The Iraqi Geological Journal

Hydrological Modelling of Extreme Events in Ouergha Mediterranean Basin, Northern Morocco, Using a Deterministic Model and Gridded Precipitations

Nourelhouda Karmouda — 2023-08-25

The objective of this study is the elaboration of a rainfall-runoff model capable of predicting future floods resulting from extreme rainfall events in a rugged Moroccan Mediterranean basin with marly lands. The integration of the deterministic hydrological modeling system, Hydrologic Engineering Center-Hydrologic Modelling System, with a Geographic Information System (GIS) was employed to construct the hydrological model. The calibration and validation of the model were performed using gridded daily occurrences from the period of 2003 to 2010. The model’s performance was assessed using various statistical indices, including R-squared (R²), root-mean-square error, percent bias, and Nash-Sutcliffe performance parameter (NSE). The results indicated a good agreement between observed and simulated flow, with an average R² of 0.81. The model exhibited low residual flow variation, averaging at 0.51, and achieved favorable NSE values, with an average of 0.69. However, in extreme events that include multiple flood hydrographs, the model tends to underestimate the initial one. Despite this limitation, the overall performance of the model was considered good for 50% of the statistical indices and excellent for an additional 25% of them. However, 25% of the indices indicated unsatisfactory performance. Future research could focus on improving the model’s accuracy by investigating indicators for predicting unscheduled releases from upstream dams, which could contribute to potential variations in observed flow. Also, it’s important to implement a reservoir control policy that optimizes storage capacity and effectively mitigates floods.

Utilizing Reservoir Model to Optimize Future Oil Production for Hydraulic Fracture Wells in Tight Reservoir

Ameer H. Hashim — 2023-08-25

The tight oil reservoir has low porosity and permeability, and generally suffers from rapid declines in production rates for oil wells, especially in southeast Iraq in the Halfaya oil field of the Sadi Formation, which is considered a tight oil reservoir with a reserve of about 25%; their OOIP accounts for more than a quarter of the total in the H oilfield. Implementing a pilot hydraulic fracture technique was a focus of attention in Iraq to increase the production rates, but the main issue faced in hydraulic fracturing wells was producing a high oil rate for a short period of time and then starting to decline rapidly, so a reservoir dynamic model was utilized to achieve the purpose of this study. The purpose of this study is to predict the production rate to prolong the production stabilization in horizontal and vertical hydraulic fracturing wells in order to avoid highly depleted fracture storage capacity and production below the bubble point. Recognize a practical procedure with horizontal hydraulic fracturing wells to reach stabilization. The reservoir simulator results show that a good history matches till 2021, predicting the rates that stabilize the production with flowing pressure above the bubble point pressure till 2025, producing rates for an eight-stage well with 700 BOPD and 900 BOPD for an eleven-stage well, whereas the rate for a vertical hydraulic fracture well is 225 BOPD. A practical procedure in horizontal hydraulic fracturing wells is achieved by keeping the wellhead pressure constant during the production period to stabilize transient behavior.

Kurra Chine Formation: Evaluation of Source Rock, Based on Rock-Eval Pyrolysis Analysis Integrated by Selected Wells and Outcrop Samples in Iraq's Kurdistan Region

