Stratigraphy and Palaeontology
Nasrollah Abbassi; Safoora Shakeri; Javad Rabbani
Abstract
Numerous Proboscidean footprints have been discovered in the outcrop (135 m) of lower rock unit of the Upper Red Formation (Middle-Late Miocene) in the north Avaj (Qazvin province), central Iran. These footprints are preserved as circular concave epi-relief in the upper bedding plans with smooth or levee ...
Read More
Numerous Proboscidean footprints have been discovered in the outcrop (135 m) of lower rock unit of the Upper Red Formation (Middle-Late Miocene) in the north Avaj (Qazvin province), central Iran. These footprints are preserved as circular concave epi-relief in the upper bedding plans with smooth or levee rims or with sediment accumulation in the front of the footprints. Five digit imprints present in some of the footprints. The frequency of footprints is considerable the most of the upper surface of layers which resulted by movement of proboscis herds. Ichnotaxonomically these footprints identified as Proboscipeda enigmatica. The footprints are classified as two size small (15 cm) and large (25 cm) categories, and based on the geometric relationships, the height of shoulder was estimated as 140-170 cm for adult and 76-106 cm immature individuals. According to reports of Miocene Proboscidean body fossils form Iran, and based on the distributions of the Proboscidean in this time, it seems that the Choerolophodon (Gomphotheriidae) is candidate as track-maker of the Avaj footprints. Among the Proboscidean footprints, there are crocodile and fish swimming imprints which were left in the shallow pools.
Stratigraphy and Palaeontology
Hamta Ranjbar; Abbas Ghaderi; Hossein Gholamalian; Vachik Hairapetian
Abstract
Middle Devonian to Lower Carboniferous siliciclastic-carbonate successions in Eastern Alborz are characterized by Khoshyeilagh Formation. It is underlain by the Devonian red siliciclastic sequences and is overlain by the Carboniferous Mobarak Formation, can be divided into three different members; lower ...
Read More
Middle Devonian to Lower Carboniferous siliciclastic-carbonate successions in Eastern Alborz are characterized by Khoshyeilagh Formation. It is underlain by the Devonian red siliciclastic sequences and is overlain by the Carboniferous Mobarak Formation, can be divided into three different members; lower carbonate, middle siliciclastic, and upper carbonate. The Khoshyeilagh Formation comprises various fossil groups of invertebrates, conodonts, palynomorphs and fish remains. In the present study, a collection of microscopic fish remains, obtained from the lower and upper carbonate members in Mighan, north of Shahrood, have been determined and described. This assemblage contains 14 different taxa of chondrichthyan fish including: Cladodoides cf. wildungensis, Ctenacanthiformis gen. et sp. indet, Dalmehodus turnerae, Deihim mansureae, Lissodus lusavorichi, Phoebodus aff. turnerae, Phoebodus fastigatus, Phoebodus gothicus gothicus, Phoebodus gothicus transistans, Roongodus phijani, Siberiodus mirabilis, Squatinactis glabrum, Stethacanthus resistens and Thrinacodus ferox. Some specimens of scales and teeth of actinopterygian and osteichthyan fishes are also present which all indicate a shallow environment of the continental shelf. The associated conodonts with this assemblage demonstrate the age of Frasnian (rhenana biozone) to early Tournaisian (duplicata biozone) for the whole succession.
Stratigraphy and Palaeontology
Toran Khamohi; Ahmad Lotfabad Arab; Mohamadreza Vaziri Vaziri
Abstract
In order to fossils study of Lower Cretaceous deposits, the Baghin section was chosen and sampled. This section consist of a sequence of green marl, limestone and shaly limestone deposits. In this section, diverse groups of microfossils (orbitolinids, algae and ostracods) and macrofossils (corals, echinoids, ...
Read More
In order to fossils study of Lower Cretaceous deposits, the Baghin section was chosen and sampled. This section consist of a sequence of green marl, limestone and shaly limestone deposits. In this section, diverse groups of microfossils (orbitolinids, algae and ostracods) and macrofossils (corals, echinoids, bivalves, brachiopods, gastropods,…) are present. The presence of diverse collection fossils, especially large orbitolinid foraminifera indicated a favorable environmental conditions and absence of planktonic foraminifera indicated a shallow environmental conditions. Also, the presence of platycopid and podocopid ostracods and corals confirm the shallow, warm, light and suitable paleoecological conditions.Key words: fossils study, Orbitolinid, Ostracod, Coral, Baghin , Kerman.
Stratigraphy and Palaeontology
Kamyar Younesi; Anoshiravan Lotfali Kani; Hormoz Ghalavand
Abstract
A conformable passage between Sarvak and Surgah Formations in Lurestan sedimentary basin reveals the potential of studying the Turonian–Coniacian boundary within Surgah Formation. Two sections of the Surgah Formation at Posht-e-Jangal and Pasan anticlines situated on the southeast of the Lurestan ...
