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 ...
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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
Fatemeh Vaez-Javadi; Mohammad Ali Ghanbarian
Abstract
Jurassic deposits are well spread in the north of Karim Abad village, north of Bahabad, central Iran. These deposits contain 41 species of palynomorphs, in which 15 spore species (12 genera), 15 pollen species (10 genera), and 10 species of dinocysts (3 genera) were identified. Vertical distribution ...
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Jurassic deposits are well spread in the north of Karim Abad village, north of Bahabad, central Iran. These deposits contain 41 species of palynomorphs, in which 15 spore species (12 genera), 15 pollen species (10 genera), and 10 species of dinocysts (3 genera) were identified. Vertical distribution of miospores allows erection within the Hojedk Formation of one biozone–Klukisporites variegatus- Chasmatosporites apertus Interval zone based on the FOO and LOO of selected taxa. Moreover, vertical distribution of dinoflagellate cysts allows erection within this formation of one biozone- Nannoceratopsis triceras-Nannoceratopsis gracilis Assemblage zone. The relative abundance of dinoflagellate cysts, spore, and pollen is 86.21%, 7.2%, and 6.6%, respectively. Therefore, the relative abundance of dinoflagellate cysts was high and the marine environment was prominent in this area during Jurassic sedimentation. Based on relative abundance of miospores' parent plant fossils, ferns, cycads, and conifers are 37%, 31.5% and 11.82%, respectively, and related sporomorph ecogroups (SEGs) indicate that they occurred in different environments such as upland, wetter / drier lowland, river and coastal with temperate-sub-tropical and humid climate.
