دانشگاه اصفهان پژوهش های چینه نگاری و رسوب شناسی 2008-7888 34 3 2018 09 23 New finding on the biostratigraphy and paleoecology of the Farrokhi Formation in northwest of Khur, Central Iran, based on palynomorphs and foraminifera بایواستراتیگرافی و پالئواکولوژی سازند فرخی در شمال باختری خور، ایران مرکزی با استفاده از پالینومورف‌ها و فرامینیفرها 1 20 23150 10.22108/jssr.2018.109056.1036 FA صدیقه جداوی کارشناسی ارشد، پژوهشکدۀ علوم زمین، سازمان زمین‌شناسی و اکتشافات معدنی کشور، تهران، ایران ابراهیم قاسمی نژاد استاد، دانشکدۀ زمین‌شناسی، پردیس علوم، دانشگاه تهران، تهران، ایران 0000-0002-4421-5068 محمودرضا مجیدی فرد دانشیار، پژوهشکدۀ علوم زمین، سازمان زمین‌شناسی و اکتشافات معدنی کشور، تهران، ایران Journal Article 2018 01 11 Introduction: Upper Cretaceous deposits of Iran do not have the same facial features everywhere. Indeed it seems that contrary to the same conditions of the lower Cretaceous the upper Cretaceous sedimentary basins were separated from each other and had a special condition on each basin accordingly, except for the Zagros and Koppeh-Dagh they have not been officially named (Aghanabati, 2006). Several sedimentary facies have been reported to be existing during the Cretaceous period. The sequences formed in these basins in different regions, although are similar in terms of fossil content but, they are very different in terms of petrography, thickness and deposition time. Also, Cretaceous rocks are diverse in Central Iran, with varying thickness and age, and have not been officially named yet and are generally investigated. Since the most complete Cretaceous sequence in Central Iran was in the Yazd block and in the Khur area, we decided that the Farrokhi formation (Aistove et al., 1984), which is the youngest Cretaceous rock unit in the Khur region, should be studied. The Farrokhi formation is one of the Upper Cretaceous rocky units, with a variable thickness of 65 to 180 meters (Aistove et al., 1984), and made up of limestone, limestone with rubble or strips which is characterized by abundance of echinoid and bivalves. The lowest part of this formation is reportedly 45 to 120 meters of marl with sandstone layers. Based on the brachiopods, bivalves and echinoid, the formation has been aged as Senonian-Danian (Aistove et al., 1984). Therefore, in order to complete the stratigraphic and paleontological data, the Farrokhi formation is selected and studied. The formation is the youngest Cretaceous rock unit in the Khur, Anarak and Jandag areas, which in most areas there is a marl body in its base. The Farrokhi formation in this section is 233 meters thick and is placed continuously on limestones of Haftuman formation while, it upper contact with the limestones of the Chupanan formation is conformable. The formation has been divided into four informal divisions. Materials and methods: In order to study lithostratigraphy and biostratigraphy of the Farrokhi informal formation, an outcrop of the formation was selected and sampled at Azizabad village northwest of Khur city. A total of 81 rock samples were taken of them 25 samples for palynological studies, 17 samples were washed for their foraminiferal contents and 39 samples were used to prepare thin sections. Discussion of Results & Conclusions: The Azizabad section is located 400 kilometers northeast of Isfahan and on the edge of the great desert, northwest of the city of Khur. In this section, the Farrokhi formation conformably overlay limestones of the Haftuman fm. while, it is in turn overlain by the Chupanan formation. The Farrokhi formation at this section is mostly composed of marl and limestone so that the lower part is formed from green to buffy marls containing sponges and in the upper parts from marly limestones and marly intercalation which turn into the massive limestones of the Chupanan formation. Study of the palynological slides showed that only two samples in the lower part of the formation were rich in dinoflagellate cysts containing 46 genera and 71 species. The assemblage is well fitted in the Odontochitina costata Interval Zone according to the previous reports of this cyst zone. Two foraminiferal biozones were also differentiable according to the assemblages and index forms identified. These include: Globotruncana aegyptiaca Interval Zone (Late to Latest Campanian) and Gansserina gansseri Interval Zone (Latest Campanian to Early Maastrichtian). According to the fossil set, the Farrokhi formation at this locality is of middle Campania to Maastrichtian age. The study of the three major groups of palynological elements, as well as the organic factors, the ratio of the transparent (AOM) to the marine elements and the lability factor in the two samples indicated that this part of the section was deposited in an open shallow marine environment forming a transitional zone to the deepest part of the basin in which planktonic foraminifera bloomed. به‌منظور مطالعه‌های چینه‌نگاری سنگی و زیستی سازند غیررسمی فرخی، برش عزیزآباد واقع در شمال باختری شهر خور انتخاب شد. ستبرای سازند فرخی در این برش 233 متر است، به‌شکل پیوسته روی سنگ‌‌آهک‌های سازند هفتومان قرار گرفته و همبری بالایی آن با سازند چوپانان ناپیوسته از نوع موازی است و به چهار بخش غیررسمی تقسیم شده است. درمجموع، 81 نمونۀ سنگی شامل 25 نمونۀ مارنی برای مطالعۀ پالینولوژیکی، 17 نمونۀ مارنی برای مطالعۀ فرامینیفرهای ایزوله و 39 نمونۀ سنگی برای تهیۀ مقاطع نازک از این سازند برداشت شدند. از مجموع نمونه‌های آماده‌شده برای مطالعه‌های پالینولوژیکی تنها 2 نمونه دارای سیست داینوفلاژله بودند. با مطالعۀ اسلایدهای پالینولوژیکی، مقاطع نازک و نمونه‌های شسته‌شده درنهایت 46 جنس و 71 گونه از داینوفلاژله‌ها، 13 جنس و 40 گونه از روزن‌بران آزاد و 9 جنس و 3 گونه از روزن‌بران بنتیک متعلق به کامپانین میانی- ماستریشتین شناسایی شدند. همچنین با مطالعه و شمارش عناصر پالینولوژیکی مربوط به 2 نمونۀ مدنظر تنها یک پالینوفاسیس (IV) تشخیص داده شد که نشان‌دهندۀ محیط دریایی باز و کم‌عمق برای این بخش از سازند و بیان‌کنندۀ یک زون انتقالی به بخش‌های عمیق‌تر حوضه است. بر ‌پایۀ داینوفلاژله‌های شاخص محیط، محیط گرم و به‌نسبت کم‌ژرفا با انرژی متوسط برای این قسمت از بخش مارنی سازند فرخی در زمان انبایش رسوبات پیشنهاد می‌شود.

