University of Isfahan Journal of Stratigraphy and Sedimentology Researches 2008-7888 35 4 2019 12 22 Plant macrofossils, ichnofossils, facies analysis and palaeoenvironment interpretation of the Hojedk Formation in the north of Kerman (Central Iran) Plant macrofossils, ichnofossils, facies analysis and palaeoenvironment interpretation of the Hojedk Formation in the north of Kerman (Central Iran) 1 38 24066 10.22108/jssr.2019.116535.1095 FA Hadis Khalilizadeh PhD student in Stratigraphy and paleontology, Department of Geology, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, Iran Abbas Ghaderi Assistant Professor - Department of Geology - Faculty of Science - Ferdowsi University of Mashhad - Mashhad - Iran Ali Reza Ashouri Professor, Department of Geology, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, Iran Hamed Zand-Moghadam Assistant Professor, Department of Geology, Faculty of Sciences, Shahid Bahonar University of Kerman, Iran Journal Article 2019 04 19 Abstract This study led to identify 30 species and 16 genera of eight different plant macrofossils orders including Equisetales, Cycadales, Bennettitales, Coniferales, Peltaspermales, Ginkgoales, Corystospermales, and Filicales at the Deh-Shiykh section, north of Kerman. According to stratigraphic ranges of the index taxa such as Otozamites furoni, Nilssoniopteris mosafolia, Nilssonia tenuicaulis, Anomozamites major, Coniopteris hymenophylloides, Nilssonia bozorga and Elatides thomasii the age of early Middle Jurassic (Bajocian–Bathonian) is assigned to the Deh-Shiykh section. Middle Jurassic ichno fossils of the Hojedk Formation in the Deh-Sheikh section have been studied for the first time. The study also led to the determination of terrestrial ichno fossils including eight ichno species, belonging to four ichnogenera such as Planolithes, Rhizoliths, Taenidium and Thalassinoides. They have been found alongside the stems of Equisetals. Combination of the results of ichno fossil studies with plant fossils help us to identify the palaeoenvironment. These plant fossils are generally indicator of humid conditions. Moreover, the identified ichnofossils in accordance with the sedimentological studies, represent deltaic environments influenced by the river systems and channels. This is the first study of the combination of three studies of paleontology (Plant macrofossils), sedimentology and ichnology in east central Iran. The results have contributed to the accurate understanding of the paleoenvironment of fossiliferous horizons of the Hojedk Formation. Keywords: Plant macrofossils, Tracefossils, Middle Jurassic, Delta, Kerman. Introduction The northern region of Kerman is one of the richest areas of Iran for the study of plant fossils and so far more than 80 taxa have been reported (Khalilizadeh 2010). The first studies on coal deposits in the Kerman region have been carried out by Houtum-Schindler (1881), Stur (1886) and Stahl (1897). In recent years, Mirzaei-Ataabadi (2002) has studied the plant macrofossils of the Hojedk Formation in the Pabdana, Bab-Nizu and Hashuni areas. Vaez-Javadi and Mirzaei-Ataabadi (2006) studied the plant macrofossils of the Hojedk Formation. Ameri et al. (2014a, b) have also studied the biostratigraphy of the Hojedk Formation deposits in the Bab-Hutk section. Studies on these plant macrofossils have been more focused on coal areas and mines, non-coal areas in this respect has been received less attention. In addition, there are no reports of ichnofossil studies of the Jurassic layers of the Kerman region, especially in association with plant fossils. Trace fossils are very useful for understanding the paleoclimates and generally interpreting paleosedimentary environments (Buatois and Mangano 2004). In the present study, which focuses on the study of plantmacrofossils of the Hojdak Formation in Deh-Sheikh section north of Kerman, trace fossils have also been studied along with this macrofossils and the general sedimentology of these layers is also considered. Material & Methods Important factors in the identification of plant macrofossils include the characteristics of veins and pinnules, rachis, the grooves on the stem as well as the nodes and inter nodes in sphenophyte. In this study, about 100 plant macrofossil specimens were studied and they were photographed using a Nikon 90D digital camera. The images were processed using Adobe Photoshop CS5. All these specimens are kept in the Museum of Ferdowsi University of Mashhad. Trace fossil studies are usually carried out in the field on a centimeter scale and samples are taken to the lab for further and more detailed examination. In this study, about 20 trace fossil samples were collected. The lithofacies described in the field are divided mainly on the sedimentary texture (especially grain size) and structures; according to the Miall (1985) classification. The identified petrofacies are based on Folk (1980) classification scheme with polarizing microscope. Also, identification of sedimentary environment and subenvironments were interpreted based on the facies characterizes. Discussion of Results & Conclusions Based on the plant macrofossils, especially Coniopteris hymenophylloides, Elatides thomasii and Nilssonia friziensis, Middle Jurassic age (Bajocian–Batonian) is confirmed for the studied section. The studied plant macrofossils, especially filicales and horsetails, grow in humid environments. The in situ Equisetal stems have paleoecological significance. Horsetails, are hygrophytes, and adapted to humid conditions (Brea et al. 2009). Osmundaceae have been to warm and humid conditions along the rivers or marshes (Gordenko 2008). Due to the abundance of cycadophyta and ferns in the study area, tropical to subtropical paleoclimate have been reported (Salyukova et al. 2013). The ichno fossil diversity of the deltaic regions is very low (Hobday and Tavener-Smith 1975). Salinity changes, water turbulence, mud influx and etc. are the most important stress in the delta area. The study of 8 ichnospecies in the Deh-Sheikh section shows these traces, are simple. They are similar to those of deltaic systems (Buatois and Mangano 2011). These trace fossils resemble specimens of deltaic systems and are related to the heteropod invertebrates of Scoyenia ichnofacie. According to sedimentological studies, the sedimentary environment of the Hojedk Formation in the Deh-Sheikh section is often interpreted as a deltaic environment (coarsening upward cycles) under the influence of the river (fining upward cycles) which indicate of channel filling and energy depletion periods. From this study, the combination of paleontological, sedimentological and lithological studies with the study of ichnofossils will be very useful and effective in better understanding the palaeoenvironment and with proper interpretation, it will helpful to recognition details and create a clear picture of the environment. Abstract This study led to identify 30 species and 16 genera of eight different plant macrofossils orders including Equisetales, Cycadales, Bennettitales, Coniferales, Peltaspermales, Ginkgoales, Corystospermales, and Filicales at the Deh-Shiykh section, north of Kerman. According to stratigraphic ranges of the index taxa such as Otozamites furoni, Nilssoniopteris mosafolia, Nilssonia tenuicaulis, Anomozamites major, Coniopteris hymenophylloides, Nilssonia bozorga and Elatides thomasii the age of early Middle Jurassic (Bajocian–Bathonian) is assigned to the Deh-Shiykh section. Middle Jurassic ichno fossils of the Hojedk Formation in the Deh-Sheikh section have been studied for the first time. The study also led to the determination of terrestrial ichno fossils including eight ichno species, belonging to four ichnogenera such as Planolithes, Rhizoliths, Taenidium and Thalassinoides. They have been found alongside the stems of Equisetals. Combination of the results of ichno fossil studies with plant fossils help us to identify the palaeoenvironment. These plant fossils are generally indicator of humid conditions. Moreover, the identified ichnofossils in accordance with the sedimentological studies, represent deltaic environments influenced by the river systems and channels. This is the first study of the combination of three studies of paleontology (Plant macrofossils), sedimentology and ichnology in east central Iran. The results have contributed to the accurate understanding of the paleoenvironment of fossiliferous horizons of the Hojedk Formation. Keywords: Plant macrofossils, Tracefossils, Middle Jurassic, Delta, Kerman. Introduction The northern region of Kerman is one of the richest areas of Iran for the study of plant fossils and so far more than 80 taxa have been reported (Khalilizadeh 2010). The first studies on coal deposits in the Kerman region have been carried out by Houtum-Schindler (1881), Stur (1886) and Stahl (1897). In recent years, Mirzaei-Ataabadi (2002) has studied the plant macrofossils of the Hojedk Formation in the Pabdana, Bab-Nizu and Hashuni areas. Vaez-Javadi and Mirzaei-Ataabadi (2006) studied the plant macrofossils of the Hojedk Formation. Ameri et al. (2014a, b) have also studied the biostratigraphy of the Hojedk Formation deposits in the Bab-Hutk section. Studies on these plant macrofossils have been more focused on coal areas and mines, non-coal areas in this respect has been received less attention. In addition, there are no reports of ichnofossil studies of the Jurassic layers of the Kerman region, especially in association with plant fossils. Trace fossils are very useful for understanding the paleoclimates and generally interpreting paleosedimentary environments (Buatois and Mangano 2004). In the present study, which focuses on the study of plantmacrofossils of the Hojdak Formation in Deh-Sheikh section north of Kerman, trace fossils have also been studied along with this macrofossils and the general sedimentology of these layers is also considered. Material & Methods Important factors in the identification of plant macrofossils include the characteristics of veins and pinnules, rachis, the grooves on the stem as well as the nodes and inter nodes in sphenophyte. In this study, about 100 plant macrofossil specimens were studied and they were photographed using a Nikon 90D digital camera. The images were processed using Adobe Photoshop CS5. All these specimens are kept in the Museum of Ferdowsi University of Mashhad. Trace fossil studies are usually carried out in the field on a centimeter scale and samples are taken to the lab for further and more detailed examination. In this study, about 20 trace fossil samples were collected. The lithofacies described in the field are divided mainly on the sedimentary texture (especially grain size) and structures; according to the Miall (1985) classification. The identified petrofacies are based on Folk (1980) classification scheme with polarizing microscope. Also, identification of sedimentary environment and subenvironments were interpreted based on the facies characterizes. Discussion of Results & Conclusions Based on the plant macrofossils, especially Coniopteris hymenophylloides, Elatides thomasii and Nilssonia friziensis, Middle Jurassic age (Bajocian–Batonian) is confirmed for the studied section. The studied plant macrofossils, especially filicales and horsetails, grow in humid environments. The in situ Equisetal stems have paleoecological significance. Horsetails, are hygrophytes, and adapted to humid conditions (Brea et al. 2009). Osmundaceae have been to warm and humid conditions along the rivers or marshes (Gordenko 2008). Due to the abundance of cycadophyta and ferns in the study area, tropical to subtropical paleoclimate have been reported (Salyukova et al. 2013). The ichno fossil diversity of the deltaic regions is very low (Hobday and Tavener-Smith 1975). Salinity changes, water turbulence, mud influx and etc. are the most important stress in the delta area. The study of 8 ichnospecies in the Deh-Sheikh section shows these traces, are simple. They are similar to those of deltaic systems (Buatois and Mangano 2011). These trace fossils resemble specimens of deltaic systems and are related to the heteropod invertebrates of Scoyenia ichnofacie. According to sedimentological studies, the sedimentary environment of the Hojedk Formation in the Deh-Sheikh section is often interpreted as a deltaic environment (coarsening upward cycles) under the influence of the river (fining upward cycles) which indicate of channel filling and energy depletion periods. From this study, the combination of paleontological, sedimentological and lithological studies with the study of ichnofossils will be very useful and effective in better understanding the palaeoenvironment and with proper interpretation, it will helpful to recognition details and create a clear picture of the environment.

