Iraqi National Journal of Earth Science

The mineralogical and geochemical constituents of the Aptian-Albian Malha Formation at the Abu Darag region, Gulf of Suez, Egypt, can be discussed here. These constituents are related to paleoweathering and paleoclimatic circumstances that managed the depositional settings. The present study aims to evaluate the geochemical conditions that have control over the depositional environments and characterizes them in terms of lithological, mineralogical, and chemical composition. To achieve this aim, selected kaolinitic clay samples were geochemically and mineralogically examined. Kaolinite and quartz are the main constituent minerals in the investigated samples, whereas anatase and hematite serve as auxiliary minerals. The presence of hematite minerals indicates precipitation in an oxidizing environment, whereas anatase is related to basaltic rock. Bivariate discrimination provenance diagrams, major oxides, and trace elements all identify felsic-intermediate igneous source rocks as the leading contenders. The examined samples were deposited in non-marine environments and underwent weak to moderate chemical weathering as well as severe physical induration in tropical climates.

The present study concerns the sedimentology of the lower part of The Bekhme Formation at the Bekhair anticline, Dohuk area, northern Iraq. This part shows a high spectrum of lithological and petrographical variations of allochthonous and autochthonous carbonate sediments. Accordingly, the formation divides into 3 Facies
1. Random clasts Carbonate Megabreccia .
2. Planktonic Foraminiferal Wackestone.
3. Rounded Clasts Intraformational Carbonate Conglomerate.
The facies analysis and their deposition mechanism suggest that the area's deposit environment represents carbonate slope, which was affected by local tectonism of syndepositional normal faulting. The architectural analysis of the sedimentary environment shows that this fault had affected the facies directly, giving considerable variation in the sedimentary environment ( depth, oxygen percent, and bioactivity). These variations are reflected in the carbonate rock types, sedimentary structures, and the early diagenetic processes. The constructed sedimentological model for the basin in this particular environment proposed that this syndepositional normal fault was directly responsible for the type of the carbonate rocks at the lower part of the formation ( the older three facies), and this was reflected by increases in the angle of carbonate slope and also increasing of carbonate sediments mobility towards the half-graben made by the fault. The Bekhme Formation represents part of the main mega sequence (AP9). Within the Late Campanian – Maastrichtian age, This period was characterized by local subsidence caused by secondary normal faults, which are responsible for the formation of the secondary basin. The proposed fault in this study is one of these faults.

The limestone of Jeribe Formation in Bekhair anticline, Duhok Governorate, was assessed as raw materials for the Ordinary Portland Cement (OPC) industry. Four sections were selected; the formation consists of fossiliferous limestone and thin layers of dolomitic limestone. The petrographic study showed that the main mineral of limestone rocks is fine calcite with a size less than 0.25 cm. The chemical analysis revealed that the mean concentration of CaO is 51.77% which dominates over other oxides, including MgO (2.06%), SiO2 (1.95%), Al2O3 (0.60%), and, Fe2O3 (0.22%), While the remaining oxides (K2O, Na2O, TiO2, MnO, P2O5, and SO3) are present in traces. The lime saturation factors (LSF) of the studied sections range from (1651.70 to 2334.89), which are over the limits necessary for high-quality cement; thus, a claystone rock from the Fatha Formation was added to achieve the best point of clinker LSF. The physical and mechanical tests of samples indicate low porosity, and the compressive strength range between (168-1291 kg/cm²), which are acceptable for the cement industry and make the rocks easy to crush and grind during the preparation of the mixture. According to the results of the analyses, we conclude that the mixture of limestone ranges between (65.9-69.3) and claystone ranges between (30.7-34.1) in the study area are of good quality and meet international standards for ordinary portland cement.

The Mishrif Formation is considered the main oil reservoir in the Buzurgan oilfield, southern Iraq. This study aims to characterize and evaluate the reservoir properties of the Mishrif Formation based on the interpretation of well logs data. The logs data for six wells have been analyzed and interpreted by using Techlog 2015.3 software. The lithology of the Mishrif Formation was determined by using the M-N cross plot method based on the interpretation of density, neutron, and sonic logs. The results showed that the Mishrif Formation is mainly composed of limestone. The shale volume in the Mishrif Formation has been estimated from the gamma-ray log. The results illustrated that the shale volume is about 20% of the bulk volume, and may increase to reach the highest value at the upper part of the MA unit of the formation. The porosity of the Mishrif Formation was calculated based on the interpretation of neutron, density, and sonic logs. To achieve accurate values of porosity, the log-derived porosity has been correlated with the core-derived porosity, and the comparison showed a good correlation between the two types of porosity. The results showed that the Mishrif Formation is characterized by low to medium porosity (about 5% to 18%). The secondary porosity of the formation is most dominant in the MB21 unit compared with the other stratigraphic units of the Mishrif Formations. This indicates that the MB21 unit was affected by the diagenesis processes. The MB21 unit of the Mishrif Formation represents the most dominant reservoir because it was delineated by high effective porosity and high oil saturation.

