University of Isfahan Journal of Stratigraphy and Sedimentology Researches 2008-7888 28 3 2012 10 22 Study of plant macrofossils from Baladeh area (Central Alborz): dating and biostratigraphy Study of plant macrofossils from Baladeh area (Central Alborz): dating and biostratigraphy 37 64 16777 FA F. Vaez Javadi Assistant Professor, Department of Geology, University of Tehran N. Abbasi, Associate Professor, Department of Geology, Zanjan University Journal Article 2016 06 14 The Shemshak Group is well-exposed and spread in the Baladeh area (Central Alborz). 22 macrofossil species allocated into 14 genera of various orders such as Equisetales, Filicales, Bennettitales, Cycadales, Ginkgoales, Czekanowskiales and Coniferales are identified. Two asseblage biozones are recognized. Assemblage zone I is established based on Ptilophyllum minor and Klukia exilis, and assemblage zone II is recognized according to Coniopteris hymenophylloides and Ptilophyllum harrisianum. Furthermore, on the basis of presence of index fossils such as Equisetites columnaris, Coniopteris hymenophylloides, Klukia exilis, Nilssonia macrophylla and Ptilophyllum minor the Early to Middle Jurassic age (?Hettangian-Toarcian to Bajocian) is suggested for these sediments.   The Shemshak Group is well-exposed and spread in the Baladeh area (Central Alborz). 22 macrofossil species allocated into 14 genera of various orders such as Equisetales, Filicales, Bennettitales, Cycadales, Ginkgoales, Czekanowskiales and Coniferales are identified. Two asseblage biozones are recognized. Assemblage zone I is established based on Ptilophyllum minor and Klukia exilis, and assemblage zone II is recognized according to Coniopteris hymenophylloides and Ptilophyllum harrisianum. Furthermore, on the basis of presence of index fossils such as Equisetites columnaris, Coniopteris hymenophylloides, Klukia exilis, Nilssonia macrophylla and Ptilophyllum minor the Early to Middle Jurassic age (?Hettangian-Toarcian to Bajocian) is suggested for these sediments.   https://jssr.ui.ac.ir/article_16777_81607d855ce02e257dc54c5ced55ba3c.pdf