https://jssr.ui.ac.ir/article_24066_45428a6ad84cca8dc572695a167778ad.pdf

University of Isfahan Journal of Stratigraphy and Sedimentology Researches 2008-7888 35 4 2019 12 22 Biostratigraphy and palaeoecology of marine microphytoplankton cysts from Member 4 of the Mila Formation, Mila Kuh, eastern Alborz Biostratigraphy and palaeoecology of marine microphytoplankton cysts from Member 4 of the Mila Formation, Mila Kuh, eastern Alborz 39 54 24071 10.22108/jssr.2019.117958.1109 FA Navid Navidi-Izad Dept of Geology Faculty of Earth Sciences Kharazmi University, Iran Hossein Hashemi Associate Professor, Department of Geology, Faculty of Earth Sciences, Kharazmi University, Tehran, Iran Journal Article 2019 07 13 Abstract Well preserved and diverse organic-walled marine microphytoplankton cysts (acritarchs sensu lato) occur in Member 4 (comprising mostly of fine-grained clastics with thin carbonate intercalations) of the Mila Formation at the type section, southwestern Damghan. Based on the association of such index acritarch taxa as Timofeevia phosphoritica, Cristallinium cambriense, Ninadiacrodium dumontii, Vulcanisphaera africana, Ooidium rossicum, Cymatiogalea cuvillieri, Caldariola glabra, and Dasydiacrodium sp. in the material studied, an local biozone, namely Ooidium rossicum-Vulcanisphaera africana assemblage biozone dated as Late Cambrian (Furongian), and a barren interval are introduced in the upper and lower parts, respectively, of the rock unit investigated. Occurrence in the examined assemblages of such middle latitude acritarchs as Ninadiacrodium indicates that the Alborz Ranges was located in southern mid-latitudes (30º–60º) during the Late Cambrian. Retrieved marine microphytoplankton cysts from Member 4 of the Mila Formation is comparable with the Late Cambrian assemblages recorded from elsewhere, this allows for the pertinent assemblages to be associated with peri-Gondwanan palynofloras. Keywords: Biostratigraphy, Palaeoecology, Acritarchs, Late Cambrian, Mila Formation. Introduction Biostratigraphic zonation of the Middle and Upper Cambrian strata is based mainly on trilobites, particularly planktonic agnostids and olenids. For example, in South China base of the Furongian Series is defined by Glyptagnostus reticulatus Zone (Peng et al. 2004). In the last decades, organic-walled microfossils (acritarchs) have been widely used for Palaeozoic stratigraphic subdivisions (Molyneux et al. 1996). The Acritarch group is defined as organic-walled microfossils of unknown biological affinities by Evitt (1963). They are a heterogeneous group of various microfossils and may include the remains of a wide range of different kinds of organisms, such as egg of small metazoans, spores of different algal classes, and resting cysts (Servais 1996). Recently, some of the acritarchs have been attributed to different groups of algae e.g. Prasinophytes or Chlorophytes (Colbath and Grenfell 1995). In the last decades, organic-walled microphytoplankton have been widely used for stratigraphic correlation both regionally and globally and their utility in dating Proterozoic and Palaeozoic marine sedimentary rocks is widely recognized (Playford 2003). Acritarchs feature a relatively rapid development of morphological innovations and a large number of new morphotypes appeared. Several palynological investigations have been undertaken on the Upper Cambrian strata across the world; e.g., Canada (Martin and Dean 1988; Palacios 2012), Russia (Raevskaya and Golubkova 2006), Germany (Montenari and Servais 2000), Iran (Ghavidel-Syooki 2006; Ghavidel-Syooki and Vecoli, 2008), North Africa (Vecoli 1999), England (Potter et al. 2012) and Spain (Albani et al. 2006). The Mila Formation is the first lithostratigraphic unit representing the Middle–Upper Cambrian strata in the Alborz Ranges and the other parts of Iran (Aghanabati 2004). Palaeontological and structural geological studies in the Alborz indicate that northern Iran, along with central Iran and Zagros located on the divergent margin of protopaleotethys and north of the Gondwana palaeocontinents. The Mila Formation at its type section measured 585 m (Stöcklin et al. 1964) and subdivided into five members: Member 1, dolostone–marl; Member 2, terrigenous – carbonate; Member 3 fossiliferous limestone; and mainly terrigenous members 4 and 5. According to palaeontological and stratigraphical studies the first 2 units attributed to the Middle Cambrian and members 3 and 4 to the Late Cambrian. The former Member 5 of this unit was later considered to be equivalent of the Lashkarak Formation (Early Ordovician). The Mila Formation at the its type section is underlain and overlain by the Lalun and Jeirud formations, respectively. The Mila Formation generally consists of dolostone, thin-bedded, crystalline, glauconitic limestone, marl, coloured shales and sandstones. Several palaeontological investigations have been conducted such as on trilobites (Kushan 1973; Peng et al. 1999), brachiopods (Popov et al. 2009, 2013), conodonts (Müller 1973; Fazli and Hamdi 2008; Jahangir et al. 2016) and palynomorphs (Ghavidel-Syooki 2006). Considering the stratigraphic significance of organic-walled marine microphytoplankton in the Lower Palaeozoic biostratigraphy, the aim of this study is to determine relative age and to derive palaeogeographic implications for the Member 4 at its type section. Material & Methods: To retrieve palynological content of the Member 4 of Mila Formation at the type section, 21 surface samples collected from this rock unit. All samples prepared in palynological laboratories at Kharazmi University, Tehran and University of Lille, France using standard palynological processing procedures, encompassing initial treatment with HCl 10-50% and HF 40% for dissolution of carbonates and silicates, respectively. Then the residues saturated with ZnCl2 solution (2.0 gr/cm3) for mineral separation. All residues are sieved with 15 and 20 µm mesh and three slides of each sample are made. Discussion of Results & Conclusions: Well-preserved and diverse palynomorphs occur in Member 4 of the Mila Formation at the Mila Kuh section. The assemblage contains 14 species assigned to 13 genera of acritarchs and one species of prasinophytes. Based on the occurrence and stratigraphic distribution of index acritarch taxa such as Timofeevia phosphoritica, Cristallinium cambriense, Ninadiacrodium dumontii, Vulcanisphaera africana, Ooidium rossicum, Cymatiogalea cuvillieri, Caldariola glabra, and Dasydiacrodium sp. one local assemblage biozone namely Ooidium rossicum-Vulcanisphaera africana assemblage biozone is introduced in 41 m of the Member 4 and assigned to the Late Cambrian (Furongian). Additionally, one barren interval zone at the base (45 m) of the rock unit is also identifiable. The biozone (Ooidium rossicum-Vulcanisphaera africana) introduced herein is comparable to microflora A2 (partial) – A6 of Martin and Dean (1981, 1988) and RA3–RA10 microflora of Parsons and Anderson (2000) as well as the upper part of VK2 to VK5 of Volkova (1990) at the East European Platform. Furthermore, it is equivalent with the Zone II to IV of Ghavidel-Syooki and Vecoli (2008) in the High Zagros Mountains, southern Iran. Occurrence of such mid-latitude taxa as Ninadiacrodium and comparison of the acritarch assemblages with those from elsewhere in the world indicates the peri-Gondawanan affinity; thus supporting a 30°-60°S palaeolatitude for the eastern Alborz in the Late Cambrian Abstract Well preserved and diverse organic-walled marine microphytoplankton cysts (acritarchs sensu lato) occur in Member 4 (comprising mostly of fine-grained clastics with thin carbonate intercalations) of the Mila Formation at the type section, southwestern Damghan. Based on the association of such index acritarch taxa as Timofeevia phosphoritica, Cristallinium cambriense, Ninadiacrodium dumontii, Vulcanisphaera africana, Ooidium rossicum, Cymatiogalea cuvillieri, Caldariola glabra, and Dasydiacrodium sp. in the material studied, an local biozone, namely Ooidium rossicum-Vulcanisphaera africana assemblage biozone dated as Late Cambrian (Furongian), and a barren interval are introduced in the upper and lower parts, respectively, of the rock unit investigated. Occurrence in the examined assemblages of such middle latitude acritarchs as Ninadiacrodium indicates that the Alborz Ranges was located in southern mid-latitudes (30º–60º) during the Late Cambrian. Retrieved marine microphytoplankton cysts from Member 4 of the Mila Formation is comparable with the Late Cambrian assemblages recorded from elsewhere, this allows for the pertinent assemblages to be associated with peri-Gondwanan palynofloras. Keywords: Biostratigraphy, Palaeoecology, Acritarchs, Late Cambrian, Mila Formation. Introduction Biostratigraphic zonation of the Middle and Upper Cambrian strata is based mainly on trilobites, particularly planktonic agnostids and olenids. For example, in South China base of the Furongian Series is defined by Glyptagnostus reticulatus Zone (Peng et al. 2004). In the last decades, organic-walled microfossils (acritarchs) have been widely used for Palaeozoic stratigraphic subdivisions (Molyneux et al. 1996). The Acritarch group is defined as organic-walled microfossils of unknown biological affinities by Evitt (1963). They are a heterogeneous group of various microfossils and may include the remains of a wide range of different kinds of organisms, such as egg of small metazoans, spores of different algal classes, and resting cysts (Servais 1996). Recently, some of the acritarchs have been attributed to different groups of algae e.g. Prasinophytes