Read More
A conformable passage between Sarvak and Surgah Formations in Lurestan sedimentary basin reveals the potential of studying the Turonian–Coniacian boundary within Surgah Formation. Two sections of the Surgah Formation at Posht-e-Jangal and Pasan anticlines situated on the southeast of the Lurestan sedimentary basin have been studied on the basis calcareous nannofossils, and based on the observed distribution of nannoflora, the presence of CC12 to CC16 nannofossil biozones is documented which points to the latest Turonian to Coniacian age for the base of this Formation, while the top boundary is estimated approximately at earliest Santonian. Due to the absence of Micula staurophora, however, separation of CC13 and CC14 biozones is not possible and therefore, the Turonian–Coniacian boundary is placed somewhere within the said undivided interval. The FO of Calculites obscurus as the marker event for the top of CC16 biozone is not identified but on the basis of suspected LO of Lithastrinus septenarius as the marker event of the top of UC11 and onset of UC12, the record of early Santonian beds seems probable.
Stratigraphy and Palaeontology
Hajar Mashayekh; Massih Afghah; Mahnaz Parvaneh- Nejad Shirazi
Abstract
In order to biostratigraphic studies of Gurpi Formation, a section was selected in the north-east of Noorabad city in Fars. Structurally, this section is located in the folded-thrust zone of Zagros and geographically in the Fars zone (coastal Fars). The Gurpi Formation is extended of 229 meters in thickness, ...
Read More
In order to biostratigraphic studies of Gurpi Formation, a section was selected in the north-east of Noorabad city in Fars. Structurally, this section is located in the folded-thrust zone of Zagros and geographically in the Fars zone (coastal Fars). The Gurpi Formation is extended of 229 meters in thickness, contains limestone, shale, marly limestone and argillaceous limestone. Its lower boundary with Sarvak Formation and its upper contact with Pabdeh Formation are discontinuous. The study conducted on foraminiferal biostratigraphy in this section led to the identification of 20 species belonging to 7 genera of planktonic foraminifera. Based on the stratigraphic distribution of the planktonic foraminifera, five biozones are determined which correspond with global biozonation. Described biozones are comprised of: 1-Globotruncanita elevata Partial range zone; 2-Globotruncana ventricosa Interval zone; 3-Radotruncana calcarata Total range zone; 4-Gansserina gansseri Interval zone; 5-Contusotruncana contusa, Contusotruncana walfischensis, Globotruncanita conica Assemblage zone. Based on these biozones, the age of Gurpi Formation is assigned to early Campanian to late Maastrichtian. The absence of the Marginotruncana and Dicarinella asymetrica in the lower part of the Gurpi Formation indicates of the Santonian-Campanian boundary and the determination of the early Early Campanian age for the base of this Formation.
Stratigraphy and Palaeontology
Parisa Mohammadi; Abbas Ghaderi; Ali Reza Ashouri
Abstract
The Julfa region in East Azerbaijan Province exhibits one of the best continuous marine sedimentary successions across the Permian to Triassic boundary. The present study is focused on the brachiopod contents of the Julfa beds in Qareh-Goz section (41.5 m thickness) in the south of Julfa. This study ...
Read More
The Julfa region in East Azerbaijan Province exhibits one of the best continuous marine sedimentary successions across the Permian to Triassic boundary. The present study is focused on the brachiopod contents of the Julfa beds in Qareh-Goz section (41.5 m thickness) in the south of Julfa. This study is led to the determination of 11 genera and 21 species of the orders Athyridida, Orthotetida, Orthida, Productida, Spiriferida, and Terebratulida, all representing the Cathaysian bioprovince for this area in the Western Paleotethys. Accordingly, four Wuchiapingian biozones, including Araxilevis intermedius Zone, Araxilevis intermedius-Permophricodothyris ovata Interval zone, Permophricodothyris ovata Zone, and Transcaucasathyris araxensis Zone, have been detected. These biozones correlate well through the other stratigraphic sections of the Julfa area in the Ali Bashi and Zal Mountains, Dorasham section in the Transcaucasia, Hembast Formation in the Abadeh area, and Nesen Formation in the central Alborz, approving the potential of these brachiopods in biocorrelation at a regional scale in the Late Permian.
Stratigraphy and Palaeontology
Fereshteh Sajjadi; Firoozeh Hashemi Yazdi; Hossein Hashemi
Abstract
Reasonably diverse and very well-preserved palynomorphs including miospores, dinoflagellate cysts, foraminiferal test linings, acritarchs (sensu lato) and fungal spores occur in the Dalichai Formation, Yonjehzar, northeastern Tehran, central Alborz. The assemblages embrace 40 species of spores (assigned ...
