دانشگاه اصفهان پژوهش های چینه نگاری و رسوب شناسی 2008-7888 36 3 2020 09 22 Investigating the reliability of Gamma Deviation log in sequence stratigraphic studies: Dariyan Formation, the central Persian Gulf بررسی ضریب اطمینان استفاده از نگارۀ انحراف معیار گاما در مطالعه‌های چینه‌نگاری سکانسی سازند داریان، بخش مرکزی خلیج‌ فارس 1 16 24604 10.22108/jssr.2020.120559.1133 FA سپیده داودی دانشکده زمین‌شناسی، پردیس علوم، دانشگاه تهران، تهران، ایران وحید توکلی دانشیار، دانشکدۀ زمین‌شناسی، پردیس علوم، دانشگاه تهران، تهران، ایران حسین رحیم پور-بناب دانشکده زمین‌شناسی، پردیس علوم، دانشگاه تهران، تهران، ایران Journal Article 2019 12 19 Abstract In this study, 110 m of carbonate rocks from one well of the Dariyan Formation in the central part of the Persian Gulf were investigated by using 390 thin-sections and gamma ray data. In order to determine the depositional sequences of this formation, facies analysis led to the identification of nine microfacies in five sub-environments deposited in a carbonate ramp platform. The sea-level changes at the time of deposition of the Dariyan Formation have resulted in formation of three third-order complete depositional sequences. To determine the boundaries by gamma deviation method, each gamma ray data was subtracted from the average data in the whole well and then the obtained values were added together to calculate cumulative deviation from the mean value. Three units and the associated main boundaries were identified by the first level analysis. The second level analysis, which was done separately on all three units, other sequence boundaries (except the boundary at a depth of 1127.2 m) were identified. Comparing the determined boundaries resulting from this method with sequence stratigraphic studies based on the core analysis results indicates that this tool is valuable in determining sequence stratigraphic boundaries in carbonate formations. Keywords: Dariyan Formation, Gamma ray, Standard deviation, Sequence stratigraphy. Introduction Given the importance of oil and gas reservoirs in the world, careful study of facies, sedimentary environments and detection of depositional sequences are very important for identifying oil and gas reservoirs. Accordingly, interpretation of facies associations from thin-sections and reconstructing the sedimentary model are recommended (Reading 1986). Sequences are determined by examining the relationship between facies and depositional environments with the unconformities in sedimentary succession (Catuneanu et al. 2009). Various types of data, such as the outcrops, cores, well logs, cuttings and seismic data are used. However, due to limitations in the production of core data, it is not possible to use them in all cases. Therefore, well log data that are available in most reservoirs can be used as the best tool for sequence stratigraphic studies. Despite the great importance of gamma ray log in determination of sequence stratigraphic framework, few studies have been performed on this subject due to the low amplitude changes of this log in carbonate formations (Aigner et al. 1995; Heimhofer et al. 2010; Peyravi et al. 2010; Ghasemi-Nejad et al. 2015; Mansouri-Daneshvar et al. 2015; Gholami Zadeh et al. 2019). Some previous studies (Tavakoli 2014, 2017; Ghiasvand 2016) determined the sequence boundaries suggested by the gamma deviation log. The present study was performed on the Dariyan Formation (Late Barremian to Early Aptian) from the Khami Group. The purpose of this study was to investigate the reliability of gamma deviation log in sequence stratigraphy analysis of carbonate successions (third-order depositional sequences). Materials and Methods For the present study, 110 m of carbonate rocks from one well of the Dariyan Formation in the central part of the Persian Gulf were investigated by using 390 thin-sections and gamma ray data. In order to understand the geological properties and determine the sequence stratigraphy framework of the Dariyan Formation, petrographic studies were carried out and samples were classified according to Dunham (1962) facies classification. Then, using the transgressive-regressive sequence method, depositional sequences were determined. To determine the boundaries by gamma deviation method, each gamma ray data (CGR-SGR) was subtracted from the average data in the whole well and then the obtained values were added together to calculate cumulative deviation from the mean value) Tavakoli 2014). Finally, the defined sequence boundaries were compared with the results of the gamma deviation log and the method was used in well B with no core data. Discussion of Results and Conclusions Facies analysis led to the identification of nine microfacies (T1, L1, L2, L3, S1, S2, R1, R2, O1) in five sub-environments (tidal zone, lagoon, shoal, proximal open marine and open marine) deposited in a carbonate ramp platform (inner- to mid-ramp). Sea-level changes at the time of deposition of the Dariyan Formation have resulted in formation of three third-order complete depositional sequences with thicknesses of 25, 30.2 and 54.8 m from bottom to the top. Three lithostratigraphic units (Lower Dariyan, Hawar, Upper Dariyan) and the main boundaries were identified by the first level analysis. The second level analysis, which was performed separately on each of the first three units, revealed other sequence boundaries (except the boundary at a depth of 1127.2 m). The reason for the uncertainty of this boundary was very limited change of facies which could not change the gamma ray values. Comparing the determined boundaries with sequence stratigraphic studies based on the core analysis indicates that this tool is valuable in determining sequence stratigraphic boundaries in carbonate succession. The method can also be used in wells with no core data (such as well B). باوجود اهمیت بسیار زیاد نگارۀ گاما در تعیین واحدهای سکانسی به‌علت تغییرات کم دامنۀ این نگاره در سازندهای کربناته، مطالعه‌های محدودی روی آن انجام شده‌اند. در مطالعۀ حاضر، 110 متر رسوبات چاهی از سازند داریان در بخش مرکزی خلیج ‌فارس با استفاده از 390 مقطع نازک میکروسکوپی و داده‌های نگارۀ گاما بررسی شد. تحلیل رخساره‌ای انجام‌شده به شناسایی 9 ریزرخساره در پنج زیرمحیط منجر شد که در پلت‌فرم رمپ کربناته نهشته شده‌اند. تغییرات سطح آب دریا در زمان رسوب‌گذاری سازند داریان به تشکیل سه سکانس رسوبی کامل ردۀ سوم انجامیده است. به‌منظور تعیین مرزها با روش انحراف از معیار نگارۀ گاما، هر دادۀ نگارۀ گاما از متوسط داده‌ها در کل چاه کسر شد و سپس مقادیر به‌دست‌آمده با یکدیگر جمع شدند تا مقدار تجمعی انحراف از معیار محاسبه شود. این روش در تحلیل مرتبۀ اول توانست سه بخش و مرزهای اصلی را مشخص کند و در تحلیل مرتبۀ دوم که به‌شکل جداگانه روی هریک از سه بخش اول انجام شد، سایر مرزهای سکانسی (به‌جز مرزی در عمق 2/1127 متری) شناسایی شدند. تطابق خوب این روش با مطالعه‌های چینه‌نگاری سکانسی در زمینۀ سکانس‌های ردۀ سوم که بر مبنای داده‌های رخساره‌ای تعیین شده‌اند، گویای ارزشمندبودن این ابزار کمکی در تعیین مرزهای سکانسی است.

