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.
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Rock beds containing plant macrofossils of Norian in Alborz region belong to two stratigraphic units of Lalehband and Shahmirzad. The same beds in Kopeh-Dagh area belong to Mian-Kuhi Formation and in Central Iran belong to Qadir submember in Tabas region and Dehroud mem More
Rock beds containing plant macrofossils of Norian in Alborz region belong to two stratigraphic units of Lalehband and Shahmirzad. The same beds in Kopeh-Dagh area belong to Mian-Kuhi Formation and in Central Iran belong to Qadir submember in Tabas region and Dehroud member in Kerman region. In general, plant diversity and vegetative cover during the Norian stage is less than Rhaetian especially Jurassic (Shemshak group) and the highest plant diversity of Norian in the Alborz basin is related to the phyllum of Pteridospermophytes (seed ferns) and in the Central Iran basin is related to the phyllum of Pteridophyta (ferns) indicating the higher humidity of the mentioned time in Central Iran basin and the drier climate in Alborz basin. The highest diversity of vegetation in Norian sediments throughout Iran belongs to the seed ferns (Pteridospermophyta) and the lowest diversity belongs to Ginkgophytes so that they comprise 32% (one third of the vegetation) and 6.5% of the total vegetation, respectively. Plant-covered areas throughout Alborz were interconnected during the Norian period and there was no extensive separation between them. The plant macrofossils assemblage in both Alborz and Central Iran basins confirms the relatively humid subtropical to tropical climate for the Norian but less humidity compared to the Rhaetian. Also, the vegetation of Norian in Alborz was less dense and scattered than Central Iran during Norian.
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