Read More
Reasonably diverse and very well-preserved palynomorphs including miospores, dinoflagellate cysts, foraminiferal test linings, acritarchs (sensu lato) and fungal spores occur in the Dalichai Formation, Yonjehzar, northeastern Tehran, central Alborz. The assemblages embrace 40 species of spores (assigned to 29 genera), 18 species of pollen (distributed among 10 genera) and 54 species of dinoflagellates (assigned to 28 genera). According to the presence of such miospores species with known worldwide stratigraphic distribution as Klukisporites variegatus, K. scaberis, Concavissimisporites verrucosus, C. pricei, Osmundacidites senectus and Striatella spp. the host strata are conceivably dated as Middle Jurassic. Based on the stratigraphic distribution of miospores, Klukisporites variegatus-Araucariacites australis-Cerebropollenites macroverrucosus Assemblage Zone is recognized. Presence of some index dinoflagellate species led to identification of four biozones in the Dalichai Formation. These include in ascending order, Cribroperidinium crispum Total Range Biozone (late Bajocian), Dichadogonyaulax sellwoodii Interval Biozone (Bathonian - early Callovian), Ctenididinium continuum Interval Biozone (early - middle Callovian) and Subzone a (early - middle Bathonian). Co-ccurrence of dinoflagellate cysts with known vertical ranges, viz., Cribroperidinium crispum, Meiourogonyaulax valensii, Carpatodinium predae, Ctenidodinium combazii and Compositosphaeridium polonicum suggests a Middle Jurassic age (late Bajocian to middle Callovian) for the host strata corroborates the available miospores-based biostratigraphy. The miospores are attributed to the Pterophyta (69%), Coniferophyta (15%), Pteridospermophyta (7%), Cycadophyta (5%), Lycophyta (2%), Ginkgophyta and Bryophytes (1%). Considering the relative abundance of fern spores (69%) and their morphological diversity (19 genera), it can be concluded that fern and fern-allies dominated the coastal vegetation around the sedimentary environments of the studied strata and that they flourished under a warm climate with notable humidity. The study of paleoclimate using the Sporomorph EcoGroups model shows a high ratio of warmer/cooler sporomorphs and a low ratio of drier/wetter sporomorphs, which is another confirmation of this type of climate. Presece of such warm water dinoflagellate cysts as Gonyaulacysta centriconnata, G. jurassica, Nannoceratopsis pellucida, Tubotuberella apatela, Ctenidodinium continuum, Pareodinia halosa, P. ceratophora, paleogeographic reconstruction and geographical location of Iran in the Middle Jurassic supports the generalization proposed.
Stratigraphy and Palaeontology
Ali Jalali; Hamed Yarahmadzahi; Mehran Arian; Abdollah Saidi; Seyed Mohsen Aleali
Abstract
The Shishtou section is located in the north of Tabas Ghezelin and Asselian sequences of Zaladou formation with 60 m thickness are divided into five units, includes sandstone, limestone, shale, sandy limestone and limestone. The lower boundary of the Gzhelian deposits with disconformity on top of the ...
Read More
The Shishtou section is located in the north of Tabas Ghezelin and Asselian sequences of Zaladou formation with 60 m thickness are divided into five units, includes sandstone, limestone, shale, sandy limestone and limestone. The lower boundary of the Gzhelian deposits with disconformity on top of the Moscovian deposits of the Abshani formation. The upper boundary of these deposits with the Tighe-Madanou formation is continuous. The assemblages of fusulinids in the Shishtou section such as Ruzhenzevites-Rauserites-Triticites are identified in the upper part of Gzhalian previously reported from equal deposits in Darvaz, Fergana, Southern Urals, Donetsk and Carnic of Alps, as well as, Central Iran, Central Alborz and Sanandaj-Sirjan zones. Also, different species of Sphaeroschwagerina, Pseudoschwagerina and Likharevites, which illustrate the Asselian age, represent the Carboniferous-Permian boundary in the studied section and allow for comparability with other structural-sedimentary zones of Iran, including Central Iran , Central Alborz (Doroud Group) and Sanandaj-Sirjan zone. This equivalence expresses the transgressive of sea level in different parts of Iran in the late Carboniferous and early Permian periods. In Shishto section 15 genera ,35 species and 2 subspecies of Fusulins have been identified, some of which are reported for the first time from Iran.
Stratigraphy and Palaeontology
Abdolvahab Kazemi; Nasrollah Abbassi
Abstract
Agha Jari Formation (Miocene-Pliocene, 788 m) comprises alternations of sandstone, siltstone, and marl in red to brown color layers in the east Gotvand, north Khuzestan province, southwest Iran. Numerous vertebrate footprints have been found in the middle part of the Formation, which includes footprints ...
Read More
Agha Jari Formation (Miocene-Pliocene, 788 m) comprises alternations of sandstone, siltstone, and marl in red to brown color layers in the east Gotvand, north Khuzestan province, southwest Iran. Numerous vertebrate footprints have been found in the middle part of the Formation, which includes footprints of wetland small bird (Aviadactyla media, Gruipeda dominguensis), artiodactyls (Lamaichnum alfi, Lamaichnum isp., Pecoripeda satyri, Pecoripeda isp.), canids (Canipeda isp.) and large reptiles (Hatcherichnus sanjuanensis). Frequency of artiodactyl imprints are more than the other footprints. These footprints proof the living of camels and crocodiles in the Zagros basin for the first time. The ichnotaxa diversity of the footprints in the studied section is more than the other reports of Agha Jari Formation in Iran and its stratigraphic equivalent in the adjacent countries.