https://jssr.ui.ac.ir/article_23150_66f8eb4ce7f084fda7ba277a1b3dec29.pdf

دانشگاه اصفهان پژوهش های چینه نگاری و رسوب شناسی 2008-7888 34 3 2018 09 23 Palynostratigraphy of the Middle Jurassic strata of central and eastern Alborz پالینوستراتیگرافی رسوبات ژوراسیک میانی (دوگر) البرز مرکزی و شرقی 21 36 23151 10.22108/jssr.2018.109218.1039 FA فیروزه هاشمی یزدی دکتری چینه‌شناسی و فسیل‌شناسی، دانشکدۀ زمین‌شناسی، پردیس علوم، دانشگاه تهران، ایران فرشته سجادی دانشیار، دانشکدۀ زمین‌شناسی، پردیس علوم، دانشگاه تهران، ایران حسین هاشمی دانشیار، دانشکده علوم زمین ، گروه زمین‌شناسی ، دانشگاه خوارزمی، تهران، ایران Journal Article 2018 03 04 Introduction In the geological history of Iran, the Mesozoic Era is of great significance since many important geological events occurred during this time interval. The tectonic and paleogeographic evolution of Iran during the Mesozoic controlled by the geodynamic interaction of Eurasian continental margin and the Tethyan oceanic belt. In the southern Alborz the Middle Jurassic marine transgression (Dalichai Formation overlying the Shemshak strata) began in upper Bajocian. The former rock unit is represented by greenish-grey calcareous shales, marls, and fossiliferous (ammonites) limestones (Steiger, 1966) widely distributed in the northern Alborz Mountains. It disconformably overlies the dark, siliciclastic coal-bearing Shemshak Formation and underlies gradually by the light-colored, rather uniform chert-bearing Lar limestones. The Dalichai Formation signifies the first rock unit of the Jurassic marine sediments in the Alborz Mountains. It embraces such diverse fauna as ammonites, belemnites, bivalves, brachiopods, echinoderms, sponges, miospores (spores and pollen grain), dinoflagellates, bryozoans and foraminifera (Stöcklin 1972; Sussli 1976; Nabavi & Seyed-Emami 1977; Alavi-Naini et al. 1982; Schairer et al. 1991; Seyed-Emami et al. 1985, 1989, 1995, 1996; Shafeizad et al. 2002; Shafeizad and Seyed- Emami 2005; Alvani 2006; , Niknahad 2007; Shahrabi 1994; Vaziri et al. 2008, 2011; Shams 2007; Makvandi 2000; Tutunchi 2001). Due to the presence of palynologically promising lithologies therein. The Dalichai Formation 8has been the subject of many palynological studies (e.g., Wheeler & Sarjeant 1990; Ghasemi-Nejad et al. 2012; Mafi et al. 2013; Dehbozorgi et al. 2013; Hashemi-Yazdi et al. 2015; Skupien et al. 2015; Dehbozorgi 2013; Saadati Jafarabadi et al. 2013; Hashemi Yazdi 2008, 2015; Orak 2010; Sajjadi et al. 2009; Sabbaghiyan 2009; Ghasemi-Nejad et al. 2008; Boroumand et al. 2011, 2013; Farisi Kermani 2003; Ghasemi- Nejad & Khaki 2002; Navidi 2013). The main aim of this study is to establish a palynostratigraphic scheme for the Middle Jurassic strata of central and eastern Alborz Mountains. Material and Methods A total of 104 palynological samples were collected exclusively from three outcrops of the Dalichai Formation in the central Alborz Mountains (Poldokhtar and Balu stratigraphic sections) and eastern Alborz (Lavan stratigraphic section). All samples were prepared following standard palynological processing procedures (e.g. Phipps & Playford, 1984; Traverse, 2007). Rock samples treated by acids (10%—50% hydrochloric acid to dissolve carbonates and 40% hydrofluoric acid to remove silicates); followed by application of hot 50% HCl to dissolve silica-gel formed during HF treatment. The residues then further treated with saturated ZnCl2 for mineral separation. All residues subsequently sieved through a 20μm mesh prior to make strew slides. Three slides of each preparation examined by transmitted light microscope. The slides are stored in the collection of Faculty of Geology, Tehran University, Tehran, Iran. Discussion of Results and Conclusions The Middle Jurassic shales and calcareous shales are widely distributed acorss northern Iran. Diverse palynofloras comprising spores (90 species belonging to 44 genera) and 22 pollen taxa (attributed to 9 genera) occur in 104 surface rock samples collected from the Dalichai Formation at Poldokhtar, Balu, and Levan stratigraphic sections in the Alborz Ranges. In addition to terrestrial elements, such well preserved marine palynomorphs as dinoflagellates, foraminiferal test linings, tasmanites, scolecodonts, and acritarchs are also encountered in the assemblages investigated. According to the presence of such miospores species with known worldwide stratigraphic distribution as Klukisporites variegatus, Concavissimisporites verrucosus, Converrucosisporites pricei, Sellaspora