Mahdi K. Aswad — 2023-08-25

The current research deal with evaluating the Late Triassic Kurra Chine Formation using the Rock-Eval Pyrolysis technique in selected wells in Sarta-2 and Tawke-17 Oil fields, and the Sirwan Valley outcrop, in Northern Iraq. A total of twenty-six samples were selected for this study; nineteen cuttings samples from the wells and seven outcrop samples from Sirwan Valley. The total organic carbon wt.% of the formation in Sarta oilfield samples ranges from 0.43–2.51, and in Tawke samples ranges between 0.13–1.52, and for Sirwan Valley ranges between 0.02–0.32. Based on the total organic carbon content the Kurra Chine Formation can be considered as poor to very good source rock in the Sarta Oil field and poor to good in Tawke, and poor to fair source rock in Sirwan samples. Generation Potential shows some potential to generate good source potential, moderate source potential, and poor generation potential in the Sarta well, Tawke well, and Sirwan Valley as Generation Potential ranges between 1.47–8.55, 0.48–4.46 and 0.02-0.11, respectively. The values of S1 range between 0.57–4.13, 0.15–1.02, and 0.01–0.03 mg HC/g rock for Sarta, Tawke, and Sirwan Valley respectively. Based on the S1 values the Kurra Chine Formation is considered fair to excellent, fair to good, and poor source rock in the Sarta, Tawke, and Sirwan respectively. The analyzed samples show an immature level with Tmax ranges between 292-405 and immature to early mature with Tmax between 425-439 and immature to postmature with Tmax values between 339–597 for Sarta, Tawke, and Sirwan respectively. Tmax-HI plot shows Kerogen types (II-III, III-IV), (II to III), and (III-IV) for Sarta, Tawke, and Sirwan Valley respectively.

Fractures and Porosity Analysis of Cretaceous Kometan Carbonate Reservoirs in Selected Oilfields Adjoining the Boundary between High Folded Zone and Low Folded Zone, Kurdistan Region, NE Iraq

Fouad M. Qader — 2023-08-25

Carbonate reservoirs in Iraq have been targets of hydrocarbon exploration for about a century. The Cretaceous Kometan Formation is widely recognized as one of the most significant and common reservoir rocks in Iraq. In this study the Kometan Formation was studied in three wells; Miran West-2, Shewashan-2B and Sangaw North-1 in the Iraqi Kurdistan Region. The research is grounded in quantitative evaluation, analysis of fractures and also their contribution to creating secondary porosity and improving porosity and permeability in tight rocks. As well as, qualitatively analyzed fractures in terms of size, dip angles and direction of fractures with their relationship to the tendency of layers. The density log, neutron and conventional acoustic logs were adopted in the three wells for the quantitative evaluation of secondary porosity and fracture index. The Kometan Formation in the wells of SH-2B, MW-2, and SN-1 have an average secondary porosity of 3.67%, 8.28%, and 10.3%, individually. The fracture index of the formation comprises 49%, 36% and 25% of the total porosity in the MW-2, SH-2B, and SN-1 wells, respectively. Likewise, advanced dip meter log techniques and imaging logs were used to conduct a qualitative assessment of the fractures. Two groups of fractures were categorized; specifically, fractures associated with the bedding plane and those not associated with the bedding plane. The first group is characterized by a low dip angle; between 5ᵒ and 20ᵒ with an average of 15ᵒ, commonly in the NE direction, and, the second group is dominated by a high dip angle; ranges between 60ᵒ and 80ᵒ with an average of 70ᵒ, typically in the NW direction.

The Using of Unconventional Method depending on Well Power in the Mishrif Formation to Release Differential Stuck Pipe, Nahr Umr Oil Field, Southern Iraq

Karrar T. Alhisnawy — 2023-08-25

One of the main drilling problems is differential stuck pipe that lead to excessive non-productive time. The drill string usually stuck in the filter cake in permeable formations because it becomes immobile as a result of the drill string movement to connect a new pipe, make a trip, handle a drilling issue, etc. because there is a high permeability zone and a pressure difference between formation and filtering. So, without first releasing it by mechanical or chemical processes, the driller is unable to reciprocate or rotate it. Nahr Umr oil field was selected to study the problem of differential stuck pipe occurred while tripping out in the Hartha Formation and procedure steps to formulate the appropriate method to release the stuck string. Used unconventional method to free stuck pipe depend on well power in the Mishrif Formation after the conventional method failed to treat the problem. Then, the results were discussed with estimating stuck pipe depth and the force needed to release the string and comparison between the methods relative to the time and cost. Also, the result can be concluded that the appropriate mud weight is 1.27gm/cc. On the other hand, it was concluded that the unconventional method cheaper than the conventional method but it can be used if the formations contain oil or salt water only.

