LITHOLOGY AND STRATIGRAPHY OF THE CENOMANIAN/ TURONIAN BOUNDARY IN ZAGROS OROGENIC BELT EXAMPLES FROM KURDISTAN REGION, NORTHEASTERN IRAQ

Cenomanian-Turonian (C/T boundary) is globally foci of intense geological study in the most part of the world due its organic matter content. In Iraq, the representative of the boundary is defined previously as bituminous black shale and named “Gulneri Formation” which is about 2.5 meters thick. In the country, the boundary is controversial both stratigraphically and lithologically; since it is assumed that its top and base are bounded by unconformity and deposited in euxinic and small relic basin. In the present study, the previous studies are critically evaluated and many new results and new fact are documented about the formation through studying of nine sections. The new results include changing of the lithology and boundary condition (rejecting of underlying and overlying previously indicated unconformities). The lithology has amended to marl and marly limestone and the depositional basin is changed to large open basin in which Balambo and Kometan formations are deposited. Additionally, many fish remains are found in the formation. The remains are three types; the first is fish scales, which have circular shape with concentric rings and about 1 to 4 mm in diameters. The second is fish backbones (skeletons), four skeletons are found, which belong to small fish about 4 to10 cm long and 5mm to2 cm wide. The third is fish fins (pectoral fin), which are well preserved in hand specimens and have grey or brown color and consist of groves and ribs. The fish remains are evidence that a depositional environment of the Gulneri Formation was deep, large and open sea. Only the bottom of the sea was anoxic, which had preserved the organism remains that had fallen down from the surface of water and rested on the sea bottom

Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London

Surgical site infection after gastrointestinal surgery in high-income, middle-income, and low-income countries: a prospective, international, multicentre cohort study

Background: Surgical site infection (SSI) is one of the most common infections associated with health care, but its importance as a global health priority is not fully understood. We quantified the burden of SSI after gastrointestinal surgery in countries in all parts of the world. Methods: This international, prospective, multicentre cohort study included consecutive patients undergoing elective or emergency gastrointestinal resection within 2-week time periods at any health-care facility in any country. Countries with participating centres were stratified into high-income, middle-income, and low-income groups according to the UN's Human Development Index (HDI). Data variables from the GlobalSurg 1 study and other studies that have been found to affect the likelihood of SSI were entered into risk adjustment models. The primary outcome measure was the 30-day SSI incidence (defined by US Centers for Disease Control and Prevention criteria for superficial and deep incisional SSI). Relationships with explanatory variables were examined using Bayesian multilevel logistic regression models. This trial is registered with ClinicalTrials.gov, number NCT02662231. Findings: Between Jan 4, 2016, and July 31, 2016, 13 265 records were submitted for analysis. 12 539 patients from 343 hospitals in 66 countries were included. 7339 (58·5%) patient were from high-HDI countries (193 hospitals in 30 countries), 3918 (31·2%) patients were from middle-HDI countries (82 hospitals in 18 countries), and 1282 (10·2%) patients were from low-HDI countries (68 hospitals in 18 countries). In total, 1538 (12·3%) patients had SSI within 30 days of surgery. The incidence of SSI varied between countries with high (691 [9·4%] of 7339 patients), middle (549 [14·0%] of 3918 patients), and low (298 [23·2%] of 1282) HDI (p < 0·001). The highest SSI incidence in each HDI group was after dirty surgery (102 [17·8%] of 574 patients in high-HDI countries; 74 [31·4%] of 236 patients in middle-HDI countries; 72 [39·8%] of 181 patients in low-HDI countries). Following risk factor adjustment, patients in low-HDI countries were at greatest risk of SSI (adjusted odds ratio 1·60, 95% credible interval 1·05–2·37; p=0·030). 132 (21·6%) of 610 patients with an SSI and a microbiology culture result had an infection that was resistant to the prophylactic antibiotic used. Resistant infections were detected in 49 (16·6%) of 295 patients in high-HDI countries, in 37 (19·8%) of 187 patients in middle-HDI countries, and in 46 (35·9%) of 128 patients in low-HDI countries (p < 0·001). Interpretation: Countries with a low HDI carry a disproportionately greater burden of SSI than countries with a middle or high HDI and might have higher rates of antibiotic resistance. In view of WHO recommendations on SSI prevention that highlight the absence of high-quality interventional research, urgent, pragmatic, randomised trials based in LMICs are needed to assess measures aiming to reduce this preventable complication

Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

Background Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide.Methods A multimethods analysis was performed as part of the GlobalSurg 3 study-a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital.Findings Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3.85 [95% CI 2.58-5.75]; p&lt;0.0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63.0% vs 82.7%; OR 0.35 [0.23-0.53]; p&lt;0.0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer.Interpretation Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

PİRAMAGRUN ANTİKLİNALİ’NİN GÜNEYDOĞUSUNUN STRATİGRAFİSİ VE YAPISAL JEOLOJİSİ, SÜLEYMANİYE, KUZEYDOĞU IRAK

Piramagrun Antiklinali (veya Piramagrun Dağı) Süleymaniye şehrinin kuzeybatısına doğru uzanır, Kuzeydoğu Irak ve bölgenin kuzeydoğu kesimi diğer birçok küçük kıvrım ile birlikte Harmetool ve Yakhyian isimli diğer iki antiklinali ve senklinallerini de içerir. Antiklinalde son yıllarda yoğun petrol aramaları gerçekleştirilmiş ve 3000 metre derinliğe kadarbir sondaj kuyusu açılmıştır ancak, herhangi bir petrol veya doğal gaz bulgusuna rastlanamamıştır. Bu çalışmada, güneydoğu kesimi stratigrafik ve yapısal açıdan incelenmekte olup bölgede petrol olmamasının nedenlerini tespit edebilmek için önceki çalışmalar eleştirel bir şekilde gözden geçirilmektedir. Çalışmada, antiklinalin stratigrafisi tanımlanır ve Kometan, Gulneri, Dokan, Balambo ve Sarmord formasyonları jeoloji haritasına ve stratigrafik istife işaretlenir; ayrıca,daha önceden yaşları tespit edilmemiş aralıkların yaşlandırılmasında nannofossiller kullanılır. Gulneri Formasyonununkalınlığı 2-4 metre arasında olup nannofosil analiziyle yaşı Geç Senomaniyen-Erken Turoniyen olarak tespit edilmiştir. Dokan formasyonunun ve Balambo formasyonunun üst seviyesinin litolojisi ve tabakalanma tipleri Kometan Formasyonuna çok benzer ve fosillerle veya kılavuz seviye olan Gulneri Formasyonuyla ayırt edilmiştir. Gulneri Formasyonununmostrası yumuşak olduğu için ayırt etmede yardımcıdır ve arazide koyu rengiyle kolaylıkla farkedilir. Antiklinalinyapısı, bazı yerlerde güneybatıya dalımlı asimetrik antiklinallerden oluştuğu için bazı yerlerde ise devrik kıvrımlaradönüştüğü ve ters faylarla deforme olduğu için komplekstir. Antiklinaller, Gulneri ve Sarmord Formasyonlarındaki sıyırmalar ve diğer yaşlı yumuşak kayaçlarla şekillenir. Oluşan antiklinaller, çoklu-sıyrılma kıvrımı veya çoklu-sıyrılma faylı kıvrım tipindedir

Tectonostratigraphic evolution of the northeastern Arabian Plate in Kurdistan since the Jurassic