https://jssr.ui.ac.ir/article_24604_56368681c14fb76c574edb1a2fd039ef.pdf

دانشگاه اصفهان پژوهش های چینه نگاری و رسوب شناسی 2008-7888 36 3 2020 09 22 Investigation of hydrocarbon generation potential of Paleocene sediments in the southern Caspian Basin بررسی توان هیدروکربن‌زایی رسوبات پالئوسن در شرق حوضۀ خزر جنوبی 17 32 24610 10.22108/jssr.2020.121232.1145 FA احسان سعید دانشجوی کارشناسی ارشد مهندسی اکتشاف نفت، دانشگاه بین‌المللی امام خمینی(ره)، قزوین، ایران سعیده سنماری دانشیار، گروه معدن، دانشکده فنی و مهندسی، دانشگاه بین‌المللی امام خمینی(ره)، قزوین، ایران بیژن ملکی استادیار، گروه معدن، دانشکده فنی و مهندسی، دانشگاه بین‌المللی امام خمینی(ره)، قزوین، ایران پرویز آرمانی دانشیار، گروه زمین‌شناسی، دانشکده علوم‏پایه، دانشگاه بین المللی امام خمینی(ره)، قزوین، ایران حسین مهاجر سلطانی کارشناس ارشد زمین‌شناسی، شرکت نفت خزر، تهران، ایران Journal Article 2020 01 21 The present study investigates the geochemical properties of potential source rocks in the eastern Caspian Basin from Alborz structural zone. For this purpose, sections of Suchelma and Purva in south of Neka and an outcrop in south of Sari were selected. The studied samples of sedimentary source rocks of the Paleocene age were analyzed based on Rock-Eval analysis method. The results of Rock- Eval pyrolysis and organic petrography results of probable source rock sediments in one of the exploration wells of Gorgan plain were also studied. According to the results, most of the outcrops samples are immature and were deposited in a regressive continental environment. The samples of exploration borehole studied, are good in terms of organic matter richness but in terms of the amount of kerogen maturation are immature. According to the results of this study, these samples have weak hydrocarbon generating power and total organic carbon content of about 1% as well as kerogen type III. It was also specified in the determination of organic facies that most of the mentioned samples show deep environmental conditions adjacent to orogenic and continental sites and are deposited in a regressive environment. Keywords: Source rock, Rock- Eval experiment, Maturity, Southern Caspian Basin, Hydrocarbon generation potential. Introduction The Caspian Sea region is well known for its abundant oil reserves and oil and gas production has played an important commercial role in the region for more than 150 years especially in Azerbaijan and to a lesser extent in Turkmenistan (Smith- Rouch 2006). Identification of hydrocarbon systems in the Caspian sedimentary basin is of great importance for exploratory studies and to achieve the production of hydrocarbon resources. One of the main pillars of any oil system is the source rock. Therefore, it is necessary to identify the source rock and determine its location in any system to avoid imposing exorbitant costs and unsuccessful excavations. The relatively low geothermal gradients (around 1.5°C 100m-1) from rapid burial provide favorable thermal conditions for the preservation of hydrocarbons at relatively great depths (up to10+ km) (Nadirov 1990). A petroleum source rock is defined as any rock that has the capability to generate and expel enough hydrocarbons to form an accumulation of oil or gas. Definitions that do not include migration and accumulation are too general, because in a sense practically all rocks contain organic matter (OM) form some hydrocarbons. A potential source rock is one that is too immature to generate petroleum in its natural setting but will form significant quantities of petroleum when heated in the laboratory or during deep burial (Hunt 1996). The main source- rocks in the south Caspian basin are considered to be Paleogene- Miocene deposits (Maykop/ Diatom) (Guliyev et al. 2001). Paleocene deposits in Iran are important for hydrocarbon reserves due to their organic matter as a source rock. Therefore, this study investigates the hydrocarbon generation potential of Paleocene sediments in the east of southern Caspian Basin. Materias and Methods Three outcrops in Mazandaran province were selected for this study. From each of Suchelma and Purva outcrops, six and seven samples, respectively, and from south of Sari two samples of potential source rock sediments of the Paleocene age were analyzed for Rock- Eval pyrolysis. The Rock- Eval pyrolysis and Organic Petrography results of eight samples of the Paleocene deposits in one of the exploration wells of Gorgan plain were also studied. The Rock- Eval pyrolysis method has been extensively used for oil and gas exploration in sedimentary basins over the world (Behar et al. 2001). Vitrinite reflectance is the most reliable maturity parameter for measuring thermal maturity of sedimentary organic matter (Tokatli et al. 2006). Discussion of Results and Conclusions According to the results, most of the outcrops samples harvested were poor in terms of total organic carbon content and in terms of kerogen maturity were before the oil window. Therefore, they are weak in terms of hydrocarbon generation potential. These samples contain kerogen type IV. Also in determining the organic facies, it was found that most of the sediments were deposited in a continental regressive environment. The well samples are good in terms of organic matter richness, immature in terms of the amount of kerogen maturation and weak in terms of hydrocarbon generation potential. The measurement results of vitrinite reflectance also confirmed that the borehole samples were immature. These samples contain kerogen type III. It was also specified in the determination of organic facies that most of the well samples show deep environmental conditions adjacent to orogenic sites and are deposited in a regressive environment در مطالعۀ حاضر به بررسی ویژگی‌های سنگ‌های منشأ احتمالی در شرق حوضۀ خزر جنوبی از پهنۀ ساختاری البرز پرداخته شد؛ به این منظور، برش‌های سوچلما و پوروا در جنوب نکا و برشی در جنوب ساری انتخاب شدند. نمونه‌های مطالعه‌شده از رسوبات سنگ منشأ احتمالی به سن پالئوسن بر اساس تجزیه‌وتحلیل راک- اول بررسی شدند. به‌منظور مطالعه‌های تکمیلی، نتایج پیرولیز راک- اول و پتروگرافی آلی نمونه‌های رسوبات سنگ منشأ احتمالی در یکی از چاه‌های اکتشافی دشت گرگان نیز استفاده شدند. باتوجه‌به نتایج مطالعۀ حاضر، بیشتر نمونه‌های رخنمون پتانسیل هیدروکربن‌زایی ندارند؛ همچنین نمونه‌های چاه اکتشافی بررسی‌شده نیز کربن آلی کل حدود 1 و کروژن تیپIII با بلوغ ناکافی دارند. در بررسی توالی‌های رسوبی مشخص شد بیشتر نمونه‌ها در حوضۀ رسوبی نزدیک به محیط قاره‌ای و در شرایط پس‌روندۀ سطح نسبی آب دریا نهشته شده‌اند.