Delineation of Subsurface Structural Geology in Buzrgan Oil Field Using 2D Seismic Interpretation

Ranya H.A. Al-Khafaji — 2023-08-25

This study focuses on the structural picture interpretation of Buzurgan oil field in the Maysan province of southern Iraq. Using 2D seismic data, Synthetic traces are created by selecting reflectors on the seismic section using the Petrel software and the well (BU-1) data currently available. Paleocene to middle Miocene is represented by these reflectors, which are L-Fars-Kirkuk-Jaddala-Aaliji. A thrust fault that solely impacts the L-Fars formation is dividing the research region into two blocks that are each affected by the examined reflectors. The fault system extends from northwest to southeast. The structural interpretation of depth maps reveals that some anticline folds were localized roughly surrounding well locations were marked on all maps.

Permeability Estimation For Upper Shale Member In Southern Iraqi Oil Field Using Machine learning and Hydraulic Flow Units Methods

Arafat Talal Saleh — 2023-08-25

Permeability estimation in the Upper Shale Member (USM) is rather complex due to the heterogeneity. Conventional logs do not provide permeability directly, but the core data does. Core operations and analysis processing are all costly. An alternative method is used by dividing the reservoir rock into groups (rock types) with similar characteristics in porosity and permeability for cored wells. These identified groups for the core wells can be applied to the uncored wells to predict their groups and permeabilities. Four wells were used in this study: one cored well and three uncored wells. Two classification methods of rock types were used; the first is the machine learning (ML) method (supervised and unsupervised), a new technics invention, and the second method is the hydraulic flow unit (HFU). Four groups were selected by using ML and HFU methods. A regression equation for each rock type was obtained to predict permeability. Then, establishing a relationship between the results of the core data groups and the logs' responses for the core well is referred to as "correlation," which is training the logs that provide an estimating model. A validation check was completed by comparing the rock type and permeability estimation from the core with the rock type and permeability estimation from the logs, which were highly matched. Finally, The rock type and permeability can be estimated for the uncored wells using only the logs that were learned from the generated training data set for the cored wells. Due to the use of more than one model to predict permeability, it was clear that one was more compatible than the other. The flow zone indicator, a classical method, still has a better rock type and permeability estimation than the new techniques, which use data mining and mathematical algorithms on a clustering basis.

Mineral Inversion Approach to Improve Ahdeb Oil Field's Mineral Classification

Usama Alameedy — 2023-08-26

Knowledge of the mineralogical composition of a petroleum reservoir's formation is crucial for the petrophysical evaluation of the reservoir. The Mishrif formation, which is prevalent in the Middle East, is renowned for its mineralogical complexity. Multi-mineral inversion, which combines multiple logs and inversions for multiple minerals at once, can make it easier to figure out what minerals are in the Mishrif Formation. This method could help identify minerals better and give more information about the minerals that make up the formation. In this study, an error model is used to find a link between the measurements of the tools and the petrophysical parameters. An error minimization procedure is subsequently applied to determine the optimal solution. The quality curve is useful for assessing the model's reliability and data depth. Gamma rays and traditional logs both show that calcite and dolomite are the most common matrix minerals in the Mishrif Formation. The clay minerals present in the formation are smectite, illite, and glauconite. Accurate detection of mineral composition resulted in improved identification of fluid content, particularly free and bound water saturation, and, by extension, hydrocarbon saturation.

