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    • List of Articles Triassic

      • Open Access Article

        1 - Cruziana ichnofacies from Nayband Formation (Late Triassic) in the Parvadeh section, Southwest Tabas, East central Iran
        Nasrollah Abbassi Mohammad ghavidel Morteza Yosefi Navid Navidi Izad
        Nayband Formation is composed of sandstone, coal bearing shales, siltstone, and fossiliferous limestone in the southwest Tabas section, east central Iran. In this section, it is 1410 m in thickness and Late Triassic in age. A divers trace fossils have been found in the More
        Nayband Formation is composed of sandstone, coal bearing shales, siltstone, and fossiliferous limestone in the southwest Tabas section, east central Iran. In this section, it is 1410 m in thickness and Late Triassic in age. A divers trace fossils have been found in the middle parts of sequence as 400-600 m. These trace fossils include Lockeia isp., Palaeophycus tubularis, Palaeophycus striatus, Planolites beverleyensis, Rhizocorallium isp., Rosselia isp., and cf. Treptichnus isp. This ichnoassemblage is attributable to Cruziana ichnofacies with presence of Lockeia isp., Rhizocorallium isp., and, Rosselia isp. This part of Nayband Formation was deposited in low energy conditions below fair-weather wave base. Manuscript profile
      • Open Access Article

        2 - Paleoclimatic and paleogeographic signatures in the upper Triassic beds of Shemshak group in Central Alborz
        Mohammad Reza Naiji
        Late Triassic deposits of Shemshak Group in Emarat section at about 30 km south of Amol and Emamzadeh Hashem section and about 50km north east of Tehran in Central Alborz have been studied for some paleoclimatic and paleogeographic indicators. The data used in this stud More
        Late Triassic deposits of Shemshak Group in Emarat section at about 30 km south of Amol and Emamzadeh Hashem section and about 50km north east of Tehran in Central Alborz have been studied for some paleoclimatic and paleogeographic indicators. The data used in this study include: 10 point counting of sandstones, 13 main oxide analyses, 8 species of plant fossils and 4 genuses of palinomorphs. Lithological and geochemical data were restricted to the Late Triassic deposits. Important events of the Late Triassic such as: Late Norian and Middle Rhaetian droughts were revealed by the presence of gypsum beds. This study indicates that lithological signatures are clearly consistent with the mentioned global event and this tracer can be a good basis for controlling other age-related paleontological data. Comparison of the Alborz and Siberian plant fossils indicated that the study area did not have significant differences compared to more northern regions such as Siberia. The investigated palinomorphs indicated that most of them are hygrophytic and mesophytic and some of them had more well-known origin which belonged to some ferns. The point counting data revealed that the source area of the sediments experienced dry to semi-humid climates. This study also confirms that the Alborz region was part of Eurasia, due to the Eo-Cimmerian orogenic event based on recognized plant fossils. Manuscript profile
      • Open Access Article

        3 - Paleoclimatic and paleogeographic signatures in the upper Triassic beds of Shemshak group in Central Alborz
        Mohammad Reza Naiji Iraj Maghfori-Moghaddam Mahboubeh Hooseni-barzi Bahman Soleimany
        Late Triassic deposits of Shemshak Group in Emarat section at about 30 km south of Amol and Emamzadeh Hashem section and about 50km north east of Tehran in Central Alborz have been studied for some paleoclimatic and paleogeographic indicators. The data used in this stud More
        Late Triassic deposits of Shemshak Group in Emarat section at about 30 km south of Amol and Emamzadeh Hashem section and about 50km north east of Tehran in Central Alborz have been studied for some paleoclimatic and paleogeographic indicators. The data used in this study include: 10 point counting of sandstones, 13 main oxide analyses, 8 species of plant fossils and 4 genuses of palinomorphs. Lithological and geochemical data were restricted to the Late Triassic deposits. Important events of the Late Triassic such as: Late Norian and Middle Rhaetian droughts were revealed by the presence of gypsum beds. This study indicates that lithological signatures are clearly consistent with the mentioned global event and this tracer can be a good basis for controlling other age-related paleontological data. Comparison of the Alborz and Siberian plant fossils indicated that the study area did not have significant differences compared to more northern regions such as Siberia. The investigated palinomorphs indicated that most of them are hygrophytic and mesophytic and some of them had more well-known origin which belonged to some ferns. The point counting data revealed that the source area of the sediments experienced dry to semi-humid climates. This study also confirms that the Alborz region was part of Eurasia, due to the Eo-Cimmerian orogenic event based on recognized plant fossils. Manuscript profile
      • Open Access Article