https://jssr.ui.ac.ir/article_24610_f3b40afadc4f5c18b2720b2104cf691d.pdf

دانشگاه اصفهان پژوهش های چینه نگاری و رسوب شناسی 2008-7888 36 3 2020 09 22 Distribution Pattern of the Heavy Metals in Stream Sediments at the East and Southeast of Angouran Mine, West of Zanjan الگوی پراکنش فلزهای سنگین در رسوبات آبراهه‌ای خاور و جنوب‌خاور معدن انگوران، باختر زنجان 33 54 24628 10.22108/jssr.2020.122336.1157 FA حدیث رشنو دانشجوی کارشناس ارشد علوم محیط‌زیست، دانشکدۀ علوم، دانشگاه زنجان، ایران میر علی اصغر مختاری دانشیار، گروه زمین‌شناسی، دانشکدۀ علوم، دانشگاه زنجان، ایران یونس خسروی استادیار، گروه علوم محیط‌زیست، دانشکدۀ علوم، دانشگاه زنجان، ایران عباسعلی زمانی دانشیار، گروه علوم محیط‌زیست، دانشکدۀ علوم، دانشگاه زنجان، ایران Journal Article 2020 04 04 Abstract In order to assess the concentrations of heavy metals in stream sediments of eastern and southeastern drainages of the Angouran Zn-Pb mine, stream sediment samples were selected from 77 stations. Results of samples analysis demonstrate that concentrations of As, Sb, Cd, Pb and Zn are higher and Co is less than the averages of upper continental crust in most stations. The elements correlation analysis indicates that there are intermediate to very strong positive correlations between Pb, Zn, Cd, Sb and As, and Co has no correlation with other elements. Investigation of distribution maps, enrichment factor and geo-accumulation index demonstrate that the highest enrichment and pollution in the study area related to Pb, Zn, Cd, Sb and As which are concentrated at the northern and northeastern parts of the study area (Allahlou-Chay catchment). Investigation of the relationship between the obtained data and geology of the study area demonstrates that the origin of these elements concentrations are geogenic and related to mineralizations and alterations. Exploitation activities at the Angouran Zn-Pb mine caused increasing the concentration of heavy metals and their entry into the surface waters which with the result of expansion of mentioned elements to northeast of study area and Allahlou-Chay catchment. Keywords: Stream sediment, Heavy metals, Spatial distribution, Geo-accumulation index, Angouran. Introduction Heavy metals are one of the most important soil contaminants which are naturally present in the soil, but large amounts of these metals are the result of human activities like mining, transportation, disposal of industrial wastewater, improper disposal of wastes and use of chemical fertilizers and pesticides (Rahimpour and Abbaspour 2014; Zare Khosh Eghbal et al. 2012). Seasonal rivers during heavy rains transfer contaminated sediments and mineral waste from adjacent mines to downstream areas and cause heavy metal dispersion. As such, studying stream sediments is one of the best ways to assess pollution. Angouran Zn-Pb mine is one of the mines that due to a large volume of extraction and mineral production has produced a lot of waste around the mine. These wastes, in turn, can cause many problems for the environment around the mine. In this study, an attempt was made to evaluate the role of mining in the environment by investigation of heavy metal concentrations in the stream sediment samples of the rivers at the east and southeast of the Angouran Zn-Pb mine (Allahlou-Chay and Kakaroud catchments). Materials and Methods In order to evaluate the environmental contamination of heavy metals at the eastern and southeastern catchments of Angouran Zn-Pb mine, 77 samples were selected from intended stations. In this stage, about 500 gr of stream sediments from a depth of 5-15 cm was selected from each station. After crushing and milling the samples, the obtained powders were dissolved by the four acid solutions and were analyzed by the ICP-OES at laboratories of Geological Survey of Iran. The studied elements in this research include As, Sb, Cd, Pb, Zn and Co. After receiving the analytical results from the laboratory, the data were processed statistically. For this purpose, statistical parameters such as the mean, median, mode, standard