asperata, Contignisporites burgeri, Osmundacidites senectus, Striatella spp. the host strata are conceivably dated as Middle Jurassic. This age determination is supported by the occurrence in the material examined of such distinct Middle Jurassic (late Bajocian-Callovian) dinoflagellates as Cribroperidinium crispum, Meiourogonyaulax valensii, Carpatodinium predae,Ctenidodinium combazii,Compositosphaeridium polonicum,and Mendicodinium groenlandicum. Based on the co-occurrence of land-derived palynomorphs a Klukisporites variegatus-Araucariacites australis-Cerebropollenites macroverrucosus Assemblage Zone is herein introduced in the Middle Jurassic strata studied. شیل و شیل‌های آهکی ژوراسیک میانی در شمال ایران پراکندگی جغرافیایی وسیعی دارند. پالینوفلورای متنوعی شامل 90 گونه اسپور (متعلق به 44 جنس) و 22 گونه پولن (منتسب به 9 جنس) در نهشته‌های سازند دلیچای در برش‌های چینه‌شناسی پل دختر و بلو (البرز مرکزی) و لوان (البرز شرقی) وجود دارد؛ علاوه‌بر پالینومورف‌های شاخص محیط خشکی، عناصر دریایی شامل داینوسیست‌ها، پوستۀ داخلی فرامینیفرها، تاسمانیتیدها، اسکلوکودونت‌ها و آکریتارک‌ها با حفظ‌شدگی خوب نیز دیده می‌شوند. با‌توجه‌به حضور میوسپورهایی مانند Klukisporites variegatus،Concavissimisporites verrucosus، Converrucosisporites pricei، Sellaspora asperata، Contignisporites burgeri، Osmundacidites senectusوStriatella spp.که پراکندگی چینه‌شناسی شناخته‌شده‌ای در رسوبات ژوراسیک میانی مناطق مختلف دنیا دارند نهشته‌های سازند دلیچای در برش‌های چینه‌شناسی مطالعه‌شده به ژوراسیک میانی نسبت داده می‌شوند. این تعیین سن باتوجه‌به وجود داینوفلاژله‌های با گسترش چینه‌شناسی شناخته‌شده (باژوسین پسین- کالووین) مانند Cribroperidinium crispum، Meiourogonyaulax valensii، Carpatodinium predae، Ctenidodinium combazii، Compositosphaeridium polonicum و Mendicodinium groenlandicumتأیید می‌شود. بر اساس گسترش چینه‌شناسی میوسپورها بایوزون تجمعی Klukisporites variegatus, Araucariacites australis, Cerebropollenites macroverrucosus Assemblage Zone در نهشته‌های سازند دلیچای در البرز مرکزی و البرز شرقی معرفی می‌شود.

https://jssr.ui.ac.ir/article_23151_7d3055a7a90b4a4aa8b95021c6ee7a11.pdf

دانشگاه اصفهان پژوهش های چینه نگاری و رسوب شناسی 2008-7888 34 3 2018 09 23 Biostratigraphy of the Gurpi Formation Based on Planktonic foraminifera in Gandab Section and it's comparison with Type section, Kabirkuh Anticline, SW Iran زیست‌چینه‌نگاری سازند گورپی‌ بر مبنای روزن‌داران پلانکتون در برش گنداب و تطابق آن با برش نمونه، تاقدیس کبیرکوه، جنوب غرب ایران 37 52 23217 10.22108/jssr.2018.112943.1068 FA سمیرا رحیمی دانشجوی دکتری چینه‌نگاری و دیرینه‌شناسی، دانشگاه فردوسی مشهد، مشهد، ایران علیرضا عاشوری استاد، گروه زمین‌شناسی، دانشکدۀ علوم، دانشگاه فردوسی مشهد، مشهد، ایران عباس صادقی استاد، گروه زمین‌شناسی، دانشکدۀ علوم زمین، دانشگاه شهید بهشتی، تهران، ایران 0000-0002-5515-0781 عباس قادری استادیار گروه زمین شناسی - دانشکده علوم - دانشگاه فردوسی مشهد - مشهد - ایران Journal Article 2018 09 23 Introduction Due to the source nature and placement of the Gurpi Formation between the Asmari and Bangestan reservoirs, it has a special importance. The name of this formation has been derived from Gurpi Mountain in the northwest of Masjid-Soleyman County. At the type section, this formation includes 320 meters of marl and bluish gray shales together with subordinate thin layers of clayey (argillaceous) limestone which overlies the limestones of the Ilam Formation, along an erosional unconformity. The Gurpi Formation has an open marine and deep sea sedimentation environment, which is why it is a good talent for biostratigraphy studies using planktonic fauna. Studies conducted by some researchers on the Gurpi Formation represent a Late Santonian – Tanetian age in different parts of the Zagros area, based on different planktonic assemblages (e.g., Kameli Azan et al., 2004; Darvishzadeh et al., 2007; Abrari et al., 2010; Senemari & Sohrabi Molla Usefi, 2012; Senemari & Azizi, 2012; Beiranvand et al., 2013; Najafpour et al., 2014; Fereydoonpoor et al., 2014; Razmjooei et al., 2014.). Materials and methods This study is based on macroscopic field description of 252 meters of Upper Cretaceous sequences (Gurpi Formation) in the Gandab section located on southern flank of Kabir Kuh anticline in Lurestan Province of Zagros, southwest Iran. In total, 192 hand specimens were taken from rock samples and sediments from these sections for paleontological study. After washing, samples were dried on sieves and put in special cellules. Released fossils were studied by binocular firstly, and then by Scanning Electronic Microscope (SEM). Determination and naming