La zone étudiée est située dans le nord de l Irak dans la Région Autonome du Kurdistan. Cette région correspond géographiquement à la partie nord-ouest de la chaîne du Zagros. La chaîne du Zagros est une chaîne plissée de couverture longue d environ 1800 km. Elle résulte du plissement de la couverture sédimentaire de la marge et de la plate-forme de la plaque arabe pendant la collision cénozoïque entre la plaque arabe et l Eurasie. Ce travail s appuie sur une étude tectono-stratigraphique des série jurassique à cénozoïque du Kurdistan. La période antérieure à la collision a principalement été étudiée, en particulier les relations entre les principaux évènements tectoniques et la sédimentation. The principaux domaines développés sont (1) la biostratigraphie à partir de l étude des assemblages de nannofossiles, (2) l analyse de la tectonique cassante et (3) l étude stratigraphique de la séquence d âge jurassique à cénozoïque (plus particulièrement crétacée). Les séries de la chaîne du Zagros montrent de nombreux changements latéraux et verticaux de facies et d environnement, plus particulièrement pendant le Crétacé. Au cours du Jurassique le Kurdistan était occupé par le bassin de Gotnia qui s ouvrait vers le sud-ouest vers le bassin de Kermansha. Du Berriasien au Barrémien le Kurdistan était couvert par les carbonates des formations de Balambo et de Sarmord. Dans l est et le sud-est du Kurdistan la formation de Sarmord passe latéralement graduellement aux facies de bassin de la formation de Balambo. De l Aptien au Cénomanien une épaisse série de carbonates d origine récifale constituant la formation de Qamchuqa s est déposé. Un premier épisode extensif peu marqué est enregistré à l Aptian. Il est associé à des changements latéraux de facies abrupts entre les formations de Qamchuqa et de Balambo. Pendant la période allant du Cénomanien au Turonien inférieur un graben apparait dans la région du Lac de Dokan dans l est du Kurdistan où se déposent des facies plus profonds (formations de Dokan et Gulneri) entourés de dépôts de plate-forme. Pendant le Turonien se déposent les facies de bassin constitués des calcaires fins à silex de la formation de Kometan qui couvrent le nord-est du Kurdistan. Ces calcaires sont absents dans le centre et l ouest du pays notamment dans les anticlinaux de Safeen, Shakrok et Harir où cette formation a été totalement ou partiellement érodée pendant la période Coniacien à Campanien inférieur. La sédimentation est très hétérogène pendant le Crétacé supérieur avec une lacune du Coniacien et Santonian. Un bassin associé à une tectonique extensive se développe au Campanien avec le dépôt des marnes et des calcaires marneux de la formation de Shiranish. La première apparition au Kurdistan des facies flyschoïdes de la formation de Tanjero a été précisément datée du Campanien supérieur au Kurdistan. La formation de Tanjero, d âge Campanien supérieur à Maastrichtien recouvre en concordance la formation de Shiranish. La formation de Tanjero se dépose dans le bassin d avant-fosse associé à l obduction des ophiolites téthysienne sur la plate-forme arabe. Le Campanien est une période de non-dépôt dans la partie centrale du Kurdistan (région de Safeen, Shakrok et Harir) alors qu à l ouest se développe une vaste plate-forme carbonatée (la plate-forme de Bekmeh). Cette sédimentation carbonatée disparait pendant le Campanien supérieur quand les calcaires marneux de la formation de Shiranish transgressent la plate-forme de Bekmeh. Dans le secteur d Aqra la formation de Tanjero passe latéralement aux facies récifaux maastrichtiens de la formation d Aqra. Cette dernière est recouverte en discordance par les carbonates de lagons de la formation de Khurmala. Pendant une grande partie du Campanien la sédimentation est contrôlées par des failles normales orientées NE-SW qui structures les grabens de Dokan, Spilk et Soran. Au cours du Maastrichtien dans l extrême nord-est du pays des extensions NE-SW et NNW-SSE se développent dans le bassin d avant-fosse et sont à l origine des structures en horsts et grabens. Les dépôts clastiques de la formation de Tanjero sédimentent dans les grabens tandis que des lentilles des calcaires récifaux se déposent sur les horsts. Ces lentilles calcaires intercalées dans la série clastique flyschoïde peuvent atteindre quelques dizaines de mètres d épaisseur et plusieurs kilomètres de long. L étude des déformations cassantes dans ces corps carbonatés du Maastrichtien moyen-supérieur a montré que l extension liée à la formation des structures en horsts et grabens était associée, par permutation des axes principaux de contraintes 1 et 2, à des régimes décrochants. Cependant l essentiel des paléo-tenseurs reconstruits dans le Zagros kurde à partir de l analyse des populations de failles à stries est associé à l orogénèse du Cénozoïque supérieur du Zagros, donc à la