IRAQI BULLETIN OF GEOLOGY AND MINING
مجلة الجيولوجيا والتعدين العراقية
ISSN 1811 - 4539
اهداف ومجال النشر تعليمات النشر للمؤلفات البحوث المنشورة هيئة التحرير
STRATIGRAPHY OF THE OLIGOCENE – EARLY MIOCENE EXPOSED FORMATIONS IN SINJAR AREA, NW IRAQ
Sahira A. Karim, Varoujan K. Sissakian and Kifah N. Al-Kubaysi
Received: 03/ 03/ 2013, Accepted: 24/ 04/ 2014
Key words: Sinjar, Stratigraphy, Miocene, Oligocene, Serikagni, Iraq
(p. 1 – 28)
ABSTRACT
Sinjar Mountain is an outstanding structural and geomorphic feature in the northwestern part of Iraq. It forms a long anticline in which the oldest exposed rocks belong to Cretaceous age represented by Shiranish Formation. The exposed succession includes rocks of many formations, which range from Cretaceous to Late Miocene. The presence of Oligocene rocks, however, has been a matter of debate. The main aim of this study is to prove the presence or otherwise of the Oligocene formations in Sinjar anticline. To achieve that, the planktonic foraminifera of an exposed section, starting from the top of Jaddala Formation (Eocene), were utilized to interpret the biostratigraphy, and zonation of the sections.
The planktonic foraminiferal assemblages of the section were found to represent the Early Miocene (Aquitanian – Early Burdigalian) of Globigerinoides quadrilobatus primordius-Paragloborotalia kugleri Zone (N.4), Globoquadrina dihescens praedehiscens-Globoquadrina dehiscens dehiscens Zone (N.5), and Catapsydrex stainforthia-Catapsydrex disimilis Zone (N.6). Sparse fauna representing the Globigerina angulisaturalias-Paragloborotalia opima opima Zone (N.2) of Late Oligocene age, representing Ibrahim Formation, which is unconformably overlain by the Serikagni Formation. The Jeribe Formation of early Middle Miocene age of Globorotalia barisanensis Zone (N.9) overlies the Serikagni Formation; the contact is also marked by a major erosional unconformity.
The regional geology, including data from the drilled oil wells in the nearby areas, was also reviewed, in order to delineate the extension of surface and subsurface basin of the Oligocene rocks. Moreover, many recently published articles that suggest the presence of Oligocene formations in Sinjar anticline were argued and it was found that the exposed studied sections belong mainly to the Early Miocene Serikagni Formations, with presence of a few centimeters of Oligocene rocks only.
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RECONSIDERATION OF THE BOUNDARY OF THE SOUTHERN PART OF THE MESOPOTAMIA FOREDEEP OF IRAQ
Jassim M. Al-Bdaiwi
Received: 20/ 08/ 2013, Accepted: 09/ 07/ 2014
Key words: Mesopotamia, Tectonics, Iraq
(p. 29 – 41)
ABSTRACT
The tectonic setting of the southern part of Iraq is reconsidered on the light of the foreland concept. The nature of the regional gravity field, regional magnetic field and the Megaseismic Line 7 reflectors are inspected and integrated. The central gravity –magnetic high of Iraq (CGMHI), behaves tectonically, as a crustal flexing zone. The eastward continual tilting of post Gotniya (U. Jurassic) depositional basins resulted in gradual increase of time thickness (across Abu Jir Fault Zone) and begining at the flexural axis. The uniform continuity of the depositional cycles across Abu Jir Fault Zone denies the tectonic role of Abu Jir Fault Zone as a main boundary fault zone. During the Cretaceous and later history, the eastern part of Salman region behaves as a part of the Mesopotamia Foredeep. The study shows also that the boundary of the (CGMHI) with the Western Desert Gravity Low is associated with more profound fault zone. During the deposition of Chia Zairi and Kora China formations, slight syndepositional uplift at the western side of (CGMHI) could be detected. The (CGMHI) marks the crustal flexural zone; it is in congruence with the Foreland Basin Concept. The results of this study could help in a better comprehension of the tectonic framework of Iraq.
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CLASSIFICATION OF THE ALLUVIAL FANS IN IRAQ
Varoujan K. Sissakian and Mawahib F. Abdul Jab'bar
Received: 12/ 11/ 2013, Accepted: 13/ 03/ 2014
Kew wards: Alluvial fans, Bajada, Pleistocene, Iraq
(p. 43 – 67)
ABSTRACT
The Iraqi territory exhibits diverse topography in its different parts; from the extreme southeast, where the coastal area along the Arabian Gulf, passing northwards to the Mesopotamia Plain, and more north and northeast to hilly, low mountainous and high mountainous areas, respectively. Whilst towards west, the plateau of the Southern and Western Deserts exist and in the northwestern part is the Jazira Plain. This diversity in the topography with climatic changes has caused development of different systems of alluvial fans, with different ages, stages, shapes, sizes and constituents.
This study aims to establish a classification of alluvial fans developed in Iraq depending mainly on the stages, for the main types and the size, shape and covering constituents for the types and sub-types. Consequently, two main types were found: Single Stage and Multi Stage Alluvial Fans. Furthermore, each main type is classified into many types, depending on the size, shape and top covering materials. The age is not included in the classification, because almost all the existing alluvial fans in Iraq have the same age range (Pleistocene – Holocene). Moreover, no accurate dating is available to use for the fan classification. The constituent factor is not used, because it depends on the type of the exposed rocks in the source area. Examples are given for each type and sub-type from different parts of Iraq. Some of the examples have fan names, used in other studies.