genera and species was based on Robaszynski et al. (1984), Caron (1985), Loeblich and Tappan (1988), and Premoli Silva and Verga (2004). Discussion of Results Biostratigraphy In this study, 57 species related to 20 genera and 7 biozones of planktonic foraminifers are recognized in Gandab section. - Globotruncana ventricosa Interval Zone This biozone is defined between Globotruncana ventricosa appearance at the bottom and Radotruncana calcarata appearance at the top. It is correlated with Globotruncana ventricosa biozone aged Middle to Late Campanian (Premoli Silva and Verga , 2004). - Radotruncana calcarata Total range Zone This biozone which its top and bottom is consistent with the appearance and extinction of Radotruncana calcarata respectively, It is correlated with Radotruncana calcarata biozone aged Late Campanian (Premoli Silva and Verga , 2004). - Globotruncana aegyptiaca Interval Zone This zone is defined according the appearance of Globotruncana aegyptiaca at the base and the appearance of Gansserina gansseri at the top and is parallel to Globotruncana aegyptiaca biozone aged the End of Late Campanian (Premoli Silva and Verga , 2004). - Gansserina gansseri Interval Zone It places between the appearance of Gansserina gansseriat the base andContusotruncana contuosaat the top. This biozone is parallel with Gansserina gansseri biozone aged the most final part of Campanian-Maastrichtian (Premoli Silva and Verga , 2004). - Contusotruncana contuosa Interval Zone This biozone is defined between the appearance ofContusotruncana contuosa at the base and Abathomphalus mayaroensis at the top and is equivalent of Contusatruncana contusa and Racemiguembelina fructicosa biozones and aged Early to Late Maastrichtian (Premoli Silva and Verga, 2004). - Abathomphalus mayaroensis Interval Zone It is defined between the appearance of Abathomphalus mayaroensis species at the base and its extinction at the top. This biozone equals Abathomphalus mayaroensisbiozone agedLate Maastrichtian(Premoli Silva and Verga, 2004). Cretaceous – Paleocene (K-P) boundary K-P boundary is located on top of the Gurpi Formation in Gandab section. It is characterized by the end of Abathomphalus mayaroensis zone and extinction of all planktonic foraminifers. In this research, because of the missing of Guembelitria cretacea Zone P0 as a result of far sampling distance, biozone of Abathomphalus mayaroensis related to Gurpi Formation, is located below Parvularugoglobigerina eugubina Zone (Pα) of the Pabdeh Formation (i.e. Danian). Correlation Biozones of the Gurpi Formation in Gandab section are compared with biozones of this formation at the in Kuh - e Siah anticline. In the Kuh - e Siah anticline studied by Fereydoonpoor et al, 2014, 8 biozones were introduced from the Gurpi Formation. These biozones give Early Santonian – Early Maastrichtianage for the Gurpi Formation in this section. Conclusions The Gurpi Formation at the Gandab section with a thickness of 252m composing of limestone and argillaceous limestone. The lower boundary with the Ilam Formation is conformable with sharp lithology and upper boundary is gradational with the Pabdeh Formation in two sections. Through this study, 57 species related to 20 genera and 7 biozones of planktonic foraminifers in Gandab section were distinguished. According to these biozones and fossil content, the age of Gurpi was determined Middle Campanian to Late Maastrichtian.Transition from Maastrichtian to Paleocene was continuous and the K-P boundary located at the top of Gurpi Formation. در پژوهش حاضر زیست‌چینه‌نگاری سازند گورپی در برش گنداب در جنوب غرب ایران مطالعه شد. سازند گورپی در برش گنداب شامل 252 متر سنگ‌آهک ‌رسی و سنگ‌آهک است و از دو عضو سیمره (لوفادار) و امام حسن تشکیل شده است. این سازند به‌طور پیوسته و هم‌شیب سازند ایلام را پوشانده و به‌طور پیوسته و تدریجی زیر سازند پابده قرار گرفته است. با مطالعۀ 192 نمونۀ برداشت‌شده از این سازند، 20 جنس، 57 گونه و 7 بایوزون از روزن‌داران پلانکتون در برش گنداب شناسایی شده است که این بایوزون‌ها شامل Globotruncana ventricosa Zone، Radotruncana calcarata Zone، Globotruncanella havanensis Zone، Globotruncana aegyptiaca Zone، Gansserina gansseri Zone، Contusotruncana contuosa Zone و Abathomphalus mayaroensis Zone در برش مطالعه‌شده‌اند. با‌توجه‌به بایوزون‌های تشخیص داده شده سن کامپانین میانی- مایستریشتین پسین برای سازند گورپی در این برش پیشنهاد می‌شود. بایوزون‌های تعیین‌شده در این برش با برشی در یال شمالی تاقدیس کبیرکوه و دیگر نواحی زاگرس و همسایه مقایسه شدند. مرز کرتاسه- پالئوژن بر رأس سازند گورپی منبطق است.

