New agglutinated Foraminifera from Early Eocene deposits of Mahallat region, Central Iran: implication on biostratigraphy and paleoecology

Abstract

This paper describes the foraminiferal associations along with the presentation of three new agglutinated conical foraminiferal species to the construction of the biozonation framework in the Mahallat region of central Iran. The stratigraphic distribution of benthic foraminifers is used to characterize three assemblage zones that are in ascending order: rotaliids-valvulinids Assemblage Zone, alveolinids-coskinolinids Assemblage Zone, and nummulitids-discocyclinids Assemblage Zone. These associations are characterized by marker fossils and localized from the inner ramp to the proximal outer ramp depositional environments. Their biostratigraphic range is assigned to the middle Cuisian to early Lutetian. In addition, three new agglutinated conical foraminiferal species: Daviesiconus mahallatensis sp. nov., Barattolites arghadehensis sp. nov., and Coleiconus minimus sp. nov. are described and figured for the first time from the lower Eocene shallow-water limestone in the studied area. These new species have common characteristics such as eccentric conical test with a low number of comparably coiled chambers in the early stage and uniserial chambers in the adult stage, but they differ in size, the form of test, and radial subepidermal partitions (beams, intercalary beams, and rafters). They are associated with the index Alveolina fauna and their biostratigraphic range is assigned to middle–late Cuisian (Ypresian, Early Eocene). Keywords: biostratigraphy, Early Eocene, new taxa, Mahallat, Iran.