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A GEOPHYSICAL STUDY OF SOME GEOLOGICAL STRUCTURES IN THE LOW FOLDED ZONE, NORTH IRAQ
Hayder A. Al-Bahadily
Received: 20/ 06/ 2013, Accepted: 09/ 07/ 2014
Key words: Gravity, Seismic reflection, Structures, Low Folded Zone, Iraq
(p. 69 – 82)
ABSTRACT
The study area, which is characterized by numerous surface and subsurface structures of NW – SE dominating trend, is located in the Low Folded Zone of Iraq. The gravity responses of these structures are studied. The study is further extended to include the vertical and horizontal variations in density derived from seismic reflection data of two seismic profiles across Jambur structure. Such variations may be helpful in clarifying the sources of some gravity anomalies and also in theoretical modeling.
There are three aims of the present study; the first is to consider these responses, which reflect the effect on the gravity field due to the continuous compression of the Alpine stresses, taking into account that these stresses also have regional effects on the gravity field. Then, the total effects may be removed to obtain a new “corrected field”. The second is to estimate the maximum thickness of the sedimentary cover affected by the Alpine stresses, which might probably be observed in the gravity field “affected depth”, and the third aim is to calculate the gravity response of Jambur anticline from the available seismic data.
The results show that the gravity field responses are observed on the Bouguer map as gravity highs, lows and high gradients. The gravity highs coincide perfectly with the surface anticlines; however, some gravity highs show subsurface extensions. The gravity highs are elongate and narrow ellipsoidal or nose-shaped, whereas their magnitudes range from 1.2 to 8.0 mGal. The gravity lows can be divided into two groups according to their “origin”; the first has good matching with the synclines, while the second may be related to depressions. The shapes of these lows are either elongated and ellipsoidal running parallel to the gravity highs or broad circular shaped. The gravity value of those lows is close to – 2.0 mGal. Some gravity highs and lows are not reflected in the geologic map.
The results also show that the maximum thickness of the sedimentary cover where the Alpine stresses may be observed in the gravity field is about seven kilometers. In addition, two dimensional models of Jambur anticline show that the structure has a residual positive gravity value ranging between 8.0 and 9.0 mGal.
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LABORATORY STUDY OF MgO PREPARATION FROM IRAQI DOLOMITE BY LEACH-PRECIPITATION – PYROHYDROLYSIS PROCESS
Alaa M. Kh. Mustafa, Dalya Kh. Al-Dahan and Tanya V. Khachik
Received: 24/ 10/ 2013, Accepted: 13/ 03/ 2014
Key words: Magnesium Oxide, Dolomite, Dolime, Precipitation, Pyrohydrolysis, Iraq
(p. 83 – 107)
ABSTRACT
In this study, a three-process approach was applied for the extraction of Magnesia (MgO) from Iraqi dolomite. The first process comprises leaching of (– 2 mm) raw dolomite in 25% solid by 22% HCl aqueous solution for 10 minutes at room temperature, extracts 99.68% of MgO in the dolomite ore. The second process, which is a separation process, includes two-steps (hydration and carbonation) for the separation of calcium as Precipitated Calcium Carbonate (PCC, 1st stage) of 90.1% purity and a magnesium recovery of 92.8% as dissolved MgCl2. Hydration was carried out by adding 55% by weight ratio of calcined dolomite (dolime)/ leached dolomite at 70 °C for 60 minute; this was followed by carbonation of the slurry formed by CO2 gas at a pressure of 2 bars for 100 minutes at room temperature. The MgCl2 solution produced was subjected for evaporation to remove the dissolved Calcium Bicarbonate by precipitation as (PCC, 2nd stage) with a purity of 97%. The purified brine was further evaporated till dry salt of MgCl2.6H2O (Bischofite) was obtained, and then subjected for pyrohydrolysis, which was the third process, at 650 °C for 60 minutes. 22% HCl was regenerated with a product of 95.48% MgO purity after washing with water and drying.
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EXTRACTION OF ALUMINA FROM IRAQI COLORED KAOLIN BY LIME-SINTER PROCESS
Abdul Wahab A. Al-Ajeel, Suhair Z. Abdullah, Wasan A. Muslim, Malath Q. Abdulkhader, Mohammed K. Al-Halbosy and Falah A. Al-Jumely
Received: 05/ 02/ 2014, Accepted: 06/ 07/ 2014
Key words: Kaolin, Alumina, Lime-sinter, Iraq
(p. 109 – 117)
ABSTRACT
In this work lime -sinter method was investigated to recover alumina from Iraqi colored kaolinitic claystone. The claystone was intimately mixed with limestone and the mixture was sintered. The annealed sintered material dusts to a fine powder which required no grinding. This material was leached with sodium carbonate solution, and an alumina extract (sodium aluminate solution) was obtained. By bubbling carbon dioxide gas into this extract solution, gibbsite [Al(OH)3] precipitated and on calcinations at 1350 °C ,alumina in the form of alpha (α – Al2O3) of high purity (98%) can be obtained. In the course of this investigation, the effect of sintering temperature and time, concentration of sodium carbonate solution, leaching time and sintered powder to sodium carbonate solution ratio were studied. About 85% of the alumina in the claystone was extracted at the optimum conditions. The alumina obtained in this method assaying 98% Al2O3, 1.45% SiO2, 0.04% Fe2O3, and 0.13% CaO and, 0.15% Na2O.
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SCIENTIFIC NOTE: THE POSSIBILITY OF STANDARDIZING THE AIRBORNE GAMMA RAY DATABASE OF GEOSURV
Ali F. Al-Dujaili
Key words: Airborn, Gamma ray, Iraq
(p. 119 – 124)