https://jssr.ui.ac.ir/article_23217_66ab8028be23fe56e5f81b78d297f08a.pdf

دانشگاه اصفهان پژوهش های چینه نگاری و رسوب شناسی 2008-7888 34 3 2018 09 23 Biogenic structures in test of large benthic foraminifers (Orbitolina): Example from Aptian-Albian sediments of SW Neo-Tethys Ocean, Zagros, SW Iran ساختار‌های زیستی در پوستۀ روزن‌بران کف‌زی بزرگ (اربیتولین) نمونه‌ای از رسوبات آپتین-آلبین در جنوب ‌غرب اقیانوس نئوتتیس، زاگرس، جنوب‌ غرب ایران 53 72 23218 10.22108/jssr.2018.110933.1054 FA سید محمدعلی موسوی زاده استادیار گروه زمین شناسی، پردیس علوم، دانشگاه یزد، یزد فاطمه موسوی زاده دکتری زمین شناسی، پردیس علوم، دانشگاه یزد، یزد Journal Article 2018 05 16 Introduction Study of carbonate sediments of the Dariyan Formation (Aptian-Albian) in northwest of Shiraz releases different types of biogenic structures in forms of encrustation and drilling in hard substrates. Generally biogenic structures are referred to as changes in soft or hard sediments, which are created by certain organisms and through biological processes (Neumann, 1966). If drilling is performed on soft substrates, it is called Burrow, and if it is created in hard substrates, it is called Bore (Golubic et al., 1975). The organisms can cause macroscale destruction and cavitation on hard surfaces, known as macroboring, which including as certain bivalves, gastropods, echinoids, sponges, polychaetes, arthropods, bryozoans or benthonic foraminiferans (Bromley, 2004). Certain organisms, like certain groups of cyanobacteria, green and red algae, as well as fungi, create microscale digestion, which, due to their small size, have been called microboring (Bromley, 2004). From paleoecology perspective, studying the hard substrates can help determine the spatial distribution and how to orientate the organisms during their lifetime. For example, an accurate investigation of encrustation or drilling on brachiopod shells can provide information on the orientation of the bedding, the pattern of feeding, coexistence, as well as the sequences of occupations by the diggers, their priority for specific mechanisms in the host shells, and that how these organisms interacted throughout life (Taylor and Wilson, 2003). Material & Methods In order to study the biological structures, 267 thin sections were studied the facies were named by Dunham (1962) and Embry and Klovan (1973) methods. For distinguished calcite and dolomite, thin sections were stained with Alizarin Red-S and Dickson (1966). In order to identify the types of existing biotechnology, their factors and classification of these effects have been used from references such as Bromley (1970), Taylor and Wilson (2003), Schlagintweit and Bover-Arnal (2013) and Schlagintweit et al (2015). Finally, the conditions of formation and characteristics of these biological structures are discussed. Discussion and conclusions One of the most selected substrates by borer organisms is orbitolina test, as an index large benthic foraminifer in this episode. Both conical and discoidal orbitolina have been subjected to these type of biogenic structure. The most likely options for producer organisms of these bioerosive structures are “colinid sponges” and “calcimicrobes” and much of them can be attributed to Entobia Ichnogenus (mostly produced by sponges). In the studied samples, Entobia has been created in parallel with the outer surface of the orbitolina wall, which is also vertically viewed in the longitudinal section and horizontally in the transverse section while others have no orientation. In these cases they also extend from the wall to the central part. Some of these types of drills are a single central cavity with radial channels leaving it. Other identified biogenic structures include tubes of serpulid worms, bacinellid encrustation, thaumatoporellaceans encrustation and channel shape borings by unknown producers. Tubes of serpulid worms are seen both in the form attached to shells and colonies within the limed mud matrix. Bacinellid encrustation has created a dark wall around the cellar and in some rare cases, the two adjacent orbitolinids form a tangential state and connect both of them, so that the encrustation extended to the limestone between two orbitolins. Thaumatoporellaceans encrustations were observed on the tests of the orbitalins (upper and lower levels) or even attached to the shells of brachiopods. The size of the chamber wall occupied by this algae is about 8 microns and in appearance is similar to Entobia. Borings by unknown producers is characterized by a straight-to-slightly irradiated channel pattern, which shows continuous increase in the diameter of the channel from the beginning to the end of the path. Often, these drills are single channels, but in some cases they are seen as branching channels. In morphological aspects, the most boring structure is parallel tunnels to external side of orbitolina test and in terms of facies distribution, they mostly found in the foraminiferal wackestone and orbitolinid floatstone facies contain orbitolina and green algae. This dispersal pattern accompanied by Thalassinoides ichnogenus somehow reflects low sedimentation rate and providing the opportunity for organism’s activities. مطالعات انجام‌شده روی رسوبات سازند داریان به سن آپتین- آلبین در شمال شیراز تنوعی از ساختار‌های زیستی از نوع قشرزایی و حفاری را در بستر‌های سخت (hard substrates) نشان می‌دهند. دیوارۀ اربیتولین‌ها که شاخص‌ترین روزن‌برهای بزرگ کف‌زی در این بازۀ زمانی معرفی شده‌اند یکی از فراوان‌ترین بسترهای انتخاب‌شده توسط جانداران است. در این رسوبات هر دو نوع اربیتولین‌های مخروطی و دیسکی‌شکل در معرض ساختار‌های زیستی قرار گرفته‌اند. عمدۀ این حفاری‌ها را جاندارانی نظیر اسفنج‌ها و کلسی‌میکروب‌ها انجام داده‌اند که بخش عمده‌ای از ‌آنها به اثرجنس Entobia نسبت داده می‌شوند (عمدتاً اسفنج‌ها آنها را ایجاد می‌کنند). سایر ساختارهای زیستی شناسایی‌شده عبارتند از: لوله‌های کرم‌های سرپولید، قشرزایی جلبک‌های Bacinellid، قشرزایی همراه با جلبک‌های Thaumatoporellaceans و حفاری‌های کانالی با جانداران سازندۀ نامشخص. فراوان‌ترین نوع حفاری ازنظر ریخت‌شناختی به‌شکل تونل‌های موازی با حاشیۀ دیوارۀ خارجی اربیتولین‌ها است و ازنظر پراکندگی رخساره‌ای، ساختار‌های زیستی عمدتاً در رخساره‌های وکستون روزن‌بردار و فلوتستون اربیتولین‌دار دیده می‌شوند. این الگو پراکندگی به همراه گسترش اثرجنس Thalassinoides در این رسوبات نشان‌‌دهندۀ کاهش میزان رسوب‌گذاری در زمان تشکیل ساختارهای زیستی و ایجاد فرصت کافی برای فعالیت جانداران سازنده است.