        4 - Paleoclimatic and paleogeographic signatures in the upper Triassic beds of Shemshak group in Central Alborz
        Mohammad Reza Naiji Iraj Maghfori-Moghaddam Mahboubeh Hooseni-barzi Bahman Soleimany
        Late Triassic deposits of Shemshak Group in Emarat section at about 30 km south of Amol and Emamzadeh Hashem section and about 50km north east of Tehran in Central Alborz have been studied for some paleoclimatic and paleogeographic indicators. The data used in this stud More
        Late Triassic deposits of Shemshak Group in Emarat section at about 30 km south of Amol and Emamzadeh Hashem section and about 50km north east of Tehran in Central Alborz have been studied for some paleoclimatic and paleogeographic indicators. The data used in this study include: 10 point counting of sandstones, 13 main oxide analyses, 8 species of plant fossils and 4 genuses of palinomorphs. Lithological and geochemical data were restricted to the Late Triassic deposits. Important events of the Late Triassic such as: Late Norian and Middle Rhaetian droughts were revealed by the presence of gypsum beds. This study indicates that lithological signatures are clearly consistent with the mentioned global event and this tracer can be a good basis for controlling other age-related paleontological data. Comparison of the Alborz and Siberian plant fossils indicated that the study area did not have significant differences compared to more northern regions such as Siberia. The investigated palinomorphs indicated that most of them are hygrophytic and mesophytic and some of them had more well-known origin which belonged to some ferns. The point counting data revealed that the source area of the sediments experienced dry to semi-humid climates. This study also confirms that the Alborz region was part of Eurasia, due to the Eo-Cimmerian orogenic event based on recognized plant fossils. Manuscript profile
      • Open Access Article

        5 - Paleoclimatic and paleogeographic signatures in the upper Triassic beds of Shemshak group in Central Alborz
        Mohammad Reza Naiji Iraj Maghfori-Moghaddam Mahboubeh Hooseni-barzi Bahman Soleimany
        Late Triassic deposits of Shemshak Group in Emarat section at about 30 km south of Amol and Emamzadeh Hashem section and about 50km north east of Tehran in Central Alborz have been studied for some paleoclimatic and paleogeographic indicators. The data used in this stud More
        Late Triassic deposits of Shemshak Group in Emarat section at about 30 km south of Amol and Emamzadeh Hashem section and about 50km north east of Tehran in Central Alborz have been studied for some paleoclimatic and paleogeographic indicators. The data used in this study include: 10 point counting of sandstones, 13 main oxide analyses, 8 species of plant fossils and 4 genuses of palinomorphs. Lithological and geochemical data were restricted to the Late Triassic deposits. Important events of the Late Triassic such as: Late Norian and Middle Rhaetian droughts were revealed by the presence of gypsum beds. This study indicates that lithological signatures are clearly consistent with the mentioned global event and this tracer can be a good basis for controlling other age-related paleontological data. Comparison of the Alborz and Siberian plant fossils indicated that the study area did not have significant differences compared to more northern regions such as Siberia. The investigated palinomorphs indicated that most of them are hygrophytic and mesophytic and some of them had more well-known origin which belonged to some ferns. The point counting data revealed that the source area of the sediments experienced dry to semi-humid climates. This study also confirms that the Alborz region was part of Eurasia, due to the Eo-Cimmerian orogenic event based on recognized plant fossils. Manuscript profile
      • Open Access Article

        6 - Plant macrofossiles of the Laleband formation (Late Triassic), Ramsar coal-bearing region, Northern Iran
        JAVAD SAADATNEJAD
        The Shemshak Group is well-exposed in Ramsar coal-bearing region and consists of four formations; Ekrasar, Laleband, Kalariz and Javaherdeh. The Laleband Formation lies conformably and gradationally on top of Ekrasar formation and its upper contact is conformable and sh More
        The Shemshak Group is well-exposed in Ramsar coal-bearing region and consists of four formations; Ekrasar, Laleband, Kalariz and Javaherdeh. The Laleband Formation lies conformably and gradationally on top of Ekrasar formation and its upper contact is conformable and sharp under Kalariz formation. It contains scattered plant macrofossils of Norian-Rhaetian age. The studied section contains well-preserved and scattered plant macrofossils belonging to three orders as Equisetales, Filicales and Pinales. Based on the occurrence of Neocalamites sp. cf. N. carcinoides, Dictyophyllum sp. cf. D. exile, Clathropteris meniscoides and Cycadocarpidium erdmani and stratigraphic position of fossil bearing layers, Late Norian – Early Rhaetian age is suggested for the studied beds. Manuscript profile
      • Open Access Article

