Iraqi Bulletin of Geology and Mining

Biostratigraphy and paleoecology of the Anah Formation are investigated for the first time in the Sangaw area, Sulaimania Governorate, Northeastern Iraq. Forty species of larger foraminifera and skeletal fragments of brachiopod, coral, pelycepods (bivalves), gastropods, bryozoan and algae shell, are described in seven samples collected from one section near the Pungala village. Based on the distribution of the larger benthic foraminifera and other skeletal grains, two assemblage biozones of Upper Oligocene (Chattian) age have been recognized. During the Chattian, the carbonate deposits of the Anah Formation in the studied section are mostly composed of coralline red algae and large flat benthic foraminifera. The biotic associations identified in this study suggest that the carbonate sedimentation of the Anah Formation thrived in tropical to subtropical waters under oligotrophic to mesotrophic middle ramp environment with normal seawater salinity to a higher salinity inner ramp setting and at water depths that ranged from 40 to 80 m.

This paper includes petrographic and paleontological observations that are used to interpret the carbonate microfaces of the Aqra-Bekhme and Shiranish formations in terms of depositional environment. These formations show lateral facies variation in the Bekhme Gorge, Mukaba and Zarda Bee sections. An understanding of the facies change is presented in this study and used in the interpretation of paleogeographic setting during deposition of the Late Cretaceous formations in northern Iraq. For this purpose, a petrographic examination of about 300 thin sections allowed the recognition of a wide range of the microfacies, that are grouped into four environmentally indicative facies associations including: 1- Back reef, 2- Reef, 3- Fore reef, and 4- Deep marine. The back reef facies association of the Aqra-Bekhme Formation in the Bekhme Gorge section is characterized by mudstone-dominated microfacies that are rich in benthonic foraminifera. The reef facies association of the Formation consists of bioclastic packstone and grainsone. The fore reef facies association of the Aqra-Bekhme Formation includes bioclastic packstone-grainstone microfacies, rich in benthonic foraminifera. The mud-dominated deep marine microfacies occur in the middle parts of the The Aqra-Bekhma Formation at the Mukaba and Zarda Bee sections and is comprised of mudstone Similar facies are observed in the Shiranish Formation at the Bekhme Gorge section.

Statistical analysis is conducted for 39 sandy samples selected from 24boreholes drilled in the Mesopotamian Plain, southern Iraq. The samples are tested for grain size analysis to reveal its textural characteristics, depositional environment, transporting mechanism, and mean flow velocity during deposition. The majority of the samples are muddy sand, few are silty and clayey sand and one sample is sand. A Graphic method of frequency distribution analysis reveals that the mean size ranges from medium sand, (1.42) φ to fine silt, (6.07) φ with an average size of (4.2) φ. Skewness parameters range from (0.15) φ (fine) to 0.89 φ (very finely skewed). About 92 % of the samples lies within the very fine skewness category implying excess of fine particles (>10) %, which is a characteristic feature of old age river sediments. Sorting values range from 1.43 φ (poorly sorted) to 4.33 φ (extremely poorly sorted) with the very poorly sorted samples dominate the population. The kurtosis values range from 0.59 φ (very platykurtic) to 3.25 φ (extremely leptokurtic). About 90% of the samples are spread within the mesokurtic to very leptokurtic categories. Scatter plot diagram of graphic mean size versus graphic standard deviation indicates a river deposition environment. Probability charts of the samples point to rolling and sliding transporting mechanism for the sediments larger than 2 φ in size, as well, the saltation mechanism for the sediments in between 1.63 and 3.7 φ in size and suspension mechanism for the grains finer than 8 φ in size. The mean flow velocity during deposition ranges between 7.34 cm/s for sample with mean size of 4.9 φ and 94.77 cm/sec for sample with mean size of 1.4 φ.

The Baluti Formation in the Galley Derash locality is comprised of 73 m brecciated dolomitic limestone in the lower part, alternating with thin bedded dolomitic limestone and dark gray shale in the middle part, then thin to medium bedded brecciated sandy limestone interbedded with dark grey shale in its upper part. The sum of 21 thin sections of the Baluti Formation carbonates are petrographically studied using polarizing microscope. The results show various types of skeletal grains including calcareous algae, ostracods, brachiopods, bivalves, benthonic foraminifera, gastropods, and echinoderms, while the non-skeletal grains include peloids, intraclasts, extraclasts and rare ooids. The Baluti Formation was subjected to differed diagenetic processes such as micritization, mechanical compaction, cementation, early dolomitization, neomorphism, stylolitization, late dolomitization, dedolomitization, silisification, soulution, fracturing and pyritization. These diagenetic modifications occurred during marine phreatic shallow burial stage and were activated during intermediate to deep burial and uplift in the late stages. Five kinds of dolomite textures are recognized: Unimodal very fine to fine-crystalline planar-s (subhedral) mosaic, unimodal very fine to fine-crystalline planar-e (euhedral) mosaic, unimodal fine to medium crystalline planar-s (subhedral) mosaic, medium to coarsecrystalline planar to non-planar-c (cement) mosaic and polymodal planar-s (subhedral) to planar-e (euhedral) mosaic. The petrographic study revealed that the secondary porosity is dominant. The paragenetic history of the Baluti Formation passed through four diagenetic environments which are: marine, meteoric, burial and uplift.