deviation, skewness, Kurtosis, range, minimum and maximum were analyzed for the 6 mentioned elements using SPSS 22 software. Furthermore, Kolmogorov-Smirnov test was used to examine the distribution of the normality of data. In the absence of normal data, the logarithm transformation method was used to normalize the data. In order to determine the level of stream sediments contamination to heavy metals in the study area, the enrichment factor and the geo-accumulation index were used. To survey elements distribution maps, interpolation of reverse weight weighting and pixel estimation were employed. Discussion of Results & Conclusions Evaluation of normality of data indicates that except for the cobalt, the other elements do not have a normal distribution. The results of sample analysis demonstrate that concentrations of As, Sb, Cd, Pb and Zn are higher and Co is less than the average of upper continental crust in most stations. The results of correlation between the elements indicate that Co has no correlation with other elements while others show moderate to strong positive correlations with each other. The element distribution maps in the study area demonstrate that the elements anomalies mainly locat in the northern and northeastern parts. Furthermore, these maps show that anomalies of Pb, Zn, Cd, As and Sb have an overlap with each other. The enrichment factor investigations indicate that the highest enrichment is related to Pb, Zn, Cd, As and Sb located on northeastern and eastern parts of the study area (Allahlou-Chay catchment). Moreover, in terms of geo-accumulation index, Cd, As, Sb, Pb and Zn caused the pollution of most parts of the study area especially the northeastern and eastern parts (Allahlou-Chay catchment). In general, the analysis of the result of samples from stream sediments of the study area demonstrates that the origin of investigated elements is partly natural (geogenic) and related to mineralizations and alterations. But, exploitation activities in Angouran Zn-Pb mine, weathering of ores and leaching of soils and waste damps led to increasing the heavy metals concentrations and their entrance into the current waters. This led, in turn, to expansion of heavy metal concentrations to other parts of the study area far from the mineralized region (northeastern part and Allahlou-Chay catchment). These data are in agreement with the results of Ghadimi and Nabatian (2014) showing that the water of catchments in upper levels of Angouran Zn-Pb mine show no pollution for Pb, Zn, As and Cd, while by crossing the mining site they become polluted because of these elements. به‌منظور ارزیابی آلودگی‌های زیست‌محیطی فلزهای سنگین در آبراهه‌های خاور و جنوب‌خاور معدن روی- سرب انگوران، نمونه‌برداری از رسوبات آبراهه‌ای در 77 ایستگاه انجام شد. نتایج تجزیه‌وتحلیل نمونه‌های یادشده نشان دادند مقدار میانگین محتوای آرسنیک، آنتیموان، کادمیوم، سرب و روی در این نمونه‌ها به‌ترتیب برابر با 81/89، 67/6، 46/10، 83/659 و 32/1189 گرم در تن و در اکثر ایستگاه‌ها بیشتر از میانگین پوستۀ قاره‌ای بالایی است و غلظت کبالت با مقدار میانگین 69/18 گرم در تن در بیشتر ایستگاه‌ها کمتر از میانگین پوستۀ قاره‌ای بالایی است. بررسی همبستگی عناصر مطالعه‌شده نشان داد همبستگی مثبت متوسط تا بسیار قوی بین عناصر سرب، روی، کادمیوم، آنتیموان و آرسنیک وجود دارد و کبالت با عناصر دیگر همبستگی ندارد. بررسی نقشه‌های پراکنش عناصر، شاخص غنی‌شدگی و شاخص زمین‌انباشت نشان داد بیشترین غنی‌شدگی و آلودگی در محدودۀ مطالعه‌شده به عناصر سرب، روی، آرسنیک، آنتیموان و کادمیوم مربوط و به‌ویژه در بخش‌های شمالی و شمال‌خاور (حوضۀ آبریز الله‌لوچای) متمرکز است. داده‌های به‌دست‌آمده نشان دادند بی‌هنجاری‌های عناصر سرب، روی، کادمیوم، آرسنیک و آنتیموان هم‌پوشانی بسیار زیادی باهم دارند. تحلیل داده‌ها و بررسی ارتباط آنها با زمین‌شناسی منطقه گویای اینست که بخشی از منشأ عناصر مطالعه‌شده، طبیعی (زمین‌زاد) و درارتباط‌با کانی‌سازی‌ها، دگرسانی‌ها و واحدهای سنگی منطقه است، ولی وجود فعالیت‌های استخراجی در معدن روی- سرب انگوران سبب افزایش غلظت فلزهای سنگین و ورود آنها به آب‌های سطحی منطقه و گسترش تمرکز عناصر یادشده در شمال‌خاور منطقه و حوضۀ آبریز الله‌لوچای شده است.

