detail in the cover thicknesses was determined by the gravity analysis. The gravity-based cover thickness maps indicates regions with shallower depths than the magnetic-based cover thickness t map which may be due to density differences between limestone and shale units within the Paleozoic sediments. The final thickness maps indicate that the Western Desert is a complicated region of basins and uplifts that are more complex than have been shown on previous structural maps of the Western Desert. These basins and uplifts may be related to Paleozoic compressional tectonic events and possibly to the opening of the Tethys Ocean. In addition, petroleum exploration could be extended to three basins outlined by our analysis within the relatively unexplored western portions of the Western Desert.

Mineralogy, geochemistry, and ore formation of Nuwaifa bauxite deposit, western desert of Iraq

Nuwaifa Formation is a part of sequence stratigraphy that belongs to the Jurassic system exposed in the western desert of Iraq. The Jurassic system consists of Ubaid, Hussainiyat, Amij, Muhaiwir, and Najmah formations. Each formation is composed of basal clastic unit overlain by upper carbonate unit. Nuwaifa karst bauxite was developed in fossil karsts within the Ubaid Formation in areas where maximum intersection of fractures and faults exist. This bauxitization process affected the upper surface of the Ubaid limestone formation, which directly underlies the Nuwaifa bauxite Formation. Nuwaifa Formation represents karst-filling deposit that consists of a mixture of allochthonous (sandstone, claystone, and mudstone) and autochthonous lithofacies (bauxite kaolinite, kaolinitic bauxite, iron-rich bauxite, and flint clay). Most bauxite bodies occur within the autochthonous lithofacies and are lenticular in shape with maximum thickness ranges from few meters to 35 m and in some place up to 100 m. Petrographically, the bauxite deposit exhibits collomorphic-fluidal, pisolitic, oolitic, nodular, brecciated, and skeletal textures indicative of authigenic origin. Mineralogy boehmite and gibbsite are the only bauxite minerals; the former is dominant in the upper parts of the bauxite profiles, whereas the latter is dominant throughout the lower and middle part of the bauxite. Kaolinite, hematite, goethite, calcite, and anatase occur to a lesser extent. The study bauxites are mainly composed of Al2O3 (33–69.6 wt.%), SiO2 (8.4–42 wt.%), Fe2O3 (0.5–15.9 wt.%), and TiO2 (0.7–6.1 wt.%) with LOI ranging from 13.5 to 19.1 wt.%. Geochemical investigations indicate that the immobile elements like Al2O3, TiO2, Cr, Zr, and Ni were obviously enriched, while SiO2, Fe2O3, CaO, MgO, Zn, Co, Ba, Mn, Cu, and Sr were depleted during bauxitization process. The results of this study strongly suggest that the bauxite deposits of the Nuwaifa Formation are derived from the kaolinite of the Lower Hussainiyat Formation.

Stratigraphic Correlation between Subsurface Maastrichtian Digma Formation and Safra Unit from Outcrop Sections, Western Desert of Iraq

In this work we try to clarify, and correlate between two Maastrichtian aged units, namely Digma and Safra Units from selected sections in western desert of Iraq. Taking in consideration the stratigraphic code of NASCENT (2005), and the results of previous studies, nine criteria have been used for the correlation, as follow: 1- From lithostratigraphic point of view, Digma Formation (Fm.) mostly composed of dark grey to blackish gray, uniform Carbonates-dominated facies, while Safra unit is characterized by light yellowish brown mixed phosphatic- siliceous-siliciclastics and carbonates facies. 2- Digma Fm. is characterized by Benthonic foraminifera assemblages (Bulimmina sp., Siphogerinoides sp. & Bolivinoides sp. ), while Safra phosphatic unit is flourished by macrofossils assemblages and vertebrates (Oyster, fish teeth’s and bones). 3- The upper and lower boundaries of the Digma Fm. are conformable, and vice versa for Safra Unit. 4- Illite/Semctite mixed layers-Illite clays assemblage and Glauconitic are predominates in Digma Fm., while Sepiolite-palygorskite-Montmorillonite, are common in Safra Unit, without any Glauconitic mineralization. 5- Digma Fm. slightly influenced by neomorphism and micritization. On other hand, Safra facies extremely influenced by phosphatization, silicification, dolomitization, and neomorphism and carbonate-silica replacement of the original evaporate minerals. 6- The predominated foraminiferal wackestone and mudstone microfacies, within Digma facies associations, mostly indicate deep trough marine condition (Anah Graben). The mixed phosphatic-carbonates (Oyster coquina band) and siliciclastics facies, (occasionally cross laminated), mostly deposited in shallower water depth, on the Arabian platform and distal steepened ramp towards Rutba flanks. 7- Sequence boundary of type one and three is bounded the Safra Unit respectively from upper and lower parts. 8- Continuously deposited Sequence was detected from the parasequences of the Safra facies, and across Maastrichtian/Danian boundary (Trafawi Unit). 9- The paleo-configuration of the basin almost influenced by the reactivity of the Anah basement faults started in the Late Campanian, and combined by shallowing upwards sequences. The conclusion is that, Digma facies can be considered as local facial changes of the Shiranish Formation, while Safra unit can be considered as a lower Member of (L. Maastrichtian-Danian) Jeed Formation, which is coincides with the whole stratigraphic frame work of the Mediterranean segments of the Tethyan phosphatic realm.