or Chlorophytes (Colbath and Grenfell 1995). In the last decades, organic-walled microphytoplankton have been widely used for stratigraphic correlation both regionally and globally and their utility in dating Proterozoic and Palaeozoic marine sedimentary rocks is widely recognized (Playford 2003). Acritarchs feature a relatively rapid development of morphological innovations and a large number of new morphotypes appeared. Several palynological investigations have been undertaken on the Upper Cambrian strata across the world; e.g., Canada (Martin and Dean 1988; Palacios 2012), Russia (Raevskaya and Golubkova 2006), Germany (Montenari and Servais 2000), Iran (Ghavidel-Syooki 2006; Ghavidel-Syooki and Vecoli, 2008), North Africa (Vecoli 1999), England (Potter et al. 2012) and Spain (Albani et al. 2006). The Mila Formation is the first lithostratigraphic unit representing the Middle–Upper Cambrian strata in the Alborz Ranges and the other parts of Iran (Aghanabati 2004). Palaeontological and structural geological studies in the Alborz indicate that northern Iran, along with central Iran and Zagros located on the divergent margin of protopaleotethys and north of the Gondwana palaeocontinents. The Mila Formation at its type section measured 585 m (Stöcklin et al. 1964) and subdivided into five members: Member 1, dolostone–marl; Member 2, terrigenous – carbonate; Member 3 fossiliferous limestone; and mainly terrigenous members 4 and 5. According to palaeontological and stratigraphical studies the first 2 units attributed to the Middle Cambrian and members 3 and 4 to the Late Cambrian. The former Member 5 of this unit was later considered to be equivalent of the Lashkarak Formation (Early Ordovician). The Mila Formation at the its type section is underlain and overlain by the Lalun and Jeirud formations, respectively. The Mila Formation generally consists of dolostone, thin-bedded, crystalline, glauconitic limestone, marl, coloured shales and sandstones. Several palaeontological investigations have been conducted such as on trilobites (Kushan 1973; Peng et al. 1999), brachiopods (Popov et al. 2009, 2013), conodonts (Müller 1973; Fazli and Hamdi 2008; Jahangir et al. 2016) and palynomorphs (Ghavidel-Syooki 2006). Considering the stratigraphic significance of organic-walled marine microphytoplankton in the Lower Palaeozoic biostratigraphy, the aim of this study is to determine relative age and to derive palaeogeographic implications for the Member 4 at its type section. Material & Methods: To retrieve palynological content of the Member 4 of Mila Formation at the type section, 21 surface samples collected from this rock unit. All samples prepared in palynological laboratories at Kharazmi University, Tehran and University of Lille, France using standard palynological processing procedures, encompassing initial treatment with HCl 10-50% and HF 40% for dissolution of carbonates and silicates, respectively. Then the residues saturated with ZnCl2 solution (2.0 gr/cm3) for mineral separation. All residues are sieved with 15 and 20 µm mesh and three slides of each sample are made. Discussion of Results & Conclusions: Well-preserved and diverse palynomorphs occur in Member 4 of the Mila Formation at the Mila Kuh section. The assemblage contains 14 species assigned to 13 genera of acritarchs and one species of prasinophytes. Based on the occurrence and stratigraphic distribution of index acritarch taxa such as Timofeevia phosphoritica, Cristallinium cambriense, Ninadiacrodium dumontii, Vulcanisphaera africana, Ooidium rossicum, Cymatiogalea cuvillieri, Caldariola glabra, and Dasydiacrodium sp. one local assemblage biozone namely Ooidium rossicum-Vulcanisphaera africana assemblage biozone is introduced in 41 m of the Member 4 and assigned to the Late Cambrian (Furongian). Additionally, one barren interval zone at the base (45 m) of the rock unit is also identifiable. The biozone (Ooidium rossicum-Vulcanisphaera africana) introduced herein is comparable to microflora A2 (partial) – A6 of Martin and Dean (1981, 1988) and RA3–RA10 microflora of Parsons and Anderson (2000) as well as the upper part of VK2 to VK5 of Volkova (1990) at the East European Platform. Furthermore, it is equivalent with the Zone II to IV of Ghavidel-Syooki and Vecoli (2008) in the High Zagros Mountains, southern Iran. Occurrence of such mid-latitude taxa as Ninadiacrodium and comparison of the acritarch assemblages with those from elsewhere in the world indicates the peri-Gondawanan affinity; thus supporting a 30°-60°S palaeolatitude for the eastern Alborz in the Late Cambrian

https://jssr.ui.ac.ir/article_24071_3d0882a7476cc90ef84f99826b4f14fb.pdf

University of Isfahan Journal of Stratigraphy and Sedimentology Researches 2008-7888 35 4 2019 12 22 Geochemistry and origin of elements in the Azarshahr travertine deposits (Eastern Azarbaijan) Geochemistry and origin of elements in the Azarshahr travertine deposits (Eastern Azarbaijan) 55 76 24208 10.22108/jssr.2019.116017.1089 FA Behnam Ebrahimzadeh Faculty of Earth Sciences, Shahrood Sniversity of Technology, Iran Mahdi Jafarzadeh Faculty of earth sciences, Shahrood University of Technology, Iran Rahim Bagheri Faculty of Earth Sciences, Shahrood University of Technology, Iran Mohammad Ali Salehi Geology Department, Faculty of Science, University of Isfahan, Iran 0000-0001-8670-5973 Journal Article 2019 03 12 Abstract: Travertine deposits cover a vast area in the southwest of Azarshahr (East Azarbaijan province) and in some parts there are active springs which currently deposit these types of sediments. Regarding the field observations in the Azarshahr area, the typical morphology of Azarshahr travertine deposits is in situ and consists of the mounds, fissure-ridge and cascades. Geochemical studies on the travertine deposits of the Taptapan and Qizildagh springs revealed that the amount of iron in travertine deposits clearly emphasizes their thermogenic nature. The amounts of strontium, barium and beryllium also indicate the thermogenesis and calcareous, evaporative or dolomite origin. The depleted oxygen isotope (δ18O) and enriched carbon isotope (δ13C) is also indicator of thermogenic source, and carbonate source rocks for these deposits. Based on geochemical studies, it can be concluded that hydrothermal fluids may have initially taken the CO2-derived from magma, and during the upward movement with carbonate rocks, decarbonization has been occurred. These fluids transport CO2 from carbonates, and then they appear as spring’s water at the surface and precipitate travertine due to the rapid release of CO2. Keywords: Geochemistry, Travertine, Thermogene, Azarshahr Introduction: Continental carbonates comprise a wide range of lithologies including speleothem, calcrete, palustrine, travertine and tufa. Travertine and tufa deposits frequently associated with limestone dissolution in superficial (epigean) or deep (hypogean) hydrogeological reservoirs (Pentecost and Viles 1994; Pentecost 2005; Jones and Renaut 2010; Capezzuoli et al. 2014; Gandin and Capezzuoli 2014). However, a large variety of other rocks can occur as substratum and source of elements building these carbonates. Many studies have shown that igneous rocks (basalts, rhyolites, ultramafics, granites) and sedimentary rocks such as dolostones, evaporates and marls may constitute derivative sources for calcium and other elements required for travertine and tufa build-up and this can be determined by elemental and isotopic geochemical studies. Travertine deposits cover a vast area in the southwest of Azarshahr (East Azarbaijan province) and in some parts there are active springs. The area is located on the western margin of Sahand volcanic complex and eastern margin of Lake Urmia. Given the importance of geochemical studies mentioned in travertine studies, the main objective of this study is to emphasize the use of geochemical data in travertine classification, determination of origion of elements building travertines, CO2 origin and comparison of Azarshahr region samples with global thermogene and metheogene travertines. Material & Methods: For petrographic studies on travertine samples deposited around Azarshahr springs, 20 samples of travertine sediments and old travertine rocks around two modern travertine springs called the Taptapan and Ghezelagh are collected. In order to compare the geochemical chatactristic of samples, ten samples of travertine rock samples in the quarry near Qizildagh spring are also colleted. Fifteen samples were examined for mineralogical composition using XRD analysis. For geochemical analysis (ICP-MS), seven travertine samples around Taptapan and Qizildagh springs and three travertines samples of quarry near Qizildagh spring, has been analysed at the Zarazma Laboratory, Zanjan. Moreover, for the purpose of isotopic analysis of δ18O and δ13C, four travertines samples around the Taptapan spring were selected and analysed at the Isotopes Research Laboratory of the Arak University. Discussion of Results & Conclusions: According to the geochemical studies of the major elements on the travertine of the Azarshahr, iron, sodium and potassium elements clearly emphasize the thermogenesis of these travertines, but other trace elements cannot definitely determine the type of travertine. The concentration of rare earth elements in Taptapan spring samples is lower than that of Qizildagh samples, indicating a lower reaction rate of this spring with source rocks and its rapid ascent to Earth's surface compared to Qizildagh spring. Due to high concentrations of strontium and low concentration of barium, the Azarshahr travertine