The Rhaetian ferns and seed ferns from the Shemshak Group, Ghoznavi area, N.E Alborz Mountain, Iran

A complete profile was measured and sampled in the study area to determine the age of the Shemshak Group. A total of 159 samples were collected from plant-fossiliferous horizons and subsequently investigated in the Geosciences Faculty of Shahid Beheshti University Laboratory. Fifteen identified plant macrofossil species (ten genera) were categorized into Osmundales, Dipteridales, Marattiales, and Peltaspermales. The species encountered are Korallipteris yipinglangensis, Cladophlebis nebbensis, Cladophlebis haiburnensis, Cladophlebis denticulata, Clathropteris meniscioides, Dictyophyllum exile, Thainguyenopteris parvipinnulata, Osmundopsis sturii, cf. Marattiopsis intermedia, Scytophyllum waehneri, and
Peltaspermum decipiense. In this study, 5 ferns and seed ferns species are reported for the first time in the northeastern Alborz Mountain. A Late Triassic (Rhaetian) age is assigned to the Shemshak Group based on ferns and seed ferns chronostratigraphy.
Also, a lowland deltaic environment, including wet and drier conditions, is suggested by ferns and seed ferns revealed in the studied area.

Mohammad Ghavidel-Syooki & Maryam Farahimanesh & Abbas Sadeghi

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