collision entre l Arabie et l Eurasie. Le champ de contrainte néogène lié à cet évènement majeur est caractérisé par une alternance de régimes compressifs et décrochants avec des axes de la contrainte principale 1 orientés NNE-SSW à ENE-WSW avec une pic principal orienté NE-SW.The studied area is located in Northern Iraq in the Kurdistan Region, which approximately corresponds to the North-Western part of the Zagros belt. The Zagros belt is an active fold and thrust belt approximately 1800 km long, mainly resulting from the deformation of the sedimentary sequence of the Arabian margin and shelf during the Cenozoic Arabian-Eurasia collision. This study concentrates on the tectono-stratigraphy evolution of Kurdistan from Jurassic up to present. However we mainly investigated the evolution of the pre-collision period, focusing on the relationship between tectonics and sedimentation. In this study we developed (1) a biostratigraphic approach using nannofossil analysis, (2) a fault tectonic analysis, and (3) a stratigraphic study of the Jurassic to Neogene sequences (more particularly the Cretaceous series). The Zagros fold belt in Kurdistan exhibits many lateral and vertical environmental and facies changes, especially during the Cretaceous times. During the Jurassic period the Kurdistan is occupied by the restricted Gotnia Basin. This basin disappeared and the Kurdistan area changed to open marine of a southwest Kermanshah Basin during the Cretaceous. During the Berriasian to Barremian the Kurdistan was covered by the carbonates of the Balambo and Sarmord formations. In the east and southeast the neritic Sarmord Formation gradationally and laterally passes to the basinal facies of the Balambo Formation. In the Aptian to Cenomanian period shallow massive reefal limestone of the Qamchuqa Formation deposited. The normal faulting that initiates during the Aptian is associated with an abrupt lateral change of the reefal Qamchuqa Formation to the Aptian-Cenomanian part of the Balambo Formation. During the Cenomanian-Early Turonian periods the graben formed in the Dokan Lake in eastern Kurdistan, where developed a deeper restricted environment (Dokan and Gulneri formations) surrounded by a shallow marine platform. During the Turonian the marine pelagic micritic cherty limestones of Kometan Formation covered northeast of Kurdistan, whereas in the Safeen, Shakrok and Harir anticlines the formation was totally, or partially, weathered during the Coniacian-Early Campanian period. The deposition during the Late Cretaceous is very heterogeneous with a gap in the Coniacian-Santonian times probably related to a non-deposition. Associated with extensive tectonics a basin developed during the Campanian with the deposition of shales, marls and marly limestones of the Shiranish Formation. The first appearance is the Kurdistan of the flysch facies of the Tanjero Formation was precisely dated of the Upper Campanian in northeastern Kurdistan. The Tanjero Formation conformably overlaying the Shiranish Formation and was deposited in the foredeep basin associated with the obduction of Tethyan ophiolites onto the Arabian Platform. The Early to Late Campanian period is a time of non-deposition in Central Kurdistan (Safeen, Shakrok and Harir anticlines). During the Late Campanian the Bekhme carbonate platform in the north disappeared when the marly limestones of the Shiranish Formation transgressed over the Bekmeh Platform. In the Aqra area the Maastrichtian Tanjero Formation laterally changed to the thick reefal sequence of the Aqra Formation that unconformably overlies by the Late Paleocene-Early Eocene lagoonal carbonate of the Khurmala Formation. The Campanian sedimentation is mainly controlled by NE- oriented normal faults forming Grabens in Dokan, Spilk and Soran areas. During the Maastrichtian in the extreme northeastern Kurdistan the NE-SW and NNW-SSE normal faults developed in the foredeep basin and originated horsts and grabens. Clastic sediments accumulated in the grabens and the reefal carbonate developed on the horsts. These bars are several tens of meters thick and commonly several kilometres long. The study of the brittle deformations in these Middle-Upper Maastrichtian carbonate bodies showed that the strike-slip faults associated with the extension, formed by permutation of the orientation of 1 and 2 axes. However most of the paleotensors reconstructed (compressional and strike-slip regimes) in the Kurdish Zagros from analysis of fault populations are associated with the Late Cenozoic Zagros orogeny, which results from the collision between Arabia and Eurasia. The Neogene stress field related to this major event is characterized by alternating compression with the principal stress axes 1 oriented NE-SW to ENE -WSW with a main peak oriented NE-SW.PARIS-BIUSJ-Sci.Terre recherche (751052114) / SudocSudocFranceF