Stratigraphy and Palaeontology
Zahra Khajehjavaran; Gholam Reza Ghadami; Mohammad Poosti; Abbas Moradian; Behrouz Karimi Shahraki
Abstract
Andesites are located in the north of shahr-e-babak , central Iran, Urumieh- Dokhtar belt. The main texture in these rocks is porphyry and their phenocrysts are plagioclase (Andesine to Labradorite), pyroxene (Augite), amphibol (Tschermakite and Magnesiohornblende). These properties are signatures of ...
Read More
Andesites are located in the north of shahr-e-babak , central Iran, Urumieh- Dokhtar belt. The main texture in these rocks is porphyry and their phenocrysts are plagioclase (Andesine to Labradorite), pyroxene (Augite), amphibol (Tschermakite and Magnesiohornblende). These properties are signatures of calc- alkaline series formed in a volcanic arc setting. Based on geochemical studies, the rocks show enrichment in LREE rather than HREE. The lack of significant Eu anomalies in REE pattern indicates oxidation state of magma during crystallization. Based on geochemical studies, the clinopyroxenes are Augite and have been crystallized from magma with almost 10% H2O. Fe3+ values of the clinopyroxenes reveal high oxygen fugacity in the magma. Based on the mineral chemistry data, pressure estimates from the clinopyroxenes in the range of 6-10 Kbr and composition yield the crystalization temperatures that range from 900-1100 OC. Typically, clinopyroxenes occure at calc-alkaline orogenic igneous rocks. The plagioclase composition yield the crystalization temperatures that range from 650-750 OC. According to the present study, the rocks are probably the result of the subduction of the Neo-Tethys oceanic lithosphere below the Sanandaj-Sirjan zone, during the Eocene and in a volcanic arc environment.
Stratigraphy and Palaeontology
Najmeh Nazeri Tahroodi; Mohammad Reza Esmaeilbeig; Mohammadreza Ghotbi Ravandi; Maryamnaz Bahrammanesh Tehrani
Abstract
Stratigraphic and paleontological studies on 6-section brachiopods from Lower to Upper Paleozoic in the Kerman region were performed by a joint Iranian-Italian team. In one of these sections in the Shabjareh area - Kerman - Kat Kouyeh Formation with geographical characteristics of 31º 5´ 56º, ...
Read More
Stratigraphic and paleontological studies on 6-section brachiopods from Lower to Upper Paleozoic in the Kerman region were performed by a joint Iranian-Italian team. In one of these sections in the Shabjareh area - Kerman - Kat Kouyeh Formation with geographical characteristics of 31º 5´ 56º, 10E, N, a complete sequence of the rotation of Ordovician sediments that had brachiopods in some horizons was studied. One of the typical brachiopods studied is Martellia shabjerehansis. Ultrastructural studies on this species and studies to study the shell changes of brachiopods from Cambrian to Devonian were selected from the samples taken by the SEM devices of the University of Milan. The reason for choosing this species was the existence of 28 completely healthy shells are very suitable for evolution from the young to adults of this specimen, two of which had well-preserved articulate shells, and the evolution of age from young to old specimens can be observed in it.
Stratigraphy and Palaeontology
Saeedeh senemari; Narges Monjezi
Abstract
Pabdeh Formation to Asmari Formation transition deposits were studied in the stratigraphic section of Khaviz located in the northeast of Behbehan. In the present research, the deposits of the upper part of Pabdeh Formation consisting shale and interbedded of argillaceous gray limestone with a thickness ...
Read More
Pabdeh Formation to Asmari Formation transition deposits were studied in the stratigraphic section of Khaviz located in the northeast of Behbehan. In the present research, the deposits of the upper part of Pabdeh Formation consisting shale and interbedded of argillaceous gray limestone with a thickness of about 66 m were studied, which are followed by deposits of the lower part of Asmari Formation with a thickness of about 21 m, including cream-colored clay limestone. As a result of this study, 33 species belonging to 15 genera of calcareous nannofossils were identified. Based on the recorded bio-events and associated fossil assemblages, the bio-zones of Sphenolithus pseudoradians Zone, Ericsonia subdisticha Zone, Helicosphaera eticulate Zone, Sphenolithus predistentus Zone, Sphenolithus distentus Zone were determined. The studied zones are consistent with CNE20- CNO4/ CNO5 from Agnini et al. (2014) zonation. Based on the introduced bio-zones, the age of the upper part of Pabdeh Formation in the studied section of the Priabonin-early Rupelian and the age of the lower part of the Asmari Formation Rupelian-Chattian are suggested. In this study, the boundary between Pabdeh and Asmari formations is continuous, which indicates sedimentation with decreasing depth in the boundary of these two formations.