The basinal part of the Damlouk Member upper sedimentary cycle of the Ratga Formation exposed in the Qaim area of the Iraqi western desert is examined. The studied section consists of marlstone, marly and phosphatic limestone, and planktic foraminifera-rich limestone beds. Detailed study of the planktic foraminiferal assemblages of these rocks revealed the occurrences of (30) species belonging to (11) genera. The stratigraphic distribution of these species permits the recognition of three biozones. These are from the lower to upper part of the section: - Acarinina bullbrooki Zone, (Middle Lutetian), Morozovelloides lehneri Zone, (Late Lutetian), Globigerinatheca semiinvoluta – Hantkenina alabamensis Zone, (Early Bartonian). These zones indicate that the studied section of the Ratga Formation (Damlouk Member) is of Middle-Late Lutetian to Early Bartonian age. These biozones are correlated with different local and regional studies.

Limestone is the main constituent of the raw materials used in manufacturing cement. In this study, the limestone deposits from the Avroman Formation are evaluated by using chemically and mineralogical techniques for their suitability to be used as a raw material for the cement industry.
Twenty-one samples of limestone are collected from different beds of the Avroman Formation for petrographic study which shows that the limestone samples consist mainly of crystalline calcite. Physical and mechanical tests are performed in addition to the mineralogical and geochemical analysis using x-ray diffraction (XRD), x-ray fluorescence (XRF). Geological review and obtained results show that there is a good potential for industrial-grade limestone. The major clay minerals in the clay samples are chlorite, illite, montmorillonite, were as kaolinite appears as minor clay minerals. The geochemical analysis indicates that the limestone of Avroman formation has a wide range of CaO (46.13-56.00), Al₂O₃ (0.01-0.86), SiO₂ (0.00-1.51), Fe₂O₃ (0.00-1.25), MgO (0.24-0.71), K₂O, Na₂O, TiO₂, and MnO are traces. The physical properties (water absorption and moisture content) and chemical-mineralogical composition of the formation reflect that the dry process is preferable for the production of Portland cement. Mechanical analyses, especially compressive strength show that the quarrying and crushing will be competitive economically during manufacturing. From the results of the analyses, we conclude that the limestone of the formation and clay material of the study area are of good quality and fulfill the international standards of Portland cement.

This study deals with the determination of lithology in the Shiranish and Mushorah Formations in wells (Az-24, Az-29, and But-15). The graphical representation of the neutron porosity log (NØ) and the bulk density ρ)b(, shows that the Shiranish (Late Campanian – Early Maastrichtian) and Mushorah (Early Campanian) Formations consist of limestone and dolomite, as well as shale. The proportion of dolomite and chert increases at the expense ofcalcite in the Mushorah Formation. Also, the graphical representation results of the M-N profile for each well indicate that the limestone of the Mushorah Formation were affected by the dolomitization with the development of secondary porosity. Moreover, the limestones were suffered silicification in the form of chert nodules. The MID profile, used in this study to determine the mineralogy gives better and more precise results than that of the M-N profile. The results showed that the dominant minerals are calcite in the Shiranish Formation while dolomite and quartz in the Mushorah Formation, regardless of the gas effects within the studied wells.

The biostratigraphical importance and systematic palaeontology of Early Turonian to Early Maastrichtian Heterohelicidae Planktic foraminifera from Kurdistan region, NE Iraq are described. Some 24 species from 11 genera are recorded. Species abundance and diversity increase from the Early Turonian to Early Maastrichtian, perhaps signifying cooler sea temperatures in the Arabian sector of the Tethys Ocean during the Early Maastrichtian. Despite the long biostratigraphical ranges of some species, the importance of the biserial and multiserial Planktic foraminifers in Late Cretaceous biostratigraphy is emphasized. From a biostratigraphic perspective, heterohelicids are important for the definition of the Campanian-Maastrichtian boundary in Kurdistan region, with Planoglobulina species being especially important in this respect, as they are in Iran, Turkey and North Africa.