https://jssr.ui.ac.ir/article_23218_696a6a87c99db776119903677f778d78.pdf

دانشگاه اصفهان پژوهش های چینه نگاری و رسوب شناسی 2008-7888 34 3 2018 09 23 Microbiostratigraphy of the Jahrum Formation in Nimbashi section, West Estahban, Fars ریززیست چینه نگاری سازند جهرم در برش نیم باشی، باختر استهبان، فارس 73 94 23584 10.22108/jssr.2019.113070.1069 FA رضا صادقی استادیار، گروه زمین‌شناسی، بخش علوم پایه، دانشگاه پیام‌نور، تهران، ایران مریم جوکار کارشناس ارشد گروه زمین‌شناسی، بخش علوم پایه، دانشگاه پیام‌نور، تهران، ایران Journal Article 2018 09 26 Introduction: Zagros sedimentary basin in the south and southwest of Iran holds oil and gas huge reservoirs. This basin which bordered the closure of the Paleotethys ocean (Berberian and King 1981), with high thickness of sedimentary sequences laid down in the Mesozoic and Cenozoic. The Jahrum Formation is carbonate sequence that has deposited during the Paleocene–Eocene series (Motiei 1993) and is the carbonate reservoirs rock of the same age in the Zagros sedimentary basin. This research investigates the sedimentary sequence of the Jahrum Formation in TangNimbashi section, to reach the purposes of biostratigraphy, determination of relative age and compare with other sections. This stratigraphic section was measured in detail at 29° 07' 49" N and 53° 55' 30" E and is located in northern flank of Tudej (Toudaj) anticline (west Estahban, Fars province), in the Interior Fars subzone, Fars sub-basin and Zagros simply folded belt. Material & Methods: Includes five stages: a) survey and recording geographic coordinates with global positioning system (GPS) and recognition of the lower and upper boundaries. b) Measuring of the degree and direction of dip (32˚SW) and strike (N85˚W) of layers with compass and determining the direction of the travelling angle (N5˚E). c) Measuring the true thickness of the strata perpendicular to their strike by Jacob Staff and numbering of beds. d) Field description (lithology, stratification, color, fossils) and photography of outcrops. e) Systematic sampling at intervals of two meters and sometimes one meter. Finally the stratigraphic section was measured 628 meters and 338 rock samples were collected and also 153 photos were taken. Then thin sections were evaluated and photographed with binocular microscope in plane polarized light (PPL). Also, different references were used to identify the genus and species of microfossils: (Rahaghi 1980; Loeblich and Tappan 1988; Vecchio et al. 2007; Hottinger 2007 & 2014; Boudagher-Fadel 2008 & 2018; Ozgen-Erdem 2008; Sirel 2009; Di Carlo et al. 2010; Alan 2011; Salih 2012; Molina et al. 2013; Zhang et al. 2013; Deveciler 2014; Bukhari et al. 2016). Discussion of Results & Conclusions: The Jahrum Formation with dolostone, dolomitic limestone and limestone units and medium to very thick stratification, has been deposited on the low-rise, foothills, limestone and marly limestone units of Sachun Formation with very thin to medium stratification. Due to the lack of a detritus unit and paleosol this boundary is sharp, homocline and probably conformable. Its upper boundary after two steps of gradual change and conversion, homocline and conformable its own longer and bladed units to low-rise and foothills units in 505-553.5, 553.5?-575.5? and 575.5-593 meters of the Pabdeh Formation, finally this formation (Jahrum Formation) is covered by Quaternary poorly consolidated alluvial deposits. So, it is impossible to get exact and certain conclusions about this boundary, now. In fact, based on field studies, petrography, microfacies, and microbiostratigraphy, it seems that inthe thicknesses mentioned above, the Jahrom and Pabdeh formations have become interfingering or intertonguing (Pinch-out) each other. With detailed field and laboratory examinations on outcrops and thin sections from the bottom to the top of the Jahrom Formation has been includes 7 lithostratigraphic units (J.1-J.7) and the Pabdeh Formation has been includes 2 lithostratigraphic units (P.1&P.2). Based on identification of 34 genus and 29 species of benthic foraminifera, and 7 genus and 1 species of planktonic foraminifera and according to their pattern of dispersal 13 zonations were recognized. In order 9 assemblage biozones, 2 barren intrazones, 1 barren interzone and 1 indeterminate zone (not well determined). Separated assemblage biozones with biozonation of the benthic foraminifera of the Paleogene sub-system in Zagros basin was suggested by Wynd (1965) and Adams and Bourgeois (1967), also with biozonation of the shallow larger benthic foraminifera (SLBF) of the Tethys basin was proposed by Serra-Kiel et al., 1998, were compared and then their age was determined. The relative age of the Jahrum Formation in this section from 0–20 meters not well determined because of processes of dolomitizatoin, recrystallization, diagenesis and finally absence of index microfossils (foraminifers). But the relative age is estimated from 20 to 143 meters: Late Paleocene? to Early Eocene series (Late Thanetian? –Ilerdian) and from 143–628 meters: Middle Eocene series (Lutetian–Bartonian). This age is suggested with 7 assemblage biozones, including: Alveolina ellipsoidalis-Orbitolites spp. assemblage biozone, Dictyoconus-Coskinolina-Haymanella assemblage biozones (this assemblage has three assemblage sub-biozones: Alveolina-Haymanella-Medocia, Dictyoconus-Coskinolina-Alveolina and Dictyoconus-Coskinolina-Haymanella), Somalina-Medocia assemblage biozone, Nummulites-Alveolina assemblage biozone, Linderina assemblage biozone, that is comparable with assemblage zone 43 and assemblage subzones 44, 48, 49, 50 and 51 (Wynd 1965), Coskinolina sp.