Boletín de la Sociedad Geológica Mexicana Volumen 75, núm. 3, A061023, 2023 http://dx.doi.org/10.18268/BSGM2023v75n3a061023

Depositional environment and sequence stratigraphy of the Qom Formation (Miocene) from the Ghalibaf section, Central Iran

Ambiente deposicional y estratigrafía secuencial de la Formación Qom (Mioceno) de la sección Ghalifab, Irán Central

Jafar Sharifi¹, Yaghub Nasiri^2,*, Mahdi Badpa³, Samira Taghdisi Nikbakht², Suman Sarkar⁴,

Mehdi Hadi⁵

¹ Department of Geology, Payame Noor University, Tehran, Iran.

² Geology Department, Faculty of Science, University of Gonabad, Gonabad, Iran.

³ Independent researcher, Graduated from Stratigraphy and paleontology, Tehran, Iran.

⁴ Birbal Sahni Institute of Palaeosciences, Lucknow - 226007, India.

⁵ Independent researcher, Graduated from Stratigraphy and paleontology, Mashhad, Iran.

* Corresponding author: (Y. Nasiri) This email address is being protected from spambots. You need JavaScript enabled to view it.

How to cite this article:

Sharifi, J., Nasiri, Y., Badpa, M., Taghdisi Nikbakht, S., Sarkar, S., Hadi, M., 2023, Depositional environment and sequence stratigraphy of the Qom Formation (Miocene) from the Ghalibaf section, Central Iran: Boletín de la Sociedad Geológica Mexicana, 75 (3), A061023. http://dx.doi.org/10.18268/BSGM2023v75n3a061023

Manuscript received: April 25, 2023; Corrected manuscript received: September 22, 2023; Manuscript accepted: October 3, 2023.

ABSTRACT

The Miocene strata of the Qom Formation from the Ghalibaf section, Central Iran (NW Semnan) documented a high diversity of shallow-marine microfacies. These deposits in the Ghalibaf section, with a total thickness of 445 m, are characterized by twenty-one microfacies. The carbonate microfacies are deposited into five facies belts, including a lagoon, upper slope, lower slope, platform-margin sand shoals and margin facies. The presence of barrier reefs, intraclasts, oncoids, and grainstone aggregates, along with the absence of vast tidal flat areas, are distinguished. According to the aforementioned evidences, these sediments were deposited on a rimmed carbonate platform. In addition, the heterolithic calciturbidite deposits also show that the carbonate sequences were sedimented on a rimmed carbonate platform. Based on the available data of sequence stratigraphy analysis, seven third-order depositional sequences are bounded by type-1 and type-2 sequence boundaries. The relative sea-level changes between the upper and lower sequence boundaries in accord with the global sea-level curves reveal a reasonable correlation. However, some differences in other sequence boundaries might be due to local tectonic activities in the Qom Formation sedimentary basin, thereby leading to local sea-level changes. Moreover, biostratigraphic data based on the larger foraminifera index markers, including Praebullalveolina curdica, Borelis melo, Dendritina rangi, Meandropsina iranica, Elphidium sp. 14, Neorotalia viennoti, and Miogypsina sp. suggests the Miocene Shallow Benthic Zones, SBZ24-SBZ25 equivalent to the late Aquitanian-Burdigalian timespan.

Keywords: Qom Formation, Miocene, Sequence Stratigraphy, Central Iran, Microfacies.