The present study deals with biostratigraphy, depositional environment and sequence stratigraphy of Kolosh Formation in two sections of Bekher anticline, northeastern Iraq by using the planktonic and benthonic foraminifera. Therefore, (48) species of planktonic foraminifera belonging to (14) genera and (34) species of benthonic foraminifera belonging to (19) genera have been recognized. The detailed planktonic foraminiferal investigation permits the recognition of seven well defined biozones and three subzones; they indicate that Kolosh Formation extends from the Early Paleocene (Danian) to Late Paleocene (Thanetian) age. The depositional environment of the formation was studied throughout relying on the variation in the diversity of planktonic forminifera, as well as throughout the ratio of the planktonic foraminifera to the whole mass of foraminifera, and the ratio of planktonic forminifera to the benthonic formiminifera. The lower part of the formation represents the upper bathyal environment, while the middle part deposited within the outer shelf environment, then deposition basin became within the middle shelf area in the upper parts of the formation.
Sequence stratigraphic analysis for the studied sections of Kolosh Formation  delineated three sequences which is interpreted as 3^rd order sequences, and it is found that the deposition of Kolosh Formation in the Badi section had been occurred in shallower level for most sedimentation intervals compared to the Linwa section which represents a somewhat deeper marine environment.

The studydeals with succession from the upper part of the Late Albian Balambo Formation which are composed of fine-grained dark gray to black calcareous shale, limestone and marly limestone rich in sedimentary structures such as lamination, fissility and platy structures. Microfacies analysis revealed that mudstone, wackstone and few of packstone are the main facies in the studied succession. The studied rocks generally are rich in organic matter and pyrite in addition to dominance of radiolaria, sponge spicules and foraminifera with elongated champers maybe “Schackoina” genus. All these characters indicate deposition in marine conditions with reduced or absent-oxygen condition that relate to oceanic anoxic event (1d).

In the current work, the Gulneri Formation (Early Turonian) is studied in three surface sections (Degala, Dokan and Azmir) from northeastern Iraq. The formation is characterized by grey to black color limestone and marly limestone in the Degala and Dokan sections, whereas in Azmir section, fissile marl and marly limestone with pale to reddish color are dominated in addition to few beds, which occasionally contain fish remains, with distinct gray color reflecting the very few amount of total organic carbon in these beds. Microfacies analysis revealed that the formation consists of three microfacies: mudstone, wackestone and packstone. The predominance of dwarfish planktonic foraminifera (Heterohilex) and thin shell filaments particularly in packstone microfacies represent Heterohelix shift event and filament event respectively. In addition to these events, fish remains, radiolarian pyritization, planktonic foraminiferal chambers elongation and glauconite are all refer to anoxic environmental conditions that may have been coincided with the Global Cenomanian-Turonian Oceanic Anoxic Event (OAE-2).

   A detail paleoenvironmental study of ostracods fauna to investigated the paleoenvironment of Khurmala Formation for two section Northern Iraq; the first (Hjran section) lies near Shaqlawa city, and the second (Dohuk section) lies near Dohuk city. Based on ostracods study conclude that Khurmala Formation were deposited in shelf environment, about (30 – 200) meter in depth.

The Naokelekan Formation (Late Oxfordian - Early Kimmeridgian) was studied at three surface sections (Rowanduz, Ranya and Sargelu), in northeastern Iraq. The Formation is composed mainly of alternating sequence of thin- bedded limestone, dolomitic limestone and bituminous black shales. Streaks of calcite veins, chert nodules and bituminous stylolite are present. Traces of Ammonite molds, flat, wavy to domal stromatolites are also present.
The Petrographic study showed that the formation contains various petrographic components represented by Ammonites, pelecypods, gastropods, calcispheres, planktonic and benthonic foraminifera, ostracods, stromatolite, radiolaria and bryozoans, pellets and intraclasts, in addition to the groundmass of micrite and microspars. The rock successions were extensively affected by many diagenetic processes and their effect is most pronounced pronounced on textural properties of these rocks. The dolomitization seems to be one of the most important diagenetic processes recognized. The other processes are; compaction, micritization, bioturbation, authigenic minerals, cementation, neomorphism, dissolution, fractures and veins, silicifaction, replacement and dedolomitization.
The detailed facies analysis reveals that the rock succession consists mainly of three microfacies and two lithofacies type. The main microfacies include lime mudstone,wackestone and packstone.  Where the lithofacies comprise limestones and shales which are represented by four sub lithofacies. The overall characters of these facies indicate that the formation was deposited in two different environments; (1) shallow marine sub tidal environment at the lower part and upper part respectively. (2) Outer shelf in a euxinic environment at its middle part.