deposits plotted in the range of hypogean Calcite and Aragonite Travertine and Tufa (CATT) originated from limestone, evaporaites and dolostones. The origins of the samples using beryllium values indicate that the Azarshahr travertine was similar to the values of this element in hypogean travertines with carbonate sources. The depleted δ18O and enriched δ13C is also indicator of thermogenic source, and carbonate or igneous source rocks for these deposits. Based on this study, it seems that hydrothermal fluids may have initially taken the CO2-derived from magma, and during the upward movement with carbonate rocks, decarbonization has been occurred. These fluids transport CO2 from carbonates, and then they appear as spring’s water at the surface and precipitate travertine due to the rapid release of CO2. Abstract: Travertine deposits cover a vast area in the southwest of Azarshahr (East Azarbaijan province) and in some parts there are active springs which currently deposit these types of sediments. Regarding the field observations in the Azarshahr area, the typical morphology of Azarshahr travertine deposits is in situ and consists of the mounds, fissure-ridge and cascades. Geochemical studies on the travertine deposits of the Taptapan and Qizildagh springs revealed that the amount of iron in travertine deposits clearly emphasizes their thermogenic nature. The amounts of strontium, barium and beryllium also indicate the thermogenesis and calcareous, evaporative or dolomite origin. The depleted oxygen isotope (δ18O) and enriched carbon isotope (δ13C) is also indicator of thermogenic source, and carbonate source rocks for these deposits. Based on geochemical studies, it can be concluded that hydrothermal fluids may have initially taken the CO2-derived from magma, and during the upward movement with carbonate rocks, decarbonization has been occurred. These fluids transport CO2 from carbonates, and then they appear as spring’s water at the surface and precipitate travertine due to the rapid release of CO2. Keywords: Geochemistry, Travertine, Thermogene, Azarshahr Introduction: Continental carbonates comprise a wide range of lithologies including speleothem, calcrete, palustrine, travertine and tufa. Travertine and tufa deposits frequently associated with limestone dissolution in superficial (epigean) or deep (hypogean) hydrogeological reservoirs (Pentecost and Viles 1994; Pentecost 2005; Jones and Renaut 2010; Capezzuoli et al. 2014; Gandin and Capezzuoli 2014). However, a large variety of other rocks can occur as substratum and source of elements building these carbonates. Many studies have shown that igneous rocks (basalts, rhyolites, ultramafics, granites) and sedimentary rocks such as dolostones, evaporates and marls may constitute derivative sources for calcium and other elements required for travertine and tufa build-up and this can be determined by elemental and isotopic geochemical studies. Travertine deposits cover a vast area in the southwest of Azarshahr (East Azarbaijan province) and in some parts there are active springs. The area is located on the western margin of Sahand volcanic complex and eastern margin of Lake Urmia. Given the importance of geochemical studies mentioned in travertine studies, the main objective of this study is to emphasize the use of geochemical data in travertine classification, determination of origion of elements building travertines, CO2 origin and comparison of Azarshahr region samples with global thermogene and metheogene travertines. Material & Methods: For petrographic studies on travertine samples deposited around Azarshahr springs, 20 samples of travertine sediments and old travertine rocks around two modern travertine springs called the Taptapan and Ghezelagh are collected. In order to compare the geochemical chatactristic of samples, ten samples of travertine rock samples in the quarry near Qizildagh spring are also colleted. Fifteen samples were examined for mineralogical composition using XRD analysis. For geochemical analysis (ICP-MS), seven travertine samples around Taptapan and Qizildagh springs and three travertines samples of quarry near Qizildagh spring, has been analysed at the Zarazma Laboratory, Zanjan. Moreover, for the purpose of isotopic analysis of δ18O and δ13C, four travertines samples around the Taptapan spring were selected and analysed at the Isotopes Research Laboratory of the Arak University. Discussion of Results & Conclusions: According to the geochemical studies of the major elements on the travertine of the Azarshahr, iron, sodium and potassium elements clearly emphasize the thermogenesis of these travertines, but other trace elements cannot definitely determine the type of travertine. The concentration of rare earth elements in Taptapan spring samples is lower than that of Qizildagh samples, indicating a lower reaction rate of this spring with source rocks and its rapid ascent to Earth's surface compared to Qizildagh spring. Due to high concentrations of strontium and low concentration of barium, the Azarshahr travertine deposits plotted in the range of hypogean Calcite and Aragonite Travertine and Tufa (CATT) originated from limestone, evaporaites and dolostones. The origins of the samples using beryllium values indicate that the Azarshahr travertine was similar to the values of this element in hypogean travertines with carbonate sources. The depleted δ18O and enriched δ13C is also indicator of thermogenic source, and carbonate or igneous source rocks for these deposits. Based on this study, it seems that hydrothermal fluids may have initially taken the CO2-derived from magma, and during the upward movement with carbonate rocks, decarbonization has been occurred. These fluids transport CO2 from carbonates, and then they appear as spring’s water at the surface and precipitate travertine due to the rapid release of CO2.

https://jssr.ui.ac.ir/article_24208_f602f0ce149468f6857c27518ad85ece.pdf

University of Isfahan Journal of Stratigraphy and Sedimentology Researches 2008-7888 35 4 2019 12 22 Depositional-diagenetic and geochemical characteristics of the Ilam Formation in northwest of Abdanan, Kabir Kuh Depositional-diagenetic and geochemical characteristics of the Ilam Formation in northwest of Abdanan, Kabir Kuh 77 104 24243 10.22108/jssr.2019.118968.1117 FA Elham Asadi Mehmandosti Kharazmi University, Iran Jahanbakhsh Daneshian Kharazmi University, Iran Mohammad Farid Mohammad Panah Kharazmi University, Iran Journal Article 2019 09 02 Abstract In this study, the Late Cretaceous Ilam Formation of the Bangestan group in the northwest of Abdanan in the Kabir-Kuh anticline has been investigated for sedimentological and geochemical properties, and diagenetic processes. Field studies indicate that this formation in studied section reach a thickness of 281 m and composed of medium to thin-bedded limestones with shales and argillaceous limestones intercalations. The upper and lower boundaries of the Ilam Formation in the studied section are disconfirmable with the Gurpi and Sarvak formations, respectively. Based on the petrographic studies, nine microfacies and one petrofacies have been identified for the Ilam Formation which mainly deposited in the outer ramp-basin setting. The main diagenetic features affecting the Ilam Formation in the studied section include micritization, cementation, mechanical and chemical compactions, dissolution, pyritization, phosphatization, and glauconitization. Geochemical characteristic (major and trace elements) of the Ilam carbonate deposits indicate closed diagenetic system. Variations of V/Cr, V/(V+Ni) and Ni/Co indicate that the carbonate samples of the Ilam Formation are subjected to suboxic and mostly anoxic conditions. Separating the Sarvak and Ilam boundary can be aided by some geochemical data variations such as Sr/Ca, Sr/Na, Sr/Mn, Ag, V, Ni, Zn, Sr, Fe, Co and P at the Kabir-Kuh anticline in the Abdanan section. Key words: Oxic-Anoxic conditions, Sedimentary environment, Zagros, Upper Cretaceous, Diagenesis Introduction During the Cretaceous, the Zagros basin had different environmental conditions so that this variation caused lateral and vertical sedimentary facies changes and numerous source rocks and oil reservoirs were created in this basin. Therefore, the Cretaceous sequences have long been of interest to many geologists (e.g. Kashfi 1976; Bahroudi and Talbot 2003; Alavi 2004; Sepehr and Cosgrove 2004; Insalaco et al. 2006; Fakhari et al. 2008; Van Buchem et al. 2010; Agard et al. 2011; Esrafili-Dizaji and RahimpourBonab 2013; Asadi Mehmandosti et al. 2013; Spina et al. 2018). From Albian to Campanian, a large sedimentary cycle of the Kazhdumi, Sarvak, Surgah and Ilam formations can be identified in the Zagros region, called the Bangestan Group. The Sarvak and Ilam formations of this group, after the Asmari Formation, are the most important reservoir rocks in the Zagros region that are exposed in Iran and the countries around the Persian Gulf basin. In this study, an outcrop of Ilam Formation in the Kabir Kuh anticline (Abdanan section) is selected to study. The aims include: to identify lithological features, study of microfacies, diagenesis processes, identification of pale-sedimentary environment and determination of redox conditions based on Ni/Co, V/Cr and V/(V+Ni) changes. In addition, due to the lithological similarities between the Ilam and Sarvak formations and the absence of the Surgah Formation in between in the study area, precise determination of the boundaries between these two formations through geochemical data is considered. These studies can provide a detailed picture