-Rhapydionina sp. assemblage zone (Adams and Bourgeois 1967) and also shallow benthic zones (SBZ.) 6, 13, 14 and 17 (Serra-Kiel et al. 1988). در این پژوهش، توالی رسوبی سازند جهرم در برش تنگ نیمباشی با برآورد اهداف زیستچینهنگاری، تعیین سن و مقایسه با برش‌های دیگر بررسی شده است. برش نامبرده در دامنه شمالی تاقدیس تودج (باختر استهبان)، زیرپهنه فارس داخلی، زیرحوضه فارس و پهنه چین‌خورده ساده زاگرس واقع گردیده و پهنای آن 5/610 یا 5/588 متر است. سازند جهرم به‌صورت ناگهانی، همشیب و احتمالاً پیوسته روی واحدهای مارنی و آهک‌مارنی سازند ساچون قرار گرفته و پس از 2 بار تغییر و تبدیل تدریجی، همشیب و پیوسته واحدهای تیغه‌ساز خود به واحدهای تپه‌مانند سازند پابده، سرانجام با نهشته‌های آبرفتی نامتراکم کواترنری پوشیده می‌شود. با شناسایی 34 جنس و 29 گونه از روزن‌بران کف‌زی، تعداد 7 زیست‌پهنه تجمعی درون آن تشخیص داده شد که با استفاده از پهنه‌بندی‌های زیست-زمانی زیرسیستم پالئوژن در گستره زاگرس و تتیس، سن نسبی سازند جهرم از پالئوسن بالایی؟ تا ائوسن میانی پیشنهاد می‌گردد.

https://jssr.ui.ac.ir/article_23584_5ee808dc71b820ed1ba3a7a7c400ba9b.pdf

دانشگاه اصفهان پژوهش های چینه نگاری و رسوب شناسی 2008-7888 34 3 2018 09 23 Geochemical Evaluation and organic facies distribution of the Pabdeh Formation in northwestern coastal Part of the Persian Gulf and southern Dezful Embayment by Rack-Eval Analysis ارزیابی ژئوشیمیایی و گسترش رخساره‌های آلی سازند پابده در سواحل شمال‌غربی خلیج فارس و جنوب فروافتادگی دزفول با استفاده از تجزیه ‌و تحلیل راک- اول 95 108 23703 10.22108/jssr.2019.114396.1079 FA زینب اورک دانشجوی کارشناسی ارشد زمین‌شناسی، دانشگاه صنعتی شاهرود، ایران معصومه کردی استادیار، گروه زمین‌شناسی دانشگاه صنعتی شاهرود، ایران احمد رضا کریمی دکتری زمین‌شناسی شرکت ملی نفت ایران Journal Article 2018 12 09 Abstract Geochemical evaluation of source rock is the first step in assessment of hydrocarbon systems for their exploration. The Pabdeh Formation with the age of Paleocene to Oligocene and lithology of marl, limestone and shale is one of the potential source rocks in the southern part of the Dezful Embayment and northwestern coastal part of the Persian Gulf. In this research, the hydrocarbon generation potential, quality and quantity of source rock, kerogen type, thermal maturation and organic facies distribution are studied. For this purpose, 47 samples from different oil fields in the studied area were analyzed by Rock-Eval 6 pyrolysis system. The kerogens are mostly type II, III and II/III, however the samples are mainly immature and are within diagenesis stage. The 90% of samples have fair to excellent hydrocarbon generation potential. The organic facies of the formation are in the rage of B, BC, C and CD. The organic facies variations are due to lateral facies changes and sea-level fluctuations during deposition of this formation. The Pabdeh Formation can be divided into 3 geochemical zones. The upper and lower zones were deposited during sea level regression with low quantity of TOC and HI as well as kerogen type III. However, the middle zone that deposited during the sea level transgression has high quantity of TOC and HI with kerogen type II. The Pabdeh Formation in the studied area can be characterized as high hydrocarbon generation potential but immature source rock and the middle zone of this formation may represent an unconventional hydrocarbon reserve. Keywords: Hydrocarbon generation potential, Pabdeh Formation, Rock-Eval, Organic facies, Kerogen. Introduction Geochemical assessment of source rock is an interdisciplinary approach which is utilized for increasing success rate of hydrocarbon exploration and efficiency of development plans. This technique can help in determining source rock distribution, source rock maturity, amount of organic matter, hydrocarbon potential generation, kerogen type, amount of production and migration pathways. On the other hand, the regional evaluation of the source rock in the sedimentary basin is necessary because different part of the basin may have different hydrocarbon potential. For this purpose, in this research, the geochemical conditions and organic facies distribution of the Paleocene to Oligocene Pabdeh Formation in northwestern coastal part of the Persian Gulf and southern Dezful Embayment have been investigated. Material and Methods In this research 47 samples from seven wells in the southern part of the Dezful Embayment and northwestern coastal part of the Persian Gulf has been analyzed by Rock-Eval 6 pyrolysis system. About 75 to 