Palynostratigraphy and paleoecology of Middle Jurassic strata, southeastern Maragheh, according to terrestrial palynomorphs

Abstract

The Dalichai Formation at the Guydagh stratigraphic section in the southeast of Maragheh, (Western Alborz), with measured thicknesses of 198 meters (consisting of limestone, Calcareous shale, shale limestone, shale and marl) contain terrestrial (spores and pollen grains) and marine (dinoflagellate cysts, acritarchs, foraminiferal test linings and scolecodont) palynomorphs. This assemblage is formed from diverse and moderately-preserved palynomorphs. The recognized palynofloras includes 16 species of spores (assigned to 14 genera) and 19 species of pollen grains (belong to 11 genera). Based on presence of Klukisporites variegatus, Klukisporites Zone and Klukisporites variegatus Subzone are identified and assigned to the Middle Jurassic (late Bajocian - Callovian) in age. Comparing obtained data from this study and data gained from Dalichai equivalent sediments in Iran (Central and Eastern Alborz, Central Iran and Kopet Dagh geological zones) and other parts of the world (Australia, Afghanistan, Egypt, China, India and etc.), resulted similar climates (mild to warm and humid) during Middle Jurassic (Dogger) in these areas (due to similar vegetation). Based on recognized miospores and their frequency, Conifers, Pteridospermophyta, Pterophyta, Ginkgophyta, Lycophyta and Cycadophyta formed Dalichai vegetation at the studied section. The presence of warm water dinoflagellates such as Gonyaulacysta jurassica, Ctenidodinium continuum and Nannoceratopsis pellucida with fungal and algal spores confirmed the domination of warm and humid climate.

Keywords

• Palynostratigraphy
• Paleoecology
• Dalichai Formation
• Middle Jurassic
• Terrestrial palynomorphs