https://jssr.ui.ac.ir/article_24628_6720d6fc7f852abe1cf4930e30784b6a.pdf

دانشگاه اصفهان پژوهش های چینه نگاری و رسوب شناسی 2008-7888 36 3 2020 09 22 Microfacies, depositional environment, sequence stratigraphy and diagenetic process affected the Doroud Formation in the Eram Section (south Neka), north flank of central Alborz بررسی رخساره‌ها، محیط رسوبی، چینه‌نگاری سکانسی و فرایندهای دیاژنزی مؤثر بر نهشته‌های سازند دورود در برش ارم (جنوب شهرستان نکا) در دامنة شمالی البرز مرکزی 55 76 24787 10.22108/jssr.2020.120968.1140 FA حمیده نوروزپور استادیار، گروه زمین شناسی ،دانشکده علوم پایه ،دانشگاه پیام نور ،تهران ،ایران Journal Article 2020 01 15 Abstract The Permian deposits (Doroud Formation) are exposed in a wide area of central Alborz. A stratigraphic section of Permian deposits in the Eram section (South Neka) has been selected for the study of facies, depositional environments, sequence stratigraphy, and diagenetic processes. The 320 m thick Doroud Formation in the study area mainly consists of intercalation of limestones and sandstones. Field and petrographic studies of thin sections led to identifying four siliciclastic petrofacies and three carbonate microfacies. These facies are deposited in four facies belts, including fluvial, coastal, lagoon, and shoal. The low diversity of facies and the gradual change of facies belts, the absence of turbidites, and the absence of large barrier reef indicate that the Permian deposits in the study area were deposited on a carbonate ramp. Also, based on the absence of turbidite deposits of a deep marine environment, it can be deduced that the depositional environment of the Doroud Formation is homoclinal. Two third-order depositional sequences have been identified in the studied interval of the Doroud Formation. Different diagenetic processes have been affected on the studied interval in the study area, most notably dolomitization, cementation, mechanical and chemical compaction, pyritization, fracturing, and neomorphism. Keywords: Doroud Formation, Facies, Sedimentary environment, Diagenesis, Permian, Alborz Introduction The Alborz zone is one of the important geological zones of Iran, which is spread east-west in the northern part of Iran and extends from Azerbaijan to Khorasan (Aghanabati 2004). The study of the rock units of the Permian system in Iran has been done by Assereto (Assereto 1963) and Glaus (Glaus 1964), so that the type section of Doroud and Ruteh formations was first introduced by Assereto (Assereto 1963). During the Permian, carbonate sediments belonging to shallow marine environments were mainly composed of small and large benthic foraminifera along with green and red algae (Vachard et al. 2001; 2002; 2011; Boudagher-Fadel 2008; Parvizi et al. 2013). The studied stratigraphic section is located in the south of Neka city and the west of Eram village and is located in the geographical position of 36◦ 25' 28" north latitude and 53◦ 36' 42" east longitude in the northern flank of Alborz. The lower and upper boundaries of Doroud Formation in the Eram section with Mobarak and Ruteh formations are in the form of erosive discontinuities. Sofar, numerous paleontological, sedimentological, and stratigraphic studies have been studied on the Doroud, Ruteh and Nesen formations, especially in the western and central Alborz and to a lesser extent, the eastern Alborz. In this research, the determination of the palaeoenvironmental model, sequence stratigraphy, and diagenesis processes of the Doroud Formation in the Eram section are the main targets. Materials & Methods This research is conducted in two stages including field and laboratory. Overall the number of 26 hand specimens collected from 320 meters thickness of the Doroud Formation in the Eram stratigraphic section. The petrographic analysis was performed by a polarizing microscope. Pettijohn classification (1987) and Dunham classification (Dunham, 1962) have been used to name clastic and carbonate rocks, respectively. The investigation of the sedimentary environment and facies types are based on the study of their lateral and vertical changes, and comparison with modern and ancient environments (Flugel 2010). The combination of the results obtained from field and laboratory studies in the study section has led to the identification and description of the main carbonate and clastic facies. Sequence stratigraphic studies have been done by considering methods described by Hunt and Tucker (Hunt and Tucker 1992). Discussion of Results & Conclusions The Doroud Formation in Eram section with a thickness of 320 meters is one of the remarkable outcrops of Lower Permian deposits in the northern flank of Central Alborz. Field observations and detailed petrographic examination of samples of the Doroud Formation in the Eram section led to the identification of seven siliciclastic and carbonate facies types (subarkose, chertarnaite, mixed calcareous sandstone, imperforate foraminifera packstone, oncoids packstone-grainstone, bioclast grainstone, and ooid grainstone) belonging to the four facies belts of the fluvial, coastal, lagoon, and sand shoal (Wilson 1975, Lasemi; 1990, Flugel 2010). The low diversity of facies and the gradual change of facies belts, the absence of turbiditic deposits, and the absence of large barrier reef indicate that the Permian deposits in the study area were deposited on a carbonate ramp. In this study, two third-order depositional sequences have been identified in the studied interval of the Doroud Formation. The most important diagnostic diagenetic processes affecting the siliciclastic and carbonate deposits of Doroud Formation can be micritization, boring, cementation, neomorphism, mechanical and chemical compaction, dolomitization and pyritization, silicification and fracturing. According to the field and petrographic studies on Permian deposits in the study area, it can be concluded that the deposits have gone through three stages of eugenics, mesogenesis, and telogenesis diagenetic environments. نهشته‌های پرمین (سازند دورود) در گسترة وسیعی از ناحیة البرز مرکزی رخنمون دارند. در این پژوهش یک برش چینه‌شناسی از نهشته‌های پرمین در برش ارم (جنوب شهرستان نکا) برای بررسی رخساره‌ها، محیط رسوبی، چینه‌نگاری‌ سکانسی و فرایندهای دیاژنزی مؤثر بر آنها انتخاب شده است. ضخامت سازند دورود در این برش، 320 متربوده و به‌طور عمده از تناوب سنگ آهک و ماسه‌سنگ تشکیل شده است. بررسی‌های صحرایی و پتروگرافی مقاطع نازک میکروسکوپی، امکان تفکیک 4 رخسارة آواری و 3 رخسارة کربناته را میسر کرده است. این رخساره‌ها در چهار کمربند رخساره‌ای رودخانه‌ای، ساحلی، لاگون و تپه‌های ماسه‌ای‌ زیرآبی نهشته شده‌اند. تنوع کم رخساره‌ها و تدریجی‌بودن روند تبدیل کمربندهای رخساره‌ای به یکدیگر، نبود نهشته‌های توربیدایتی و نیز نبود آثار ریف‌های بزرگ سدی نشان می‌دهد بخش‌های آواری نهشته‌های پرمین در ناحیة بررسی‌شده در محیط ساحلی و رودخانه‌ای و بخش‌های کربناته در یک پلتفرم کربناته از نوع رمپ با شیب یکنواخت ته‌نهشت یافته‌اند. در توالی مطالعه‌شده از سازند دورود، دو سکانس رسوبی درجه 3 شناسایی شده است. در ناحیة بررسی‌شده، فرایندهای گوناگون دیاژنز بر توالی مطالعه‌شدة این سازند مؤثر بوده که مهم‌ترین آنها، دولومیتی‌شدن، سیمانی‌شدن، فشردگی مکانیکی و شیمیایی و پیریتی‌شدن، شکستگی و نوشکلی است.

