Benthic Foraminiferal and Calcareous Algae Assemblages in the Tirgan Formation (Urgonien Facies Type) in South Flank of Ghorogh Syncline (North of Chenaran), NE Iran

Abstract

In this research, the Tirgan Formation in the south flank of Ghorogh Syncline (north of Chenaran), northeastern Iran with the thickness of 251 was studied. This section consists of limestone, marly limestone and shale with impressions of echinoderms toxasteridae family, many of foraminifera from orbitolinidae family and also lots of calcareous algae that create facies variation along with other non-skeletal allochems. Micropaleontological investigation has been carried out on 90 thin-sections. These criteria reveal that an equivalent of the Urgonian facies type (in France-Swiss area) and open marine, low depth sedimentary basin are extended in the Kopet-Dagh basin. In this article, we tried to introduce some of the important foraminiferal and calcareous algal assemblages of this area.

Microbiostratigraphy, microfacies analysis and lateral basin evolution of Lower Cretaceous deposits in the south of Kerman region, SE Iran

“…In general, the identified foraminifera assemblage in the studied area shows higher diversity than other studied areas in CEIM, Alborz, Zagros and kopet Dagh structural zones (Yazdi-Moghadam and Amiri, 2010; Roozbahani, 2011;Rami et al, 2012;Bucur et al, 2013;Schlagintweit et al, 2013aSchlagintweit et al, , 2013bWilmsen et al, 2013;Khodashenas et al, 2014;Schlagintweit and Wilmsen, 2014;Babazadeh and Dehej, 2015;Hanifzadah et al, 2015;Hosseini et al, 2016;Hassani, 2016a, 2016b;Yavarmanesh et al, 2017;Yazdi-Moghadam et al, 2017;Gheiasvand et al, 2020;Moosavizadeh et al, 2020).…”

“…http://dx.doi.org/10.18268/BSGM2022v74n2a240322 2013c; Khodashenas et al, 2014;Yavarmanesh et al, 2017;Yazdi-Moghadam et al, 2017;Neamţu, 2019).…”

The Lower Cretaceous Tirgan Formation in the Gelian Section (Kopet Dagh, North Iran): Microfacies, Microfossils, and Their Biostratigraphic Significance

“…Based on micropaleontological assemblages, the carbona-te deposits of the Tirgan Formation were attributed to the Barremian-lower Aptian by the vast majority of previous authors who studied these limestones. Numerous sections were sampled from West to East across the Kopet Dagh basin, over the entire outcrop surface of the Tirgan Formation (Taherpour Khalil Abad et al, 2009;2010;Javanbakht et al, 2011;Carević et al, 2013;Taherpour Khalil Abad et al, 2013;Molaei et al, 2017;Yavarmanesh et al, 2017;Javanbakht et al, 2018). Surveying the previously figured micropaleontological assemblages shows that in many of these publications, several species were incorrectly identified (e.g., Carević et al, 2013;Molaei et al, 2017, Yavarmanesh et al, 2017, with the notable exception of the work of Taherpour Khalil 2010; (2017), the basal part of this formation may comprise the Berriasian-Hauterivian, or even part of the upper Tithonian.…”

“…Several previous studies focused on its structure and stratigraphic succession (Afshar Harb, 1979;Ruttner, 1991;Moussavi-Harami and Brenner, 1993;Immel et al, 1997;Majidifard, 2003;Kavoosi et al, 2009;Javanbacht et al, 2011;Robert et al, 2014;Majidifard et al, 2017). In the last decades, important contributions addressed the microbiostratigraphy of the Lower Cretaceous Tirgan Formation (Majidifard, 2003;Bucur et al, 2013;Taherpour Khalil Abad et al, 2009;2010a, 2010b, 2015: Yavarmanesh et al, 2017. Important thickness and content variations define this formation throughout the basin, as indicated by literature data.…”