Palynomorph-Based Palaeoecology of the Kashafrud Formation, Eastern Mashhad, Koppeh-Dagh


Kashafrud Formation in the Ghale Sangi Section (east of Mashhad), has been selected and measured for palaeoecological studies. Moderately diverse and reasonably well-preserved palynoflora occurred in the middle to upper parts of the Ghale-Sangi Section (with a thickness of about 1090 meters). In this section, the Kashafrud Formation overlies with a strong angular unconformity Sina Formation and it is disconformably overlain by the limestone of Mozduran Formation. In this study 60 species of spore (distributed among 36 genera), 22 species of pollen (distributed among 12 genera), 19 species of dinoflagellates (distributed among 14 genera), 2 species of algal spores (distributed among 2 genera), 3 species of fungal spore (distributed among 3 genera) and 1 species of acritarch have been identified. Of these, the miospores are mainly radiosymmetrical and triletes, wheras the pollen are represented by monosulcate, monosaccate, bisaccate and three saccate taxa. Inferred natural relationship spores and pollen grains imply derivation from a diverse parental flora (e. g. Pterophyta, Bryophyta, Cycadophyta, Ginkgophyta, Coniferophyta, and Lycopodophyta). Furtheremore the abundance of Dictyophyllidites, Klukisporites and Cyathidites which are related to Pterophyta indicate the domination of Pterophyta suggestive a moist warm climate during Bajocian – Bathonian. The presence of some proximate dinoflagellates such as Sentusidinium villersense, Chytroeisphaeridia chytroeides, Lithodinia sp. cf. L. jurassica, Rhynchodiniopsis cladophora, Gonyaulacysta centriconnata, Pareodinia antenata, Pareodinia ceratophora, Cribroperidinium sp., Dichadogoyaulax culumula, Egmonthodinium sp. cf. E. polyplacophrum accompanied by fungal spores testified warm temperate conditions during Bajocian-Bathonian. The association of marine palaeontological evidence (amonites contents) and marine palynomorphs (proximate dinoflagellates, acritarch and foraminiferal test lining) with terrestrial palynomorphs (spores and pollen) collectively indicate an open marine, nearshore depositional setting for the Kashafrud Formation at Ghale-sangi Section. A detailed comparision of the Ghale-sangi palynoflora (east of Mashhad) with the Senjedac suite (southeast of Mashhad) indicates that, except for the presence of some different species, the two assemblages feature significant similarities and suggest a similar depositional and climate conditions in the east and southeast of Mashhad during the Bajocian-Bathonian.