Assessment of Carbonate Rocks , Western Desert of Iraq as Dimension Stones for Building

Carbonate Rocks | Dimension Stones| Western Desert of Iraq | Physical and Mechanical Properties | ASTM | الصخور الكاربوناتية | الصخور البعدية | الصحراء الغربية العراقية | الخواص الفيزيائية و الميكانيكية | المواصفات الأمريكية لاختبار المواد

Suitability of groundwater of Dabaa region –Iraqi western desert for agricultural use

The study included evaluating water ten wells in the area Dabaa within the western region of Iraq for agricultural use, as has been the study of water quality of these wells during the year by conducting a full analysis of water samples and assess suitability for irrigation depending on the standard specifications of the Food and Agriculture Organization. As the analysis results showed that all the studied wells located within the water of light to moderate in terms of the seriousness of Electrical conductivity if used for irrigation, and sodium adsorption ratio values for all water wells studied were within the Has no influence soil permeability. It turned out that the Toxic Effect of these water plants were mild to moderate effect for sodium either chloride was degree selection of non-toxic to light moderate, and that the use method Piper for the classification of water showed that it quality predominantly Na+, Mg +2, Ca+2 - Mg+2 , Ca+2 for positive ions and water quality sulphurous HCO3-, SO4 = predominantly basal in terms of negative ions.

Evaluating the suitability of some of the water wells in the Al- Rutba area for human use within the Western Desert of Iraq

Evaluating the suitability of some of the water wells in the Al- Rutba area for human use within the Western Desert of Iraq

Heavy mineral concentrations in the sandstones of Amij Formation with particular emphasis on the mineral chemistry and petrographic characteristics of monazite, western desert of Iraq

The heavy minerals in the clastic unit of the Lower Jurassic Amij Formation exposed in the western desert of Iraq were studied. The uppermost part of the clastic unit contains thin, placer-like black sandstone horizons that are radioactive and abnormally rich in heavy minerals (0.6–56%), dominated by opaque (65%) and transparent (35%) heavy minerals. The minerals, in the order of decreasing abundance are pseudorutile, goethite, zircon, hematite, magnetite, monazite, rutile, leucoxene, tourmaline, ilmenite, chromite, and few others. Electron probe microanalysis (EPMA), microscopic and autoradiographic observations and analysis showed that the monazite is monazite-(Ce) type with an average composition of (Ce0.39Nd0.16La0.19Pr0.04Sm0.02Gd0.02Eu0.01Y0·04Th0·06U0·01Ca0·05Fe0.01)(P0·98Si0.03)O4.Monazite consists predominantly of REE-oxides (57.93%) and P2O5 (29.31%), with minor amounts of ThO2 (6.60%), Y2O3 (1.92%), UO2 (0.76%), CaO (1.14%), SiO2 (0.69%), and FeOt (0.17%). The dominant compositional substitution operating between REE and P were a mixture of the complex cheralite type substitution ([REE]−2 [Th][Ca]) and the coupled huttonite type substitution ([REE]−1 [P]−1 [Th][Si]). The chondrite-normalized REE distribution patterns of monazite show enrichment in LREE with positive Eu- and Pr-anomalies of 1.46 and 9.13, respectively. The median values of (La/Sm)CN and (La/Nd)CN ratios are 4.35 and 1.97, respectively. Zircon which is the dominant transparent mineral is Hf-rich that is composed of 30.61% SiO2, 57.58% ZrO2, 7.03% HfO2, 2.04% Y2O3, 0.56% ThO2, 0.19% UO2, and 0.19% Al2O3 corresponding to a formula (Zr0.909Hf0.065Th0·004U0·001Y0.031)Σ1.011(Si3·966Al0.028)Σ0.999O4. Rutile and tourmaline form 7% and 4% of the heavy minerals. Ilmenite which is one of the predominant heavy minerals forms 2.5% of the opaques because it is pervasively altered to Ti-Fe oxides. In addition of zircon and monazite, the chemical compositions of most of the other heavy minerals are also given in this study. The expected dominant source of heavy minerals and their host sandstones are most probably the felsic igneous and metamorphic complexes of the Arabian Shield, currently located ∼600 kms to the south of the studied area. The heavy minerals were carried from the source area by northward moving rivers and sorted out by ocean waves as black sand concentrations at the delta mouth along the southern beaches of the Neo-Tethys Ocean under passive margin tectonic setting. This border was apparently bordering the current western part of Iraq during Upper Jurassic period.