Stratigraphy and Palaeontology
Nasrollah Abbassi; Mohammad Vahidinia; Saeid Tavana; Pooria Vaeznia
Abstract
Numerous vertebrate footprints have been found in the dislocated sandstone slabs in the Mashhad city, northeast Iran. Neogene sediments of Chenaran township are supposed to be provenance of the studied slabs. Identified footprints includes artiodactyl tracks as ichnotaxa Bifidipesvelox, Lamaichnum guanicoe, ...
Read More
Numerous vertebrate footprints have been found in the dislocated sandstone slabs in the Mashhad city, northeast Iran. Neogene sediments of Chenaran township are supposed to be provenance of the studied slabs. Identified footprints includes artiodactyl tracks as ichnotaxa Bifidipesvelox, Lamaichnum guanicoe, Pecoripeda amalphaea, Pecoripeda isp., Carnivore tracks as Canipeda isp., and Felipeda isp., and bird tracks as Avidactyla isp., Avipeda gryponyx, Fuscinapeda texana. Among studied slabs, bird tracks are abundant. This is the first report of Cenozoic vertebrate tracks from the Kopeh Dagh geological zone. Discovery of Lamaichnum guanicoe shows Camelidae distribution in Iranian Plateau is as old as Neogene, and it is the first report of Camelidae sign from Iran. Presence of diverse footprints from Kopeh Dagh shows attenable biodiversity in the region of Iran.
Stratigraphy and Palaeontology
Peiman Rajabi
Abstract
The Asmari carbonate formation in Lorestan is seen in the form of a medium to the thick limestone-rich layer of benthic foraminifera and often as a rock formation. In this study, the stratigraphic sequence of Asmari carbonate formation in the Chenareh Anticline section located in the south of Lorestan ...
Read More
The Asmari carbonate formation in Lorestan is seen in the form of a medium to the thick limestone-rich layer of benthic foraminifera and often as a rock formation. In this study, the stratigraphic sequence of Asmari carbonate formation in the Chenareh Anticline section located in the south of Lorestan basin and Amiran Anticline section located in the middle part of Lorestan basin were studied in terms of lithology and micro biostratigraphy. The thickness of the Chenareh Section was 180 meters and the Section of Amiran Anticline was 158 meters. In total, more than 290 thin sections of both were prepared and examined in the laboratory. The results of fossil studies based on the expansion of foraminifera finally lead to the introduction and presentation of 1 Assemblage biozone in the Amiran anticline section and 3 Assemblage biozones related to the Chenareh anticline stratigraphic section. Accordingly, the age of the Asmari Formation is in the Chenareh section is Oligo-Miocene (Chattian-Bordigalian) and in the Amiran section is Miocene (Bordigalin). According to the lithostratigraphic studies, the border of the Asmari Formation in both sections of Chenareh and Amiran with Shabazan Formation is progressive-continuous and discontinuous, and in both sections of the upper boundary with Gachsaran Formation can be seen in the same way as evaporative sediments.
Stratigraphy and Palaeontology
Ahmad Lotfabad Arab
Abstract
In order to identify, classify and paleoecological study of Lower Cretaceous echinoid fauna in northwest of Kerman area, the stratigraphic section of Siriz, was selected and its specimens were sampled and studied. Echinoids were studied and identified from a rich and diverse collection of macrofossils ...
Read More
In order to identify, classify and paleoecological study of Lower Cretaceous echinoid fauna in northwest of Kerman area, the stratigraphic section of Siriz, was selected and its specimens were sampled and studied. Echinoids were studied and identified from a rich and diverse collection of macrofossils (echinoids, brachiopods, bivalves, gastropods and corals) and microfossils (foraminifera and ostracods), which present in this deposits. Sixteen genera and species of echinoids are reported for the first time from the region, among which six species are new and reported from Kerman area previously. The co-existence of echinoids and other fossil groups in Siriz area confirms an Aptian age for the sediments. Also, it can be concluded that a shallow, less than 50 meters and warm platform environment was prevailed during the deposition of the strata.
Stratigraphy and Palaeontology
Fatemeh Vaez-Javadi; Mahdi Abbaszadeh
Abstract
Middle Jurassic sediments of the Hojedk Formation have been well-exposed in the Central East of Iran. In this study, plant macrofossils, which are collected from a coal exploratory well in the Mazino area, southwest of the Tabas were studied, so that 29 species of well-preserved plant macrofossils belonging ...
