New data on the Late Viséan-Late Serpukhovian foraminifers of northern Alborz, Iran (biostratigraphic implications)

摘要

The Upper Viséan-Upper Serpukhovian deposits of northern Alborz (Iran) consist of thin-bedded, fine sandstone and siltstone, marly and ooidal limestone and marly shale. Rich and diverse foraminiferal assemblages have been analyzed in two sections (Dozdehban and Naserabad). Five biozones and most foraminifers are first described from Upper Viséan-Upper Serpukhovian deposits of Iran. The Late Viséan of the area is subdivided into a Neoarchaediscus Zone and a Howchinia gibba-Archaediscus/Paraarchaediscus at angulatus-tenuis stage-Neoarchaediscus akchimensis Zone correlated to the Upper Mikhailovian-Venevian and Early to Late Brigantian substages of the Russian Platform and Western Europe. The Early Serpukhovian corresponds to the Biseriella parva-Climacammina Zone, and the Late Serpukhovian includes the Turrispiroides multivolutus-Brenckleina-Eostaffellina protvae zone that correlate to the Tarusian-Steshevian and Protvian substages of the Russian Platform, respectively. Furthermore, the upper beds in the Naserabad section contain the Plectostaffella-Globivalvulina kamensis? Zone, which is dated as Zapaltyubian?, lastest Serpukhovian.