Stratigraphic importance and migration trend of Miscellaneidae family in the Paleogene of Tethys basin, Sistan suture zone

Abstract Miscellaneidae is Paleogene larger index microfossils (middle Paleocene–early Eocene) that for determination of stratigraphic and palaeobiogeographic distributions are investigated in the Neo-Tethys Ocean. For biostratigraphic studies, depositional ages and systematic determinations of family Miscellaneidae, middle Paleocene–lower Eocene deposits in the Hormak section, in the north of Zahedan, are investigated. This stratigraphic section (470 meters) mainly consists of an alternation of marls, marly limestones, and limestones. Study of different miscellaneidae taxa led to identifications of Miscellanea miscella, Miscellanea juliettae, Miscellanites primitivus, and Miscellanites minutes that indicated standard biozone SBZ3–SBZ6 and therefore suggested late Paleocene–early Eocene age. Paleocene–Eocene boundary is identified with the appearance of Nummulitids and Alveolinids (SBZ5/6) in the western Neo-Tethys, whilst in the eastern Neo-Tethys these group of large benthic foraminiferas are absent. Some of Alveolina species accompanied by Glomalveolina, Miscellanea, and Ranikothalia species are seen which shows similarities between the Hormak section and other sections in the Indus basin and Tibet in the eastern Neo-Tethys. Based on biostratigraphic investigations, family Miscellaniedae, firstly appeared in SBZ1/2 in the western Neo–Tethys (Europe and Africa) whereas in the eastern Neo-Tethys (India, Tibet, and Pakistan) are not seen although the mentioned family in SBZ3/4 are recognized in the both western and eastern Neo-Tethys. In biozones SBZ5/6, SBZ7 and SBZ8, in the western Neo-Tethys family, Miscellaniedae disappeared whereas in the eastern Neo-Tethys are seen in the SBZ5/6 biozones. With respect to identified Miscellaniedae genus and species in the Hormak section and similarities with eastern Neo-Tethys, it seems that, with the omission of palaeoceanogrphic barrier in the Paleocene–Eocene boundary, the Miscellaniedae genus and species are migrated to the eastern Neo-Tethys. Keywords: Late Paleocene–early Eocene, Large Benthic Foraminifera, Sistan Suture Zone Introduction Large benthic foraminifera (LBF) are important fossils with large tests and complex internal structures. In biostratigraphic studies of Paleogene large benthic foraminiferas from Alveolina, Assilina (Hottinger 1960; Drobne 1977), and Nummulites (Schaub 1981) are used for introduction of 20 shallow benthic zones in the western Tethys (Serra-Kiel et al. 1998). Large benthic for