Hard ground at the uppermost part of Bekhme Formation is studied at three outcrop sections located in the Dohuk area, northern Iraq, and it is found that it consists of two distinct facies associations. The first includes limestone beds that comprise the hard ground and its omission surfaces. The second consists of limestone, marly limestone, and marl, which is interbedded with successive hard ground. The overall characters of these two facies associations indicate that deposition took place in a carbonate ramp setting. Vertical variations of sedimentary components suggest that the hard ground was developed by three successive stages. These are the end of shallow carbonate sedimentation and the drowning of the platform, the formation and modification of hard grounds, and finally the deposition of pelagic carbonate sediments of the Shiranish Formation.
The second stage is characterized by intercalations of continuous depositional and biological processes. These include bioturbation, bioencrustation, and secondary mineralization in addition to other early and late diagenetic processes. The depositional area had been affected by tectonic drowning of carbonate ramp with a wide gradual marine transgression associated with a period of local marine regression that is, in turn, responsible for deposition, transportation, redeposition, submarine erosion and formation of hard grounds. Thus, the hard ground zone represents drowning unconformity surfaces between Bekhme and Shiranish formations through the Campanian- Maastrichtian boundary.

Planktonic Foraminifera is studied from Shiranish &Aaliji formations in PulkanaWell No. 7 North Iraq between the depth intervals (1948-2240) m, six biostratigraphy zones are recognized in the formation as arranged from bottom to top:
1. Globotruncanita stuarti–stuartiformis Partial Range Zone.
2. Globotruncana aegyptiaca Interval Zone.
3. Gansserina gansseri Total Rang Zone.
4. Morozovella angulata  Partial Range Zone.
5. Globanomalina  pseudomenardii  Total Rang Zone .
6. Morozovella velascoensis Partial Range Zone.
The result of this study is compared with the work of others inside and outside Iraq, The age of the Shiranish Formation is Early Late Campanian to Earliest Maastrichtian whereas Aaliji Formation is Late Paleocene.

The rock successions of Barsarin Formation Late Kimmeridgian was studied at three surface sections the type section "17m", Sarglu "19m" and Rania "10m"; northeastern Iraq. The detailed sedimentological study reveals that the formation consists mainly of dolomite and dolomitic limestones. A wide spectrum of diagenetic – processes are recognized in the rock successions; these are dolomitization, compaction, cementation, micritization, dissolution, replacement, neomorphism and silisification. By the far, dolomitization and compaction are the most common and widespread processes. Stromatolites are the dominant primary sedimentary structures in this Formation. Based on field observation and textural characteristics four stromatolite types are distinguished: planar, wavy, domal, and bedded. They are normally formed by carbonates (lime muds) and extensively suffered early dolomitization

Twenty Samples of Shiranish Formation from the well (K-306), Kirkuk area, northern Iraq, are collected and studied on the basis of stratigraphic ranges of the recorded calcareous nannofossils. Eighty-nine species in the studied section reveals five biozones arranged from oldest to youngest as follows:
1.Quadrum trifidum Interval Biozone (CC22) Part
2.Tranolithus phacelosus Interval Biozone (CC23)
3.Rienhardtites lives Interval Biozone (CC24)
4. Arkhangelskilla cymbiformis Interval Biozone (CC25)
5. Nephrolithus frequens Rang Biozone (CC26) Part
These Biozones are correlated with other calcareous nannofossils biozones, from both local and regional sections, leading to conclude the age of Campanian- Maastrichtian.

