Biostratigraphy of the Kazhdumi Formation (Albian), northeast of Shiraz, Zagros Basin (SW of Iran)

Abstract

The Kazhdumi Formation is one of the most significant rock units in the Bangestan Group in Zagros Basin. In this study, one section of the Kazhdumi Formation (Kuh-e-Rahmat) was selected for research. The section is extended approximately 89 m thick. The lower lithostratigraphic limit of the Kazhdumi Formation is marked by an oxidized zone, while the upper boundary is described as gradational type. The stratigraphic distribution of foraminifer taxa confirms two biozones in the studied section: Hemicyclammina sigali and Mesorbitolina subconcava in the Assemblage Zone and Mesorbitolina aperta in the range zone. Based on the investigated calcareous algae, Trinocladus tripolitanus, Range Zone is described. The identified calcareous algae are well distributed along Kazhdumi Formation. According to the received data of the established biozones, the age of the Kazhdumi Formation is Albian.

Larger benthic and planktonic biostratigraphy and facies of Albian sediments in Coastal Fars Zone (Zagros area, south‐west Iran)

“…Further, Hemicyclammina sigali was previously recorded as an Early Albian taxon. In fact, this species was known as an endemic Albian taxon in previous records from Khuzestan and Fars Carbonate Platform (Afghah et al, 2020; Parvaneh Nejad Shirazi et al, 2011; Wynd, 1965), whereas this taxon was also reported from the Cenomanian (Omaña et al, 2019; Vaziri et al, 2005). With regard to the recorded stratigraphic range of the mentioned specimen as an endemic taxon of the Zagros area and both the first appearance datum and last appearance datum of orbitolinids ( Mesorbitolina subconcava and Orbitolina discoidea ) in Fahliyan, logically Mesorbitolina subconcava , Orbitolina discoidea Total Range Zone is approved, which is synchronous with Hemicyclammina sigali , Mesorbitolina subconcava Zone in Interior Fars area (Table 1).…”

“…Sampling was systematically conducted at distinct intervals and changes in lithological characteristics. The foraminifers were identified by utilizing the published works of several researchers (e.g., Afghah et al, 2020; Afghah & Shaabanpour Haghighi, 2014; Ghanem & Kuss, 2013; Ghanem et al, 2012; Hosseini et al, 2016; Rahiminejad & Hassani, 2016; Schroeder et al, 2010; Simmons et al, 2000; Vincent et al, 2010). Determination of microfacies, (Husinec et al, 2000; Permoli Silva & Verga, 2004) development of a depositional model followed the previous works of Afghah (2016); Mülayim et al (2016); Raspini (2012), and Upadhyay (2014).…”

“…(a) The location of Kazerun Fault, studied area, Coastal and Interior Fars zones, other Zagros tectonic subdivisions combined with other faults of adjacent areas (from Sepehr et al, 2002) and studied section as (1), and (2) is the Kazhdumi Formation in NE of Shiraz (Afghah et al, 2020). (b) Geological maps of selected section of Kazhdumi Formation in the studied area (geological map of 1/100,000 Fahliyan (Oil Service Company of Iran, Mc Quillan, 2001).…”

“…Hemicyclammina sigali forms the main association. Favusella washitensis was previously from the Albian sequence of the Zagros Basin (Afghah et al, 2020; Afghah et al, 2014). Permoli Silva and Verga (2004) documented this species as an Albian‐Cenomanian taxon.…”

“…Thus, studying the biostratigraphy of Albian sediments in the Zagros Basin is a means to identify the palaeo‐fault activity during this time, which is obviously distinguishable as sharp changes in the litho and bio‐facies. In addition, several previous works (e.g., Afghah et al, 2020; Parvaneh et al, 2011) have presented stratigraphic details of foraminifers in some parts of the Carbonate Platform (Interior Fars).…”