Read More
Middle Jurassic sediments of the Hojedk Formation have been well-exposed in the Central East of Iran. In this study, plant macrofossils, which are collected from a coal exploratory well in the Mazino area, southwest of the Tabas were studied, so that 29 species of well-preserved plant macrofossils belonging to 15 genera of various orders such as Equisetales, Filicales, Caytoniales, Bennettitales, Cycadales, and Pinales were identified. One local biozone- Ptilophyllum harrisianum-Klukia exilis interval zone was recognized. The lower and the upper boundaries of this biozone were identified by the first and the last occurrences of index species. Based on the occurrences of the Equisetites sp. cf. E. beanii, Klukia exilis, Ptilophyllum harrisianum, Nilssonia macrophylla, and Elatides thomasii, an early Middle Jurassic age (Aalenian-Bajocian) was suggested for this plant assemblage. The relative abundance of Filicales (ferns), Cycadales, Pinales, and Equisetales are 43.18, 31.82, 13.63, and 4.64 percent, respectively. Moreover, the results of similarity indices of plant macrofossils indicate relatively strong value of similarity between the plant macrofossil assemblage of the Mazino area and elsewhere in the Tabas Block. Besides, the floral gradient score of this assemblage is 54.89. Based on the paleontological and lithological evidence, a humid ‘warm temperate biome’ is considered for this locality. Moreover, it is confirmed that a uniform vegetation and palaeoclimate occurred in Tabas Block during the Middle Jurassic and that Iran was located within Vakhrameev’s Euro-Sinian region, as Transcaspian subprovince.
Stratigraphy and Palaeontology
Parinaz Rasolui Ghadi; Mehdi Sarfi; Seyed Mohsen Aleali; Zahra Maleki
Abstract
Identification of key sequence stratigraphic surfaces is a crucial task in geological characterization of hydrocarbon reservoirs. The uppermost Jurassic–lower Cretaceous carbonate successions of the Manifa member and Fahliyan Formation are as an important oil reservoir of Northwestern Persian Gulf. ...
Read More
Identification of key sequence stratigraphic surfaces is a crucial task in geological characterization of hydrocarbon reservoirs. The uppermost Jurassic–lower Cretaceous carbonate successions of the Manifa member and Fahliyan Formation are as an important oil reservoir of Northwestern Persian Gulf. This study addresses the application of GR D-INPEFA curve to discriminate and correlate key stratigraphic surfaces and sequences of the studied carbonates in five wells a giant oil field of the Persian Gulf. To achieve this goal, identified key stratigraphic surfaces of core and thin sections were compared with interpretation of GR D-INPEFA curve. From sequence stratigraphic point of view and based on the results from geological studies, the Late Tithonian-Neocomian sequence has been discriminated into four third-order sequences which are described and interpreted. The top sequence boundary of the Manifa carbonate corresponds to a significant discontinuity that associated with evidence of karstification and distinct facies variation above and below this key surfaces. Based on the applied D-INPEFA curve, the identified sequence can be effectively discriminated and correlated in the field scale.
Stratigraphy and Palaeontology
elahe zarei
Abstract
The Dalichai Formation in Ahvanu section in the north of Damghan city with a thickness of 78 meters consisting of an alternation of bluish-gray marls and limestone, was studied. Based on the presence and stratigraphic distribution of miospore, Klukisporites variegatus and Callialasporites dampieri of ...
Read More
The Dalichai Formation in Ahvanu section in the north of Damghan city with a thickness of 78 meters consisting of an alternation of bluish-gray marls and limestone, was studied. Based on the presence and stratigraphic distribution of miospore, Klukisporites variegatus and Callialasporites dampieri of pollen are identified (Middle Jurassic) and presence of some index dinoflagellate species led to the identification of three biozones in the Dalichai Formation. These include in ascending order, Cribroperidinium crispum Total Range Biozone (late Bajocian), Dichadogonyaulax sellwoodii Interval Biozone (Bathonian - early Callovian), Ctenididinium continuum Interval Biozone (early to middle Callovian). Also, this Formation was divided into two biozone on the basis of Lenticulina varians-Ophtalmidium Assemblage zone and Globigerina bathoniana Taxon range zone. The close similarities of fauna assemblages of Dalichai Formation in this region (eastern Alborz ((dinoflagellate cyst, foraminifera, posidonia and radiolar) with assemblages recorded from different parts of Iran (such as central and eastern, western Alborz and Binalud and south of Iran) and other parts of world (northwest of Europe, and the northwestern Tethys and …) confirm the marine connection and faunal exchange between the mentioned basins during Middle Jurassic.
Stratigraphy and Palaeontology
Ali Asaadi; Ali Imandoust; Mehdi Sarfi; Mehdi Ghane Ezabadi
Abstract
The Lower Cretaceous Fahliyan Formation is one of the main oil reservoirs in the Persian Gulf. In this study, for investigating facies characteristics, depositional environment, diagenetic features, sequence stratigraphy and describing factors controlling reservoir quality, the integration of the results ...
