Biostratigraphy and paleoecology of the Asmari Formation in east of Dow-Gonbadan based on foraminifera



Distributions of larger benthic foraminifera in east Dow-Gonbadan section are used to determine the age of the Asmari Formation. Two assemblage zones have been recognized by distribution of the larger benthic foraminifera in the study area. The distribution of the Oligocene larger benthic foraminifera indicate that shallow marine carbonate sediments of the Asmari Formation at the study areas have been deposited in the photic zone of tropical to subtropical oceans. Based on analysis of larger benthic foraminiferal assemblages and microfacies features three major depositional environments are identified. These include inner shelf, middle shelf and outer shelf. The inner shelf facies characterized by wackestone-packstone, dominated by various taxa of imperforate foraminifera. The middle shelf is represented by packstone with a diverse assemblage of larger foraminifera with perforate wall. Basinwards is dominated by argillaceous wackestone characterized by planktonic foraminifera and large and flat nummulitidae and lepidocyclinidae.