KD IRAK’TA İLK KEZ TANIMLANAN RUDİSTLER (BIVALVIA): SİSTEMATİK PALEONTOLOJİ VE PALEOBİYOCOĞRAFYA

KD Irak’ta Mawat-Chwarta Bölgesi’nde (Süleymaniye şehri) Mastrihtiyen yaşlı Aqra Formasyonu kırıntılı ve biyoklastik kireçtaşlarından yapılıdır ve yaşam konumunda bol miktarda rudistlerle simgelenir. Formasyonda rudist biyostromları yaygın olarak gözlenir ve rudistlere bentik foraminiferler, gastropodlar, pelesipodlar ve az miktarda ekinidler ve bireysel mercanlar eşlik eder. KD Irak’ta bu çalışmayla ilk kez tanımlananan rudist faunası Dictyoptychus aff. morgani, Sauvagesia somalica, Hippurites cornucopiae, Praeradiolites subtoucasi ve Lapeirousia jouanneti türlerinden oluşur ve bazı tanımlanamayan radiolitid kesitleri de içerir. Rudist türleri orta-Geç Mastrihtiyen yaşını işaret eden Hippurites cornucopiae aralık biyozonu’na aitlerdir. Dictyoptychus, Arap Plakası için endemik bir rudist cinsidir. Sauvagesia somalica türü de Arap Plakası’na özgü gibi görülmektedir. Tanımlanan diğer tüm türler esas olarak Akdeniz Tetisi’nin Orta ve Doğu Bölgelerinde, ancak kısıtlı olarak da Arap Plakası’nda dağılım gösterirler. KD Irak’ta rudistlerin tanımlanması, taksonomik ve paleobiyocoğrafik veri boşluğunu doldurması açısından önem taşır. Rudist faunasına ilişkin veriler, Mastrihtiyen’de Zagros Kuşağı boyunca GD Anadolu’dan KD Irak boyunca GB İran’a kadar rudist larvalarının ulaşımını sağlayan bir sığ su yolunun varlığını ortaya koyar

Üst Kretase Zagros tebeşirli kireçtaşının (Kometan Formasyonu) jeolojisi ve eleştirel değerlendirmesi (Süleymaniye, KD Irak)

Tebeşirli kireçtaşları (Kometan Formasyonu) Geç Türoniyen – Orta Kampaniyen yaşlı olup, Kuzeydoğu Irak’ta, Süleymaniye bölgesindeki Yüksek, İmbrike ve Bindirme Zonlarında yüzeylemektedir. Bu kireçtaşları yanal olarak, Kuzeybatı ve Batı Irak’a doğru sırasıyla Bekhme ve Mushurah formasyonlarına geçmekte olup, resifal eşdeğerleri ise Orta Irak’taki petrol sahalarının altında yer almaktadır. Stratigrafik olarak üstteki Shiranish Formasyonu (Orta-Geç Kampaniyen) ile alttaki Gulneri Formasyonu (Geç Senomaniyen-Erken Türoniyen) arasında yer almaktadır. 40-120 metre arası bir kalınlığa sahip olan birim pelajik ortamda çökelmiştir. Önceki bütün çalışmalarda, tabaka yüzeyleri üzerinde veya yakınında yoğun çört nodülleri ve stilolitlerin olduğu, tabaka düzlemleri belirgin ve ince taneli derin deniz fasiyesindeki kireçtaşları olarak tanımlanmıştır. Fosil kayıtlarında yalnızca nannofosil ve planktik formlar ile az miktardaki bentik foraminiferlere rastlanır. Bütün bunların aksine, son zamanlarda yapılan bir çalışmada yukarıdaki tüm özellikler reddedilmiş ve litoloji, bol miktarda Thalassinoides iz fosili içeren masif, homojen bir kireçtaşı olarak değiştirilmiştir. Buna ilaveten tabakalanma yüzeylerinin aslında gerçek tabakalanma olmadığı (yalancı tabakalanma); depolanma ile değil, stilolitleşme ile meydana geldiği sonucuna varılmıştır. Bu çalışma Kretase yaşlı tebeşirli kireçtaşlarının jeolojisine ilişkin bilgileri güncelleme ve eleştirel bir değerlendirme üzerine odaklanmakta; yukarıda belirtilen tüm fikirlerin karşılaştırılmasına ek olarak yeni fikirleri de tanıştırmayı amaçlamaktadır. Önceki yazarların belirttiği Thalassinoides, masiflik ve yalancı tabakalanma özellikleri tartışılmış ve bulunmayışları arazi ve laboratuvar çalışmaları ile teyit edilmiş ve doğrulanmıştır. Ayrıca masiflik durumu reddedilmiş ve tabaka düzlemlerinin belirginliği (nispeten ince tabakalı) bütün kesitlerde formasyonun temel bir özelliği olarak ortaya konmuştur. Bu çalışma ayrıca çört nodülleri ve çört tabakalarının; biyotürbasyon, kırıntılı malzeme, derecelenme, laminasyon ve renk değişiminin yokluğuna bağlı olarak iz fosiller ile bir ilişkisinin olmadığını göstermektedir. Öte yandan Kometan Formasyonunun Zagros önülke (foreland) havzasında depolanması fikri reddedilmekte; ofiyolit üzerlemesi ve önülke oluşumu öncesinde Neotetis Denizi’nin (ya da okyanusu) kıtasal kenarında depolandığı fikri kabul edilmektedir