Read More
The Lower Cretaceous Fahliyan Formation is one of the main oil reservoirs in the Persian Gulf. In this study, for investigating facies characteristics, depositional environment, diagenetic features, sequence stratigraphy and describing factors controlling reservoir quality, the integration of the results from core description, petrographic studies, and petrophysical data was utilized. Nine main facies were recognized and grouped in four facies belts of lagoon, shoal, patch reef and shallow open marine, indicating deposition of the formation in a carbonate ramp platform. Various diagenetic processes that influenced facies, occurred in marine, meteoric, and burial diagenetic realms. Four main pore types have been identified in the reservoir that include interparticle, moldic, vuggy, and microporosity. From the sequence stratigraphy point of view, three third-order sequences which are correlatable within the Fahliyan Formation were identified. The development of grainstone and algal rudstone/floatstone in shoal/ patch reef sub-environment played an important role in developing the high reservoir. In view of their controls on reservoir quality and pore system, diagenetic features can be categorized into two classes: (1) diagenetic processes enhancing reservoir quality that include dissolution and fracturing, and (2) diagenetic processes reducing reservoir quality that include cementation and compaction.
Stratigraphy and Palaeontology
Nasrollah Abbassi; Reza Aharipour
Abstract
Mila Formation includes five members in the Tuyeh-Darvar section, west Damghan. Fifth Member of formation comprises alternations of calcareous shale, limestone and green shales. Trace fossils of this member includes Cruziana problematica, Gordia isp., Helminthopsis abeli, Helminthopsis tenuis, Palaeophycus ...
Read More
Mila Formation includes five members in the Tuyeh-Darvar section, west Damghan. Fifth Member of formation comprises alternations of calcareous shale, limestone and green shales. Trace fossils of this member includes Cruziana problematica, Gordia isp., Helminthopsis abeli, Helminthopsis tenuis, Palaeophycus striatus, Planolites beverleyensis, Psammichnites gigas, Scolicia strozzii and Treptichnus pedum. Circulichnis montanus abundant in the upper most layers of the fifth Member and is circular cylindrical ring in shape. Circulichnis is a fodinichnion, that produced by progressive and plasticity behaviors of annelids. It seems that these trace fossils are belong to the mid parts of the turbidite rhythmic sequences and formed in the turbidity conditions of the sedimentary environment.
Stratigraphy and Palaeontology
Narges Ghader; Ali Asghar Ciabeghodsi; Mir Amir Salahi; Mohammad sadegh Zangeneh
Abstract
In the present study, In order to study of the planktonic foraminiferal biostratigraphy of Qom Formation in north of Khoy city, West Azarbayjan province (Sanandaj-Sirjan fore-arc basin), stratigraphic section of Sagatlu was selected and sampled. Thickness of Sagatlu section 216 meters was measured. Lithology ...
Read More
In the present study, In order to study of the planktonic foraminiferal biostratigraphy of Qom Formation in north of Khoy city, West Azarbayjan province (Sanandaj-Sirjan fore-arc basin), stratigraphic section of Sagatlu was selected and sampled. Thickness of Sagatlu section 216 meters was measured. Lithology of this section contain shale, siltstone, conglomerate and sandstone. The lower boundary of these deposits is alluvium, and its upper boundary is hard limestone deposits of Qom Formation. Study of the planktonic foraminifera communities found in the mentioned section to identify 16 genera and 37 species of planktonic foraminifers. In this research, 4 biozone are included, Subbotina linaperta assemblage Zone, Paragloborotalia opima Highest-occurrence Zone, Ciperoella ciperoensis Partial-Range Zone, Globigerinoides italicus assemblage Zone were identified as being age equivalent to Priabonian-Burdigalian and comparable to world standard biozones..
Stratigraphy and Palaeontology
Mahmoud sharafi; Nasim Mousavi; Mehran Moradpour; Bijan Biranvand; ebrahin Abdollahi; Hossein Soltani
Abstract
Based on lithostratigraphy analysis, Cheleken Formation in the studied section of the Gorgan plain, subdivided into lower sandstone and upper mudstone/marl units. Based on petrographic analysis, the sandstone sediments include low textural and compositional maturity litharenite and sublitharenite. Conglomerates ...
Read More
Based on lithostratigraphy analysis, Cheleken Formation in the studied section of the Gorgan plain, subdivided into lower sandstone and upper mudstone/marl units. Based on petrographic analysis, the sandstone sediments include low textural and compositional maturity litharenite and sublitharenite. Conglomerates are polymictite orthoconglomerate with variables carbonate and chert grains. High percentage of the porosity as vuggy, channels and fractures in the sandstone and conglomerates and even mudstone deposits displays high reservoir potentional for the studied sediments and hence necessitates the exploration studies in the Iranian part of the SCB. Based on the youngest nannofossil species, a late Miocene to middle Pliocene (?) age is defined for the Cheleken Fm. in the studied area. Nannofossils distribution of the studied succession displays the SCB was connected to the Black Sea and Mediterranean Basin in the late Miocene- early Pliocene and the Pleistocene and was isolated in the main part of the Pliocene.
Stratigraphy and Palaeontology
Hamideh Noroozpour
Abstract
In this research the biostratigraphy and lithostratigraphy of the Talou section (northwest Damghan) have been studied based on brachiopods of Lower Carboniferous in Mobarak Formation. The 580 me thick Mobarak Formation in Talou section consists of dark gray limestone with intercalation of organic rich ...