https://jssr.ui.ac.ir/article_24787_e38d868a8634d1929166f9b0efc370c1.pdf

دانشگاه اصفهان پژوهش های چینه نگاری و رسوب شناسی 2008-7888 36 3 2020 09 22 Study of water-level fluctuations throughout the deposition of the Gurpi Formation based on palynological data in the west of Dehrolan, south of Ilam بررسی نوسانات سطح نسبی آب دریا طی نهشته‌شدن سازند گورپی برمبنای داده‌های پالینولوژیکی در غرب دهلران 77 96 24789 10.22108/jssr.2020.120553.1132 FA مهسا امیری کارشناسی ارشد گروه زمین‌شناسی، دانشکدة علوم زمین، دانشگاه دامغان، دامغان، ایران الهه زارعی استادیار، گروه زمین‌شناسی، دانشکدة علوم زمین، دانشگاه دامغان، دامغان، ایران Journal Article 2019 12 17 Abstract To analyze the sedimentary palaeoenvironment of the Gurpi Formation in Bisheh–Deraz section in south of Ilam, various factors including diversity and abundance of dinocysts, a ratio of Peridinioid to Gonyaulacoid (P/G) dinoflagellate cysts, palynofacies parameters and "selective preservation of organic matter" have been used. In lower parts of the Gurpi Formation of Campanian age is very argillaceous and then shallows up in the upper part of Lopha Limestone that contains the small size of bivalve shell debris. This is followed by a stagnant condition due to sea-level rise that favored the preservation of organic matter in early Maastrichtian. The Emam-Hassan Limestone with high percentages of non-fluorescent amorphous organic matter represents a basin environment. The Latter member is overlain by the marls of Late Maastrichtian. Microbiostratigraphy, sedimentology, and palynofacies observation indicate sea-level fall and a 3.5 Ma hiatus at the K/P boundary. This is followed by deepening and the deposition of the basal purple shale of the Pabdeh Formation. The relative sea-level changes curve drawn based on palynomorphs in this study is well in accord with the existing eustasy curves that indicate the great effect of eustasy factor relative to other factors. Key Words: Sea level change, Palynology, Gurpi Formation, South of Ilam, Zagros Introduction The reconstruction of water depth is an important factor to explain the palaeoecology/palaeoenvironment. Qualitative and Quantitative palynological analysis provides a high-resolution database for biostratigraphy and determines the main palaeoenvironment parameters, these parameters include diversity and abundance of dinocysts, a ratio of Peridinioid to Gonyaulacoid (P/G) dinoflagellate cysts, palynofacies parameters and "selective the preservation of organic matter" factors. The Gurpi Formation in Bisheh–Deraz section in south of Ilam with a thickness of 201 meters consisting of an alternation of blueish-gray shales and marls, with two main members of Seymareh (Lopha) and Emam-Hassan limestones. The lower boundary with the Ilam Formation is continuous and without any erosion and its upper boundary with the Pabdeh Formation is gradual. The Bisheh–Deraz section, with grid coordinates of N 32° 49´ 52˝ and E 46° 59´ 01˝, is located in the southwest flank of Anaran Anticline in the west of Dehloran. The main aim of this paper is the study of palynofacies analysis and paleontological data (foraminifera and index dinocyst) to elucidate sedimentary environments and sea-level changes of the Gurpi Formation. Material & Methods The present study is based on seventy-four samples that were collected from the Gurpi Formation. The samples were processed by standard (HCl-HF) palynological preparation technique, without oxidation or ultrasonic treatments. The palynological residue was sieved through 20 μm nylon sieves. Three to five permanent slides were prepared using glycerin jelly as a mounting medium. The palynofacies analysis is based on the percentage frequency of different POM constituents categorized by Tyson (1995). Discussion of Results & Conclusions The changes in the palynofacies composition in the Bishederaz section and the AOM-palynomorph-phytoclast (APP) ternary plot reveal seven (II, IV, IX, V, VI, VII, VIII) palynofacies types in the Gurpi Formation. The percentage of each palynomaceral component is derived from the total POM frequencies. However, abundance (the number of all dinocyst taxa counted from two slides) and a simple diversity index (the number of species of dinocyst counted from two slides) and the ratio of Peridinioid to Gonyaulacoid (P/G) dinoflagellate cysts, were obtained from the total dinoflagellate cysts frequencies. The difference in the organic matter found in these regressive and transgressive offshore marine sediments have been documented and assessed within a sea-level change. The lower part of the Gurpi Formation of middle Campanian age is very argillaceous and is characterized by an abundance of fluorescence AOM and marine palynomorphs. The minimal size of the black equant phytoclasts and dinoflagellate cyst show that this interval was deposited in a quiet water environment under anoxic conditions in a pelagic environment. This formation shallows upward to boundstones of the Lopha Member in uppermost Campanian with very low amounts of organic matter. The Lopha Limestone consists of macrofossil assemblages (bivalves, oysters (Exogyra type) and echinoids) in different directions and recessive, bioturbated marly layers with scattered large Lopha in life position showing that this member was probably reworked and deposited on