Iraqi Bulletin of Geology and Mining

The Upper Jurassic Naokelekan Formation is mainly composed of organic calcareous shale with some limestone and dolomite. According to the lithology of the formation in two selected sections, three units can be identified as follow, from bottom to top: a) soft, black, fissile, and highly bituminous, calcareous shale and thin-medium bedded, dark brown, bituminous limestone and dolomitic limestone, b) hard, fine-grained, highly mottled and stylolitic, fossiliferous, dark grey, medium-thick bedded limestone and dolomitic limestone, c) fissile, soft black, calcareous, medium-grained, fetid shale and dark grey, hard, dolomitic and argillaceous medium grained limestone. The microfacies include Lime-Mudstone, Lime-Wackestone and Lime-Wackestone/ Packstone. The Benthic (Miliolid) and pelagic (Globigerina) foraminifera, ammonites, ostracods, pelecypods, gastropods and calcispheres of various sizes are the most common skeletal grains, while peloids are the main non-skeletal grains. Based on lithology and microfacies analysis, the formation was deposited in two different sedimentary environments including lagoon (subtidal) environment for the lower and upper units and shallow marine environment for the middle unit. The upper contact with the Barsarin Formation and lower contact with the Sargelu Formation are gradational and conformable.

The Mawat ophiolite Complex, with an exposed surface area of ~235 Km2, is one of the largest ophiolitic segments in the Zagros Imbricate Zone in Iraq of the main Zagros ophiolite belt. The ultramafic portion is studied in this paper to verify petrogenetic nature, occurrences and mineral constitutes of the dunites in the Mawat Ophiolite Complex. The dunites in Mawat ophiolite can be grouped into cumulate and tectonite based on the field observations, petrographic study and mineral chemical data of the constituents and stratigraphic succession. The lower tectonite member of the Mawat ophiolite is mainly composed of harzburgite-dunite association and the upper cumulate member is composed of dunite, cross cut by clinopyroxenite veins. The lower tectonite dunite shows typical characteristics of alpine-type II dunite which is characterized by metamorphic deformed rocks with a strong deformed fabric. These rocks have been subjected tosepentinization, spherical weathering, spinel alteration and chloritization of the dominant mineral phases. The upper cumulate dunite comprises the top summit of Mawat Ophiolite Complex. The rock is coarse crystalline massive highly fractured in the outcrop and shows granular mosaic texture in thin sections. The petrographic study shows that the cumulate dunite consists of primary mineral assemblages of olivine (black and green) + pyroxene (cpx and opx) + chromian spinel. No evidence of secondary alteration and metamorphism observed in hand samples and thin section, which may be attributed to crystallization in hydrous magmatic condition at crust-mantle boundary. As it was crystallized in equilibrium conditions with H2O rich fluid, thus would be stable during emplacement and exposure on the earth surface and unsusceptible to water to convert it to serpentine. Chromian spinels in dunites from Mawat ophiolite retain the peculiar major element signature of boninite melt and upper mantle peridotite, which are involved in the formation of cumulate and tectonite dunites in Mawat ophiolite respectively. Olivine and spinel from cumulates dunites have compositions in the range Fo 90 – 92 and Cr#0.81 – 0.82, whereas the same minerals in tectonite dunintes have compositions Fo 91 and Cr# 0.62 – 0.63. The black colored olivine in cumulate dunite may attribute to occurrences of minute inclusions of spinel + diopside, in addition to low Fo 90 – 91, MnO and NiO as compared to green olivine generation.

The study area covers about 5600 Km2 comprising three main watersheds; Torsaq, Shosharin and Badrah. It is built up of sedimentary formations (Oligocene – Pliocene) beside various types of Quaternary sediments. Different morphometric parameters are computed in this study using Geographical Information system (GIS) and Remote sensing techniques through the ease of uses of high resolution Digital Elevation Models (DEMs). The highest stream order of the studied basins is 6th order. The drainage density analysis indicates medium value suggesting coarse to moderate drainage texture. The values of bifurcation ratio range from 2.2 to 11. The values of form factor and circulatory ratio indicate that the studied basins are elongated in shape. According to dissection index value, the overall basins are moderately dissected; however the upper parts of the basins, which are located within the Zagros Fold-Thrust Belt, are characterized by their high tectonic activity, whereas their lower parts, located within the Mesopotamian Zone, are characterized by low tectonic activity.

A geophysical remote sensing obstruction and debris survey is performed in this work to investigate and describe the shipwrecks and submerged debris at Shatt Al-Arab River in the extreme southern part of Iraq. The study area is extended in a section of Shatt Al-Arab River from Ashar to Siba cities – Basra governorate-Southern Iraq, with approximately 60 Km distance. Side Scan Sonar (SSS) and Sub-Bottom Profiler (SBP) techniques were applied. Seventeen distinct locations were identified that containing numerous objects on the river bottom, however, eleven of them ware correlated with reflections by SBP, included vessels, boats (medium and small sizes), tankers and bridge, as well as some unidentified debris. A total of 25 sonar targets wrer mapped. Two detected targets were found to have indicative signatures of an ancient shipwreck. The most identified objects are the charted shipwreck located near the Maaqal quay northern the study area. Most of the targets are localized in the northern part of the study area particular vicinity of the Basra city center on the river banks in which mostly human activities and old functional port were established. The most number of these wrecks which completely or partially submersible were Pontoon boats or small tanks, that have about 40 meters long and 8 meters wide.