      Gercus Formation is exposed in northern Iraq. When the passive Arabian continental margin collided with the active continental margin of the Turkish and Iranian plates, a part of the source rocks of Gercus red beds were carried out from Iran and Turkey territories and deposited in the molasses trough, parallel to the suture zone of the collision, and the others were driving from the longitudinal paleo-high lying parallel to the trough basin of Gercus Formation.
     The present study is based on three surface sections, Bekhme, Sarsank and Amadiya areas in Northern Iraq. Generally, the Gercus Formation consists of reddish brown to light grey, well bedded sandstones and mudstones in addition to thin beds of conglomerates. The most of sandstone particles are composed of polycrystalline and monocrystalline quartz (of metamorphic and plutonic origin), K and Na – feldspar (derived from igneous and metamorphic source rocks), and chert grains of sedimentary source. Carbonate and other rock fragments with low ratio of mica group and heavy minerals (magnetite and rutile) are present too.
       The sandstones of Gercus Formation, generally contain low-moderate quantities of clay as matrix in all sections, therefore, they are texturally immature. On the other hand, the low ratio of quatrz and chert to feldspar and other components indicates to mineralogically immature sandstones. According to McBride classification, it is sublith arenite - Lithic arenite sandstone. Petrographic analysis of sandstones in Bekhme section revealed that it consist of variable amount of detritus, represented by the abundance of quartz and chert rock fragments with low content of feldspar, and at Sarsank and Amadiya sections, the Gercus sandstones are characterized by the abundant chert rock fragments with high percentage of metamorphic rock fragments. So they lay in the recycled provenance source of collision orogen.

Thirteen samples of Aaliji Formation from the well (K-116), Kirkuk area, Northern Iraq, are studied on the basis of the stratigraphic ranges of the recorded calcareous nannofossils for sixty species, the studied section reveals five biozones arranged from oldest to youngest as follows:

Fasciculithus tympaniformis Interval Biozone (CP4)
Heliolithus kleinpellii Interval Biozone (CP5)
Discoaster mohleri Interval Biozone (CP6)
Discoaster nobilis Interval Biozone (CP7)

5. Discoaster multiraditus Interval Biozone (CP8)
These biozones are correlated with other calcareous nannofossils biozones from both local and regional sections leading to conclude the age of Middle Paleocene to Early Eocene.

This study covered most of Kolosh Formation exposure areas in northern Iraq. Description of the lithology and measuring the actual thickness of the Formation from exposures and well logs were performed. The isopach map of the Formation was constructed. The sedimentation of the Formation was affected by the tectonic activity of the northeastern edge of the Arabian plate during the closure of the Neo-Tethys Ocean. The tectonic setting outlined the depozone of foreland basin system and controlled the variation of the deposits of the Kolosh Formation along the orogenic front (It revealed that there are more than one basin of deposition). The deviations of the depocenters of the Kolosh deposit basins from the current folds are depicted. The counterclockwise rotation of Arabian plate and its oblique collision with   Iranian plate as well as the rejuvenation of the basement faults during the peak of the orogeny might cause such deviation.

The present research includes a biostratigraphic study of calcareous nannofossils of the lower part of Balambo Formation (Lower Cretaceous) in Azmir anticline - northeastern Iraq. Lithologically, the lower part of the studied section (Balambo Formation) consists of limestone containing nodules of chert, marly limestone, with intercalations of green and gray-blue shale. In this work, it has been relied on calcareous nannofossils assamblages in biostratigaphy and age determination of this part because it does not contain planktonic foraminifera. First occurrences (FOs) and last occurrences (LOs) of marker species were used to identify biozones. The section was divided into four main biozones and two subzones and its correlation with collection from global, regional, and local biozones. Thus, the age of this part of the formation extends from the Late Early Hauterivian - Late Aptian. These are from older to younger:
1- Speetonia  colligata  Interval  Zone (part)
2- Lithraphidites  bollii  Interval  Zone
3- Micrantholithus  hoschulzii  Partial range  Zone
4- Chiastozygus  litterarius Interval  Zone
     Hayesites  irregularis  Interval  Subzone 
    Eprolithus  floralis Interval  Subzone (part)

The studied surface section of Khurmala Formation which lies in the northeast of Dohuk city north Iraq consists of mixed carbonate and clastic sediments, package about 60 meter thick of Early Eocene age. The carbonate sediment is comprising four microfacies association allocated to shoal bank (Kh2), lagoon (Kh1), intertidal (Kh1, Kh3), and supratidal (Kh4), while the clastic sediment included two lithofacies affiliated to estuaries depositional environment. A depositional model of the Khurmala Formation was proposed.
Diagenetic processes of dissolution and dolomitization are recognized in microfacies (Kh3).