the foreland bulge depocenter. This is followed by an abrupt deepening and the deposition of pelagic marl. The high contents of transparent AOM, as well as the presence of pyrite and phosphates in these layers, suggest a dysoxic to the anoxic condition due to sea-level rise that favored accumulation and preservation of organic matter in early Maastrichtian. The Emam-Hassan Limestone represents a more pelagic fauna in a carbonate-rich deepwater setting. The high percentages of non-fluorescent AOM and black phytoclast indicate oxic conditions that were unsuitable for the preservation of marine organic matter. This member is overlain by the marls of Late Maastrichtian. Microbiostratigraphy, sedimentology, and palynofacies observation indicate sea-level fall and a hiatus at the K/P boundary. This is followed by deepening and the deposition of the purple shale of the base of the Pabdeh Formation. This interpretation is supported by sedimentological observation. The Gurpi Formation is entirely influenced by the compressional regime of the foreland basin. به‌منظور بررسی محیط رسوبی سازند گورپی در برش بیشه‌دراز در جنوب استان ایلام از عوامل مختلفی ازجمله تنوع و فراوانی داینوسیست‌ها، نسبت داینوسیست‌های پریدینوئید به گونیالاکوئید (P/G)، مطالعات پالینوفاسیسی و فاکتورهای حفاظت از مواد آلی استفاده شد. از ابتدای سازند گورپی به سن کمپانین تا لایه‌های شیلی قسمت فوقانی بخش آهکی سیمره (لوفا) شامل دوکفه‌ای‌های ریز و خرده‌های خشکی، شرایط پس‌رونده را شاهد هستیم. بخش آهکی سیمره خرده‌های ماکروفسیلی در زمینه‌ای از رسوبات تخریبی سست و در جهات مختلف به‌صورت خردشده و در لایة مارنی به‌هم‌خورده دارد که احتمالاً این عضو آهکی نابرجا بوده و روی سطح بالاآمدگی حوضه نهشته شده است. افزایش سطح نسبی آب در ابتدای ماستریشتین باعث ایجاد شرایط پایدار برای حفظ‌شدگی مواد ارگانیکی می‌شود. روی آن عضو آهکی امام حسن با درصد زیادی از مواد آمورف تیره‌رنگ قرار می‌گیرد که نشان‌دهندة محیطی عمیق است. این عضو با مارن‌های انتهای ماستریشتین پوشیده می‌شود. بررسی‌های فسیل‌شناسی، رسوب‌شناسی و مشاهدات صحرایی در این پژوهش، وقفه‌ای رسوبی را در گذر از مرز کرتاسه– پالئوژن در این برش نشان می‌دهد. پس از مرز برمبنای شواهد لیتولوژیکی و پالینولوژیکی تا شیل‌های ارغوانی‌رنگ سازند پابده، پیشروی و بالاآمدگی سطح آب دیده می‌شود. انطباق نسبتاً خوب منحنی تغییرات سطح آب با منحنی‌های تغییرات جهانی سطح آب حاکی از تأثیرپذیری زیاد این نهشته‌ها از تغییرات ائوستازی است.

https://jssr.ui.ac.ir/article_24789_ad163a2a9b2d23304258b734bb0834fa.pdf

دانشگاه اصفهان پژوهش های چینه نگاری و رسوب شناسی 2008-7888 36 3 2020 09 22 Stratigraphic importance and migration trend of Miscellaneidae family in the Paleogene of Tethys basin, Sistan suture zone اهمیت چینه‌نگاری و روند مهاجرت خانوادة Miscellaneidae در پالئوژن نئوتتیس نمونة پژوهش: حوضة سیستان، جنوب شرق ایران 97 118 24713 10.22108/jssr.2020.121205.1144 FA محمدنبی گرگیج دانشیار گروه زمین شناسی دانشکده علوم دانشگاه سیستان و بلوچستان، زاهدان، ایران شیما کیخا گروه آموزشی زمین شناسی-دانشکده علوم-دانشگاه سیستان و بلوچستان-زاهدان، ایران سمیه شهرکی میرزایی گروه زمین شناسی-دانشکده علوم-دانشگاه سیستان و بلوچستان-زاهدان، ایران Journal Article 2020 01 21 Abstract Miscellaneidae is Paleogene larger index microfossils (middle Paleocene–early Eocene) that for determination of stratigraphic and palaeobiogeographic distributions are investigated in the Neo-Tethys Ocean. For biostratigraphic studies, depositional ages and systematic determinations of family Miscellaneidae, middle Paleocene–lower Eocene deposits in the Hormak section, in the north of Zahedan, are investigated. This stratigraphic section (470 meters) mainly consists of an alternation of marls, marly limestones, and limestones. Study of different miscellaneidae taxa led to identifications of Miscellanea miscella, Miscellanea juliettae, Miscellanites primitivus, and Miscellanites minutes that indicated standard biozone SBZ3–SBZ6 and therefore suggested late Paleocene–early Eocene age. Paleocene–Eocene boundary is identified with the appearance of Nummulitids and Alveolinids (SBZ5/6) in the western Neo-Tethys, whilst in the eastern Neo-Tethys these group of large benthic foraminiferas are absent. Some of Alveolina species accompanied by Glomalveolina, Miscellanea, and Ranikothalia species are seen which shows similarities between the Hormak section and other sections in the Indus basin and Tibet in the eastern Neo-Tethys. Based on biostratigraphic investigations, family Miscellaniedae, firstly appeared in SBZ1/2 in the western Neo–Tethys (Europe and Africa) whereas in the eastern Neo-Tethys (India, Tibet, and Pakistan) are not seen although the mentioned family in SBZ3/4 are recognized in the both western and eastern Neo-Tethys. In biozones SBZ5/6, SBZ7 and SBZ8, in the western Neo-Tethys family, Miscellaniedae disappeared whereas in the eastern Neo-Tethys are seen in the SBZ5/6 biozones. With respect to identified Miscellaniedae genus and species in the Hormak section and similarities with eastern Neo-Tethys, it seems that, with the omission of palaeoceanogrphic barrier in the Paleocene–Eocene boundary, the Miscellaniedae genus and species are migrated to the eastern Neo-Tethys. Keywords: Late Paleocene–early Eocene, Large Benthic Foraminifera, Sistan Suture Zone Introduction Large benthic foraminifera (LBF) are important fossils with large tests and complex internal structures. In biostratigraphic studies of Paleogene large benthic