Read More
In this research the biostratigraphy and lithostratigraphy of the Talou section (northwest Damghan) have been studied based on brachiopods of Lower Carboniferous in Mobarak Formation. The 580 me thick Mobarak Formation in Talou section consists of dark gray limestone with intercalation of organic rich black shale. This formation in the studied area is conformably overlie on Jeirud Formation. Vermiculate limestone of Elika Formation overlies the Mobarak Formation with an erosional surface. In the studied interval 25 genera and 30 species of brachiopods were identified. 4 assemblage zones have been identified in the early Carboniferous.Biozone 1 (Early Tournaisian): this zone is characterized by the following indicator species community. Spinocarinifera nigra, Rugosochonetes cf. hardrensis (Phillips,1841), Rossirhynchus adamantinus, Shumardella sp., Cleiothyridina transversa., Rossirhynchusadamantinus, Shumardella sp.; Biozone 2 (Middle Tournaisian): Spirifermissouriensis, Spirifer attenuatus (Sowerby,1839), Spirifer cf. trigonalis (Martin, 1809), Athyrishibernica Syringothyriscospidata; Biozone 3 (Late Tournaisian): Tomiproductus elegantulus, Marginatia aff. burlingtonensis (Hall,1893), Leptagonia cf. regularis, Fusellatornacensis, Marginatiaburlingtonensis; Biozone of 4 (Early- Middle Visean): Buxtonia cf. praejuresanensis, Marginatia cf. kinghirica, Cleiothyridina cf. okensis (Grunt,1980). therefore, the age of Mobarak Formation in the Talou section, is Tournaisian to Middle Visean. The sedimentary environment of Brachiopods of the Mobarak Formation are lagoon, bar or reef and fore-reef.
Stratigraphy and Palaeontology
Zeinab Manouchehri; Tayebeh Mohtat; Seyed Ali Aghanabati; Morteza Khalatbari Jafari; Fatemeh Vakil Baghmisheh
Abstract
The sediments are generally limestone and marl. The lower boundary with the loer red Formation is disconfomity and the upper boundary with the equivalent formatin of Bakhtiari Firmation is paraconformity. The total number of fossils found in this section is 69 species, 72 genera and 46 families. These ...
Read More
The sediments are generally limestone and marl. The lower boundary with the loer red Formation is disconfomity and the upper boundary with the equivalent formatin of Bakhtiari Firmation is paraconformity. The total number of fossils found in this section is 69 species, 72 genera and 46 families. These sediments are formed in an open shelf and under the open sea and lagon environment. The variety and abundance of bentic foraminifer’s forms and the low presence of plagic forms testify to the shallow basin in this section, which is also confirmed by the study of other fossils. One of the Markable features of this section is the presence of Ammonia species, especially Ammonia parkinsonia. This section has a complete sequence of members of Qom Formation. This species are profe of shallow water and continental shelf for this carbonates. This section consist all of members of Qom Formation and based on identified foraminifera comparable to assemblage zone 1 & 2 introduced by Adams & Bourgeois (1967). These zones that inclod: 1-Borealis Melo Group- Meandropsin; 2- Miogypsinoides- Archaias- Valvulinid. Based on index foraminifer's species and their stratigraphic distribution the age of this section is Chatian- Burdigalian (Upper Oligocene-Lower Miocene)
Stratigraphy and Palaeontology
Ebrahim Mohammadi; Mohammad Javad Hassani
Abstract
Paleoecology of the Qom Formation ostracods in the Bojan and Varkan sections have been studied. The age of the sections has determined base on foraminifera and is Rupelian-chattian for the Bujan and Chattian for the Varkan Section. Ostracoda content of the Bujan and Varkan sections include 44 and 33 ...
Read More
Paleoecology of the Qom Formation ostracods in the Bojan and Varkan sections have been studied. The age of the sections has determined base on foraminifera and is Rupelian-chattian for the Bujan and Chattian for the Varkan Section. Ostracoda content of the Bujan and Varkan sections include 44 and 33 species respectively. The pecies of genus Cytheridea are the most abundant and the most dominant ostracods of the Bujan section. In the lower part of the Bujan section, different species of Cytherella and Cytheridea constitute the dominant ostracods, but upward the abundance of Cytherella is declined and Cytheridea, Neonesidea, and Bairdia are dominant. Podocopids constitute 76% and 86% of the Bujan section ostracods during Rupelin and Chattian, respectively. Neonesidea elegans, Bythocypris pseudoreniformis, Paracypris pandyai, Paracypris sapperi and Paracypris naalunensis constitute the dominant ostracods of the Varkan Section. Podocopid ostracods are dominant in the Varkan marls and constitute 77% of the ostracods. The high percentage of podocopid ostracods indicates that the environment was oxygen-rich and without the ecological stresses in both section; while in the Varkan Section, the ecological conditions are stable but in the Bujan section, the oxygen enriches upward and ecological conditions become closer to normal marin basins.