Petrography and geochemistry of the Baska Piwaza ore mineralization, Halgurd Mountain, Iraqi Kurdistan Region: Insights on the Genesis

Muhammad Ali Ahmed — 2023-08-26

This paper is the first attempt to study the mineralogical and geochemical features of mineralization hosted within the volcanic rocks of the Baska Piwaza section, at Halgurd mountain, which is the highest mountain in Kurdistan and the whole of Iraq, the host lithologies in the studied section represent mostly volcanic rocks, basalts to andesites, and secondary sedimentary lithologies, such as radiolarian chert. There are two main stages of oxide and sulfide mineralization that can be recognized under three-time epochs which are early, middle and late stages that caused the formation of oxide and sulfides ore minerals. The most dominant oxide mineral is hematite, with minor contribution of magnetite, goethite, and rutile. In terms of sulfides, pyrite is the predominant mineral phase with secondary contribution of chalcopyrite. The petrographic study along XRD data of the host volcanic rocks reveal that the most abundant minerals are plagioclase, K-feldspar, pyroxene, and amphibole, while the secondary minerals are quartz, calcite, clinochlore, sericite, prehnite, pumpellyite, and muscovite. Additionally, the radiolarian chert is comprised by quartz, hematite, calcite, ankerite, clay minerals, and apatite which is carecterized by low silica content and high iron oxide. Low concentration of TiO₂ ,and Fe₂O₃ are suggesting the quartz vein occurred with the volcanic rocks are formed due to low hydrothermal fluid.Field observation, petrographical and geochemical data indicate that the rocks of the Baska Piwaza Section are influenced by hydrothermal alteration, due to the high value of Loss On Ignition (LOI) and the high ratio of alkalis (Na₂O+K₂O). Moreover, evidences of chloritization and sericitization of the mafic minerals, and plagioclases and feldspars respectively support the hydrothermal impact.

The Effect of Nickel, Vanadium, Asphaltene, NSO and Sulfur on Crude Oil Quality

Salih M. Awadh — 2023-08-26

The Mishrif reservoir (Cenomanian - Turonian) in the Z, H, B and N oilfields in southern Iraq was investigated to clarify how nickel, vanadium, asphaltene, NSO and sulfur content affect the crude oil quality. The GC-Mass and ICP-MS analyses were used to provide fruitful hydrocarbon results. Classification of crude oil based on API gravity broadly indicates the oil's density and general properties. Typically, lighter crude oils are easier to refine, yield higher percentages of valuable products such as gasoline and diesel, and have a higher market value. Heavier crude oils require more processing and may yield more residual products, such as heavy fuel oil and asphalt. The Mishrif crude oil was classified as a medium sour crude oil containing high sulfur content (%) in Z oilfield (5.22), H oilfield (5.1), and B (5.12); more significant than those in N crude oil, which is classified a sweet based on less than 5% sulfur. The content of asphaltene, nickel, NSO, and vanadium affects the quality of crude oil and the market price because of its negative impact on refining processes, susceptibility to corrosion, and environmental damage later after fuel consumption and burning.

Geochemistry of Sabkhas in Abu Ghraib, Western Baghdad, Iraq

Yaser B. Mohammad — 2023-08-26

The study aims to detail the chemistry of Sabkha located in Abu-Graib, western Baghdad to know the content of the rare elements distributed. Sabkhas are found in dry areas with significant evaporation rates. The quantity of dissolved salts rises as water evaporates from the shallow basins, eventually causing salt to crystallize. The creation of the distinctive salt pans and crusts on the top is greatly influenced by this process. The trace elements (Ti, V, Cr, Mn, Ni, Cu, Zn, Ga, As, Se, Rb, Sr, Y, Zr, Nb, Mo, Sn, Ba, Ta, Tl, Pb, Th, U, I, and Br) beside the major oxides were analyzed using XRF technique. There are no clear significant differences in the distribution of the elements between the two Sabkhas in the village of Kadim Alaa’ab and the village of Haj Shiaa. Sabkhas are characterized by limited oxygen supplies in the brine, high temperatures, and precipitation of evaporite minerals including chlorides, sulfates, and sulfides. Halite predominates in the Sabkha sediments due to the association of chloride with Na₂O. The CaO is distributed forming calcite, dolomite and gypsum as well as a small amount of clay minerals. The association of trace elements, especially Ni, Rb, Ta, Tl and Br, is mainly concentrated with clay minerals, followed by their concentration in silica, especially Y, Zr and Th. As for halite, it is not associated with trace elements.