of the sedimentological status of the studied basin at the time of the Ilam Formation carbonate deposition. Material & Methods: To determine sedimentary characteristic of the Ilam Formation, 90 thin sections have been studied. Thin sections were stained with potassium ferricyanide and alizarin-red S solution (Dickson 1965). The petrographic classification for carbonates is based on the Dunham limestone classification (1962) and Embry and Klovan (1971). Flügel (2010) facies belts and sedimentary models were also used. After petrographic studies, twenty powdered micrite samples (18 samples from Ilam Formation and 2 samples from Sarvak Formation) were analyzed by inductively coupled plasma atomic emission spectroscopy (ICP-AES) by 4-Acid Digestion method for trace, major and rare earth element contents at the Met-Solve Analytical Services Inc., BC, Canada. Discussion of Results & Conclusions Field work studies in the Kabir Kuh anticline (Abdanan section) indicate that the Ilam Formation has 281 m thickness and composed of medium to thin-bedded limestones with shales and argillaceous limestones intercalations. Based on the petrographic studies, nine microfacies and one petrofacies have been identified for the Ilam Formation as follows: MF T1: Bioclast Ooid Packstone, MF T2: Algal Bioclast Packstone, MF T3: Peloid/Benthic Foraminifera Packstone, MF T4: Bioclast Packstone, MF T5: Echinoderm Fragments Oligosteginid Packstone, MF T6: Peliodal/Planktonic Foraminifera/Oligosteginid Wackestone to Packstone, MF T7: Oligosteginid Packstone, MF T8: Planktonic Foraminifera/Oligosteginid Wackestone to Packstone, MF T9: Planktonic Foraminifera Mudstone, PF: Shale/Calcareous Shale. The Ilam Formation mainly deposited in the outer ramp- basin setting at studied section. The main diagenetic features affecting the Ilam Formation in the studied section include micritization, cementation, mechanical and chemical compactions, dissolution, pyritization, phosphatization, and glauconitization. The diagenesis sequence were effected the Ilam Formation carbonates during the three stages of eogenesis, mesogenesis and telogenesis. Investigation of geochemical data shows high amounts of Fe, V/Cr, V/(V+Ni) and Ni/Co ratios in studied carbonates and indicate that the carbonate samples of the Ilam Formation are subjected to suboxic and mostly anoxic conditions. Early pyrite observed in the Ilam Formation also indicates the abundance of iron ions in seawater and the dominance of the reductive conditions at their formation. In addition, Sr/Mn and Sr/Ca changes indicate that the Ilam Formation diagenetic system is closed in the studied section, which is in agreement with the low porosity observed in these carbonates. Therefore, with respect to the sedimentary environment, the existence of anoxic conditions at the time of formation and close diagenetic system that prevented the formation of suitable porosities in the Ilam sediments in Abdanan section, it can be concluded that this formation do not have a good reservoir quality in studied section. Separating the Sarvak and Ilam boundary can be aided by some geochemical data variations such as Sr/Ca, Sr/Na, Sr/Mn, Ag, V, Ni, Zn, Sr, Fe, Co and P at the Kabir-Kuh anticline in the Abdanan section. Abstract In this study, the Late Cretaceous Ilam Formation of the Bangestan group in the northwest of Abdanan in the Kabir-Kuh anticline has been investigated for sedimentological and geochemical properties, and diagenetic processes. Field studies indicate that this formation in studied section reach a thickness of 281 m and composed of medium to thin-bedded limestones with shales and argillaceous limestones intercalations. The upper and lower boundaries of the Ilam Formation in the studied section are disconfirmable with the Gurpi and Sarvak formations, respectively. Based on the petrographic studies, nine microfacies and one petrofacies have been identified for the Ilam Formation which mainly deposited in the outer ramp-basin setting. The main diagenetic features affecting the Ilam Formation in the studied section include micritization, cementation, mechanical and chemical compactions, dissolution, pyritization, phosphatization, and glauconitization. Geochemical characteristic (major and trace elements) of the Ilam carbonate deposits indicate closed diagenetic system. Variations of V/Cr, V/(V+Ni) and Ni/Co indicate that the carbonate samples of the Ilam Formation are subjected to suboxic and mostly anoxic conditions. Separating the Sarvak and Ilam boundary can be aided by some geochemical data variations such as Sr/Ca, Sr/Na, Sr/Mn, Ag, V, Ni, Zn, Sr, Fe, Co and P at the Kabir-Kuh anticline in the Abdanan section. Key words: Oxic-Anoxic conditions, Sedimentary environment, Zagros, Upper Cretaceous, Diagenesis Introduction During the Cretaceous, the Zagros basin had different environmental conditions so that this variation caused lateral and vertical sedimentary facies changes and numerous source rocks and oil reservoirs were created in this basin. Therefore, the Cretaceous sequences have long been of interest to many geologists (e.g. Kashfi 1976; Bahroudi and Talbot 2003; Alavi 2004; Sepehr and Cosgrove 2004; Insalaco et al. 2006; Fakhari et al. 2008; Van Buchem et al. 2010; Agard et al. 2011; Esrafili-Dizaji and RahimpourBonab 2013; Asadi Mehmandosti et al. 2013; Spina et al. 2018). From Albian to Campanian, a large sedimentary cycle of the Kazhdumi, Sarvak, Surgah and Ilam formations can be identified in the Zagros region, called the Bangestan Group. The Sarvak and Ilam formations of this group, after the Asmari Formation, are the most important reservoir rocks in the Zagros region that are exposed in Iran and the countries around the Persian Gulf basin. In this study, an outcrop of Ilam Formation in the Kabir Kuh anticline (Abdanan section) is selected to study. The aims include: to identify lithological features, study of microfacies, diagenesis processes, identification of pale-sedimentary environment and determination of redox conditions based on Ni/Co, V/Cr and V/(V+Ni) changes. In addition, due to the lithological similarities between the Ilam and Sarvak formations and the absence of the Surgah Formation in between in the study area, precise determination of the boundaries between these two formations through geochemical data is considered. These studies can provide a detailed picture of the sedimentological status of the studied basin at the time of the Ilam Formation carbonate deposition. Material & Methods: To determine sedimentary characteristic of the Ilam Formation, 90 thin sections have been studied. Thin sections were stained with potassium ferricyanide and alizarin-red S solution (Dickson 1965). The petrographic classification for carbonates is based on the Dunham limestone classification (1962) and Embry and Klovan (1971). Flügel (2010) facies belts and sedimentary models were also used. After petrographic studies, twenty powdered micrite samples (18 samples from Ilam Formation and 2 samples from Sarvak Formation) were analyzed by inductively coupled plasma atomic emission spectroscopy (ICP-AES) by 4-Acid Digestion method for trace, major and rare earth element contents at the Met-Solve Analytical Services Inc., BC, Canada. Discussion of Results & Conclusions Field work studies in the Kabir Kuh anticline (Abdanan section) indicate that the Ilam Formation has 281 m thickness and composed of medium to thin-bedded limestones with shales and argillaceous limestones intercalations. Based on the petrographic studies, nine microfacies and one petrofacies have been identified for the Ilam Formation as follows: MF T1: Bioclast Ooid Packstone, MF T2: Algal Bioclast Packstone, MF T3: Peloid/Benthic Foraminifera Packstone, MF T4: Bioclast Packstone, MF T5: Echinoderm Fragments Oligosteginid Packstone, MF T6: Peliodal/Planktonic Foraminifera/Oligosteginid Wackestone to Packstone, MF T7: Oligosteginid Packstone, MF T8: Planktonic Foraminifera/Oligosteginid Wackestone to Packstone, MF T9: Planktonic Foraminifera Mudstone, PF: Shale/Calcareous Shale. The Ilam Formation mainly deposited in the outer ramp- basin setting at studied section. The main diagenetic features affecting the Ilam Formation in the studied section include micritization, cementation, mechanical and chemical compactions, dissolution, pyritization, phosphatization, and glauconitization. The diagenesis sequence were effected the Ilam Formation carbonates during the three stages of eogenesis, mesogenesis and telogenesis. Investigation of geochemical data shows high amounts of Fe, V/Cr, V/(V+Ni) and Ni/Co ratios in studied carbonates and indicate that the carbonate samples of the Ilam Formation are subjected to suboxic and mostly anoxic conditions. Early pyrite observed in the Ilam Formation also indicates the abundance of iron ions in seawater and the dominance of the reductive conditions at their formation. In addition, Sr/Mn and Sr/Ca changes indicate that the Ilam Formation diagenetic system is closed in the studied section, which is in agreement with the low porosity observed in these carbonates. Therefore, with respect to the sedimentary environment, the existence of anoxic conditions at the time of formation and close diagenetic system that prevented the formation of suitable porosities in the Ilam sediments in Abdanan section, it can be concluded that this formation do not have a good reservoir quality in studied section. Separating the Sarvak and Ilam boundary can be aided by some geochemical data variations such as Sr/Ca, Sr/Na, Sr/Mn, Ag, V, Ni, Zn, Sr, Fe, Co and P at the Kabir-Kuh anticline in the Abdanan section.