Estimation the Physical Variables of Rainwater Harvesting System Using Integrated GIS-Based Remote Sensing Approach

Geographic Information System (GIS) are an intelligence technique skilled to extract, store, manage and display the spatial information for various applications of water resources management. Practically, arid and semi-arid environments suffer from several restrictions (e.g., lack of socio-economic and physical data, limited precipitation, and poor rain water management). In this research, Remote Sensing (RS) approach was integrated with GIS conducted to estimate the physical variables of reservoir system (i.e., elevation-area-volume curve). First and foremost, computing an accurate and reliable elevation-area-volume curve is a challenging task for the purpose of identifying the optimal depth, minimum surface area and maximum reservoir storage. Accordingly, a field study consisting of three constructed small earth dams were demonstrated the use of the geospatial approach in the western desert of Iraq, where the elevation-area-volume curve was extracted. The surface areas and the reservoir volumes that were obtained from field survey and spatial intelligence techniques were compared. A comprehensive analysis have been carried out for the evaluation purposes. The results indicate that the proposed approach efficiently applied with remarkable level of accuracy.

A comparative study between the depositional environment and provenance of the Hussainiyat (Lower Jurassic) and the Rutbah (Upper Cretaceous) Formations, Western Desert of Iraq

This work deals with the sedimentology of the Hussainiyat Formation (Lower Jurassic) and Rutbah Formation (Upper Cretaceous) in the Western Desert of Iraq with special emphasis on their depositional environments and nature of their source rocks. These formations are particularly chosen since they belong to different episodes, which are before (Hussainiyat Formation) and after (Rutbah Formation) the late Kimmerian deformation phase. Both units comprise supermature sandstone and contain a fairly similar suite of heavy detrital accessories (almost ultrastable minerals only). Such nature of the clastics impairs the identification in the usual methods, commonly carried out by sedimentary petrologists, although petrographic textures of quartz sand grains and the polycrystalline quartzitic pebbles are found useful. Five sections were described from both formations, and a total of 58 sandstone samples were collected, in addition to 153 gravel samples. The Hussainiyat Formation represents the classic model for high-sinuosity (meandering) river system, and the Rutbah Formation represents deposition in low-sinuosity (braided) river system resembling Platt-type model. Paleocurrent analysis of the Hussainiyat sandstones showed a southeasterly flow, and the Rutbah sandstone showed a northeasterly flow. Provenance analysis of the Hussainiyat and Rutbah Formations showed that they have different sources. Petrographic analysis of the quartz sand grains and the heavy minerals indicates derivation from sedimentary rock and plutonic or medium- to high-rank metamorphic rocks, but there is a marked difference between the percentages of the constituents in each formation. The textural features encountered in the majority of the studied pebbles characterize low-grade metamorphic rocks, and the statistical procedure (ANOVA) used shows that they have been derived from two different sources. Petrofacies studies show that the tectonic setting of the provenance area of both sandstones is craton interior of the continental block.