foraminiferas from Alveolina, Assilina (Hottinger 1960; Drobne 1977), and Nummulites (Schaub 1981) are used for introduction of 20 shallow benthic zones in the western Tethys (Serra-Kiel et al. 1998). Large benthic foraminiferas in the eastern and western Tethys similarly described but are different with regard to taxonomy (Hottinger 1971). The Paleocene of western Neo-Tethys are dominated with coralgal reefs (e.g. Accordi et al. 1998; Turnsek and Drobne 1998; Baceta et al. 2005; Scheibner et al. 2007) although in the eastern Neo-Tethys, the large benthic foraminiferas are dominated (Wan et al. 2002; Afzal et al. 2009, 2011; Zhang et al. 2013). Based on high biodiversity of Lockhartia in the Paleocene of Ronikot Formation in India, eastern Neo-Tethys ocean is named Ranikothalia Sea (Davies 1937) or Lockhartia Sea (Hottinger 1998) that occupied southern Turkey in the west to the Tibet and Pakistan in the east and Egypt in the south (Hottinger 2007, 2014). Another important aspect of large benthic foraminifera biodiversity is that the Lockhartia genus has a distinct chronostratigraphic position in the Paleocene resemble that Alveolina, Assilina, and Nummulites in the Eocene. For example, Lockhartia retiata Sander 1962 and Lockhartia praeheimi Smout 1954 are accepted as index fossils of the shallow benthic zone 3. The objectives of this study are the determination of stratigraphic importance and migration trend of Miscellaniedae family across the Tethys ocean in the late Paleocene–early Eocene time. Material & Method For LBFs biostratigraphic investigations of the Hormak section, in field studies, 100 rock specimens are collected and 350 thin sections are prepared from them for the study of different genus and species of Miscellaniedae family. The systematic determination of this group of large benthic foraminiferas is, in the level of genus and species, are done by using a binocular microscope and then based on identified LBFs, the age of the Hormak section is suggested. Discussion of Results & Conclusions In the eastern Neo-Tethys, SBZ3 and SBZ4 are identified with increasing generic diversity and reflect the time in which LBF have experienced the new morphology (Hottinger 2001; Scheibner and Speijer 2008). In India basin (eastern Neo-Tethys) the mentioned biozones are initiated with the appearance of new taxonomic trends such as Rothalids (Kathina and Lockhartia), Miliolids (Triloculina and Quinqueloculina) Pellatispirids (Miscellanea), Alveolinids (Glomalvelina), Coskinolinids (Coskinon), Spirocyclinids (Saudia), Dictyoconids (Fallotella, Dictyoconus), Nummulitids (Ranikothalia, Assilina, and Operculina) and Lepidorbitoids (Daviesina, Orbithosiphon, and Setia) (Afzal et al. 2009) that are correlatable with a faunistic scheme in the other part of the Tethys (Hottinger 1997, 1998; Jauhri 1998; Serra-Kiel et al. 1998; Jauhri and Agarwal 2001; Jauhri et al. 2006; Green et al. 2008; Scheibner and Speijer 2008, 2009; Zamagni et al. 2008; Mathur et al. 2009; Tewari et al. 2010). Studies of different genera of Miscellaneidae in the thin sections and isolated forms led to the identification of Miscellanea miscella, Miscellanea juliettae, Miscellanites primitivus, Miscellanits minutus that accompanied with other fossils are suggested the late Paleocene–early Eocene age. In the Hormak section, SBZ3 and SBZ4 biozones are identified with Kathina, Triloculina, Idalina, Quinqueloculina, Miscellanea, glomalveolina, Ranikothalia, and Discocyclina that in respect to abundance and diversity, correlatable with eastern Neo-Tethys foraminiferal assemblage (Afzal et al. 2009). خانوادة Miscellaneidae از روزن‌داران کف‌زی بزرگ پالئوژن هستند که به‌منظور بررسی پخش و انتشار چینه‌نگاری و جغرافیای زیستی گذشتة آنها در حوضة نئوتتیس مطالعه شده‌اند. برش چینه‌نگاری حرمک شامل 470 متر تناوبی از مارن، سنگ‌آهک مارنی و سنگ‌آهک است. با بررسی مقاطع نازک، گونه‌های Miscellanea miscella،Miscellanea juliettae، Miscellanites primitivus و Miscellanites minutus شناسایی شدند که سن پالئوسن پسین- ائوسن پیشین برای نهشته‌های مدنظر پیشنهاد می‌شود. مرز پالئوسن- ائوسن با ظهور اولیة جنس‌های Alveolina و Nummulites مشخص می‌شود که ویژگی نئوتتیس غربی در اوایل ائوسن پیشین است؛ در حالی که این نمونه‌ها در حوضة نئوتتیس شرقی در این زمان دیده نمی‌شوند و فقط گونه‌هایی از Alveolina به‌صورت کمیاب در پالئوسن پسین و اوایل ائوسن و گونه‌هایی از جنس Glomalveolina حضور دارند که به همراه جنس‌های Ranikothalia و Miscellanea بیان‌کنندة شباهت نهشته‌های برش حرمک با حوضة ایندوس و تبت در نئوتتیس شرقی است. براساس پژوهش‌های انجام‌شده در نئوتتیس شرقی و غربی، میسلانیدآ برای نخستین‌بار در بیوزون‌های SBZ1-SBZ2 در نئوتتیس غربی (اروپا- آفریقا) ظاهر شده است؛ در حالی که در نئوتتیس شرقی (هند- تبت و پاکستان) دیده نمی‌شود و در SBZ3-SBZ4 در دو حوضة نئوتتیس شرقی و غربی وجود دارد. در بیوزون‌های SBZ5/6 –SBZ7 و SBZ8، این گروه در حوضة نئوتتیس غربی ناپدید شده‌اند، اما در نئوتتیس شرقی در بیوزون‌های SBZ5/6 فقط در ناحیة هند و پاکستان دیده و پس از آن ناپدید شده‌اند. با توجه به نتایج به‌دست‌آمده از شناسایی جنس‌ها و گونه‌های این خانواده در برش چینه‌نگاری حرمک و شباهت فونی توالی‌های بخش جنوبی حوضة سیستان با حوضة ایندوس در هند- تبت و پاکستان (نئوتتیس شرقی)، به نظر می‌رسد با از بین رفتن سد اقیانوس‌نگاشتی در پالئوسن پسین- ائوسن پیشین از حوضة نئوتتیس غربی به این ناحیه مهاجرت کرده‌اند.

https://jssr.ui.ac.ir/article_24713_1926db575791d77381f602731395f89d.pdf