Two sections in north Alborz Mountain were selected and palynologically studied. The first one, Paland section, is located approximately 30 km in the south of Zirab city. This sequence is 200 m thick and consists mainly of limestone and shale beds and assigned to the Upper Triass. This study resulted in the identification of a relatively rich assemblage of palynomorphs. The age of Late Triassic (Late Norian- Rhaetian) is attributed to the formation by. The known Dinoflagellates taxa.
The second section, Galandrud section is located about 16 km in the south of Ruian city (Alam - Deh). This section attains a thickness of 590m and consists of limestone, shale, sandstone and siltstone beds. Eighty-one palynomorph taxa were encountered form a total of 30 samples from the base of the Shemshak Group which were selected and treated in the palynological laboratory of the geological survey of Iran. The known species were arranged in the following three local bioassemblage zones:
Biozone I, Enzonalasporites vigens: occurs in a thickness of 125m, suggesting the Early - Middle Norian age.
Biozone II, Vitreisporites pallidus: with 335m thickness represents the Late Norian age.
Lastly, Biozone III, Concavisporites kermanense: occurs in a thickness of 130m indicating the Early Rhaetian age. Statistical study of the recorded palynomorphs indicate an open marine environment for the Upper Triassic sediments for this area.