Iraqi Bulletin of Geology and Mining

The Dammam Formation in S and SW of Iraq is an Eocene carbonate succession consisting of limestone and dolostone. Two boreholes are selected in Al-Najaf area to investigate its biostratigraphy. The biostratigraphy of Dammam Formation consists of 22 species belonging to 13 foraminiferal genera.
Two biozones are distinguished in Dammam Formation depending on the benthonic foraminiferal genus Nummulites. Those biozones are Nummulites gizehensis range zone and Alveolina sp. – Coskinolina sp. assemblage zone. According to those biozones the age of Dammam Formation is considered to be of Middle Eocene, whereas the absence of those biozones represents Lower and Upper Eocene.

Various diagenetic processes have affected the Rus and Dammam Formations of Eocene age. These include dolomitization, dedolomitization, neomorphism, micritization, dissolution, cementation and silicification. In the present study the prominent and distinguished diagenetic process that influenced the rocks of the studied boreholes is the silicification. The petrographic examinations confirm the presence of three main types of silicification including selective, pervasive and minor. The selective silicification is the most common type in the Rus Formation as pore- filling cement after dissolution of sulfates while in the Dammam Formation occurs primarily as replacement material and as late diagenetic void-filling quartz. The pervasive silicification occurs within the Dammam Formation particularly in the middle part where both matrix and bioclasts are completely silicified. Minor silicification only affects echinoderm plates in the Dammam Formation. The petrographic study of the subsurface rocks show that the silicification of the Rus Formation and few rocks of the Dammam Formation occur in meteoric environments as the silica replaced sulfates while the silicification of the Dammam Formation occur within a mixs zone environment where meteoric water, which is the carrier of silica, mixed with marine water producing a solution supersaturated with silica and undersaturated in calcite.

The main objective of this study is to map of the groundwater quality irrigation index (IWQI) in the western part of Iraq for the purpose of determining ideal locations for groundwater quality, to meet the demand for water in the future. To achieve this purpose, 84 wells distributed in the study area have been sampled. The collected samples analyzed chemically for varies parameters that affect to the irrigation water quality. These chemical parameters are Electrical Conductivity (EC), Na+, Cl-, HCO3- and calculated sodium adsorption ratio (SAR). These chemical analyses have been transferred to the platform of geographic information systems (GIS) to create water quality database including spatial distributions map for each parameter using the inverse distance interpolation technique (IDW). These parameters were used to calculate the values of Irrigation Water Quality Index that have been moved to the platform of GIS for the production of IWQI map. The results show that small part of the study area belong to Low Restriction (LR) categories for irrigation water and about 50% of the groundwater samples belong to Moderate Restriction (MR) category. The results also showed that 28% of the groundwater covering 39 Km2 falls within the High restriction (HR) category while 20% of studied water samples classified as Sever Restriction (SR). Accordingly, this groundwater is only suitable to use with high permeability soils, which have the ability to tolerate high content of salts.

To identify potable water in the city of Az-Zintan, Libya is achieved by the chemical analysis of different resources of drinking water supplied to Az-Zintan City. These resources are, rain water, groundwater and municipal water. This was carried out by subjecting twenty one groundwater samples, collected from twenty one selected sites, to comprehensive chemical analysis. Ten parameters have been considered for calculating the Water Quality Index (WQI) such as: pH, total hardness, calcium, magnesium, potassium, sodium, bicarbonate, chloride, sulphate, and total dissolved solids. Based on the computed water quality index values showed that the water that originates from rain is the most suitable for drinking and the water that originates from municipal water is unsuitable for drinking under normal conditions and therefore further action for salinity control is required.

The studied samples were collected from Butmah, Adaiyah, Mus, and Sargelu formations in Zab-1 Well which lies about 25 Km to the south of Kalak town, Erbil Governorate. The hydrocarbon potential parameters, including type and amount of bitumen and kerogen, and thermal maturity of eight samples were assessed using Rock-Eval pyrolysis techniques. In general, Sargelu Formation samples have PI values of 0.15 – 0.25 (average 0.19) and Tmax values varying between 422 °C and 431 °C (average 427 °C), indicating thermally immature to early mature oil. They can be considered as poor to fair source, where TOC (Total original Carbon) content ranges from 0.27 to 0.77 of percentage weight (average 0.48). The Mus, Adaiyah, and Butmah formations’ samples are considered to be poor source rocks with TOC content of 0.39, 0.64, and 0.44 wt. percentage, respectively.

Samples of Sargelu, Mus, Adaiyah, and Butmah formations contain kerogen types II, III, and mixture of types II and III indicating marine and non-marine organic matter derived mainly from algae and higher plants organisms suggesting oil and gas prone sources.

The study of the Euphrates River system from Qaem-Ameriyat Falluja was performed by regional spatial analysis of geological, structural, hydrogeological, hydro-metrological phenomena supported by geo-statistical analyses and concentration pattern fluctuation of hydrochemical information derived from regime observation in fifteen water pointes.

The hydrochemical processes in Euphrates River are determined, using the analysis results of 28 physo-chemical variables including major, minor ions, trace elements, acidity, hardness and electrical conductivity during 2008 water year. According to the combined interpretation among geological, hydro-metrological and hydrochemical phenomena, which indicate the final results of all environmental and geological effectiveness occurring on the rocks and sediments of the hydrologic basin; the hydrologic system of Euphrates River divided into three subsystem including Qaem – Haditha hydrologic system, Haditha – Ramadi hydrologic system and Ramadi – Ameriyat Falluja hydrologic system.