Trace and Rare Earth Elements Geochemistry of the Mudstone Rocks from the Injana Formation: Implications for Provenance and Paleoclimate

Anwar S. Al-Maadhidi — 2023-08-26

Late Miocene-Pliocene mudstones of the Injana Formation were examined to provide insight into the nature of the source rocks and paleoclimate. For these purposes, 23 mudstone samples from three locations Mirawa and Degala in the Erbil, northern Iraq and Najaf from southern Iraq. These samples were analyzed by ICP-MS to measure the concentrations of the trace and rare-earth elements (REE). The chondrite-normalized REE of all samples are similar and shows slight enrichment with LREE relative to the HREE with negligible negative Eu anomaly. The discriminant plots of the trace elements and the enrichment factors suggest that the source was intermediate-mafic rocks, and the climate was warm and humid during the deposition of the mudstone of the Injana Formation.

Suitability of Dental Stone Preparation Using Local Gypsum and Sodium Chloride

Saja K. Othman — 2023-08-26

The current research included the preparation of dental stones from local raw gypsum and boiling it with a solution of 30% sodium chloride using reflex method. According to the current study, there is no country in the Middle East that produces dental stones. As the details of the method of manufacturing dental stones are not published and are considered very confidential by international companies, and when taking into account that the price of the dental stone is twice the price of plaster, it becomes very important to manufacture dental stones for optimal utilization of the natural wealth in the country. Raw gypsum samples were collected from the Al-Qadisiyah quarry, which is located 19 km southeast of Kirkuk. All samples were subjected to chemical analyses and physico-mechanical tests, including specific weight, particle size, solidification time, longitudinal expansion coefficient, compressive strength, and water-to-powder ratio. The method used for preparing dental stones included the use of a reflex device within a closed system, as there is no loss in sodium chloride solution. The ideal conditions for preparing dental stone were obtained, which are the use of a grain size ranging between -500 and +300 microns and boiling for an hour, followed by drying for an hour at 105 °C, whereby it became possible to prepare dental stone with physiomechanical properties superior to dental stone type III dental stone, according to the American specification for dentists, which indicates that the desired goal of this research has been achieved.

Estimation the Q-Value and some Mechanics Parameters of Fifth Caves in a Haditha Area to Determine their Suitability for Underground Storage

Mustafa I. Ahmed — 2023-08-26

The main purpose of this research is to identify the rock mass quality of fifth caves in the Haditha area using the rock mass quality method, In order to determine the suitable way to support and use them for the purposes of underground storage . The first cave is located in the village of Aloos, the second and third caves are in the Khafajia area, the fourth is in the Barwana area, and the fifth cave is in the Al-Subhani area. The Q system is based on six parameters are direction, spacing, aperture, roughness, and condition of rock mass discontinuities, it also depends on groundwater and RQD ,were determined by geological field study. The rock mass quality in the fifth caves is Fair According to the Q system. Caves can be used for underground storage, but not for all materials, as they can be used for solid materials, as well as by placing steel, plastic or concrete tanks in them. It can also be used in the form of small warehouses because these places are characterized by conditions that differ from the surface conditions in terms of temperature, as they help to provide a sustainable environment due to the use of energy in them and therefore the lack of harmful substances emitted to the atmosphere.