        7 - Application of Sporomorph EcoGroups (SEGs) and parent plants of miospores in palaeoenvironmental recontruction of the Qadir Member (Nayband Formation), south of Tabas
        Firoozeh Hashemi Yazdi F. Sajjadi Hezaveh Narges Sadat  Mirpoor Shah Abolghasemi Zahra  Mohammadi Manesh Mohsen   Allameh
        Sporomorph EcoGroups data and the relevant plant communities are considered as a possible routine used to draw palaeoecological inferences for their host strata. Occurrence of high abundant and diverse miospores in the Qadir Member (Nayband Formation), from the explorat More
        Sporomorph EcoGroups data and the relevant plant communities are considered as a possible routine used to draw palaeoecological inferences for their host strata. Occurrence of high abundant and diverse miospores in the Qadir Member (Nayband Formation), from the exploratory well no. 954 (Exploratory Area of Parvadeh 4), south of Tabas, central Iran allows for this method to be used to obtain certain palaeoecological implications. By classifying spores and pollens (sporomorphs) in Sporomorph EcoGroups (SEGs), all six plant ecogroups (including plants adapted to Upland, Lowland, River, Pioneer, Coastal, and Tidally-influenced) were identified in examined material. The high ratio of warmer/cooler sporomorphs and the low ratio of drier/wetter sporomorphs suggests deposition under a moist, ±warm climate during the Late Triassic in south of Tabas. From the investigation of miospore parent plants, it was approved that, in descending order, pteridophyta (44%), cycadophyta (34%), coniferophyta (9%), lycophyta (8%), pteridospermophytes (2%), ginkgophytes (2%) and bryophyta (1%) were surrounded the environment of the studied formation. Notable abundance of fern spores (Kyrtomisporis and Foveogleicheniidites) and cycads pollen (Ovalipollis and Ricciisporites) in the palynofloras studied indicate the predominance of warm to semi-warm climate with high humidity. Paleogeographic position of Iran during the Late Triassic in the southern active margin of Eurasia (Turan Plate) tends to support this palaeoclimate generalization. Manuscript profile
      • Open Access Article

        8 - Palaeotectonic reconstruction of sandstones from the Triassic Nakhlak Group in Central Iran, using U-Pb zircon dating
        S.H. Hashemiazizi peiman rezaie
        <p>The Triassic Nakhlak Group in Central Iran is an important sedimentary succession that helps us better understand the closure of Palaeotethys and the Eo-Cimmerian orogeny in the Middle East. The Nakhlak Group consists of the Alam (Olenekian to Middle Anisian), Baqoro More
        <p>The Triassic Nakhlak Group in Central Iran is an important sedimentary succession that helps us better understand the closure of Palaeotethys and the Eo-Cimmerian orogeny in the Middle East. The Nakhlak Group consists of the Alam (Olenekian to Middle Anisian), Baqoroq (?Upper Anisian to Middle Ladinian), and Ashin (Upper Ladinian to ? Carnian) formations, which are mainly composed of volcaniclastic sandstones, mixed siliciclastic conglomerates, and marine carbonates. Here we examine the detrital zircon UPb ages from the Nakhlak Group to determine its provenance and constrain its palaeotectonic position within the Palaeotethyan realm. Most detrital zircons from the Nakhlak Group are euhedral and subhedral with Permian&ndash;Triassic ages (ca. 280&ndash;240 Ma), indicating they likely came from the Silk Road Arc's Permian&ndash;Triassic magmatic rocks. Minor zircon populations show pre-Permian Palaeozoic ages, around 320 Ma and 480 Ma, which probably originated from the basement on which the magmatic arc developed. Zircon grains with Neoproterozoic&ndash;latest Mesoproterozoic (ca. 550&ndash;1100 Ma) and Palaeoproterozoic (ca. 1800&ndash;2200 Ma) ages are anhedral or rounded, with the latter being more prominent in the upper Baqoroq Formation (Middle Ladinian), suggesting the recycling of older sedimentary rocks. Sandstone petrography indicates an additional metamorphic provenance for this formation, possibly due to a tectonic uplift in the source area, resulting in the erosion of metamorphosed rocks with a northeast Gondwanan affinity. This suggests that northeast Gondwana-derived continental fragments likely belonging to the Cimmerian blocks had already arrived at the southern Eurasian margin in pre-Late Triassic time.</p> Manuscript profile