100 mg of the powdered cuttings from different depth of the Pabdeh Formation was heated up to 850 °C with the range of 25 °C/min in anoxic condition. The amount of released hydrocarbons, CO and CO2, was measured and the S1, S2, S3 picks were obtained. Discussion of Results and Conclusions In geochemical analysis, assessment of oil contamination in samples is very important as it ruins the quality of results. Based on the S1/TOC diagram, three samples had oil contamination and thus they have not been considered for the evaluations. The two diagrams of TOC/S2 and TOC/(S1+S2) demonstrated that the Pabdeh Formation has fair to excellent hydrocarbon generation potential in the studied area. Among the all samples analyzed, 10 percentage of samples are in poor, 18 percentage in fair and 72 percentage in good to excellent ranges of hydrocarbon generation potential. The S2/TOC diagram showed that the kerogens are mostly types II, III or a combination of these two types. The Van-Kerevelen diagram also confirmed that the kerogen types are II, III and II/III. Based on the kerogen types, the Pabdeh Formation could generate both natural gas and crude oil. However the maturity diagram (Tmax/HI) showed that the formation is immature and within diagenesis stage. This diagram showed that only 6.8 percentage of the samples are within oil generation window. In general, the Pabdeh Formation in northwestern coastal part of the Persian Gulf and southern Dezful Embayment has good hydrocarbon generation potential but it is immature and has not generated hydrocarbon. Therefore another source rock should be considered for the generated hydrocarbon in the studied area. For determining the organic facies and sedimentary environments of the Pabdeh Formation in the Persian Gulf and southern Dezful Embayment, the Jones and OI/HI diagrams were used. Based on this study, variety of sedimentary environments (B, CD, BC and C) have been involved in deposition of the Pabdeh Formation in the studied area. These ranges were mostly associated with redux to semi oxide sedimentary conditions. Different sedimentary environments and lateral facies changes are the most important reasons for wide distribution of organic facies and different kerogen types. In addition to sedimentary environments, relative sea level changes also could have controlled the vertical facies changes in sedimentary successions. This could control the different organic facies and kerogen types of the formation with different sources from continental to oceanic environments. Correlation between hydrocarbon generation potential, TOC, HI and kerogen type showed that the Pabdeh Formation could be divided into three (A, B and C) geochemical zones. The zones A and C, which are upper and lower parts of the formation respectively have lower amount of TOC and HI, deposited during regression. This was the time of relative sea level fall associated with kerogen type III, sourced from continental environments which could have mostly gas generation potential. However the zone B, which is middle part of the formation with brown shale lithology has higher amount of TOC and HI, deposited during transgression. This was the time of relative sea level rise associated with kerogens type I and II, sourced from marine environments which could have commonly oil generation potential. In general the Pabdeh Formation in the southern part of the Dezful Embayment and northwestern coastal part of the Persian Gulf can be characterized as high hydrocarbon generation potential but immature source rock. However, the middle part (B zone) of the formation could be considered as a potential unconventional reservoir. ارزیابی ژئوشیمیایی سنگ منشأ نخستین گام در بررسی سیستم‌های هیدروکربنی طی برنامه‌های اکتشافی است. سازند پابده با سن پالئوسن تا الیگوسن و سنگ‌شناسی مارن، آهک و شیل یکی از سازندهای محتمل برای زایش هیدروکربن در سواحل شمال‌غربی خلیج فارس و جنوب فروافتادگی دزفول است. در پژوهش حاضر، توان هیدروکربن‌زایی، کمیت و کیفیت سنگ منشأ، نوع کروژن، بلوغ حرارتی و گسترش رخسارۀ آلی سازند پابده بررسی شدند؛ به ‌این منظور، تعداد 47 نمونه از میدان‌های واقع در نواحی موردمطالعه با دستگاه راک- اول 6 تجزیه‌وتحلیل شدند. نتایج نشان دادند کروژن‌ها از نوع II، III و مخلوطی از کروژن III و II هستند، ولی اکثراً نابالغند و در مرحلۀ دیاژنز قرار گرفته‌اند. پتانسیل هیدروکربن‌زایی 90 درصد نمونه‌ها در بخش متوسط تا عالی قرار دارد. رخساره‌های آلی این سازند در محدودۀ B، BC، C و CD قرار دارند. این تنوع رخساره‌های آلی از تغییرات جانبی رخساره‌ها و تغییرات نسبی سطح آب دریا طی زمان رسوب‌گذاری این سازند ناشی می‌شود. سازند پابده در منطقۀ مطالعه‌شده به سه زون ژئوشیمیایی تقسیم می‌شود: زون‌های بالایی و پایینی در زمان پسروی آب دریا با مقادیر TOC و HI کم و کروژن نوع III ته‌نشست یافته‌اند؛ درحالی‌که زون میانی در زمان پیشروی آب دریا با مقادیر TOC و HI زیاد و کروژن نوع II نهشته شده است. سازند پابده در منطقۀ مطالعه‌شده سنگ منشأیی با پتانسیل هیدروکربن‌زایی خوب ولی نابالغ شناخته می‌شود و زون میانی این سازند منبع هیدروکربنی غیرمتعارف در نظر گرفته می‌شود.

https://jssr.ui.ac.ir/article_23703_9242a737d8f0486b5122faeb99f9c456.pdf