Palynostratigraphy based-microflora of the upper part of Chamanbid Formation at the type section

The Chamanbid Formation at the type section has been measured for palynostratigraphical studies, however, the upper part of section (with a thickness of 240 m) was palynologically productive. Diverse and well- preserved palynofloras occur in the upper part of the type section. Microflora (trilete and monolete spores and pollen) together with dinoflagellate cyst, scolecodont, foraminiferal test linings, fungal and algal spores are present. Thirty nine species of spores (28 genera) and 13 species of pollen (11 genera) are identified. Representatives of Corollina, Klukisporites and Cicatricosisporites are particularly abundant.Based on stratigraphic distribution of miospores, three distinctive stratigraphically successive palynofloras informally termed in ascending order Assemblages zone A, B and C are identified within the upper part of Chamanbid Formation. The oldest of the three assemblages, Assemblage zone A is characterized by the appearance of miospore species Ruffordiaspora australiensis. The Assemblage zone B is defined by the co-occurrence of the Laevigatosporites ovatus and Trilobosporites trioreticulatus. The Assemblage zone C is marked by the appearance of Plicatella sp. Based on the co-occurrence of certain miospore species, Ruffordiaspora australiensis (Tithonian-Campanian) and Ruffordiaspora ludbrookiae (Tithonian-Albian) the upper part of Chamanbid palynofloras are collectively dated as Upper Jurassic (Tithonian), thus corroborating the ammonoid evidence.