Boletín de la Sociedad Geológica Mexicana Volumen 76, núm. 1, A280224, 2024 http://dx.doi.org/10.18268/BSGM2024v76n1a280224

Biostratigraphy and facies around the D/C boundary interval of the Tuye-Darvar section, Eastern Alborz Range, NE Iran

Bioestratigrafía y facies en torno del intervalo del límite D/C de la sección Tuye-Darvar, Este de Montañas Alborz, NE de Irán

Elaheh Sattari¹, Ali Bahrami^1,*, Peter Königshof ², Hossein Vaziri-Moghaddam¹, Azizollah Taheri⁴

¹ Department of Geology, Faculty of Sciences, University of Isfahan, Isfahan, Iran.

² Senckenberg, Research Institute and Natural History Museum, Senckenberganlage 25, 60325 Frankfurt am Main, Germany.

³ Faculty of Earth Sciences, Shahrood University of Technology, Shahrud, Iran.

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

How to cite this article:

Sattari, E., Bahrami A., Königshof, P., Vaziri-Moghaddam, H., Taheri A., 2024, Biostratigraphy and facies around the D/C boundary interval of the Tuye-Darvar section, Eastern Alborz Range, NE Iran: Boletín de la Sociedad Geológica Mexicana, 76 (1), A280224. http://dx.doi.org/10.18268/BSGM2024v76n1a280224

Manuscript received: January 1, 2024; Corrected manuscript received: February 20, 2024; Manuscript accepted: February 29, 2024.

ABSTRACT

The 1st order mass extinction at the Devonian/Carboniferous transition, known as the Hangenberg Crisis, is characterized by major transgressive/regressive cycles which led to widespread ocean anoxia during the Hangenberg Black Shale Event, as well as to a global major sea-level fall and the worldwide deposition of regressive Hangenberg Sandstone equivalents. The Devonian/Carboniferous transition at the Tuye-Darvar section in the eastern Alborz Range is studied in terms of conodont biostratigraphy, litho-, microfacies and sequence stratigraphy. In order to examine the biostratigraphical framework, forty conodont samples were systematically taken from the studied interval. Thirty-two conodont species belonging to ten genera led to the discrimination of twelve conodont zones, ranging from the Pseudopolygnathus granulosus Zone to the Scaliognathus anchoralis-Doliognathus latus Zone. Due to facies, the conodont record also exhibits some hiatuses. Field observations and sedimentological and microfacies studies led to the identification of thirteen facies types from sub-tidal environments to the fully marine environments, including seven microfacies types. The sediments deposited in a mixed carbonate-siliciclastic platform, revealed four third-order sequences. The Hangenberg Black Shale is not recorded in the Tuye-Darvar section as a result of depositional facies.

In comparison with other studied Devonian/Carboniferous Boundary (DCB) sections of the central and northern Iran, the Tuye-Davar section suggests a tectonic position, which is most likely placed on a separate tectonic block.

Keywords: Mixed carbonate-siliciclastic platform, sequence stratigraphy, D/C boundary, conodont biostratigraphy.