Mineralogical and Grain Size Analysis of Bai Hassan Formation Terraces in Al-Teeb Area, SE Iraq

Muqdad T. Sedkhan — 2023-08-26

Bai Hassan Formation is exposed as remnants of beds from previous formations due to severe erosion that were removed. Results from grain size analysis revealed that most of the studied sediments were coarse-grained sediments ranging from coarse sand to gravel. The study shows that the sediments are poorly sorted. The values of skewed coefficients ranged from fine to strongly skewed, and the negative values indicate the occurrence of hard changes in the environment. Meanwhile, the kurtosis values for the studied sediment indicate that the differences in these values are due to changes in the flow and sediment sorted in a relatively high energy environment. Light minerals like quartz, and feldspars, and rock fragments are identified. Heavy minerals such as chlorite, amphibole, pyroxene, mica, epidote, zircon, garnet, tourmaline, rutile, kyanite, and staurolite can provide information about the geological processes and environments that occurred in a particular area. These minerals can be indicative of specific rock types, metamorphic or igneous formations, that are derived from high Zagros mountains. The collision between the Arabian Plate and the Eurasian Plate resulted in the formation of the Zagros Fold and Thrust Belt, leading to the uplift and deformation of the Zagros Mountains. The Bai Hassan Formation in Iraq originated during the Miocene epoch from fluvial and alluvial fan environments. Sediments carried by rivers and streams from the elevated mountains in Iraq and Iran were deposited, forming conglomerates, sandstones, and mudstones that reflect various depositional settings such as braided river channels and floodplains indicating a rapidly sinking basin with freshwater and lacustrine environments.

Slopes Stability Simulation of the Proposed Makhool Dam Against Earthquake Action

Hasan K. Hameed — 2023-08-26

This study was designed to analyze the stability of the slopes of the proposed Makhool dam under the influence of the highest seismic acceleration experienced by the dam area since (1997-2022), which is 0.29g with a degree of 7.3ML, due to the earthquake that struck most of the cities of Iraq in 2017. Makhool Dam is a zoned earth dam that is proposed to be built on the Tigris River in north Iraq with length of 3670 m. The study was carried out using Geoslope programs, which used the finite element method. The stability of the dam slopes were analyzed under the influence of the earthquake for three cases, the first at the end of construction (the reservoir is empty), and the second at the maximum level of the reservoir (152.15 m), As for the third, in the case of rapid emptying of the reservoir . The results indicate that the seismic safety factors for the upstream and downstream slopes of the dam are stable and correspond to the minimum acceptable safety factors for the Makhool Dam project. With the exception of the case of the earthquake coinciding with the case of the rapid emptying of the reservoir, where critical stability or collapse of some parts of the upstream slope of the dam may occur, and this case is rare.

Integration of Ground Penetrating Radar and Electrical Resistivity Methods to Investigate Subsurface Features at Kish Archaeological site, Babylon, Iraq

Zubayda A. All-Rawi — 2023-08-26

Several geophysical techniques, including magnetic, Electrical Resistivity Imaging, and Ground Penetrating Radar, have been used to investigate archaeological features because they are non-destructive and inexpensive compared to traditional methods such as excavation. Ground Penetrating Radar has been used in the Governorate of Babylon, Kish archeological site to investigate the subsurface ancient features. The Ground Penetrating Radar survey carried out on three parallel profiles. The length of each profile is 29 m and the spacing between each adjacent profile is 15 meters. The antennas 450 MHz and 750 MHz were used. The data was processed using Ground Penetrating Radar SliceV7 software. The Ground Penetrating Radar profiles indicate the presence of buried features, which may be an ancient wall. The wall is buried at a depth range between 0.5 and 3 m. Outside the study area, some part of the wall is visible on the surface. Three Electrical resistivity image profiles (1, 2 and 3) were carried out by using wenner array to check the main features detected by Ground Penetrating Radar method. The Electrical resistivity imageresults are confirmed the Ground Penetrating Radar profiles (1, 2, and 3). Both methods indicate the existence of an ancient wall trending NW-SE. The thickness of the wall is approximately 3m and is located at distance 7.5-10.5 meters at profile 1 in the south and at distance 10-13 m in profiles 2 and 3. The depth of the wall ranges from 3–3.5 m. Another deep wall was also detected in the Ground Penetrating Radar profile 1 and in the three profiles of Electrical resistivity imagemethod. The current work confirmed the importance of using Electrical resistivity image method with Ground Penetrating Radar method to investigate shallow subsurface features.