The study area is located in the Kuradawe village, 30 Km NE of Sulaimania City, in the east of the Kurdistan Region. The sulfide mineralization in the Kuradawe area is hosted by gabbro of the Mawat ophiolite. The petrographic study shows that the metagabbro has various microdomains, which contain different amphiboles and plagioclase. This indicates that the original magmatic rock and minerals were influenced by metamorphic overprint. The mineral assemblage of the metagabbro is represented by white amphibole, green amphibole, plagioclase, chlorite, quartz, epidote, pyrite, chalcopyrite, goethite and hematite. The metamorphic history can be subdivided into three stages (M1, M2, and M3). The first stage of metamorphism is recorded by the formation of green amphibole (tschermakite) replacing clinopyroxene. The second stage shows a decrease of temperature and pressure which resulted in the formation of white amphibole (tremolite); growing on the previous amphibole. While the late stage of metamorphism is recorded by the formation of chlorite and epidote. Three stages of mineralization are concluded from ore microscopic study: orthomagmatic stage, hypogene stage and supergene enrichment stage. Pyrite and chalcopyrite represent the main primary sulfide ore minerals. Hematite and goethite are the secondary ore minerals occurring as alteration products of the primary ore minerals. The δ34S values of the sulfides range from + 7 to + 9 ‰, which indicate granitic composition for the mineralized fluids.

One of the most expressive and well documented oceanic anoxic events; the OAE 2, is preserved at the Cenomanian/ Turonian boundary in the Pecínov section of the Bohemian Cretaceous Basin in the Czech Republic. This study aims at recording and discussing the impact of this oceanic anoxia on some potential redox parameters in the sediments of this event. It is focused on the behavior of redox-sensitive chemical elements, stable carbon and sulfur isotopes and type of fossil bacteria in the black marine mudstones and phosphate nodules deposited during the OAE 2. The results show variable concentrations of redox-sensitive elements relative to average shale, negative values of δ13C in CO3-apatite and δ34S in pyrite in addition to dominant sulfur-reducing fossil bacteria. The mudstones are depleted in organic carbon and hence some trace elements (e.g., Cd, Zn, Cu and Co), usually associated with organic matter, are not significant as redox indicators in the case studied. The most prominent geochemical indicators of anoxia are expressed in the elevated Ce-anomaly and Ce/La ratio, and depleted Mn concentrations found in all samples, with the phosphate nodules holding the highest anoxic indicators. The stratigraphic correlation of geochemical redox parameters with the δ13Corg curve at the Pecínov section shows general compatibility with some exceptions; two δ13Corg excursions have their signature in some geochemical redox indicators. The OAE 2 section at the Pecínov quarry represents an extreme case of reduced concentrations of organic carbon and most redox-sensitive elements relative to other OAE 2 sequences in Europe and the Atlantic Ocean, which can indicate frequent oxygenation events caused by sea-level fluctuation during deposition, marked by bioturbated surfaces.

Representative samples from the investigated kaolin clay at the Ga'ara Depression, Iraqi Western Desert, are assessed in the present work for various industrial applications. Mineralogical, physical and chemical analyses are carried out. The main clay mineral present is kaolinite with occasional traces of illite. The main non-clay admixtures present are quartz, iron oxyhydroxides, anatase and organic matter. Particle size analysis showed that eight deposits are very fine c1ays, three deposits are fine, six deposits are medium and two deposits are coarse clays. The kaolin clays are of various brightness and whiteness, but mostly they are off-white. Ten deposits are plastic and nine of them are super-plastic clays. Silica and alumina are the main constituents. Iron and titanium oxides are present in significant amount whereas the total alkalis are generally low. Nine of the clay deposits are fat, six are moderately fat and four are lean. Although the quality of all white clays can be improved by some processing, nine deposits are sufficiently of high quality to be used after minimal beneficiation in the manufacture of paper, paints, rubber and plastics. In addition, after calcination, some of the samples become suitable for the above end uses. Each of the investigated clay deposit is suitable for use in ceramic manufacture whereas only nine of them are sufficiently high in alumina to be used for the manufacture of chamotte refractories.

To assess the paleoecology of the Ostracoda and their significance as paleoenvironmental indicators in the Fatha Formation (Middle Miocene), eighteen samples are collected in this study from one section located in the Hammam Al-Alil area, northern Iraq. Thirty Ostracoda Species belonging to (16) genera are described, of which (14) species are previously described from Iraq and other regions; twelve species most probably represent new forms, whereas the rest (4) species are left for open nomenclature due to the lack of material. Based on the habitat of the investigated Ostracoda species and their paleoecological significance, in terms of depth, salinity, temperature, oxygen and substratum, it is suggested that the sampled part of the Fatha Formation sequence was deposited in a semi-closed shallow basin under high, brackish to normal salinity and normal oxygen concentration, with some indications of oxic environment, suggested by the occasional change of the shells color. Based on the results of the present study, the Fatha Formation in the studied section can be divided into two Ostracoda Assemblage Biozones. The first is Cytherelloidea sp.1 Assemblages Biozone, and the second is Dentokrithe indica Assemblages Biozone.