https://jssr.ui.ac.ir/article_24243_d82d60e9dc8419c13fecb3b7450796cf.pdf

University of Isfahan Journal of Stratigraphy and Sedimentology Researches 2008-7888 35 4 2019 12 22 Geochemical study of water and sediments in the Badavar River, Lorestan Province: environmental iImplications Geochemical study of water and sediments in the Badavar River, Lorestan Province: environmental iImplications 105 128 24216 10.22108/jssr.2019.118373.1112 FA Nahid Hasanvand Msc student, Faculty of Earth Sciences, Shahrood University of Technology, Shahrood, Iran Giti Forghani Tehrani Assistant Professor, Faculty of Earth Sciences, Shahrood University of Technology, Shahrood, Iran Journal Article 2019 07 28 Abstract The Badavar River is an important surface water resource in Lorestan province. The purpose of this study is to assess the quality of the Badavar water and sediments. For these purpose, 19 water and five surface sediment samples were collected. The physicochemical properties of the water (i.e. pH, electrical conductivity, the major ion concentrations, microbial analysis, and potentially toxic element concentrations) and sediment samples (i.e. pH, organic matter, carbonate calcium, cation exchange capacity, major and trace element concentrations) were determined using standard methods. The obtained results indicate that the concentration of major ions influenced by natural processes (i.e. halite and gypsum dissolution, calcite, aragonite and dolomite precipitation, and ion exchange) and anthropogenic factors (i.e. discharge of domestic wastewater and agricultural runoff into the river). The concentration of the potentially toxic elements, especially Pb, is influenced by anthropogenic activity. The results of the microbial analysis confirm the pollution of the water samples with pathogenic agents. On the basis of pH values, the sediment samples are placed in neutral to alkaline class. Sediment samples are rich in organic matter and CaCO3, and their cation exchange capacity is high. The total concentration of elements in sediments shows that there is a risk of pollution with Cd, Cr, and Ni. The contamination degree values show that the studied sediments are highly polluted, which is due to the discharge of urban and agricultural wastewaters into the Badavar River. Keywords: Hydrogeochemistry, pollution, Sediment, Badavar River Introduction Rivers are the most available water resources for different usage purposes in the world (Chidya et al. 2011). The environmental quality of surface waters is influenced by both natural and man-made factors, the most important of which are mixing, mineral precipitation/dissolution, ion exchange, and discharge of the urban, agricultural and industrial wastewaters (Suthar et al. 2009; Zhang et al. 2010). Naturally- and anthropogeically- sourced pollutants are typically distributed between water and sediments. Therefore, for evaluating the environmental pollution of the river systems, both water and sediment chemistry must be considered. River sediments usually act as a sink and source for the pollutants; therefore, they are a very important component of river systems (Malvandi 2017). The Badaver is an important river in the Lorestan Province, west of Iran. This river provides the water required for agricultural and livestock usage. This river recharges from the Garin Mountains, East of Noorabad, and discharges into Seymareh River. The long of the Badavar River (with a E–W trend is about 75 Km and its drainage area is about 1800 Km2. The average water discharge of Badavr in spring and summer is 8.5 and 0.8 m3/sec, respectively. A part of the Badaver River passes through the Noorabad City. Indeed, agricultural activity is a usual practice around the river. Thus, the quality of water and sediments in Badavar River can be influenced by discharge of agricultural and domestic wastewaters. The aim of the present study is to investigate the environmental quality of water and sediments of Badavar River, and to find the impact of natural and anthropogenic factors on the river. Material & Methods Nineteen water and five surface sediment samples were collected in selected sites. At each sampling site, water samples were collected in 1-litre prewashed polyethylene bottles; indeed, one sample was collected in sterile dark bottles for microbial analysis. The first samples were filtered using a vacuum pump and 0.45μm pore-size filter papers in order to separate particulate matter. The filtered samples were then split into two portions: one portion was acidified with HNO3 for the measurement of dissolved elements and the second unacidified portion was used for determination of dissolved major ions. The samples were kept at 4°C prior to analysis. Some physicochemical properties of the water samples (i.e. pH and electrical conductivity) were measured in situ using a portable multi-meter. The major ion concentrations, microbial analysis, and potentially toxic element concentrations (in water samples) and pH, organic matter, carbonate calcium, cation exchange capacity, and element concentrations (in sediment samples) were determined using standard methods. In order to find the source of major ions in water samples and to determine the most significant processes controlling the water chemistry, ionic ratios, correlation coefficients, and the saturation index of minerals were calculated. The water quality for irrigation usage was accessed through the calculation of sodium adsorption ratio (Zhang et al. 2012) and magnesium hazard (Ravikumar and Somashekar 2011). Indeed, the EC and pH values of the samples were compared with standard values (Sundaray et al. 2009). Water Quality Index (WQI) as a useful method for quality assessment (Kumar et al. 2015, Vasanthavigar et al. 2010) was calculated on the basis of ion concentration, EC, pH and Total Hardness. The concentration of toxic elements in the water samples were compared with standard values of FAO (1985) for irrigation purposes and the standard values in world fresh waters (Markert 1994). For sediment quality assessment, some indices including geo-accumulation index (Muller 1969), enrichment factor (Sutherland, 2000), contamination factor (Hakanson 1980), and modified contamination degree (Abrahim and Arker 2008) were calculated. Discussion of Results & Conclusions: The EC and pH of the water samples vary between 430-730 µs/cm and 5.6-7.1, respectively. The EC values of the samples collected in the city district are higher than other samples, whereas their pH values are a little lower, showing the influence of domestic wastewater discharge on EC and pH of the water samples. The lower pH values may also be an indication of calcite precipitation (Das 2005). The calculation of ionic ratios, saturation index of minerals and correlation coefficient values indicate that the natural and anthropogenic factors influence the environmental quality of both water and sediments in Badavar River. The most important natural factors which affect the hydrochemical properties of the water samples (i.e. the concentration of major ions) include the dissolution of halite, gypsum and anhydrite, the precipitation of calcite, aragonite and dolomite, and ion exchange. Discharge of agricultural runoff and domestic wastewaters into the river is the most important anthropogenic factor decreasing the water quality, especially with respect to PO4, Pb, Cd, Cr, Cu, Mn and Zn concentrations. The values of Magnesium Hazard are mostly lower than 50%; indeed, the Sodium Adsorption Ratios are <2meq/l. Therefore, the water of Badavar River is suitable for irrigation. The values of WQI of the Badavar River varies between 58.4–42.7; indicating the good to excellent quality of the water samples. However, the river water is microbially polluted, mainly because of domestic wastewater discharge. The concentration of Pb in most sites is higher than FAO standard (5µg/L; FAO 1985) and the concentrations of Cd, Co, Cr, Cu, Fe, Mn, Ni, Se and Zn are lower than FAO guidelines (1, 50, 100, 200, 5000, 200, 200, 20, and 2000 µg/L, respectively; FAO 1985). The concentrations of Cd, Co, Ni, Pb and Se in some samples, and the concentrations of Cr, Cu, Mn and Zn in all samples are higher than their values in natural fresh waters (Markert 1994) which confirms the impacts of anthropogenic activities (i.e. agricultural and domestic wastewater discharge into the river) on water quality. Physicochemical properties of sediments play a significant role in retention, adsorption and re-adsorption of pollutants (Duodu et al. 2017). The pH value of the sediment samples ranges between 7.7 to 8.5; thus the samples are placed in neutral to alkaline class. Sediment samples are rich in organic matter (7.8–14.7%) and CaCO3 (26–45.5%), and their cation exchange capacity is high (37.4–77.3 meq/100 gr). On the basis of total concentration data, the concentration of Cu in some stations and the concentration of Cr and Ni in all sites are higher than TEC values (36.1, 34.4, and 22.7 mg/kg, respectively; MacDonald et al. 2000). Moreover, the concentration of Ni and Cr in all stations is higher than Probable Effect Concentration (PEC) values (111 and 149 mg/kg; MacDonald et al. 2000). This evidences show that the ecosystem of the Badavar River is at risk of being threatened by Ni and Cr. On the basis of total concentration data, the Badavar River sediments are polluted with Cd, Pb, Cr, Zn, Cu, Mn and Ni. The calculation of enrichment factor shows that Pb, Cd and Cr are mainly from anthropogenic activities (EF>1.5), whereas Zn, Cu, Mn and Ni are mostly from natural sources (EF<1.5). The contamination factor values are higher in sediments collected in the city district, confirming the effect of anthropogenic factors on sediment quality. The contamination degree values show that the studied sediments are placed in highly polluted class, which is due to the discharge of urban and agricultural wastewaters into the Badavar River. The obtained results in this study emphasize on the necessity of environmental management in the study area. The discharge of different kinds of wastewaters must be controlled. Abstract The Badavar River is an important surface water resource in Lorestan province. The purpose of this study is to assess the quality of the Badavar water and sediments. For these purpose, 19 water and five surface sediment samples were collected. The physicochemical properties of the water (i.e. pH, electrical conductivity, the major ion concentrations, microbial analysis, and potentially toxic element concentrations) and sediment samples (i.e. pH, organic matter, carbonate calcium, cation exchange capacity, major and trace element concentrations) were determined using standard methods. The obtained results indicate that the concentration of major ions influenced by natural processes (i.e. halite and gypsum dissolution, calcite, aragonite and dolomite precipitation, and ion exchange) and anthropogenic factors (i.e. discharge of domestic wastewater and agricultural runoff into the river). The concentration of the potentially toxic elements, especially Pb, is influenced by anthropogenic activity. The results of the microbial analysis confirm the pollution of the water samples with pathogenic agents. On the basis of pH values, the sediment samples are placed in neutral to alkaline class. Sediment samples are rich in organic matter and CaCO3, and their cation exchange capacity is high. The total concentration of elements in sediments shows that there is a risk of pollution with Cd, Cr, and Ni. The contamination degree values show that the studied sediments are highly polluted, which is due to the discharge