The importance of Sporomorph EcoGroups and palynofacies in recognition of paleoenvironments and paleoecology of the Middle Jurassic strata of the central and eastern Alborz

The spores and pollen (miospores) are classified as Sporomorph EcoGroups (SEGs). Relative frequency changes within successive sporomorph assemblages predominantly reflect changes in parent plants communities composition, on the other hand changes in the plant macrofossil communities composition also reflect paleoclimatical and paleoenvironmental changes. Occurrence of well-preserved miospores in the Dalichai Formation at the Kanz stratigraphic section (central Alborz) and Talu stratigraphic section (eastern Alborz) allows for this method to be used to recognition of certain paleoecological and paleoenvironmental inferences of this formation. Quantitative analysis of the sporomorphs shows various plant communities, which coexisted during the deposition of the Dalichai Formation at the both stratigraphic sections: Upland, Lowland, River, Pioneer, Coastal and Tidally-influenced. Changes in Upland/Lowland and Lowland/Coastal+Tidally influenced ratios accompanied by quantitative palynofacies analysis at the Kanz and Talu stratigraphic sections indicate low sea level at the beginning of the formation, which gradually towards the end of the both stratigraphic sections, the sea level is rising and the basin is witnessing a slight increase in depth. The depth of the basin has increased more compared to the previous stage and continues until the deposition of nodular limestones of the Upper Jurassic Lar Formation. The Relative frequency pattern of warmer/cooler and wetter/drier elements represents a moist, ±warm condition during the deposition of the Dalichai Formation at the both stratigraphic sections. This general paleoclimate reconstruction is also supported by abundance of fern spores in the study material.