Determining Attenuation Q-Factor Values for Selected Seismic Stations n Iraq

Fatima K. Khagoory — 2023-08-26

The coda wave decay (CWD) method was used to estimate the quality factor from the coda wave amplitude decay rate for the broadband seismic stations (IBDR, MSL, and NSR4) using a single backscattering model. This research aims to calculate the attenuation coefficient and the frequency-dependent coefficient (α) for three stations and compare them to comprehend the details of Earth's crust structure in those stations. Then, to test if they are homogenous or not. Also, investigate how sensitive extracted values to tectonic differences in study stations. The attenuation properties are important for providing information about the medium that seismic waves pass through and can also be applied to areas with seismic activity as initial disaster mitigation. The study used data from the Mesopotamian Network (MP) and the Iraqi Meteorological Organization and Seismology (IMOS) from 2011 to 2021. The selected earthquakes have less than < 100 km epicentral distances, and magnitudes ranging from 3.5 to 5.6. Forty-six earthquakes were recorded by three stations (IBDR, MSL, and NSR4). These earthquakes were analyzed at eight center frequencies (1, 2, 3.5, 6, 8, 10, 12, and 16 Hz) and a 30-sec length window by using the SEISAN Earthquake Analysis Software. The Q_C values are computed by the frequency-dependent relationship Q_C= Q₀ f ^α, where Q₀ is Q_C at 1Hz and α denotes frequency dependence degree. The attenuation relationship of the station IBDR is obtained as Q_C =98 f ^1.07, Q_C = 99 f ^1.09 in the MSL station, and Q_C = 77 f ^0.98 in the NSR4 station. The results showed that low Q₀ corresponds to high attenuation. The comparison of the estimated Q_C for these three stations indicates that attenuation is highest at NSR4, followed by other stations.

Variation of b-value of Normal, Reverse and Strike-Slip Faulting Earthquakes with Focal Depth

Huda F. Rafea — 2023-08-26

A crucial factor in evaluating seismic activity, seismotectonics, and seismic hazard assessment is the distribution of earthquake sizes (b-value). The goal of this research is to explore the relation between depth and the b-constant values of normal, inverse, and strike-slip faulting earthquakes. The earthquake catalog used in this work was extracted from the Global Centroid Moment Tensor Catalog (GCMTC) and covers the period from 2008 to 2017. The focal depth of the selected tremors ranges from zero to 700 km. The magnitude of completeness for normal and reverse faulting events is 5.2 and 5.1 for strike-slip faulting events. The value of the b- constant was estimated using the maximum likelihood technique. The findings of regression analysis showed that there is an insignificant negative poor correlation relation between the b- value of the normal and strike-slip faulting events and depth, while that relation is an insignificant positive poor correlation for reverse faulting. The depth of the turning point for the b-constant value of normal and reverse faulting earthquakes is near the mantle seismic discontinuities 410 and 520 km. The depth of inflection points of b-constant value strike-slip faulting earthquakes is near to lithosphere-asthenosphere boundary (LAB) at depth of 250km and the mantle seismic discontinuity of 520km.

Biostratigraphy of Jeribe Formation at Selected Sections in Wasit Governorate, Eastern Iraq

Younes N. Ibrahim — 2023-08-26

The present study is concerned with Biostratigraphy of the Early-Middle Miocene outcrops of Jeribe Formation in the Zurbatiyah area, Wasit Governorate, Eastern Iraq. Forty-two Samples collected from Shur Sharin and AL-Hashima outcrop sections. The fossil content is rich in large and small benthic foraminifera; Twenty-one species and genus are identified in this study, in addition to coral, gastropoda, pelecypoda, ostracoda, alge, echinoid and shell fragments. According to the presence of benthic foraminifera, two Biozone have been identified in Jeribe Formation as follows:

Austrotrillina asmariensis-Dendritina rangi Concurrent Zone.
Borelis melo curdica range zone. The age of the Formation determined as Early-Middle Miocene depending on these Biozone

Palaeoenvironment Conditions During Deposition of Sargelu, Naokelekan, and Najmah Formations in Zey Gawara Area, Kurdistan Region, Iraq: Implications from Major and Trace Elements Proportions

Chrokhan T. Mina — 2023-08-26

Palaeoenvironment conditions during deposition of Jurassic Sargelu, Naokelekan, and Najmah formations were studied based on samples from well Z1 in Zey Gawara area, Kurdistan region, Iraq. For the purpose of determining the palaeoredox, palaeoclimate conditions as well as palaeoweathering, tectonic setting, and provenance indices, the inorganic geochemical analysis to indicate the number and amount of different elements were performed. Based on the occurrence and proportionalities of trace elements e.g., V, Ni, Cu, Sr, the Sargelu Formation was probably accumulated in suboxic to anoxic conditions, while the Naokelekan and Najmah formations were deposited under the suboxic to dysoxic conditions. Relatively semiarid condition have suggested for Sargelu and Naokelekan formations, and relatively semi humid condition for Najmah Formation. The chemical index of alteration and the high plagioclase index of alteration suggest for modest to intense weathering source area for the Sargelu and Naokelekan formations. The index of chemical variability (<1) implies that the Sargelu, Naokelekan, and Najmah formations are probably immature sediments and deposited inside a tectonically active setting. Based on the tectonic indicators, the Sargelu and Naokelekan formations were deposited in an active continental margin, and the Najmah Formation was deposited in an oceanic island arc. The felsic for the Sargelu and Naokelekan and the felsic- intermediate igneous rocks were proposed as plausible source rocks for the Najmah Formation.

Petrogenesis of Amphibolite/Hornblendite Dikes in Qala-Diza Area, Kurdistan Region, Iraq

Jolyana R. Petros — 2023-08-26

The amphibolite and hornblendite dikes occur as part of the igneous complexes of Bulfat Ophiolite within the Zagros Suture Zone, NE Iraq. The igneous complex is part of the upper allochthonous ophiolite terrane w ithin the second unit of the Penjween-Walash Subzone. This article discusses the petrogenetic characteristics and tectonic setting of the amphibolite rocks based on their petrography, mineral chemistry, and whole-rock geochemistry. Petrographically, both banded and massive amphibolites reveal that the main mineral constituents are amphibole and plagioclase with accessory clinopyroxene, opaques, sphene, apatite, rutile, zircon, sericite, epidote and chlorite; meanwhile the hornblendites consist of >90% amphibole with minor amounts of pyroxene, opaques, plagioclase, titanite, quartz, apatite, zircon, and chlorite. The amphibolites are divided into two types, banded (foliated) and massive, (non-foliated). The dominat textures of amphibolites are porphyroblastic, granoblastic, poikiloblastic, nematoblastic, and blasto-ophitic; meanwhile those of hornblendites are equigranular, poikilitic, cataclastic, and intergranular. The electron microprobe analysis (EPMA) showed that the amphiboles of the banded amphibolite range between tschermakite, magnesio-hornblende and pargasite; and those of the massive amphibolites range between magnesio-hornblende and actinolite; meanwhile those of hornblendites are dominantly tschermakite with minor magnesio-hornblende and pargasite. The plagioclase of the banded amphibolites is mainly oligoclase and andesine; and those of the massive amphibolites are mostly anorthite. Chemical classification diagrams indicated that the studied rocks are had low alkalies (Na2O+K2O), tholeiitic, ultrabasic to basic, alkaline to subalkaline and divided between foidite, picrobasalt and basalt. Various tectonic discriminating diagrams showed that most of studied rocks are mid-ocean ridge basalt (MORB). The studied amphibolites have been subjected to amphibolite facies metamorphism.