Biostratigraphy, Microfacies, Sedimentary Environments and Sequence Stratigraphy of the Late Devonian–Carboniferous Deposits at the Anarak Section, Central Iran

Abstract

The Late Devonian–early Carboniferous deposits of the Anarak section in northeastern Isfahan, Central Iran, evaluated based on conodont biostratigraphy, sedimentary environment and sequence stratigraphy. According to the field observations, five lithological units were identified. Investigating the conodont fauna of the Late Devonian–Carboniferous (Mississippian–Pennsylvanian) deposits of Bahram, Shishtu, and Qaleh (Sardar 1) formations in Anarak section led to the identification of 67 species of 18 conodont genera, and accordingly 22 conodont biozones were differentiated. The correlation of sea-level change curves, regarding to the conodont biofacies with the global sea-level curve, demonstrates the relative correlation in the mentioned times due to the shallow condition of the central Iran basin compared to the European and American basins. The microfacies analysis led to the identification of 12 microfacies related to the open sea, bioclastic barrier, lagoon and tidal flat sub-sedimentary environments in a homoclinal carbonate ramp environment. Based on sequence stratigraphy studies, three 3rd order sequences were identified. The first sequence, which is of the Late Devonian (upper part of the Bahram Formation, 32.5 m), the second sequence (12.5 m) is the Late Devonian (uppermost part of the Bahram Formation), and the third sequence (68 m) is the early Carboniferous (the Shishtu I Formation). © 2023 Geological Society of China.