Sequence stratigraphy and platform to basin margin facies transition of the Lower Cretaceous Dariyan Formation (northeastern Arabian Plate, Zagros fold-thrust belt, Iran)

Abstract

The Lower Cretaceous (Aptian-Albian) Dariyan Formation (northeastern Arabian Plate, Iran) represents the youngest sediments of the Khami group in the Zagros fold belt. This study is based on six sections located in the Izeh Zone and Interior Fars Province documenting transition from platform to a basin margin facies. Three assemblage zones based on benthic foraminifers have been identified and provide an early Aptian-early Albian age. Petrographic and microfacies analyses characterize thirteen carbonate microfacies and two mud rock lithofacies-types. The vertical and lateral facies variations observed in this study for the Dariyan Formation are in agreement with a depositional environment going from a homoclinal carbonate ramp to margin of intra-shelf basin type. Based on the identification of three sequence boundaries (SB), the Dariyan Formation sediments has been divided into three 2 nd -order depositional sequences which encompasses six and five 3 rd -order sequences in the margin of intra-shelf basin and the shallow platform settings, respectively. The early Aptian sea-level rise led to the extension of the carbonate platform and deposition of pelagic facies as a maximum flooding surface on margin of intra-shelf basin. In the late Aptian highstand phase, the platform was exposed as a result of glacio-eustatic mechanisms, whereas sediments continued to accumulate in the margin of intra-shelf basin. This study supports the general paleogeography of the studied area documented by previous studies and provides better insight to the interpretation of the evolution in this area and other similar basins.•

Aptian Oceanic Anoxic Event 1a in the shallow, carbonate‐dominated intrashelf Kazhdumi Basin, Zagros Mountains

“…The normally‐graded shell beds with broken and disarticulated ostreid bioclasts suggest a vigorous reworking and/or resedimentation on a storm‐influenced mid‐ramp (e.g. Moosavizadeh et al ., 2015; Kroth et al ., 2021), where bioturbation and micritization were taking place as the storms waned and the background sedimentation became predominant (Schülke & Popp, 2005). Locally abundant peloids were likely produced by echinoids and gastropods (cf.…”

“…Peybernès, 1982; Vilas et al ., 1995; Husinec et al ., 2000; Husinec, 2001; Velić, 2007; Granier et al ., 2017). Its association with Choffatella decipiens is characteristic for the lower part of the Lower Dariyan (earliest early Aptian in age) in the Kazhdumi Intrashelf Basin, with their last appearances associated with the regional establishment of deep open‐marine and intrashelf settings (Schroeder et al ., 2010; Moosavizadeh et al ., 2015). This interval corresponds to the Apt1 third‐order sequence of the Arabian Plate (van Buchem et al ., 2010b) which ties with the depositional sequence DS1 in the study area.…”

“…Based on the orbitolinid foraminifera assemblage, the Dariyan Formation was deposited during the early Aptian to possibly earliest Albian (e.g. Schroeder et al, 2010;van Buchem et al, 2010b;Moosavizadeh et al, 2015Moosavizadeh et al, , 2020Yavari et al, 2017). The eustatically-controlled deposition in the Kazhdumi Basin was significantly affected by the Kazerun fault system in the early Aptian, and the Hendijan fault system in the late Aptian (Fig.…”

Developing Best Practice in Micropalaeontology: Examples From the Mid-Cretaceous of the Zagros Mountains

“…If applied correctly, this makes orbitolinids of immense practical value for biostratigraphic studies of the sediments in which they occur. This has been adopted by a number of workers on Zagros biostratigraphy (e.g., Yazdi Moghadam et al, 2008;Safari et al, 2010;Parvaneh Nejad Shirazi & Abedi, 2013;Moosavizadeh et al, 2014Moosavizadeh et al, , 2015Moosavizadeh et al, , 2020, but not by all. Herein we remark upon a number of significant misidentifications, use of archaic taxonomy, and implausible suggested stratigraphic ranges.…”