Sulaimania City, is located in, the northeastern part of Kurdistan Region of Iraq within the series of Zagros Mountains. It is situated within the High Folded and Imbricate zones, in an intermontane depression surrounded from the east by the Azmar Mountain and from the north by the Pira Migrun Mountain, and from the southwest by the Qaradagh Mountain range. This situation makes the Sulaimania City an excellent model for a big mountainous city in Iraq with geologic and geomorphologic environment greatly influencing the city growth modes. Digital Elevation Model (DEM), satellite images, different kinds of maps, in addition to field observations of the city and surrounding areas are used to investigate the impact of the geomorphologic factors on the city expansion pattern. A set of digital maps are constructed to show the interaction between the city urban growth pattern with: i) topography and geologic features, ii) geomorphic units and overall landscape style, iii) slope type and hazards, iv) lineaments density, v) flood hazards, and (vi) drainage system. All the maps are displayed in a GIS environment and some of them are made for different periods to show the city growth. Three basic stages of city growth were inferred and mapped to show the relation between city expansion and physical environment components and hazards. The results of this work show that the circular growth patterns of the Sulaimania City at early stages (1925 – 1973) prefer growth over areas covered by the fluvio-denudational landscape. Progressive stages of expansion move over flood-plains, alluvial fans margins as well as rolling hills areas. Growth at early stages avoids sloping or elevated areas with high drainage intensity and lineaments density, as well as, areas with high flooding risk. Recent explosive expansion pattern (after 1973) shows more irregular shapes with effective expansion over slopping areas, which are covered by Quaternary depression fills or soft sediments of the older geologic units. These areas are located along the northwest, northeast and southeastern directions over mountain's lower slopes, badlands, and rugged rocky terrains of the city- suburban areas are following major roads entering the city.

The Tertiary oil reservoirs in the Khabbaz Oil Field comprise the Jeribe, Anah, Azkand, and Ibrahim formations. This study aims to manage unpredicted pressure changes that occur in wells drilled in the carbonate reservoirs, which are potentially dangerous and financially cost during petroleum exploration. It has studied from pore pressure and reservoir compartmentalization points of view. Eaton method has been used to predict the pore pressure from the sonic log data. The basic assumption for this technique is the interrelation between observed transit time from log reading and normal transit time that locates on the normal compaction trend (NCT). The bulk density is determined from sonic log and has a good match with the bulk density derived from the density log. It shows that the sonic log can be used as a good alternative to obtain the bulk density and consequently to determine lithostatic pressure. Pore pressure depends upon changes in the overburden gradient. Based on predicted pore pressure, the studied reservoirs compartmented into four pressure zones. The number of the zones is identified by using a graphical method of probability plot of the predicted pore pressure on the basis of cluster analysis. All reservoirs are assumed to be overpressured zone. According to predicted pore pressure, the Azkand Formation is the most potential reservoir because it has the highest-pressure value measured from the top of the Azkand Formation to the bottom of the Ibrahim Formation. Direct relation between pressure, temperature and thickness of hydrocarbon zones (oil and gas) gives indications that most of the studied reservoirs are of good productivity at primary recovery stage.

The Kurdistan Region has an enormous number of different carbonate rock units, which vary widely in their geological age and sedimentary depositional environment. Limestone quarried from the exposures has a wide range of usages and applications, such as dimension stone, crushed stone, building stone and paving stones. Since antiquity, limestone was used as building materials in areas where they were naturally available and abundant. Little work has been done to indicate the physical and mechanical properties of the limestone, especially under humid environment. In this study, the physical and mechanical properties of some carbonate rocks of the Pila Spi Formation (Eocene) are investigated. samples are collected from the Pila Spi Formation in the Qara Dagh area at two sites close to each other to assess their suitability for use as dimension stone. Geological, petrographical, geochemical and geotechnical properties of the carbonate rocks in the study area are determined based on field studies and laboratory tests. The field studies indicate that the carbonate rocks of the Pila Spi Formation in the studied area are mostly well-bedded to massive, crystalline, white in color, sometimes become chalky towards the top with small oxidation signs on the surface. Petrographical study reveal that the carbonate rocks are characterized as dolomitic limestone and have a grayish and yellowish-white color after polishing. The carbonate rocks are mostly dolomites or recrystallized dolomitic limestone. Geochemical analyses of the studied samples show that CaO and MgO are the most abundant oxides and the rocks can be classified as impure limestones. According to the American Standard for Testing and Materials, ASTM C568-03 (2006) the carbonate rocks in the studied sites are acceptable for use as dimension stone.