of urban and agricultural wastewaters into the Badavar River. Keywords: Hydrogeochemistry, pollution, Sediment, Badavar River Introduction Rivers are the most available water resources for different usage purposes in the world (Chidya et al. 2011). The environmental quality of surface waters is influenced by both natural and man-made factors, the most important of which are mixing, mineral precipitation/dissolution, ion exchange, and discharge of the urban, agricultural and industrial wastewaters (Suthar et al. 2009; Zhang et al. 2010). Naturally- and anthropogeically- sourced pollutants are typically distributed between water and sediments. Therefore, for evaluating the environmental pollution of the river systems, both water and sediment chemistry must be considered. River sediments usually act as a sink and source for the pollutants; therefore, they are a very important component of river systems (Malvandi 2017). The Badaver is an important river in the Lorestan Province, west of Iran. This river provides the water required for agricultural and livestock usage. This river recharges from the Garin Mountains, East of Noorabad, and discharges into Seymareh River. The long of the Badavar River (with a E–W trend is about 75 Km and its drainage area is about 1800 Km2. The average water discharge of Badavr in spring and summer is 8.5 and 0.8 m3/sec, respectively. A part of the Badaver River passes through the Noorabad City. Indeed, agricultural activity is a usual practice around the river. Thus, the quality of water and sediments in Badavar River can be influenced by discharge of agricultural and domestic wastewaters. The aim of the present study is to investigate the environmental quality of water and sediments of Badavar River, and to find the impact of natural and anthropogenic factors on the river. Material & Methods Nineteen water and five surface sediment samples were collected in selected sites. At each sampling site, water samples were collected in 1-litre prewashed polyethylene bottles; indeed, one sample was collected in sterile dark bottles for microbial analysis. The first samples were filtered using a vacuum pump and 0.45μm pore-size filter papers in order to separate particulate matter. The filtered samples were then split into two portions: one portion was acidified with HNO3 for the measurement of dissolved elements and the second unacidified portion was used for determination of dissolved major ions. The samples were kept at 4°C prior to analysis. Some physicochemical properties of the water samples (i.e. pH and electrical conductivity) were measured in situ using a portable multi-meter. The major ion concentrations, microbial analysis, and potentially toxic element concentrations (in water samples) and pH, organic matter, carbonate calcium, cation exchange capacity, and element concentrations (in sediment samples) were determined using standard methods. In order to find the source of major ions in water samples and to determine the most significant processes controlling the water chemistry, ionic ratios, correlation coefficients, and the saturation index of minerals were calculated. The water quality for irrigation usage was accessed through the calculation of sodium adsorption ratio (Zhang et al. 2012) and magnesium hazard (Ravikumar and Somashekar 2011). Indeed, the EC and pH values of the samples were compared with standard values (Sundaray et al. 2009). Water Quality Index (WQI) as a useful method for quality assessment (Kumar et al. 2015, Vasanthavigar et al. 2010) was calculated on the basis of ion concentration, EC, pH and Total Hardness. The concentration of toxic elements in the water samples were compared with standard values of FAO (1985) for irrigation purposes and the standard values in world fresh waters (Markert 1994). For sediment quality assessment, some indices including geo-accumulation index (Muller 1969), enrichment factor (Sutherland, 2000), contamination factor (Hakanson 1980), and modified contamination degree (Abrahim and Arker 2008) were calculated. Discussion of Results & Conclusions: The EC and pH of the water samples vary between 430-730 µs/cm and 5.6-7.1, respectively. The EC values of the samples collected in the city district are higher than other samples, whereas their pH values are a little lower, showing the influence of domestic wastewater discharge on EC and pH of the water samples. The lower pH values may also be an indication of calcite precipitation (Das 2005). The calculation of ionic ratios, saturation index of minerals and correlation coefficient values indicate that the natural and anthropogenic factors influence the environmental quality of both water and sediments in Badavar River. The most important natural factors which affect the hydrochemical properties of the water samples (i.e. the concentration of major ions) include the dissolution of halite, gypsum and anhydrite, the precipitation of calcite, aragonite and dolomite, and ion exchange. Discharge of agricultural runoff and domestic wastewaters into the river is the most important anthropogenic factor decreasing the water quality, especially with respect to PO4, Pb, Cd, Cr, Cu, Mn and Zn concentrations. The values of Magnesium Hazard are mostly lower than 50%; indeed, the Sodium Adsorption Ratios are <2meq/l. Therefore, the water of Badavar River is suitable for irrigation. The values of WQI of the Badavar River varies between 58.4–42.7; indicating the good to excellent quality of the water samples. However, the river water is microbially polluted, mainly because of domestic wastewater discharge. The concentration of Pb in most sites is higher than FAO standard (5µg/L; FAO 1985) and the concentrations of Cd, Co, Cr, Cu, Fe, Mn, Ni, Se and Zn are lower than FAO guidelines (1, 50, 100, 200, 5000, 200, 200, 20, and 2000 µg/L, respectively; FAO 1985). The concentrations of Cd, Co, Ni, Pb and Se in some samples, and the concentrations of Cr, Cu, Mn and Zn in all samples are higher than their values in natural fresh waters (Markert 1994) which confirms the impacts of anthropogenic activities (i.e. agricultural and domestic wastewater discharge into the river) on water quality. Physicochemical properties of sediments play a significant role in retention, adsorption and re-adsorption of pollutants (Duodu et al. 2017). The pH value of the sediment samples ranges between 7.7 to 8.5; thus the samples are placed in neutral to alkaline class. Sediment samples are rich in organic matter (7.8–14.7%) and CaCO3 (26–45.5%), and their cation exchange capacity is high (37.4–77.3 meq/100 gr). On the basis of total concentration data, the concentration of Cu in some stations and the concentration of Cr and Ni in all sites are higher than TEC values (36.1, 34.4, and 22.7 mg/kg, respectively; MacDonald et al. 2000). Moreover, the concentration of Ni and Cr in all stations is higher than Probable Effect Concentration (PEC) values (111 and 149 mg/kg; MacDonald et al. 2000). This evidences show that the ecosystem of the Badavar River is at risk of being threatened by Ni and Cr. On the basis of total concentration data, the Badavar River sediments are polluted with Cd, Pb, Cr, Zn, Cu, Mn and Ni. The calculation of enrichment factor shows that Pb, Cd and Cr are mainly from anthropogenic activities (EF>1.5), whereas Zn, Cu, Mn and Ni are mostly from natural sources (EF<1.5). The contamination factor values are higher in sediments collected in the city district, confirming the effect of anthropogenic factors on sediment quality. The contamination degree values show that the studied sediments are placed in highly polluted class, which is due to the discharge of urban and agricultural wastewaters into the Badavar River. The obtained results in this study emphasize on the necessity of environmental management in the study area. The discharge of different kinds of wastewaters must be controlled.

https://jssr.ui.ac.ir/article_24216_e0308c6a2ba00b4b9ddff4ff10844b8f.pdf

University of Isfahan Journal of Stratigraphy and Sedimentology Researches 2008-7888 35 4 2019 12 22 Reservoir quality evaluation of the Late Jurassic Manifa carbonate sequence in one of oilfield in the Persian Gulf Reservoir quality evaluation of the Late Jurassic Manifa carbonate sequence in one of oilfield in the Persian Gulf 129 148 24292 10.22108/jssr.2019.119649.1123 FA Ali Asaadi Tehran Energy Consultants. Geology division, geological study Mehdi Sarfi School of Earth Sciences, Damghan University, Damghan, Iran Ali Imandoust Research Institute of Petroleum Industry Journal Article 2019 10 14 Abstract The late Tithonian Manifa carbonate is one of the important oil producing intervals in some oil fields of the Northwestern Persian Gulf. The combination of geological and petrophysical data in three key wells in one of oilfield, enabled us to clarify the effects of depositional facies and diagenesis on reservoir quality in a sequence stratigraphic framework. Nine microfacies were recognized that deposited in three facies belts: tidal flat, lagoon and leeward shoal in a homoclinal carbonate ramp. The carbonate interval of the Manifa has been subjected to a variety of diagenetic processes, including micritization, bioturbation, recrystallization, dissolution, cementation, dolomitization, dedolomitization and compaction in three realm of marine, meteoric and burial diagenesis. From the identification of sequence boundaries and maximum flooding surfaces, one third-order sequence was recognized and interpreted. The sequence boundaries are important local and regional disconformity surfaces. Investigation of reservoir quality of different facies demonstrates that diagenetic features have considerable effects on the reservoir characteristics and regulated pore system characteristics. After deposition of the shallow marine Manifa carbonate was drastically subjected to the fresh-water diagenesis in the meteoric realm. The main important meteoric diagenesis alterations including karstification, dissolution, cementation and recrystallization are mainly concentrated below disconformity surfaces of the Manifa carbonate. The poroperm properties are very good related to dissolution phenomena creating interconnected pore space. Vuggy and solution enlarged interparticle porosities are the two dominant interconnected pore types within the reservoir. Considering the reservoir significance of the Manifa carbonate in the northwest Persian Gulf, the conclusion drawn from this investigation can be utilized for a better reservoir characterization. Keywords: Manifa, Persian Gulf, Facies, Diagenesis, Sequence Stratigraphy, Reservoir Quality Introduction Reservoir quality of carbonate reservoirs is controlled by many interrelated factors such as depositional facies, diagenetic processes and tectonic setting (Lucia 2007; Ahr 2008; Moore & Wade 2013). In fact, by controlling the pore system properties, these parameters affect the fluid flow and saturation within the reservoirs (Ahr 2008). Although, the original sedimentary properties substantially control the reservoir quality, but diagenesis may exert considerable influence on pore characteristics (Lucia 2007; Ahr 2008; Moore & Wade 2013). The reservoir quality may be enhanced or deteriorated depending on the type of dominant diagenetic processes (Ahr 2008). The Late Tithonian sequences of the Manifa carbonate is notable carbonate reservoir in some part of the Arabian Platform. Despite of this importance, a little is known about various geological and petrophysical characteristics in Iranian northwestern part of the Persian Gulf. This study is the first report of sedimentological and reservoir