Upper Barremian–Aptian Planktonic Foraminifera Biostratigraphy of The Sarcheshmeh Formation, Hosein Abad Section, Northeast Of The Kopet Dagh Basin, Iran

ABSTRACT The Sarcheshmeh Formation of the Kopet Dagh Basin in northeastern Iran is composed of gray to green marls with interbedded marly limestone layers. In this study, a 90-m-thick stratigraphic section at Hosein Abad was selected for detailed analysis. Based on planktonic foraminiferal assemblages, 15 species belonging to three genera were identified. Accordingly, two biozones are proposed: the Globigerinelloides aptiensis Interval Zone (upper Barremian to lower Aptian) and the Globigerinelloides ferreolensis Interval Zone (lower to upper Aptian). These biozones confirm a late Barremian to early late Aptian age for the Sarcheshmeh Formation at the Hosein Abad section. The Hosein Abad section is correlated with the Takal Kuh and Amand sections in northeastern Iran. Micropaleontological events are well correlated with ammonite data from previous fieldwork. The identified biozones were also compared with previous studies in central Morocco, southeastern France, and southern Tibet, revealing a good correlation of the Sarcheshmeh Formation with biozones from the upper Barremian to upper Aptian.