geological aspects of this carbonate sequences in subsurface sections of the northwestern Persian Gulf. In this study, by using a complete dataset of drilled cores, thin sections, petrophysical well log and porosity-permeability data, interpretation of reservoir quality evaluation has been carried out on the Manifa carbonate. The aims of this study are to investigate the facies characteristics, depositional environments, diagenetic alterations and evaluate pore system and reservoir properties in relation to the disconformity surface of the Manifa Formation in the northwestern part of the Persian Gulf Material & Methods A continuous, 52-m-thick core through the Manifa Formation was logged in one of oilfield in the northwestern Persian Gulf. To differentiate the calcite from dolomite, all thin sections were stained with Alizarin Red-S (Dickson 1966). Also, in order to determine pores types and their properties, epoxy resin was injected to the samples (130 thin section), and all samples were scanned by a high-resolution (Up to 10000 DPI) scanner (CREO-IQSMART3) at the Petroleum Industry of Research Institute. Petrographic studies were carried out to identify different types of depositional facies, and based on the allochems type and their frequency, different sub-environments were distinguished. Also, the important diagenetic processes affecting the pores system were identified. Based on the combination of the results of facies/diagenesis studies the framework of sequence stratigraphy was introduced and one third-order sequences interpreted. Due to the interpreted distribution of depositional and diagenetic characteristics, petrophysical well logs were used for their correlation between the three studied wells in the studied field. Discussion of Results & Conclusion The core description and petrographic studies resulted in the identification of nine microfacies. These microfacies were attributed to three facies belts including tidal flat, lagoon, and leeward shoal. The carbonate ramp model proposed for the Manifa Formation is comparable with the model and facies distribution presented for this interval in the neighboring area. The Manifa carbonate has been subjected to a variety of diagenetic processes including micritization, bioturbation, recrystallization, compaction, cementation, dissolution, dolomitization, dedolomitization and fracturing. Dissolution, cementation, dolomitization, compaction, along with fracturing have had the greatest impact on the pore system and reservoir properties of the Manifa carbonate. In order to establish a sequence stratigraphic framework and specify the sequence boundaries and maximum flooding surfaces for the studied formation, the results from depositional and diagenetic studies were integrated. Hence, sequence stratigraphic analysis of the studied interval has resulted in the recognition of one third-order depositional sequences with aggradational-progradational stacking pattern. At the Late Tithonian, a eustatic sea-level fall caused platform emersion and subaerial exposure at top of the Manifa carbonate. This sequences are bounded with two local and regional disconformities. From reservoir quality point of view, intense meteoric dissolution of grain-to mud-dominated facies exert a main improving effect and development of intervals with high porosity and permeability. Core poroperm data interpretation clearly demonstrate that most grain- and mud-dominated facies related to different sub-environments have a good reservoir quality due to the high impact of dissolution related to meteoric diagenesis. With respect to the effect of diagenesis on the reservoir properties, the defined diagenetic facies display a distinct trend on poroperm distribution. Porosity-permeability distribution indicating the high heterogeneity is strongly related to the effects of both depositional and diagenetic characteristics. Vuggy and solution interparticle pore spaces are two dominant pore types and show high pore connectivity. Thus, an integrated sedimentological and petrophysical reservoir evaluation of the Manifa carbonate in one of oilfield in the northwestern Persian Gulf indicate that diagenetic alterations had main role in pore system characteristics and reservoir evolution. Abstract The late Tithonian Manifa carbonate is one of the important oil producing intervals in some oil fields of the Northwestern Persian Gulf. The combination of geological and petrophysical data in three key wells in one of oilfield, enabled us to clarify the effects of depositional facies and diagenesis on reservoir quality in a sequence stratigraphic framework. Nine microfacies were recognized that deposited in three facies belts: tidal flat, lagoon and leeward shoal in a homoclinal carbonate ramp. The carbonate interval of the Manifa has been subjected to a variety of diagenetic processes, including micritization, bioturbation, recrystallization, dissolution, cementation, dolomitization, dedolomitization and compaction in three realm of marine, meteoric and burial diagenesis. From the identification of sequence boundaries and maximum flooding surfaces, one third-order sequence was recognized and interpreted. The sequence boundaries are important local and regional disconformity surfaces. Investigation of reservoir quality of different facies demonstrates that diagenetic features have considerable effects on the reservoir characteristics and regulated pore system characteristics. After deposition of the shallow marine Manifa carbonate was drastically subjected to the fresh-water diagenesis in the meteoric realm. The main important meteoric diagenesis alterations including karstification, dissolution, cementation and recrystallization are mainly concentrated below disconformity surfaces of the Manifa carbonate. The poroperm properties are very good related to dissolution phenomena creating interconnected pore space. Vuggy and solution enlarged interparticle porosities are the two dominant interconnected pore types within the reservoir. Considering the reservoir significance of the Manifa carbonate in the northwest Persian Gulf, the conclusion drawn from this investigation can be utilized for a better reservoir characterization. Keywords: Manifa, Persian Gulf, Facies, Diagenesis, Sequence Stratigraphy, Reservoir Quality Introduction Reservoir quality of carbonate reservoirs is controlled by many interrelated factors such as depositional facies, diagenetic processes and tectonic setting (Lucia 2007; Ahr 2008; Moore & Wade 2013). In fact, by controlling the pore system properties, these parameters affect the fluid flow and saturation within the reservoirs (Ahr 2008). Although, the original sedimentary properties substantially control the reservoir quality, but diagenesis may exert considerable influence on pore characteristics (Lucia 2007; Ahr 2008; Moore & Wade 2013). The reservoir quality may be enhanced or deteriorated depending on the type of dominant diagenetic processes (Ahr 2008). The Late Tithonian sequences of the Manifa carbonate is notable carbonate reservoir in some part of the Arabian Platform. Despite of this importance, a little is known about various geological and petrophysical characteristics in Iranian northwestern part of the Persian Gulf. This study is the first report of sedimentological and reservoir geological aspects of this carbonate sequences in subsurface sections of the northwestern Persian Gulf. In this study, by using a complete dataset of drilled cores, thin sections, petrophysical well log and porosity-permeability data, interpretation of reservoir quality evaluation has been carried out on the Manifa carbonate. The aims of this study are to investigate the facies characteristics, depositional environments, diagenetic alterations and evaluate pore system and reservoir properties in relation to the disconformity surface of the Manifa Formation in the northwestern part of the Persian Gulf Material & Methods A continuous, 52-m-thick core through the Manifa Formation was logged in one of oilfield in the northwestern Persian Gulf. To differentiate the calcite from dolomite, all thin sections were stained with Alizarin Red-S (Dickson 1966). Also, in order to determine pores types and their properties, epoxy resin was injected to the samples (130 thin section), and all samples were scanned by a high-resolution (Up to 10000 DPI) scanner (CREO-IQSMART3) at the Petroleum Industry of Research Institute. Petrographic studies were carried out to identify different types of depositional facies, and based on the allochems type and their frequency, different sub-environments were distinguished. Also, the important diagenetic processes affecting the pores system were identified. Based on the combination of the results of facies/diagenesis studies the framework of sequence stratigraphy was introduced and one third-order sequences interpreted. Due to the interpreted distribution of depositional and diagenetic characteristics, petrophysical well logs were used for their correlation between the three studied wells in the studied field. Discussion of Results & Conclusion The core description and petrographic studies resulted in the identification of nine microfacies. These microfacies were attributed to three facies belts including tidal flat, lagoon, and leeward shoal. The carbonate ramp model proposed for the Manifa Formation is comparable with the model and facies distribution presented for this interval in the neighboring area. The Manifa carbonate has been subjected to a variety of diagenetic processes including micritization, bioturbation, recrystallization, compaction, cementation, dissolution, dolomitization, dedolomitization and fracturing. Dissolution, cementation, dolomitization, compaction, along with fracturing have had the greatest impact on the pore system and reservoir properties of the Manifa carbonate. In order to establish a sequence stratigraphic framework and specify the sequence boundaries and maximum flooding surfaces for the studied formation, the results from depositional and diagenetic studies were integrated. Hence, sequence stratigraphic analysis of the studied interval has resulted in the recognition of one third-order depositional sequences with aggradational-progradational stacking pattern. At the Late Tithonian, a eustatic sea-level fall caused platform emersion and subaerial exposure at top of the Manifa carbonate. This sequences are bounded with two local and regional disconformities. From reservoir quality point of view, intense meteoric dissolution of grain-to mud-dominated facies exert a main improving effect and development of intervals with high porosity and permeability. Core poroperm data interpretation clearly demonstrate that most grain- and mud-dominated facies related to different sub-environments have a good reservoir quality due to the high impact of dissolution related to meteoric diagenesis. With respect to the effect of diagenesis on the reservoir properties, the defined diagenetic facies display a distinct trend on poroperm distribution. Porosity-permeability distribution indicating the high heterogeneity is strongly related to the effects of both depositional and diagenetic characteristics. Vuggy and solution interparticle pore spaces are two dominant pore types and show high pore connectivity. Thus, an integrated sedimentological and petrophysical reservoir evaluation of the Manifa carbonate in one of oilfield in the northwestern Persian Gulf indicate that diagenetic alterations had main role in pore system characteristics and reservoir evolution.

https://jssr.ui.ac.ir/article_24292_69e16195d0bd0723cc868922ed7bd1bb.pdf